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The Dynamics of Ocean CurrentsThe ocean is a vast and complex system that plays a critical role in regulating the Earth's climate. One of the most important components of this system is ocean currents. These currents are driven by a variety of factors, including wind, temperature, and salinity, and they have a profound impact on everything from marine ecosystems to global weather patterns.At their most basic level, ocean currents are simply the movement of water within the ocean. But this movement is far from random. Instead, currents are shaped by a complex interplay of physical and environmental factors that create a dynamic and ever-changing system.One of the most significant drivers of ocean currents is the wind. As wind moves across the surface of the ocean, it creates friction that causes the water to move in the same direction. This creates surface currents, which can be seen as the movement of waves and the drift of floating objects.But wind is just one piece of the puzzle. Ocean currents are also influenced by temperature and salinity gradients. In areas where water is warmer or saltier than surrounding areas, it will tend to sink, creating a flow of water that can extend thousands of feet below the surface. This is known as a thermohaline current, and it plays a critical role in regulating the Earth's climate by transporting heat and nutrients around the globe.Another important factor in ocean currents is the Coriolis effect. This is a phenomenon that occurs because the Earth is rotating, causing objects that move across its surface to appear to veer off course. In the case of ocean currents, this effect causes water to move to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.All of these factors combine to create a complex and dynamic system of ocean currents that have a profound impact on the planet. For example, ocean currents play a critical role in regulating the Earth's climate by transporting heat from the equator to the poles. Theyalso help to distribute nutrients and oxygen throughout the ocean, supporting marine ecosystems and the many species that depend on them.But ocean currents are not static. They are constantly changing in response to a wide range of factors, including climate change, ocean acidification, and human activity. As the planet warms, for example, the melting of polar ice caps is altering the salinity of the ocean, which could have significant impacts on thermohaline currents and global climate patterns.In addition to these natural factors, human activity is also having a profound impact on ocean currents. Pollution, overfishing, and the destruction of marine habitats are all contributing to a decline in the health of the ocean, which could have significant consequences for the entire planet.In conclusion, the dynamics of ocean currents are a complex and ever-changing system that plays a critical role in regulating the Earth's climate and supporting marine ecosystems. They are shaped by a wide range of factors, including wind, temperature, salinity, and the Coriolis effect, and they have a profound impact on everything from global weather patterns to the health of marine life. As the planet continues to change, it is more important than ever to understand and protect these precious resources.。
高一英语气候科学研究进展练习题40题1.Climate change has led to more frequent extreme weather events. The word “extreme” in this sentence is a/an _____.A.nounB.adjectiveC.adverb答案：B。
“extreme”在这个句子中修饰“weather events”，是形容词，用来描述“天气事件”的性质。
A 选项“noun（名词）”错误，因为它在这里不是名词。
C 选项“adverb（副词）”错误，因为它没有以副词的形式在句子中出现。
2.Scientists are studying the impact of climate change. The word “impact” in this sentence is a/an _____.A.nounB.adjectiveC.adverb答案：A。
“impact”在这个句子中是名词，表示“影响”。
B 选项“adjective（ 形容词）”错误，因为它在这里不是形容词。
C 选项“adverb 副词）”错误，因为它没有以副词的形式在句子中出现。
3.The climate is becoming more and more unstable. The word “unstable” in this sentence is a/an _____.A.nounB.adjectiveC.adverb答案：B。
“unstable”在这个句子中修饰“climate”，是形容词，用来描述“气候”的状态。
A 选项“noun（名词）”错误，因为它在这里不是名词。
C 选项“adverb（副词）”错误，因为它没有以副词的形式在句子中出现。
4.The research on climate change is very important. The word “important” in this sentence is a/an _____.A.nounB.adjectiveC.adverb答案：B。
高一地理与气候变化英语阅读理解25题1<背景文章>Global warming is one of the most significant environmental issues of our time. The Earth's climate is changing at an alarming rate due to human activities. The main cause of global warming is the increase in greenhouse gases, such as carbon dioxide, methane, and nitrous oxide. These gases trap heat in the atmosphere and cause the Earth's temperature to rise.One of the major sources of greenhouse gases is the burning of fossil fuels, such as coal, oil, and gas. Power plants, factories, and vehicles all burn fossil fuels and release large amounts of greenhouse gases into the atmosphere. Another cause of global warming is deforestation. Trees absorb carbon dioxide and release oxygen. When forests are cut down, less carbon dioxide is absorbed, and more is left in the atmosphere.The effects of global warming are far-reaching. Rising temperatures can lead to more extreme weather events, such as heat waves, droughts, floods, and storms. Melting ice caps and glaciers can cause sea levels to rise, threatening coastal communities and low-lying islands. Changes in climate can also affect agriculture, wildlife, and human health.To address global warming, we need to take action on multiple fronts.We can reduce our carbon footprint by using energy-efficient appliances, driving less, and using public transportation. We can also support renewable energy sources, such as solar and wind power. In addition, we can plant trees and protect forests to help absorb carbon dioxide.1. The main cause of global warming is ___.A. deforestationB. the increase in greenhouse gasesC. natural disastersD. overpopulation答案：B。
高二英语气候经济学视角练习题20题1.The impact of climate change on the economy is _____.A.neglectableB.negligibleC.noticeableD.unnoticeable答案：C。
“noticeable”表示“显而易见的”，气候变化对经济的影响是明显的。
“neglectable”表示“可忽略的”，与实际不符；“negligible”也有“可忽略的”意思；“unnoticeable”是“不引人注意的”，不符合实际情况。
2.Climate economics focuses on the relationship between climate and _____.A.economical situationB.economic conditionC.economyD.economics答案：C。
“economy”表示“经济”，气候经济学关注气候和经济之间的关系。
“economical situation”是“经济形势”；“economic condition”是“经济状况”；“economics”是“经济学”，意思不准确。
3.The measures to reduce carbon emissions are _____ for sustainable economic development.A.essentialB.unnecessaryC.optionalD.inessential答案：A。
“essential”表示“必要的”，减少碳排放的措施对可持续经济发展是必要的。
“unnecessary”是“不必要的”；“optional”是“可选择的”；“inessential”是“非必要的”，都不符合题意。
4.Climate change poses a great threat to global _____.A.economic stabilityB.economical stabilityC.economic unstableD.economical unstable答案：A。
Understanding UK & IrelandKey to Chapter 9 A General Survey of UKI. 1.T 2. F 3. F 4. TII. 5. C 6. D 7. BIII. 8.C 9. B 10. AIV.a11. What are the four regions of Britain?The four regions of Britain are England, Scotland, Wales and Northern Ireland. England is the largest of the four with an area of 130,000 square kilometers，making up the south and east, which takes up nearly 60% of the British Isles. It is the most populous and richest section of the country.12. What kind of geographical position doesBritain have?Britain is an island country. It lies in the NorthAtlantic Ocean off the north coast of Europe.It is separated from the rest of Europe by theEnglish Channel in the south and the NorthSea in the east.13. Which places in Great Britain are mostlyhighland and lowland？The north and west of Britain are mainlyhighland，while the south and south-east aremostly lowlands.14. Does Britain have a favorable climate?Yes，it has a favorable climate，because ithas a maritime type of climate ——winters aremild，not too cold and summers are cool，nottoo hot. It has a steady reliable rainfallthroughout the whole year. It has a smallrange of temperature，too.15. What are the factors which influence theclimate in Britain? Which part of Britain hasthe most rainfall and which part is the driest?The factors which influence the climate inBritain are the following three：1) The surrounding waters balance theseasonal differences；2) The prevailing south-west winds bringwarm and wet air in winter and keep the temperatures moderate；3) The North Atlantic Drift ，a warm current，passes the western coast of the British Isles and warms them.The northwestern part has the most rainfall，while the south-eastern corner is the driest. Key to Chapter 10Geography & History of UK◆Key to Section ExercisesSection A. GeographyI. 1.F 2.F 3.TII. 4.A 5.B 6.A 7.D 8.A 9.C 10.ASection B．HistoryI. 1.T 2.T 3.T 4.F 5.TII. 6.D 7.B 8.B 9.B 10.C◆Key to Chapter ExercisesI. 1. T 2. F 3.F 4.T 5.FII. 6. A 7. D 8.D 9.D 10.BIII.11. The total area of Britain is about244,110 square kilometers.12. Britain is separated from the European continent by North Sea, Strait of Doverand English Channel.13. The capital of the Scotland is 1) Edinburgh, the capital of Wales is2) Cardiff and the capital of Northern Ireland is 3) Belfast.14.England is the largest and most populous of the three political divisions on the island of Great Britain.15. The first steam engine was devised by Thomas Newcomer at the end of the 17th century, and the Scottish inventor James Watt modified and improved the design in 1765.IV.16. The Hundred Years' War: it refers to thewar between England and France that lasted intermittently from 1337 to 1453. The causes of the war were partly territorial and partly economic. The territorial causes were related with the possession by the English kings of the large duchy in France. The economic causes were connected with cloth manufacturing towns in Flanders. Besides, England's desire to stop France from giving aid to Scots and a growing sense of nationalism were the other causes.17. The Lowland Zone: the island of Great Britain can be divided into two major natural regions—the lowland area and the highland area. The north and west of Britain are mainly highlands; and the east and southeast are mostly lowlands. The lowland zone has a milder climate and better soils for farming. Historically, most people in Britain have lived in the lowland zone rather than in the harsher highland zone. The lowland area comprises Midland, southern and eastern England.18. Norman Conquest of 1066: In January 1066, King Edward, the last Saxon king, died childless. He had promised to leave the English throne to his cousin William, but he chose Harold, his wife’s brother as king. So William led his army to invade England. In October 1066, during the important battle of Hastings, William defeated Harold and killed him. One Christmas Day, William was crowned king of England, thus beginning the Norman Conquest of England. The Norman Conquest of 1066 is perhaps the best-known event in English history.19. Industrial Revolution: The industrial Revolution refers to the mechanization of industry and the consequent changes in social and economic organization in Britain in the late 18th and early 19th centuries.The Industrial Revolution forever transformedthe way people live and work in most parts ofthe world. It changed the world so much thatpeople called it a revolution.Typical inventions during the IndustrialRevolution:John Kay’s flying shuttle in 1733;James Hargreaves’ Spinning Jenny in 1766;Richard Arkwright’s water frame in 1769;Edmund Cartwright’s power looms in 1784;James Watt’s steam engine in 1765.20. The Chartist Movement: Chartism was oneof the major popular reform movements of the Victorian era. The Chartists sponsored aPeople’s Charter demanding suffrage for allmale citizens over age 21, a secret ballot, andother rights. Chartist leaders are shown here addressing a large crowd in 1848. Most oftheir demands eventually became law.The Reform Bill of 1832 was the firstsuccessful attempt to correct these inequities.In 1836, a group of skilled workers and small shopkeepers formed the London WorkingMen’s Association. They drew up a charter ofpolitical demands (a People’s Charter) in 1838,with the intention of presenting it toParliament. It had six points: 1)the vote for alladult males; 2)voting by secret ballot;3)equal electoral districts; 4)abolition ofproperty qualifications for members ofParliament; 5)payment of members ofParliament; 6)annual Parliaments, with aGeneral Election every June.Key to Chapter 11Political System & National Economy of UK ◆Key to Section ExercisesA．Political SystemI. 1.F 2.F 3.T 4.F 5.TII. 6.A 7.B 8.D 9.BIII. 1０．1)-e 2)-a 3)-dB．National EconomyI. 1.T 2.F 3.TII. 4.A 5.D 6.B 7.B 8.B 9.AIII. 1０．1)-ｂ2)- d 3)- e◆Key to Chapter ExercisesI．1. The British were the first in the world to enter the Industrial Revolution.2. The main textile producing regions of Britain are the East Midlands, Yorkshire, Humberside, and Northern Ireland.3. An industrial complex in suburban Glasgow dubbed "Silicon Glen" is the center of Scotland’s thriving technology industry.4. Historically, the financial services industry has been based in the city of London in an area called the Square Mile.5. The Bank of England, chartered in 1694, was nationalized in 1946 and is the only bank that issues banknotes in England and Wales.6. The predecessor of the English parliament is the Great council.7. There are three political divisions on the island of Great Britain.8. In the UK, the party which wins the second largest number of seats in the House becomes the Opposition, with is one leader, and forms a Shadow cabinet.9. The Tories were the forerunners of the Conservative Party.10. In the United Kingdom, the party which wins the second number of seats in the House of Commons becomes the official Opposition. II．11. Constitutional monarchy：Constitutional monarchy means that the power of the monarch is limited by the country’s constitution, the legal authority is given to Parliament, and the executive authority to thegovernment. Theoretically, the Queen has the power，but in reality , she has no power at all. The Sovereign reigns, but does not rule; the country is governed, in the name of the Sovereign, by His or Her Majesty’s Government, who is responsible to the Parliament.12. Primogeniture: Primogeniture refers tothe passing of the throne to the eldest son when a monarch dies, has been the rule of succession, and when there are no sons, the eldest daughter ascends the throne.13. First past the post:The current voting system in UK is called “first past the pos t.” This means that the party and candidates receiving the most votes win the election and become the party in power even if they do not receive more than 50 percent ofthe vote.14. The Conservative Party and the Labor Party: The Conservative Party developed outof the Tory Party(托利党). It supports private enterprise and is opposed to nationalization （国有化）and extending social services. It openly helps the monopolists to getsuper-profits.The Labor Party was founded in 1900 by a union between the Trade Union, the Independent party and the Fabian Society. It practices social democracy or bourgeois reformism.15. High Street Banks: High Street Banks are the main banks, such as Royal Bank of Scotland, HSBC, NatWest, Citibank, and Barclays.III.16. What is a general election?The election of all Members of Parliament (MPs) for each constituency (local area) is called aGeneral Election. In the US it is like voting fora Congressman or Senator. However, unlike the US, the voters do not choose the Prime Minister (PM). He/she is voted for within their party.17. What is the supreme legislative authorityin Britain? What does it consists of?British Parliament is the supreme legislative authority in the realm. It consists of the Sovereign, the House of Lords（上院）and the House of Commons（下院）. Most of the power of Parliament is in the House of Commons. The Parliament was called in 1264 and is generally considered the beginning of “parliament”.18. What are the three areas in Britain which have seen some high-tech industrial growth? The three areas in Britain which have seen some high-tech industrial growth are:1)the area between London and South Wales,2)the Cambridge area of East Anglia and 3)the area between Glasgow and Edinburgh in Scotland. The third area is the most spectacular of the three and is now often referred to as the “Silicon Glen”.19. What is the British government’s role inthe economy?Like many modern developed countries, the United Kingdom has a mixed economy. This means that some sectors of the economy are operated by the government and some are operated by private businesses.After World War II, the government nationalized a number of large and troubled industries including coal, electricity, transport, gas, oil, steel, certain car and truck manufacturing, shipbuilding, and aircraft building. Since the 1950s, the governmenthas privatized a number of these industries. The Conservative governments between 1979and 1996 denationalized oil companies, telecommunications, car and truck production, gas, airlines and aircraft building, electricity, water, railways, and nuclear power. The government also seeks to encourage competition in the economy and increase productivity by sponsoring and subsidizing training and educational programs.20. How did the structure of British industry change in the last half of the 20th century? The coal mining and cotton textile industries declined sharply. As coal production declined, oil production replaced it as a major industry. Motor vehicle production became a significant part of the industrial base but was subject to severe foreign competition. As incomes increased, consumer demand rose for durable goods such as cars and kitchen appliances. British industrial production also expanded into communications equipment, including fiber optics, computers, computer-controlled machine tools, and robots.Key to Chapter 12Society & Culture of UK◆Key to Section ExercisesSection 1 British People & Their Ways of Life I. 1.T 2.T 3.F 4.FII. 5.A 6.D 7.B 8.-c 9.-a) 10.-dSection 2 Holidays and Special DaysI. 1.T 2.F 3.TII. 4. C 5. B 6.C 7.-c 8.-d 9.-a 10.-bSection 3 EducationI. 1.T 2.F 3.T 4.FII. 5.C 6.A 7.AII. 8.-f 9.-e 10.-aSection 4 English LiteratureI. 1.F 2.T 3.T 4.FII. 5.C 6.D 7.AIII. 8. 1)-b 2)-a 3)-dIV. Gap-filling9. Romance is the most popular literary form in the medieval period.10. The Romantic Movement appeared on the literary arena of England from the publication of Lyrical Ballads by Wordsworth and Samuel Coleridge in 1798 to the deathof Sir Walter Scott in 1832. The literary form which is the most flourishing during the Romantic Period is poetry.11. Samuel Richardson was the master of writing epistolary novels and the first novelist of sentimentalism tradition. His novels have a moral purpose, trying to inculcate virtue and good deportment. Pamela was his best novel.12. W. M. Thackeray was another representative of critical realism in 19th England. In 1847 he published his masterpiece Vanity Fair with a subtitle “a Novel without a Hero”.13.Hamlet, Othello, King Lear, and Macbeth are considered as Shakespeare's four greatest tragedies.V.1. Spenserian stanzaA nine-line verse stanza originated by Edmund Spenser is known as the Spenserian stanza. In the nine-line Spenserian stanza the first eight lines are iambic pentameter and the ninth, iambic hexameter, with the rhyme scheme being ababbcbcc. This form of stanza creates a special musical effect and contributes greatly to the technique of poetry composition.2. Stream of ConsciousnessIt is a literary technique in which a character’s thoughts are presented in the confusing, jumbled, and inconsequential manner of real life without any clarificationby the author. The aim of the technique is toprovide a textual equivalent to the stream ofa fictional character’s consciousness. Itcreates the impression that the reader is eavesdropping on the flow of conscious experience in the character’s mind, gainingintimate access to their private “thoughts”.James Joyce and Virginia Woolf are mastersof this literary technique.Key to Chapter 13 Understanding Ireland ◆Key to Section ExercisesSection 1 A General SurveyI. 1.F 2.T 3.TII. 4.B 5.A 6.A 7.DII. 8.-d 9.-a 10.-bSection 2 Geography and HistoryI. 1.F 2.T 3.FII. 4.C 5.B 6.A 7.DII. 8.-b 9.-a 10.-cSection 3Political System and National EconomyI. 1.F 2.T 3.TII. 4.B 5.D 6.C 7.AII. 8.-d 9.-a 10.-cSection 4 Society and Culture of IrelandI. 1.T 2.F 3.TII. 4.B 5.A 6.D 7.CII. 8.-c 9.-e 10.-b◆Key to Chapter Exercises1. Ireland means "Eire land". Eire is the Irishname for the country and is believed tomean "western land".2. Originally founded as a centre for theViking slave trade, Dublin has been Ireland's capital city since medieval times.3. In 432, St. Patrick arrives in Ireland and confronts King Laoghaire who allows him tospread the word of Christianity in Ireland.4. In 1914, the implementation of home rulebill is postponed because of the outbreak ofWorld War I.5. The state operates under the Constitution of Ireland, adopted in 1937. The constitution may only be amended by referendum.6. The population within the administrative area controlled by Dublin City Council was 505,739 at cork the census of 2006. A person from Dublin is known as a Dubliner or a Dub. is the country’s secondlargest city and major port. English is the main language used in Ireland (spoken with an Irish accent). The traditional Gaelic language is spoken mainly in areas along the west coast of Ireland. The major religions of Ireland are Roman Catholic and Protestant. The Republic of Ireland's flag is made of three equal-sized rectangles of orange, white, and green. The green color on the flag represents the native people of Ireland, most are the native people of Ireland.7. Two popular national sports in Ireland probably are: Gaelic football and hurling, both strictly amateur sports. Soccer has become a particularly popular spectator sport in the 1990s. Besides, rugby, sailing, cycling, golf, and horse and greyhound racing are also favorite activities.8. Major public holidays observed in the Republic of Ireland include: New Year's Day, St Patrick's Day, Easter Monday, Labor Day（May Day）and Christmas Day, among which St Patrick’s Day honors the patron saint of Ireland and Labor Day was newly introduced in 1994.9. The Republic of Ireland's education system is quite similar to that of most other western countries. There are three distinct levels of education in Ireland: primary, secondary and higher.10. Ireland's most widely-known literary works are undoubtedly in English. Particularly famous examples of such works are those of James Joyce, Oscar Wilde, and Ireland's four winners of the Nobel Prize for Literature: William Butler Yeats, George Bernard Shaw, Samuel Beckett and Seamus Heaney.II. Terms Explanation1. The River ShannonThe River Shannon is the longest river in Ireland, rising in northwestern County Cavan and flowing for about 259 km in a southerly direction to enter the Atlantic Ocean via a 113-kilometre estuary below. It drains an area of 15,695 square km. Dividing Ireland almost in two and dominating the midlands landscape, the River Shannon has acted as a formidable barrier to movement from East to West while providing a marine highway from North to South. It is the longest river in both Ireland and Britain, and has influenced the military, social and economic history of Ireland since the beginning of time. Traveling over 300 km. from its source to the sea, it is home to over a dozen lakes and more than a hundred islands. It is joined on its journey by dozens of smaller rivers and streams some of which are also navigable. The River Shannon is now the backbone of a vast network of inland waterways, joined to the Erne via the newly restored Shannon-Erne link.2. The Irish Free StateIn 1921 a treaty between southern Ireland and Britain established the Irish Free State, a self-governing dominion within the British Commonwealth of Nations. This allowed the Northern Ireland Parliament to take the six northern counties out of the dominion. Inthe Free State it led quickly to a vicious civil war between both sides; those who agreed with the Treaty, and those who disagreed, but ultimately the treaty stood.3. ShamrockAccording to the legend, the shamrock was used by St. Patrick, the patron saint of Ireland, in the fifth century to demonstrate the meaning of the Trinity when converting the Celts to Christianity. To this day it remains one of Ireland's most famous national emblems.4. George Bernard ShawIrish-born British playwright. A founder of the Fabian Society, he wrote plays of iconoclastic social criticism, including Arms and the Man (1894), Pygmalion (1913), and Saint Joan (1923). He won the 1925 Nobel Prize for literature.5. The Supreme CourtThe final court of appeal is the Supreme Court, which consists of the Chief Justice and seven other justices. The Supreme Court has the power of judicial review and may declare to be invalid both laws and acts of the state which are repugnant to the constitution.III. Answer the Following Questions1. What kind of holiday is St Patrick's Day? Saint Patrick’s Day (March 17), which honors the patron saint of Ireland, is the most important national holiday and is marked by parades, shamrock decorations, Irish songs and jigs and sometimes the wearing of green (the national color) to represent the lushness of Ireland - The Emerald Isle. Today St. Patrick's Day is celebrated by the Irish as well as many Americans, Canadians and English people.2. What is the origin of the Irish nationalanthem “The Soldier's Song”?The Soldier's Song was written in 1907 by Peadar Kearney, but was not widely known until it was sung both at the General Post Office during the Easter Rising in 1916 and later at various camps where republicans were interned. Soon after, it was adopted as the national anthem, replacing God Save Ireland.3. What is “the Potato Famine”?The potato crops of the 1840s failed and a devastating famine resulted. The English government were so slow to react to the crisis that by the time the famine was over, an estimated one million people had died, and a further one million had left Ireland, arriving in the US and Britain, penniless and desperate. The Irish potato famine created a legacy of emigration from Ireland that did not stop until the late 20th Century. By 1960, the population of Ireland had dwindled to 4.3 million from an 1841 population of over eight million.4. What do Protestant groups in Ireland include?Protestant groups include the Church of Ireland (Anglican) and the Presbyterian and Methodist denominations.5. How much do you know about James Joyce?The novels and short stories of James Joyce are distinguished by their keen psychological insight and use of literary innovations, most notably the stream of consciousness technique. The stories in Dubliners, his only collection of short fiction, are generally regarded as models of the genre. His works include Ulysses (1922) and Finnegans Wake (1939).。
Seasons are the natural divisions of the year based on the position of the Earth in relation to the Sun.Each season brings its own unique characteristics and experiences, and they are a source of inspiration for many writers and poets.Here is a detailed essay on the seasons in English:IntroductionThe Earths rotation and revolution around the Sun create the phenomenon of seasons.As the Earth tilts on its axis,different parts of the planet receive varying amounts of sunlight, leading to the distinct seasonal changes we experience throughout the year.SpringSpring is the season of rebirth and renewal.It marks the transition from the cold of winter to the warmth of summer.The days become longer,and the temperatures begin to rise, melting the snow and ice.Flowers start to bloom,and trees sprout new leaves,painting the landscape in vibrant hues of green,pink,and yellow.In spring,animals that hibernated during the winter awaken and begin their mating rituals. Birds return from their southern migrations,filling the air with their melodic songs. People often take this time to clean their homes,plant gardens,and enjoy outdoor activities after the long winter months.SummerSummer is the season of warmth and growth.It is characterized by long,sunny days and high temperatures.This is the time when many fruits and vegetables ripen,and farmers work hard to harvest their crops.The warm weather also encourages outdoor activities such as swimming,hiking,and picnicking.Summer is also a popular time for vacations and travel.Families often plan trips to the beach or mountains to escape the heat and enjoy leisure time together.However,with the increased heat,summer can also bring challenges such as droughts and heatwaves,which can affect both human and natural ecosystems.AutumnAutumn,also known as fall,is the season of change and preparation for the coming winter.The days become shorter,and the temperatures start to drop.The most striking feature of autumn is the transformation of leaves,which turn from green to shades of red,orange,and yellow before falling to the ground.Autumn is a time of harvest,with many crops being gathered in preparation for the winter months.It is also a season of festivals and celebrations,such as Halloween in the United States and Thanksgiving in Canada and the United States.The cooler weather and changing scenery make autumn a favorite season for many people.WinterWinter is the season of cold and rest.The days are short,and the nights are long,with the Earths axis tilted away from the Sun.In many parts of the world,winter is marked by snowfall and freezing temperatures,which can make outdoor activities more challenging.During winter,many animals hibernate or migrate to warmer climates.Humans often spend more time indoors,engaging in activities such as reading,crafting,and enjoying the warmth of a fire.Winter sports,such as skiing and ice skating,become popular as people take advantage of the cold weather.ConclusionEach season offers its own unique beauty and experiences.They are an integral part of the Earths natural cycle and have a profound impact on the environment,agriculture,and human activities.Appreciating the changes that each season brings can enrich our understanding of the world and inspire us to live in harmony with nature.。
关于气候研究的英文研究文章以下是一篇关于气候研究的英文研究文章的示例：Title: The Influence of Climate Change on Ecosystem Dynamics in a Tropical RainforestAbstract:Climate change is a major global issue that has far-reaching impacts on various aspects of the environment, including ecosystems. This study aims to investigate the influence of climate change on ecosystem dynamics in a tropical rainforest. Data from weather stations and ecological surveys were analyzed to identify patterns and changes in temperature, precipitation, and vegetation over a 20-year period.Results indicate a significant increase in average annual temperature (+0.8°C) and a decrease in annual precipitation (-10%) over the study period. These changes have had noticeable effects on the dynamics of the tropical rainforest ecosystem. Vegetation composition analysis shows a shift towards drought-resistant species and a decline in species diversity. The tree growth rate has also slowed, suggesting decreased productivity in response to changing climate conditions.Furthermore, the study found that extreme weather events, such as heatwaves and heavy rains, have become more frequent and intense. This has resulted in increased forest mortality, as well as changes in the distribution and abundance of certain plant and animal species within the ecosystem. These findings support the hypothesis that climate change is impacting the stability andresilience of the tropical rainforest.The implications of these findings are significant for conservation and management efforts in tropical rainforests. Strategies for preserving biodiversity and promoting ecosystem resilience should consider the projected impacts of climate change. Additionally, further research is needed to understand the long-term effects of climate change on ecosystem dynamics and to develop effective adaptation strategies.Keywords: climate change, tropical rainforest, ecosystem dynamics, temperature, precipitation, vegetation composition, species diversity, tree growth rate, extreme weather events. Introduction:Climate change is an unprecedented challenge facing the Earth's ecosystems. The Intergovernmental Panel on Climate Change (IPCC) has reported that human activities, particularly the emission of greenhouse gases, are driving global warming and altering regional climates. The consequences of climate change are evident in both natural and human systems, and ecosystems are particularly vulnerable to these changes.Tropical rainforests are among the most diverse and complex ecosystems on the planet, providing habitat for millions of plant and animal species. However, the impacts of climate change on tropical rainforests are not well understood. This study aims to fill this research gap by investigating the influence of climate change on ecosystem dynamics in a tropical rainforest.Methods:Data from weather stations located within the study area were collected and analyzed to examine long-term trends in temperature and precipitation. Additionally, ecological surveys were conducted to assess changes in vegetation composition and species diversity. Tree growth rates were measured through dendrochronology analysis.Results:The analysis of climate data revealed a significant increase in average annual temperature (+0.8°C) and a decrease in annual precipitation (-10%) over the 20-year study period. Vegetation composition analysis showed a shift towards drought-resistant species and a decline in species diversity. Tree growth rates have also decreased, indicating reduced productivity in response to changing climate conditions.Discussion:The observed changes in temperature and precipitation have direct and indirect effects on the tropical rainforest ecosystem. Higher temperatures and reduced precipitation are likely to result in increased water stress for vegetation, leading to changes in species composition and reduced productivity. Extreme weather events, such as heatwaves and heavy rains, have become more frequent and intense, further impacting forest dynamics.Conclusion:This study provides evidence of the significant influence of climate change on tropical rainforest ecosystems. By understanding these dynamics, conservationists and policymakers can developstrategies to mitigate the impacts of climate change and promote the resilience of these valuable and fragile ecosystems. Further research is required to assess the long-term effects and potential adaptation strategies for tropical rainforests facing ongoing climate change challenges.Acknowledgements:The authors would like to acknowledge the funding support provided by the XYZ Foundation for this research project. We are also grateful to the staff at the weather stations for their assistance with data collection and analysis.References:[List of relevant references according to citation style guidelines.]。
小学上册英语第3单元真题试卷(有答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.Which of these is a type of fish?A. EagleB. SalmonC. LizardD. Mouse答案: B2.My grandpa tells me __________ (关于战争的故事).3.What do you call the person who manages a restaurant?A. ChefB. ManagerC. WaiterD. Host答案: B4.The _______ (鸟) sings sweetly in the morning.5.Did you hear the _____ (小鸟) singing in the morning?6.The butterfly has beautiful ______.7.He plays the ______ very well. (guitar)8.Plants can create ______ (栖息地) for wildlife.9.The __________ was a social and political movement in the 1960s.10.The __________ is the imaginary line that circles the Earth halfway between the poles.11.The cake is _____ with icing. (covered)12.The _____ (花卉市场) sells a variety of plants and flowers.13.I think it’s important to ________ (学习新事物).14.The chemical formula for aluminum sulfate is _______.15. A ____ is often used in research and is very curious.16.The train goes _____ (fast/slow) on the tracks.17.green initiatives) promote sustainability in cities. The ____18.We will go _____ tomorrow. (shopping)19.What do you call the middle of the Earth?A. CrustB. MantleC. CoreD. Shell答案: C20.I like to ________ with my friends.21.The __________ (历史的学习) informs citizenship.22.What do we call a baby cat?A. PuppyB. KittenC. CubD. Calf答案: B23.My brother has a ______ (new) bike.24.The chemical symbol for potassium is ______.25.My brother loves to read ____.26.The dog is barking ________.27.She is an athlete, ______ (她是一位运动员), and runs fast.28.The _______ (鸽子) flies in the park.29.What is the smallest planet in our solar system?A. VenusB. EarthC. MarsD. Mercury答案:D30.My dad is a ________ (工程师).31.What is the name of the activity where you run a race?A. CompetitionB. MarathonC. GameD. Meet答案: B32.The dog is ________ the ball.33. A __________ is a substance that cannot be broken down into simpler substances.34.The ____ hops around and loves to chase things.35.What is the name of the famous scientist who developed the theory of relativity?A. Isaac NewtonB. Albert EinsteinC. Nikola TeslaD. Galileo Galilei 答案: B36.I like to ________ my friends.37.My cat loves to chase _______ (光点) from a flashlight.38.I enjoy ________ (玩) video games.39.The ______ is a common pet that barks.40.The _______ can help create a relaxing environment.41.My mom loves to __________ (分享) her knowledge.42.He runs very ________.43. A ______ is a type of animal that swims in the ocean.44.What instrument do you play to create music?A. BookB. GuitarC. ChairD. Table答案:B45.What do you call the study of ancient civilizations?A. ArchaeologyB. AnthropologyC. SociologyD. History答案:A46.She is _______ (smiling) at the camera.47.The __________ (历史的准确性) is paramount.48.The process of evaporation involves heat and ______.49.The _____ (山) is covered with green trees and shrubs.50.The chemical formula for ethylene glycol is ______.51.What do we call the seasonal migration of animals?A. HibernationB. MigrationC. MatingD. Feeding答案: B52.The stars are ______ (shining) brightly.53.My dad loves to play ____ (cricket) with friends.54.I love _______ (玩游戏) with my friends.55. A ______ is a bird that swims well.56.ers open up at _____ (早晨). Some flo57. A _______ is a reaction that produces a gas as a product.58.The owl has big _________. (眼睛)59.Ancient Greece is known for its contributions to ________ (哲学).60.The ________ (植物适应性) is impressive.61. A chemical that can accept hydrogen ions is called a ______.62.Gardening can be a wonderful way to foster a deeper appreciation for ______. (园艺是培养对自然更深刻欣赏的绝佳方式。
小学上册英语第六单元测验卷(有答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The bird has bright _______ (鸟有鲜艳的_______).2.The cat is ___ (climbing) the shelf.3.The first human to reach the North Pole was ______ (阿蒙森).4.The __________ (城市与乡村) have different lifestyles.5.She is _______ (非常聪明).6. A ____ is a gentle creature that enjoys being around people.7. A ____ hops around and has big ears.8._______ can help clean the air.9.My sister plays ________ with her friends.10.I have a ________ for my birthday.11.This ________ (玩具) inspires me to be creative.12.I help my sister with her __________. (画画)13.I see a ___ (cloud/rainbow) above.14.The bobcat is a skilled _______ (猎手).15.The __________ (历史的叙述模式) shape our perceptions.16.She is ___ (laughing/sobbing) at the movie.17.The _____ (avocado) is creamy.18.What color do you get when you mix red and white?A. PinkB. PurpleC. OrangeD. Brown答案: A. Pink19.What do you call the sound made by a cat?A. BarkB. MeowC. RoarD. Tweet答案: B20.The _______ (金鱼) can come in various colors.21.The capital of Kyrgyzstan is __________.22.My ________ (姑姑) is getting married next month.23.My pet _____ loves to chase its tail.24.The _______ of an object can change based on its position.25.Electricity can create a ______.26. A _______ is a reaction that occurs in the atmosphere.27.I have a toy _______ that can make me smile.28.Which instrument has keys?A. GuitarB. ViolinC. PianoD. Drums答案: C29.The ______ has a unique call.30.The flower needs sunlight and ______.31.The chemical formula for glucose is ______.32.What do you call the act of watching something closely?A. ObservingB. ViewingC. GazingD. Glancing答案: A33. A reaction involving the transfer of electrons is called a ______ reaction.34.My cousin is a __________ (演员).35.The __________ (历史故事) can inspire future generations.36.The ______ (绿色技术) often utilizes plant resources.37.My dog loves to play with a ______ (球).38.My favorite sport is ______ (美式足球).39. A ________ (植物观察活动) encourages interest in nature.40. (Japanese) feudal system included samurai warriors. The ____41.The capital of Nepal is _____.42.The __________ (全球视野) broadens perspectives.43.We can ___ a movie night. (have)44.The flower pot is colorful and ______.45.Eclipses occur due to the alignment of the sun, moon, and ______.46.My _____ (姑姑) has a lovely collection of flower pots. 我姑姑有一个美丽的花盆收藏。
On the dynamics of the seasonal variation in the South ChinaSea throughflow transportJiayan Yang,1Xiaopei Lin,1,2and Dexing Wu2Received22August2013;revised12November2013;accepted13November2013;published16December2013.[1]The Luzon Strait transport(LST)of water mass from the Pacific Ocean to the SouthChina Sea(SCS)varies significantly with seasons.The mechanisms for this large variabilityare still not well understood.The steady-state island rule,which is derived from a steady-state model,is not applicable to seasonal time scale variations in a large basin like thePacific Ocean.In this paper,we will use a theoretical model that is based on the circulationintegral around the Philippines.The model relates the LST variability to changes in theboundary currents along the east coast of the Philippines,including the North EquatorialCurrent(NEC)Bifurcation Latitude(NECBL),the transports of Kuroshio and MindanaoCurrents(KC and MC),and to the local wind-stress forcing.Our result shows that anorthward shift of the NECBL,a weakening of the KC or a strengthening of the MC wouldenhance the LST into the SCS.This relationship between the LST and the NEC-KC-MC isconsistent with observations.The analytical result is tested by a set of idealized numericalsimulations.Citation:Yang,J.,X.Lin,and D.Wu(2013),On the dynamics of the seasonal variation in the South China Sea throughflow transport,J.Geophys.Res.Oceans,118,6854–6866,doi:10.1002/2013JC009367.1.Introduction[2]The South China Sea(SCS)is a large semienclosed marginal sea with several straits that are connected to the Pacific and Indian Oceans.The Luzon Strait is the deepest passage(>2000m in depth)through which there is a net westward transport from the Pacific Ocean into the SCS [Wyrtki,1961;Qu et al.,2000;Yaremchuk and Qu,2004; Tian et al.,2006].The transport into the SCS through the Luzon Strait is balanced by outflows to the East China Sea (ECS)through the Taiwan Strait(<200m in depth),to the Sulu Sea through the Mindoro Strait(<200m in depth)and to the Java Sea via the Karimata Strait(<100m in depth). This interbasinflow system,as schematized in Figure1a, forms a South China Sea Throughflow(SCSTF)and serves as an important route for Indo-Pacific exchanges[Qu et al., 2005;Yu et al.,2007;Yaremchuk et al.,2009].Many pre-vious studies showed that the intrusion of the Kuroshio water into the SCS is highly seasonal[Centurioni et al., 2004].Several mechanisms likely contribute to this season-ality,including local wind stress and its curl on both sides of Luzon Strait[e.g.,Farris and Wimbush,1996;Metzger and Hurlburt,2001;Jia and Chassignet,2011;Wu and Hsin,2012].In a recent study,Wu and Hsin[2012]argued that the northeasterly wind in winter forces a westward Ekman transport and contributes to a larger transport in winter.It was not clear whether the Ekman transport would enhance the net transport through the Strait.As we will show later in Figure6,an intrusion of the Kuroshio water is not necessarily the same as the net SCSTF transport—the integrated transport across the strait.[3]The Luzon Strait Transport(LST),which has been commonly used to measure the SCSTF,varies considerably with the seasons.It increases from as low as near0Sv in the summer to as high as5Sv in the late fall and the early winter according to Yaremchuk and Qu[2004].This large seasonal variability was also revealed by trajectories of satellite-tracked drifters[Centurioni et al.,2004]and moor-ing acoustic Doppler current profilers[Liang et al.,2008]. The dynamical underpinning for this seasonal variability remains not well understood.Previous studies[e.g.,Yarem-chuk and Qu,2004]indicated some coherences between seasonal variations in the LST and in boundary currents along the east coast of the Philippines.The goal of this study is to examine their dynamical linkage and to develop a better understanding of the leading mechanism for the seasonal variability of the LST.[4]The SCSTF is primarily wind driven and so the island rule[Godfrey,1989]has been used to examine both the mean transport and its interannual variability[Qu et al., 2000;Wang et al.,2006a,2006b].The original island rule is based on the steady Sverdrup dynamics in the open ocean.So it applies only to variations with periods that are considerably longer than the adjustment time scale of the wind-driven circulation in the vast open ocean to the east of the island.A baroclinic Rossby wave would take longer1Department of Physical Oceanography,Woods Hole OceanographicInstitution,Woods Hole,Massachusetts,USA.2Physical Oceanography Laboratory,Ocean University of China,Qing-dao,China.Corresponding author:J.Yang,Department of Physical Oceanography,Woods Hole Oceanographic Institution,Woods Hole,MA02543,USA.(jyang@)©2013.American Geophysical Union.All Rights Reserved.2169-9275/13/10.1002/2013JC009367JOURNAL OF GEOPHYSICAL RESEARCH:OCEANS,VOL.118,6854–6866,doi:10.1002/2013JC009367,2013than1year to propagate across the Pacific basin from the Central American coast to the east coast of the Philippines. Oceanic currents along the western boundary,including the LST,cannot be in equilibrium state with wind-stress forc-ing over the Pacific Ocean on the seasonal time scale[Qiu and Lukas,1996]and so the island rule is not suitable for studying the seasonal variability of the LST.Firing et al. [1999]extended the island rule to time-dependentflows.A main difference is the addition of a storage term that relates to the thermocline depth changes in the area to the east of the island.Additional information is needed to compute this time-dependent storage term.Furthermore,there is an uncertainty regarding whether the island rule,even in the time-dependent form,is applicable to the SCS where there are multiple passages,and therefore possibly multiple choices for integration contours in the island rule.Here we will derive a relationship that is based mainly on the momentum balance along the east coast of the Philippines between point A and point C in Figure1a.[5]The atmospheric circulation in the region is highly seasonal and closely tied to the Asian Monsoon(Figure2). The surface wind is predominantly northeasterly in the winter and reverses to southwesterly in the summer.The LTS variability is closely tied to variations in three major currents off the east coast of the Philippines,namely the Kuroshio and Mindanao Currents(KC and MC)along the coast and the North Equatorial Current(NEC)—a westward interior current that eventually impinges on the coast of the Philippines(Figure1a).The NEC,once it reaches the east coast of the Philippines,bifurcates to form the KC and MC—two western boundary currents(WBC)thatflow in opposite directions.The NEC bifurcation latitude (NECBL)varies seasonally between13 and15 N off the coast of the Philippines according to observations and model simulations.A descriptive relationship has been established between the LST variability and variations in the NEC-KC-MC[Yaremchuk and Qu,2004].In this paper, we seek to develop a simple model that can explain the essential dynamics in this linkage.[6]The remainder of the paper is organized as follows. In section2,we will review previous studies of seasonalvariations in the NEC-KC-MC along the east coast of the Philippines,the LST variability,and the local wind-stress forcing.In section3,we will compare results from a numerical simulation that uses a realistic wind stress and geometry with the island rule.In section4,we will formu-late a simple analytical model that links the LST to bound-ary currents and wind stress.Results from several idealized simulations will be used to test the analytical solution. Some further discussion and a brief summary will be given in section5.2.The LST and the Low-Latitude WBCs in the North Pacific Ocean[7]Direct measurements of the LST are scarce.So LST variability has been mainly estimated from geostrophic cal-culations from hydrographic data and/or from the sea sur-face height(SSH)measured by satellite altimeters. Numerical simulations,especially those with data-assimilation,add additional insights.The LST,according to previous studies,varies strongly with the seasons,strengthening in the fall and early winter and weakening in the summer.In a comprehensive analysis of both the sea surface height(altimetry)and hydrographic data,Yarem-chuk and Qu[2004]showed that the geostrophic transport through the Luzon Strait varies from as low as0–1Sv in August to as high as5Sv in December.This pattern of sea-sonal changes is consistent with trajectories of satellite-tracked drifts reported by Centurioni et al.[2004].[8]Along the east coast of the Philippines,theflow is strongly dominated by several major currents that include the NEC,KC,and MC.The latter two are formed when the NEC impinges on the east coast of the Philippines and bifurcates to two boundary currents,i.e.,the northward KC, and the southward MC[Nitani,1972].This low-latitude NEC-KC-MC current system varies considerably on both seasonal and interannual time scales[Toole et al.,1988, 1990;Qiu and Lukas,1996;Qu and Lukas,2003;Qiu and Chen,2010].It has been postulated that the seasonal vari-ability of the LST is influenced by variations in the NEC bifurcation latitude(NECBL)and transports of KC and MC[Yaremchuk and Qu,2004].In situobservations Figure 1.The bathymetry in the vicinity of the SCS (color in the top plot)with schematics of major currents in the region.The SCS Throughflow pathways are from Qu et al.[2005].(bottom)Schematic of the island rule integra-tion.In the classic island rule[Godfrey,1989],the transport around the island depends solely on the wind stress along the close line l5cfedc and the planetary vorticity differ-ence between the two extremities of the island, D f5f N2f S.indicate that the NECBL is located at about 13N [Toole et al .,1988,1990].But Qu and Lukas [2003]argued that the NECBL moves northward with depth and so the depth-averaged position should be located north of 13N.Yarem-chuk and Qu [2004]combined altimetry and hydrography data and showed that the NECBL moves southward to 13.8N in the summer and northward to 15.8N in the fall.They estimated that the mean position of NECBL is at 14.3N.This pattern of the seasonal movement was consist-ent with what was found earlier by Qu and Lukas [2003]who suggested that the NECBL is located in the southern-most latitude in July and the northernmost latitude in December.[9]In addition to the seasonal excursion of the NECBL,both the KC and MC vary considerably in their transports.The KC is weak in the fall while the MC transport is sea-sonally low in the summer.The annual mean transports are27.6and 30.1Sv,respectively,for KC and MC off the Philippines coast [Yaremchuk and Qu ,2004].The main seasonal variability of low-latitude WBCs along the Philip-pines coast is summarized as follows.The NECBL shifts northward and KC weakens in the fall.The NECBL moves southward and MC transport decreases in the summer.But we will like to point out that the KC and MC vary on sea-sonal and interannual time scales.There are considerable differences in previous estimates.3.The Island Rule and Seasonal Variation in the LST[10]The spin-up time scale of a wind-driven gyre in a large basin like the Pacific Ocean is typically longer than 1year.The premise of this study is that the island rule,which is derived from a steady state model,does not apply totheFigure 2.Surface wind stress in the vicinity of the South China Sea (the wind stress is from the monthly mean climatology product from the Objective Analyzed Flux Wind,OAFlux-Wind (L.Yu,http//:oafl).It is derived from a 21year daily product from 1988to 2008,an era with satel-lite wind stress observations.The surface wind is monsoonal and reverses its direction seasonally.seasonal variability of the LST.Here we will test this assump-tion by using a one-layer nonlinear and reduced-gravity model.The model is governed by the following equation:d ~u dt1f ~k 3~u 52g 0r h 1~s q h 1A H r 2~u @h@t1r Áh ~u ðÞ50(1)where h 5h 01h 0is the layer thickness (h 05400m),g ’50.0156ms 22is the reduced gravity and its value is chosen so that the shallow-water gravity wave speed C 5(g’h 0)1/252.5ms 21represents the first baroclinic mode.The model uses lateral mixing for the momentum dissipation with a viscosity A H 51000m 2s 21.A large vis-cosity is used so that the frictional Munk boundary layer can be better resolved in the model [Yang ,2003].The model uses a staggered C-grid.Two sets of experiments will be used,one with a realistic coastline and observation-based wind stress and the other with idealized forcing and model geometry.The idealized experiments will be intro-duced and discussed in section 4after the analytical model is presented.In this section,we will discuss the results from a simulation forced by a realistic wind stress.[11]The model extends from 20S to 45N with a resolu-tion of 1/4 .We use the wind stress from the monthly cli-matology from the Objectively Analyzed Flux-Wind (OAFlux-Wind)(L.Yu,http//:oafl).It is a cli-matology that was derived from a 21year daily product from 1988to 2008,an era with satellite wind stress obser-vations.Figure 2shows the OAFlux wind stress in Febru-ary,May,August,and November.The northern and southern boundaries are closed.[12]This simple reduced-gravity model,like other simi-lar ones in previous studies,is capable of simulating some basic features of basin-wide circulations,including the sub-tropical gyre and equatorial currents that are relevant to the LST.Here we will only discuss the transport through the Luzon Strait and flows around the Philippines.Figure 3shows the sea surface height (SSH)in August and Decem-ber—when the minimum and maximum LST transports occur as reported by Yaremchuk and Qu [2004].The monthly averaged transport is <0.1Sv in August and reaches 7.4Sv in December.The seasonal variability of the LST transport is shown in Figure 4a.The overall pattern of the seasonal variation in the LST is very similar to that derived from data [Yaremchuk and Qu ,2004,Figure 14in their paper]except that the amplitude is considerablylarger(a) Sea surface height (cm), Aug115E 120E 125E 130E 5N10N15N20N25N(b) Sea Surface Height, Dec115E 120E 125E 130E−20−16−12−8−40481216202428323640Figure 3.The sea surface height (SSH,unit:cm),in August and December,produced by a nonlinear and reduced-gravity model forced by the OAFlux-Wind (Figure 2).The transport is maximum in Decem-ber and minimum in August,and is consistent with an observation-based estimate.The seasonal move-ment of the phase of the NECBL movement is consistent with the observation that it moves to the northernmost position in fall and the southernmost latitude in summer.The extent of the seasonal move-ment of the NECBL is smaller than the observation,a model feature that was noted and explained by Qiu and Lukas [1996].in the model.Yaremchuk and Qu [2004]showed that LST varies from 0–1Sv in August to about 5Sv in December.But a more recent update from Yaremchuk et al .[2009]revised the seasonal variation that ranges from 1Sv in July to about 7Sv in January.So the magnitude of the model transport compares more favorably with the latter.[13]Is the island rule able to capture this seasonal vari-ability in the LST?Following Godfrey [1989],we integrate the linear version of the momentum equation (1)along a closed path l 5fedcf ,a thin black line shown in Figure 1b:@þlh ~u Ád ~l 1Q N f N 2Q S f S ðÞ5þl~s wind Ád ~l(2)[14]In a steady state,there is no convergence of massflux into the area bounded by l and so Q N 5Q S in (2).The time change of the circulation integral,the first term in (2),is also zero in a steady state.So equation (2),in a steady state,becomes:Q island 2rule 51þl~s wind Ád ~l (3)where Q island -rule 5Q N 5Q S in a steady state and D f 5f N 2f S .This is the original form of Godfrey’s island rule.When applied to the SCSTF,the integration is along a closed path l along the west coast of the Philippines,across the Pacific Ocean from the southern tip of the island,c in Figure 1a,to the eastern oceanic boundary,continuing along the eastern boundary to the latitude of the northern tip of the island (a in Figure 1a,which is also the southern boundary of the Luzon Strait),and zonally across the Pacific Ocean to the northern coast of the Philippines,and D f 5f N 2f S is the difference of the planetary vorticity f between a and c in Figure 1a.[15]Figure 4b shows the seasonal variability of the LST transport that is derived by the island rule (3)by using the same OAFlux wind stress as that applied in the numerical model shown in Figures 3and 4a.It varies from 215Sv in February to 22Sv in October.Both the phase and the amplitude are very different from the model result (Figure 4a)and also different from any observation-based estimates from previous studies [e.g.,Yaremchuk and Qu ,2004].Obviously the island rule does not apply to the LST on the seasonal time scale.[16]What can cause such a large difference between the numerical simulated result (Figure 4a)and the island rule estimate (Figure 4c)?Is it the nonlinearity that was neglected by Godfrey [1989]?Our analysis indicates that the nonlinear effect is small and not responsible for the dif-ference between Figures 4a and 4b.Another possibility is the friction along the oceanic eastern boundary and the northern,southern,and western coasts of the Philippines.Friction along these segments is ignored in the island rule.As discussed in previous studies [e.g.,Pedlosky et al .,1997;Pratt and Pedlosky ,1998;Wajsowicz ,1993],the friction only plays a small role unless the west coast of the island is close to the oceanic western boundary (in our application,it would be the Vietnamese and Chinese coasts)according to Pratt and Pedlosky [1998].Furthermore,the friction tends to reduce the transport not to change the phase of the tempo-ral variations.So it is very unlikely that the friction has played any role in the difference between the model and IR.Topographic effect or the bottom pressure torque is also neglected in IR.It may weaken transport substantially between the open ocean and the marginal sea.But in our recent analysis [Yang et al .,2013],the topographic barrier weakens near the equator.This may help explain why the island rule is able to give a reasonable estimate of the SCS throughflow transport in the mean state despite that it exits the SCS through shallow straits.[17]Figure 4c shows the seasonal variations of the KC and MC transports,indicating the transient forcing from theJanMarMayJulSepNovJan0.02.04.06.0 8.0(a) Modeled Throughflow transportT r a n s p o r t (S v )T r a n s p o r t (S v)T r a n s p o r t (S v )Figure 4.(top)Seasonal variation of the monthly mean LST (positive for the westward transport into the SCS in the northern strait).The variation is similar to the observation-based estimation [Yaremchuk and Qu ,2004;Yaremchuk et al .,2009].(middle)The seasonal transport computed from the Island Rule [Godfrey ,1989].It shows that the island rule does not apply to the LST on the sea-sonal time scale.The lower panel shows the transports of Kuroshio (black line)and Mindanao Current (red line).When the LST is strong in the fall,the Kuroshio is weak and the Mindanao is strong,and vice versa in the summer.ocean interior.One could use the time-dependent form of the island rule,i.e.,equation(2),for the seasonal variability of the LST.A similar form has been used by Firing et al. [1999]in their study of the Hawaiian Ridge Currents.But the most attractive feature in the island rule is its mathematical simplicity and its dynamical transparency.The transport into the area bounded by l is no longer nondivergent since the thermocline depth variation changes the upper-layer water volume within the area bounded by l.An additional model is needed for computing the thermocline depth changes.4.The Seasonal Variability in the LST and Its Relationship to the NEC-KC-MC and the Local Wind Stress[18]We have argued that the island rule,in either a steady or a time-dependent form,is not ideal for studying the dynam-ics that control the seasonal variability in the LST.A simple dynamical framework is still needed.Here we will try to for-mulate a dynamical relationship between the LST and the NEC-KC-MC.Observation-based analyses show that the NEC bifurcation and the partition of KC and MC transports vary seasonally.The bifurcation is displaced northward and the KC is weaker in the fall when the LST is strongest,and vice versa in the summer when the LST is weak.We will derive an analytical relationship based on a reduced-gravity model with Munk WBC layer dynamics.This will be followed by a set of idealized experiments to test the analytical solution.[19]Consider an idealized model that is schematized in Figure5.An idealized SCS is separated from the open ocean by an island,with a coast line l5ABCDE,that is meant to represent several islands of the Philippines.Two straits connect the SCS to the open ocean.The northern channel is for the Luzon Strait and all southern SCS pas-sages are collectively represented by one southern channel.A westward North Equatorial Current bifurcates at pointB and forms a northward Kuroshio and a southward Minda-nao Current.Transient adjustment for the pressure around the island involves fast Kelvin waves.The1st baroclinic mode Kelvin waves typically travel at a speed of2–3m/s and would take less than a month to propagate around an island that has the size of the Philippines.Follow Pratt and Pedlosky[1998]we can rewrite equation(1)as@~u@t1f1nðÞ~k3~u52r~uÁ~u21g0h1~s windh1~F(4)where h5h01h0is the layer thickness and~F is the friction. Now let’s integrate equation(4)around the island’s coast l5ABCDEA.Along a solid boundary thefirst term is zero due to the no-slip boundary condition and the second term is also zero due to the no-normalflow condition.The inte-gral of thefirst term on the right hand side around a closed path around the island(l5ABCDEA)is zero.So the inte-gral of equation(4)is simplified to:þl5ABCDEA~s windh1~FÁd~l50(5)[20]It is worth noting that we do not assume theflow is steady in this model.The change of the circulation around the island is zero due to the nonslip boundary condition.So the friction and the wind stress have to adjust to each other instantaneously.[21]Following the same argument made by Godfrey [1989]and Pedlosky et al.[1997],we assume that the fric-tion is important only along the island’s east coast ABCwhere a frictional western boundary layer exists,i.e.,Þl5ABCDEA~FÁd~l%Ðy5y Cy5yFdy.equation(5)becomes:þl5ABCDEA~s windhÁd~l1ðy5y Cy5yFdy50(6)4.1.The Roles of the NEC,KC,and MC[22]First,we would like to separate the local wind stress effect from the WBC dynamics.Here we assume that the local wind stress is negligible,and equation(6)becomesðy5y Cy5yFdy50(7)[23]Equation(7)indicates that the friction induced by the western boundary current cannot be unidirectional along the island’s east coast ABC.If the model uses the Stommel WBL,the friction has the form,~F52k~u(k is a linear drag coefficient)and(7)becomes:2kðy5y Cy5yv dy50(8a)[24]If the model uses the Munk WBL model,(which was used in our numerical model(1)),equation(7)becomes: Figure5.The schematic of our analytical model.ðy 5y Cy 5yA H @2v =@x 2dy 50(8b)[25]Note:The assumption that j @2v =@y 2j (j @2v =@x 2j is invalid within a narrow width of the NEC incidence at the wall.Within this width,v increases rapidly in the y direction.The overall scaling argument that the integrated friction is proportional to the WBC transport remains valid.[26]Either (8a)or (8b)requires that the velocity along the east coast of the island cannot be unidirectional.So the incoming NEC must bifurcate to two boundary currents with opposite directions,i.e.,the Kuroshio and Mindanao Currents.The velocity integral from the southern to the northern tip of the island must be zero.To be consistent with our numerical model,we will use the Munk WBL model in the following analyses.The result will remain−2.0−1.5−1.0 −0.5 0 0.5 1.0I n t e g r a l o f F r i c t i o n (m 2s −2)−40−32−24−16−80816243240Figure 6.(a)The SSH and velocity in the first idealized experiment using a nonlinear and reduced-gravity model.The model is forced by prescribed inflow and outflows.In this experiment,the forcing is symmetric,i.e.,a westward inflowing NEC is located at y 50,and two outflows with equal transport are specified on the northern and southern boundary,respectively.The throughflow transport is negligible (0.012Sv);(b)a similar experiment but with widened gaps.Sheremet [2001]showed that whether a WBC can leap over a gap depends on a ratio between the width of the gap and the Munk WBL width.This experiment shows that our result remains valid even if the WBCs cannot leap over the gaps and have to make detours within the marginal sea The net throughflow transport remains very small in this case (<0.1Sv);(c)a clockwise integration of the friction along the island’s boundary.It shows that the accumulative friction exerted by the northward WBC (from A to B)cancels that induced by the south-ward boundary current (B to C).The friction along the west coast (D to E)is negligible.Through this integral constraint,we can formulate a simple model that relates the throughflow transport to the strengths and lengths of the WBCs along the island’s east coast.qualitatively the same if we use the Stommel model.Equa-tion (8b)can be written as:ðy 5y By 5yA H @2v =@x 2dy 1ðy 5y By 5yA H @2v =@x 2dy 50(9)[27]The essence of equation (9)is that the total accumu-lated friction exerted by the Kuroshio along the island’s coast must exactly cancel that induced by the Mindanao Current.Equation (9)is derived from integration of the momentum equation around the island in a time-dependent,nonlinear and one-layer model.The basic dynamics can be better illuminated in terms of linear dynamics of boundary currents.In absence of a local wind-stress forcing,the zero-order dynamical balance along a boundary is:21qr p 1~FÁ~l 50(10)[28]As noted earlier,both the inertia and Coriolis force terms vanish along a boundary due to the nonslip and no-normal flow boundary conditions.The pressure gradient along the island’s west coast is zero due to the lack of a frictional boundary layer (any initial pressure gradient would be erased by Rossby-wave radiation).So the pres-sure must be the same between point E and point D in Fig-ure 5.One could make a similar argument regarding a northern or southern boundary layer and assume that the pressure is the same between A and E ,and between D and C .These are the same assumptions that were made in pre-vious studies of flows around an island [Pedlosky et al .,1997;Pratt and Pedlosky ,1998].With these assumptions,the pressure at A must be the same as that at C ,i.e.,p A 5p C .Integrating (10)from A to C yields:ðy 5y Cy 5y AFdy 51qp C 2p A ðÞ50[29]This is the same as equation (7).So the integrated friction from the southeastern tip of the island C to the northeastern corner A must be zero.In other words,the integrated friction induced by the Kuroshio Current along the island’s east coast must cancel exactly that inflicted by the Mindanao Current.[30]In the Munk (or Stommel)WBL model,the friction is therefore proportional to the magnitude or the transport ofthe boundary current,i.e.,Ðy 5y2y 5y A H @2v =@x 2d y /Q y 22y 1ðÞ(where Q is the WBC transport).The WBC transport Q off the coast of the Philippines between the NECBL and the Luzon Strait consists of two parts,the Kuroshio Current transport due to the subtropical gyre in the Pacific Ocean Q K and the SCSTF transport through the Luzon Strait Q L ,i.e.,Q 5Q K 1Q L .Similarly,the WBC transport south of the NECBL can be decomposed to Q 5Q M 2Q L ,where Q M is the WBC transport associated with the North Pacific tropical gyre.With these notations,equation (9)becomes:y A 2y B ðÞQ K 1Q L ðÞ5y B 2y C ðÞQ M 2Q L ðÞ(11)[31]Let’s assume the total meridional length of the island is 2L and the NECBL is a distance of D L northwardof the central position of the island (or southward of the central position if D L is negative)as depicted in Figure 5.So (11)can be expressed as:L 2D L ðÞQ K 1Q L ðÞ5L 1D L ðÞQ M 2Q L ðÞ[32]A rearrangement gives a simple relationship between the transport through the Luzon Strait (Q L ),the NECBL (D L )and transports of the Kuroshio and Mindanao Currents (Q K and Q M ):Q L 5Q M 2Q K ðÞ=21D L Q M 1Q K ðÞ=2L(12)[33]Equation (12)is derived from a circulation integral constraint around an island.The same result is implicit in previous studies of the island rule [e.g.,Pedlosky et al .,1997;Pratt and Pedlosky ,1998;Firing et al .,1999].Here we emphasize the application of equation (12)in explain-ing the relationship between LST and the Kuroshio and Mindanao Currents,rather than the theoretical novelty of equation (12).[34]What does equation (12)mean in terms of dynam-ics?First let’s consider a special case in which the NECBL is located right at the center position of the island,i.e.,D L 50.The LST,which becomes Q L 5Q M 2Q K ðÞ=2according to (12),would increase when the Mindanao Cur-rent strengthens or when the Kuroshio Current transport weakens,and vice versa.This seems counter intuitive con-sidering that the LST is supplied by the Kuroshio Current.One would expect intuitively that a stronger Kuroshio would lead to a greater transport into the SCS.Our solu-tion,Q L 5Q M 2Q K ðÞ=2,is actually consistent with previous observation-based studies.The LST Q L peaks in October–December when the Kuroshio transport is at its seasonally minimum while Q L is weak in May–September when the Kuroshio Current is strongest [Yaremchuk and Qu ,2004].How do we make sense of this relationship?[35]The dynamics behind this relationship can be explained in terms of the dynamical constraint expressed by (9)or (11).When the two WBCs,i.e.,the KC and MC,have the same lengths along the east coast of the island (i.e.,y A 2y B 5y B 2y C Þ,the WBC transports north and south of the NECBL must have the same magnitude so that the friction exerted by them can cancel each other when inte-grated from A to C in Figure 5,i.e.,Q K 1Q L 5Q M 2Q L .When the northward KC transport (Q K )weakens,the LST (Q L )must increase to enhance the net northward WBC transport (Q K 1Q L )and to weaken the net southward WBC transport (Q M 2Q L )so that the two transports have the same magnitude,and vice versa when the Kuroshio strengthens.[36]Now let’s consider another special case in which the transports of the Kuroshio and Mindanao Currents are equal (i.e.,Q K 5Q M )but the NECBL is shifted away from the center position of the island.The LST,according to equation (12),becomes Q L 5D LQ K =L .The transport Q L is positive (into the SCS via the northern strait)when the NECBL moves northward (i.e.,D L >0)and negative when the NECBL shifts southward.The dynamics can be explained as follows.When the NECBL shifts northward,the northward WBC runs a shorter length before reaching。
