首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
The recent, apparently successful prediction by mathematical models of an appearance of El Nino—the warm ocean current that peri
The recent, apparently successful prediction by mathematical models of an appearance of El Nino—the warm ocean current that peri
admin
2009-04-27
40
问题
The recent, apparently successful prediction by mathematical models of an appearance of El Nino—the warm ocean current that periodically develops along the Pacific coast of South America—has excited researchers. Jacob Blerkness pointed out over 20 years ago how winds might create either abnormally warm or abnormally cold water in the eastern equatorial Pacific. Nonetheless, until the development of the models no one could explain why conditions should regularly shift from one to the other, as happens in the periodic oscillations between appearance of the warm El Nino and the cold so-called anti-El Nino. The answer, al least if the current model that links the behavior of the ocean to that of the atmosphere is correct, is to be found in the ocean.
It has long been known that during an El Nino, two conditions exist: (1) unusually warm water extends along the eastern Pacific, principally along the coasts of Ecuador and Peru, and (2) winds blow from the west into the warmer air rising over the warm water in the east. These winds tend to create a feedback mechanism by driving the warmer surface water into a "pile" that blocks the normal upwelling of deeper, cold water in the east and further warms the eastern water, thus strengthening the wind still more. The contribution of the model is to show that the winds of an El Nino, which raise sea level in the east, simultaneously send a signal to the west lowering sea level. According to the model, that signal is generated as a negative Rossby wave, a wave of depressed, or negative, sea level that moves westward parallel to the equator at 25 to 85 kilometers per day. Taking months to traverse the Pacific, Rossby waves march to the western boundary of the Pacific basin, which is modeled as a smooth wall but in reality consists of quite irregular island chains, such as the Philippines and Indonesia.
When the waves meet the western boundary, they are reflected, and the model predicts that Rossby waves will be broken into numerous coastal Kelvin waves carrying the same negative sea-level signal. These eventually shoot toward the equator, and then head eastward along the equator propelled by the rotation of the Earth at a speed of about 250 kilometers per day. When enough Kelvin waves of sufficient amplitude arrive from the western Pacific, their negative sea-level signal overcomes the feedback mechanism tending to raise the sea level, and they begin to drive the system into the opposite cold mode. This produces a gradual shift in winds, one that will eventually send positive sea-level Rossby waves westward, waves that will eventually return as cold cycle-ending positive Kelvin waves beginning another warming cycle.
选项
A、cold coastal water near Peru.
B、winds blowing from the west.
C、random occurrence.
D、worldwide effects.
答案
B
解析
事实细节题。本文第二段首句指出"人们早已知道,在厄尔尼诺出现期间,有两个条件存在:(1)异常的暖流沿东太平洋延伸,主要是沿着厄瓜多尔和秘鲁沿岸;(2)风从西部吹入东部温暖的海水上方所升起的较暖空气"。因此风从西部吹过来是厄尔尼诺的一个特征,这正是答案选项内容。
转载请注明原文地址:https://kaotiyun.com/show/jPa4777K
0
考研英语一
相关试题推荐
Inresponsetoscandalsrockingthestudentloanindustry,theHousehasquicklypassedreformlegislationtorequiremorediscl
Howsoonyourperformancewillberatedmayinfluencehowwellyoudo,accordingtoanewstudypublishedinthejournalPsychol
WithJapan’swelfaresystembucklingunderthedemandsofanageingsociety,theworld’soldestmanapologizedyesterdayforhis
Governmentsarerestrainingbusinesstravelersandtouristswithcumbersomevisarequirementsthatdolittletomaketheircount
Runningmaybethesinglemosteffectiveexercisetoincreaselifeexpectancy,accordingtoanewreviewandanalysisofpastre
[A]Identifypeoplewhoyouwanttotalkto[B]Findoutwhereyoursupportis[C]Askfortheflooratconferences[D]
ThemagnificencedisplayedlastmonthinLondonconvincedmillionsaroundtheworldtonotonlywatchtheweddingceremonyofth
Manisbornfreebutiseverywhereindebt.Intherichworld,gettingholdofyourfirstcreditcardisariteofpassagefarm
Manisbornfreebutiseverywhereindebt.Intherichworld,gettingholdofyourfirstcreditcardisariteofpassagefarm
随机试题
______thenews,shejumpedwithjoy.
房地产中的投资利息与会计上的财务费基本相同。()
设α=i+2j+3k,β=i一3j一2k,与α、β都垂直的单位向量为()。
《期货从业人员执业行为准则(修订)》规定,期货从业人员在执业过程中应当对()高度负责,诚实守信,恪尽职守,珍惜、维护期货业和从业人员的职业声誉,保证期货市场稳健运行。
计算应缴纳的房产税是()元。
由于麦收季节快要来临,根据市场需求情况,某汽车制造厂决定动用前一纳税期购买的钢材X吨,用于首批联合收割机的生产。为此,当期增值税进项税额应进行以下处理()。
徐锡麟起义
材料1:杨先生和李女士是一对夫妻。一天,杨先生打了李女士一拳头,结果,李女士的面容被毁,其婚姻也随之解体了。邻居和同事纷纷猜测:杨先生为什么打人?禀性暴躁?仅仅是一时冲动?为了专门毁掉他人面容?为了毁掉他人婚姻?双方厮打是为了自卫?人们无法确定事件的原因。
已知3阶矩阵A与3维列向量x,使x,Ax,A2x线性无关,且满足A3x=3Ax-2A2x,令P=(x,Ax,A2x).求3阶矩阵B,使A=PBP-1;
WeakergrowthinthenextsixmonthswilloccurinInItaly,consumerconfidencehasdropped
最新回复
(
0
)