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
外语
The recent, apparently successful prediction by mathematical models of an appearance of EI Nino—the warm ocean current that peri
The recent, apparently successful prediction by mathematical models of an appearance of EI Nino—the warm ocean current that peri
admin
2020-12-14
55
问题
The recent, apparently successful prediction by mathematical models of an appearance of EI Nino—the warm ocean current that periodically develops along the Pacific coast of South America—has excited researchers. Jacob Bjerknes 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 appearances of the warm EI Nino and the cold so-called anti-El Nino. The answer, at 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: unusually warm water extends along the eastern Pacific, principally along the coasts of Ecuador and Peru, and 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 cast, 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, mat 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.
The primary purpose of the text as a whole is to______.
选项
A、introduce a new explanation of physical phenomenon
B、explain the difference between two natural phenomena
C、illustrate the limits of applying mathematics to complex problems
D、clarify the distinction between an old explanation and a new model
答案
A
解析
主旨题。回顾全文。第一段提到了利用数学模式对厄尔尼诺现象的发生进行的预测,接着介绍了该模式的重要性,第二、三段具体介绍了该模式的观点。这说明,本文主要是在介绍对厄尔尼诺现象的一种新解释。所以答案选A。
转载请注明原文地址:https://kaotiyun.com/show/K8P7777K
0
大学英语六级
相关试题推荐
Who’sReallyAddictingYoutoTechnology?[A]"NearlyeveryoneIknowisaddictedinsomemeasuretotheInternet,"wroteTonyS
Who’sReallyAddictingYoutoTechnology?[A]"NearlyeveryoneIknowisaddictedinsomemeasuretotheInternet,"wroteTonyS
Manycurrentdiscussionsofimmigrationissuestalkaboutimmigrantsingeneral,asiftheywereabstractpeopleinanabstract
A、Hostingatelevisionshow.B、Reviewinganewbiography.C、Interviewingamoviestar.D、Discussingteenagerolemodels.A从选项预测本
A、Generatedifferentspeeches.B、Identifyobjectsinpictures.C、Improveroadconditions.D、Reproducehumanbrains.B录音提到,认知计算机系
A、Overdoseofdrugs.B、Lackofnutrition.C、Lackofphysicalexercise.D、Imbalanceinbrainactivity.DDr.Brdesen认为包括生活方式在内的很多因素
A、Theremightbealinkbetweensugarlevelsandnegativesocialbehaviors.B、Thosewithlowersugarlevelshavethesamenegati
A、You’llbemoresuccessful.B、You’llliveinpainandregret.C、You’llkeepoptimistic.D、Yourlifewilltakeondeepermeaning
VictoriaBarzilaiopenedhermouthwidesothedoctorcouldlookathersorethroat.Not【C1】______aremarkableevent,excepttha
Carmakershavelongusedsextoselltheirproducts.Recently,however,bothBMWandRenaulthavebasedtheirlatestEuropeanm
随机试题
受伤当时无明显症状,几天后突然出现急性大出血的危险情况的内脏损伤是
某房屋建筑工程施工总承包二级企业,通过招标投标方式承建了城区A住宅楼工程,工程为框架一剪力墙结构,地上17层,地下1层,总建筑面积16780m2。该工程采取施工总承包方式,合同约定工期20个月。工程中标后,施工企业负责人考虑到同城区的B工程已临近竣
机内总分类账和明细分类账不能同时结账。()
()属于不作为义务。
在接受检查过程中,银行业从业人员应该配合监管人员审核所在机构()的一致性。
Today,peopleallovertheworldaremovingoutofsmallvillagesinthecountrytogoandliveinbig,noisycities.Theyarem
电子邮件软件向邮件服务器发送邮件时使用的协议是_______。
若有程序:main(){inti,j;scanq("i=%d,j=%d",&i,&j);printf("i=%d,j=%d\n",i,j);}要求给i赋10,给j赋20,则应该从键盘输入【
Whydidn’tthemanmisshistrain?
DoctorsinBritainarewarningofanobesity(肥胖症)timebomb,whenchildrenwhoarealreadyoverweightgrowup.So,whatshouldwe
最新回复
(
0
)