不同厄尔尼诺事件期间风对热带太平洋海平面变化的影响

发布时间：2018-06-25 08:21

本文选题：年际变化 + 海平面　；参考：《中国海洋大学》2014年硕士论文

【摘要】：本文利用海平面异常、海水温度和风场数据，区分了两种分布型厄尔尼诺事件期间，热带太平洋海平面年际变化特征和规律；采用物理模型定量估计了菲律宾以东海域风场对海平面变化的贡献；在此基础上，结合ROMS模式，探讨了风影响热带太平洋海平面年际变化的机理。热带太平洋海平面具有显著的年际变化特征，变化显著的区域位于西太暖池区与热带东太平洋。周期为30个月（准两年）和52个月的年际变化最为显著。准两年振荡的显著区位于菲律宾以东海域和整个赤道太平洋；52个月振荡则主要位于菲律宾和新几内亚岛以东海域，以及赤道东太平洋。过去的60年里共发生了21次厄尔尼诺事件，其中包括11次东太平洋型（东太型）厄尔尼诺事件，以及10次中太平洋型（中太型）厄尔尼诺事件。每个年代都有中太型事件发生，近二十年，中太型厄尔尼诺事件较东太型事件频繁发生，且强度变化不大。不同厄尔尼诺事件期间的海平面变化特征差异显著。中太型事件期间，热带太平洋海平面呈梭子型变化，赤道中太平洋海平面升高，较东太型时期升高9cm；在东太型事件期间，海平面变化呈东高西低的跷跷板型，西太暖池区海平面下降，东太平洋海平面升高，整个太平洋海盆的海平面倾斜可达46cm。中太型和东太型事件期间的海平面变化规律明显不同。中太型事件的海平面演变特征主要体现在两个关键区：菲律宾以东海域海平面为负异常，鼎盛阶段海平面负异常达到最大；赤道中太平洋海平面正异常显著，在鼎盛阶段达到最大。东太型事件期间海平面演变主要体现在以下三个关键区：西太暖池北侧——菲律宾以东海域，海平面为负异常逐渐减小，呈上升趋势；暖池南侧——南太平洋辐合带海平面负异常逐渐增大，下降趋势显著；而赤道东太平洋海平面正异常逐渐减弱，海平面呈下降趋势。区域海平面变化受大气风场年际尺度变化的影响，两种事件期间的风场差异是引起同期海平面年际变化的重要因素。中太型厄尔尼诺事件期间，赤道中太平洋风场辐聚，温跃层加深，海洋层化加强，垂直运动减弱。有利于同期上层海洋热含量正异常的维持，海平面上升。而菲律宾以东海域风场辐散，海洋层化减弱，垂直运动加强，加剧了次表层与表层的热量交换，海水冷异常显著，海平面下降。与中太型事件明显不同，东太型厄尔尼诺事件期间，风场的辐聚区主要位于赤道东太平洋海域，该海区海平面上升；而风场辐散区主要位于西太暖池区，该海区海平面下降。两种事件期间风场通过Ekman效应和Rossby波效应对菲律宾以东海平面的变化的贡献不同。中太型事件期间，风场通过Rossby波效应对海平面变化的贡献持续存在，量值在35%。东太型事件期间，该效应的贡献范围随着事件的演变逐渐向西北退去，量值鼎盛期到达最大，变动范围在43-53%。局地Ekman效应的贡献随两种事件的演变逐渐较小，到中太型事件衰落时期，风场仍有贡献，，而东太事件的这一时期，Ekman效应对海平面变化几乎无贡献。两种事件期间，海面风场通过Rossby波效应对海平面变化的贡献比局地Ekman效应显著。数值模拟结果表明，风场是影响海平面变化的重要因素，且区域特征显著，特别是在东太型事件期间。东太型事件期间，风场是影响海平面变化的主要因素，不同阶段，其影响均有40-60%，在暖池区的发展阶段这一影响最大。中太型事件期间，风场对海平面变化有贡献，这一贡献主要体现在鼎盛和衰落阶段的菲律宾以东海区，平均贡献可达37%。
[Abstract]:In this paper , sea level anomaly , sea water temperature and wind field data are used to distinguish the interannual variability of sea level in tropical Pacific during El Nio events .
The contribution of wind field to sea level change in the east of the Philippines was estimated by using physical model .
On this basis , combined with ROMS model , the mechanism of wind influence on interannual sea level change in tropical Pacific Ocean is discussed .

The sea level in the tropical Pacific Ocean is characterized by significant interannual variability , which is located in the west Pacific Ocean region and the tropical eastern Pacific Ocean . The period is 30 months ( quasi - two years ) and the annual variation of 52 months is the most significant . The significant region of the quasi - two - year oscillation lies in the east of the Philippines and the entire equatorial Pacific Ocean ;
The 52 - month oscillation is mainly located in the east of the Philippines and New Guinea , as well as the equatorial eastern Pacific Ocean .

There have been 21 El Ni帽o events in the past 60 years , including 11 East Pacific ( East Pacific ) El Ni帽o events , and 10 medium - Pacific ( medium - Pacific ) El Ni帽o events . There were middle - Pacific ( medium - and - Pacific ) El Ni帽o events in each of the decade . Over the last two decades , the events of El Nio in the medium - Pacific were frequent and the intensity changes were not large .

There was a significant difference in sea level change during different El Nio events . During the medium - Pacific events , the sea level in the tropical Pacific was changed , and the Pacific sea level in the equatorial Pacific increased , while the Eastern Pacific sea level rose 9cm ;
During the Eastern Pacific Ocean , sea - level change is seen as a seesaw type with low east - west sea level , sea level in the Western Pacific Ocean is decreased , sea level in the east Pacific is increased , and sea level tilt of the whole Pacific basin can reach 46cm .

The sea level evolution characteristics of medium - sized and east - Pacific events are obviously different . The sea - level evolution characteristics of medium - Pacific events are mainly reflected in two key areas : sea level in the east of the Philippines is negative anomaly , and sea level negative anomaly in the peak period reaches the maximum ;
The sea level evolution in the equatorial Pacific Ocean is very abnormal and the maximum is reached during the peak period . The sea level evolution in the east Pacific Ocean is mainly reflected in the following three key areas : the north side of the West Pacific Warm Pool and the east of the Philippines , and the sea level is gradually decreased and the trend is rising ;
The sea level negative anomaly gradually increases in the South Pacific convergence zone of the warm pool , and the decreasing trend is remarkable ;
The sea level in the equatorial Pacific Ocean is gradually weakened and sea level decreases .

The change of sea level in the region is affected by the interannual scale change of atmospheric wind field . The difference of wind field during the two events is an important factor causing the interannual variation of sea level in the same period .
and the wind field divergence area is mainly located in the west Pacific warm pool area , and the sea level of the sea area decreases .

During the two events , the contribution of wind field to sea level changes in the east of the Philippines is different through the Ekman effect and the wave effect . The contribution of the wind field to sea level change continues to exist in the period of 35 % . The contribution of the effect to sea level change gradually decreases with the evolution of the event . The Ekman effect has little contribution to sea level change . During the two events , the contribution of the surface wind field to sea level change is more remarkable than the local Ekman effect .

Numerical simulation results show that the wind field is an important factor affecting sea level change , and the regional characteristics are prominent , especially during the east Pacific region . Wind field is the main factor affecting sea level change . During the development stage of the warm pool area , the influence of wind field is 40 - 60 % . During the middle - type event , the wind field contributes to sea level change . This contribution is mainly reflected in the sea area east of the Philippines in the peak and decline stage , and the average contribution can reach 37 % .
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P732;P731.23

【参考文献】