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A study of the Indian Ocean response to ENSO and IOD using satellite observations.

机译：印度洋对ENSO和IOD的卫星响应研究。

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摘要

Satellite altimetry data from TOPEX/POSEIDON and Jason-1 were used in conjunction with a geoid from GRACE and hydrographic profiles to observe the effect of the El Nino/ Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) climatic signals on tropical Indian Ocean dynamics during the period 1993-2004. Ocean heat storage anomalies were computed from the sea surface height anomaly data using a linear regression relationship. Geostrophic currents were calculated at the surface and subsurface levels of the Indian Ocean using the beta-plane approximation near (+/-1º) the equator and the thermal wind equations elsewhere. The results of this method were validated with currents measured using Acoustic Doppler Current Profilers moored along the equator at 77°E, 83°E, and 93°E. The measured and computed currents compared reasonably well with similar features present in both. The presence of the seasonal Wyrtki Jets, the North Equatorial Current, and the Equatorial Undercurrent and their variability was observed in the estimated currents. The area-averaged heat storage anomalies were computed for two geographical boxes representing the tropical western Indian Ocean (TWIO, 55º-75ºE, 5ºN-5ºS) and the tropical southeastern Indian Ocean (TSEIO, 85º-95ºE, 0º-10ºS). This revealed a three-month lag in annual heat storage maxima during neutral ENSO and IOD conditions in the TSEIO with respect to the TWIO. The heat storage maxima co-occurred during the simultaneous El Nino/ positive IOD events in 1994 and 1997, but the lag was present during 2002. During the extreme event of 1997-1998 the positive heat storage anomalies in the TWIO doubled in magnitude while simultaneously the heat storage anomalies in the TSEIO decreased in magnitude. Time-longitude and time-depth profiles of zonal geostrophic currents at various locations were analyzed. The fall Wyrtki Jets were greatly reduced during the co-occurring El Nino/ positive IOD events of 1994 and 1997, but not in 2002. The heat storage estimates and the geostrophic currents both suggest that (1) it is the strength of the IOD signal rather than the strength of the ENSO signal than controls the weakening of the fall Wyrtki Jet and (2) there was not a positive IOD event during 2002.
机译：来自TOPEX / POSEIDON和Jason-1的卫星测高数据与来自GRACE的大地水准面和水文剖面图一起使用，以观察厄尔尼诺/南方涛动（ENSO）和印度洋偶极子（IOD）气候信号对热带印度洋的影响1993-2004年期间的动态变化。使用线性回归关系从海面高度异常数据中计算出海洋储热异常。使用靠近赤道（+/-1º）的β平面近似值和其他地方的热风方程式，计算了印度洋地表和次表层的地转流。该方法的结果通过使用在沿赤道停泊在77°E，83°E和93°E处的声学多普勒电流剖面仪测得的电流进行了验证。测得的和计算出的电流与两者中存在的相似特征进行了合理的比较。在估计的洋流中观察到了季节性Wyrtki喷气机，北赤道洋流和赤道暗流的存在及其变化。计算了两个地理区域的平均储热面积异常，分别代表热带印度洋西部（TWIO，55º-75ºE，5ºN-5ºS）和热带东南印度洋（TSEIO，85º-95ºE，0º-10ºS）。这表明在TSEIO的中性ENSO和IOD条件下，相对于TWIO，年度储热最大值有三个月的滞后。在1994年和1997年同时发生厄尔尼诺现象/ IOD正向事件时，同时出现了最大储热量，但在2002年期间出现了滞后现象。在1997-1998年的极端事件中，TWIO的正向储热异常幅度增加了一倍，而同时TSEIO中的储热异常幅度减小。分析了不同位置的纬向地转流的时空分布。在1994年和1997年同时发生的厄尔尼诺现象/ IOD阳性事件中，秋天的Wyrtki Jets大大减少了，但在2002年却没有。储热估计和地转流均表明（1）这是IOD信号的强度而不是ENSO信号的强度而不是控制下降的Wyrtki Jet的减弱，并且（2）在2002年期间没有发生积极的IOD事件。

著录项

  • 作者

    Cadden, Dara Dawn Hooker.;

  • 作者单位

    University of South Carolina.;

  • 授予单位 University of South Carolina.;
  • 学科 Physical Oceanography.;Remote Sensing.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 121 p.
  • 总页数 121
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋物理学;遥感技术;
  • 关键词

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