Dissertation > Excellent graduate degree dissertation topics show

Asymmetry of Temperature Anomaly in the Tropical Pacific Ocean and Tropical Indian Ocean in an OGCM

Author: HuaLiJuan
Tutor: YinBaoShu；YuYongQiang
School: Graduate School , Chinese Academy of Sciences ( Institute of Oceanography )
Course: Physical oceanography
Keywords: ENSO Skew coefficient Tropical Indian Ocean IOD Asymmetry Average state
CLC: P732
Type: Master's thesis
Year: 2010
Downloads: 67
Quote: 0
Read: Download Dissertation

Abstract

This article first half CFD numerical simulation State Key Laboratory of Atmospheric Sciences and Geophysical Institute of Atmospheric Physics, Chinese Academy of Sciences (LASG) the development of a global ocean circulation model LICOM2.0, observing wind stress forcing a series of numerical experiments to explore the relationship between the physical mechanism of ENSO asymmetry and its contribution to the climate average state, and both of them. In this paper, the ocean general circulation model a controlled trial and two sensitivity tests to assess the mode of wind stress response: the control experiments driven by climate average wind stress integral 44 years; two sensitivity tests in climate average only on the basis of the wind stress in the tropical Pacific between 30 degrees latitude north and south add ERA40 monthly mean wind stress anomalies as a force field, the same integral 44 years. The two susceptibility test difference is that wind stress anomalies in the opposite direction. Observation and simulation results have shown that the ENSO asymmetries not only in the sea surface in the subsurface. The main features in the eastern Pacific SST skew coefficient is positive, while in the western Pacific SST skew coefficient is negative. Abnormal warming of the eastern Pacific SST amplitude greater than the cold anomaly amplitude West Pacific SST cold anomaly amplitude is larger than the amplitude of the warm anomaly. The sub-surface ocean temperatures in the eastern equatorial Pacific skew coefficient is positive, while the sub-surface ocean temperatures in the western equatorial Pacific skew coefficient is negative. The eastern equatorial Pacific Ocean warm anomaly amplitude is larger than the cold anomaly amplitude, and subsurface ocean temperatures in the western equatorial Pacific cold anomaly amplitude is larger than the amplitude of the warm anomaly. These features and characteristics of the ENSO warm phase during the eastern Pacific SST warm anomaly and subsurface ocean temperatures in the western Pacific as cold anomaly. Thus Description: El Nino strength greater than the strength of the La Nina, ENSO warm and cold phase is asymmetric. Mode the trial also discussed the contribution of ENSO mean state of the climate. Found that ENSO equatorial eastern Pacific ocean temperatures reduce the western equatorial Pacific sea surface temperature. In this mode test given to explain. The sub-surface ocean temperature nonlinear advection and vertical convection term may be the main reason leading to the warming of the eastern equatorial Pacific, Rossby wave excitation of vertical upwelling and the convergence is the main cause of the western equatorial Pacific cooling. At the same time, taking into account the many atmospheric article the use of eddy momentum and heat to explain the rise in atmospheric flow and decreased flow, the article also takes advantage of the eddy momentum and heat to explain the vertical upwelling in the ocean. In the latter part of the article, we use the same method for the numerical experiments, a lookout stress plus anomalies in the tropical Indian Ocean region, the use of ocean circulation mode LICOM simulated tropical Indian Ocean interannual anomalies of asymmetry and its impact on the climate average state impact. Mode of tropical Indian Ocean seasonal changes in of observing wind stress anomalies forced to assess the sea surface temperature anomaly dipole modes (IOD) asymmetry simulation capabilities, and analyzed by numerical experiments IOD asymmetry feature and their impact on the climate mean state. Against observed data, the models were able to reproduce the seasonal variations of the tropical Indian Ocean SST in monsoon driven. Interannual time scales, the model is not only capable of reproducing the trend of the IOD index, and can successfully simulate the spatial distribution of the IOD modal characteristics, surface and subsurface ocean temperatures in the Western Indian Ocean showed positive anomalies in the performance of the eastern Indian Ocean negative anomalies. Be seen in terms of the tropical Indian Ocean IOD modal wind stress anomalies response. The tropical Indian Ocean SST correlation analysis with Nino3.4 Index indicates that the model can simulate ahead tropical Pacific ENSO phenomenon at 2 to 4 months SST dipole type distribution, but about two month lag ENSO phenomenon can not be simulated The full basin warming mode, mode test does not consider the role of inter-annual exception of the heat flux. Simultaneously simulated IOD mode observations similar asymmetry further sensitivity tests showed less asymmetric wind stress on the asymmetry of the contribution of the dipole index, sub-surface and below the sea surface temperature not symmetry may be mainly due to the impact of nonlinear dynamical processes in the ocean interior. Through numerical experiments, we also found that the asymmetry of the tropical Indian Ocean temperatures the average state have an impact on the climate, the asymmetry of the long-term accumulation will cause the temperature stratification in the upper tropical Indian Ocean stabilized state.

Related Dissertations

CLC: > Astronomy,Earth Sciences > Oceanography > Marine basic science > Marine Meteorology
© 2012 www.DissertationTopic.Net Mobile