NUMERICAL SIMULATION OF SSTA IMPACTS UPON THE INTERDECADAL VARIATION OF THE CROSS-EQUATORIAL FLOWS IN EASTERN HEMISPHERE |
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| Authors: | ZENG Gang SUN Zhao-bo DENG Wei-tao LIN Zhao-hui and LI Chun-hui |
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| Institution: | Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 China;Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 China;Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 China;International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 China;Guangzhou Institute of Tropical Marine Meteorology, China Meteorological Administration, Guangzhou 510080 China |
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| Abstract: | Impacts of regional sea surface temperature (SST) anomalies on the interdecadal variation of the cross-equatorial flows (CEFs) in Eastern Hemisphere are studied using numerical simulations with a global atmospheric circulation model (NCAR CAM3) driven with 1950-2000 monthly SSTs in different marine areas (the globe, extratropics, tropics, tropical Indian Ocean-Pacific, and tropical Pacific) and ERA-40 reanalysis data. Results show that all simulations, except the one driven with extratropical SSTs, can simulate the interdecadal strengthening of CEFs around Somali, 120oE, and 150oE that occurred in the midand late-1970s. Among those simulated CEFs, the interdecadal variability in Somali and its interdecadal relationship with the East Asian summer monsoon are in better agreement with the observations, suggesting that changes in the SSTs of tropical oceans, especially the tropical Pacific, play a crucial role in the interdecadal variability of CEFs in Somali. The interdecadal change of CEFs in Somali is highly associated with the interdecadal variation of tropical Pacific SST. As the interdecadal warmer (colder) SST happens in the tropical Pacific, a "sandwich" pattern of SST anomalies, i.e. "+, -, +" ("-, +, -"), will occur in the eastern tropical Pacific from north to south with a pair of anomalous anticyclone (cyclone) at the lower troposphere; the pair links to another pair of anomalous cyclone (anticyclone) in the tropical Indian Ocean through an atmospheric bridge, and thus strengthens (weakens) the CEFs in Somali. |
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| Keywords: | cross-equatorial flow in Eastern Hemisphere numerical simulation interdecadal variation sea surface temperature anomaly |
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