| Causes of the Intraseasonal SST Variability in the Tropical Indian Ocean |
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| 作者姓名： | Tim Li Francis Tam Xiouhua Fu 周天军 朱伟军 |
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| 作者单位： | IPRC and Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA;IPRC and Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA;IPRC and Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA;中国科学院大气物理研究所，北京;Joint Climate Institute of CMA & NUIST, 南京信息工程大学 |
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| 摘 要： |
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Causes of the Intraseasonal SST Variability in the Tropical Indian Ocean |
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| Tim Li,Francis Tam,Xiouhua Fu,ZHOU Tian-Jun and ZHU Wei-Jun.Causes of the Intraseasonal SST Variability in the Tropical Indian Ocean[J].Atmospheric and Oceanic Science Letters,2008,1(1):18-23. |
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| Authors: | Tim Li Francis Tam Xiouhua Fu ZHOU Tian-Jun and ZHU Wei-Jun |
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| Institution: | IPRC and Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA;IPRC and Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA;IPRC and Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA;Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China;Joint Climate Institute of CMA & NUIST, Nanjing University of Information Science & Technology, Nanjing, China |
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| Abstract: | Satellite observations reveal a much stronger intraseasonal sea surface temperature (SST) variability in the southern Indian Ocean along 5-10oS in boreal winter than in boreal summer. The cause of this seasonal dependence is studied using a 2?-layer ocean model forced by ERA-40 reanalysis products during 1987-2001. The simulated winter-summer asymmetry of the SST variability is consistent with the observed. A mixed-layer heat budget is analyzed. Mean surface westerlies along the ITCZ (5-10oS) in December-January-February (DJF) leads to an increased (decreased) evaporation in the westerly (easterly) phase of the intraseasonal oscillation (ISO), during which convection is also enhanced (suppressed). Thus the anomalous shortwave radiation, latent heat flux and entrainment effects are all in phase and produce strong SST signals. During June-July-August (JJA), mean easterlies prevail south of the equator. Anomalies of the shortwave radiation tend to be out of phase to those of the latent heat flux and ocean entrainment. This mutual cancellation leads to a weak SST response in boreal summer. The resultant SST tendency is further diminished by a deeper mixed layer in JJA compared to that in DJF. The strong intraseasonal SST response in boreal winter may exert a delayed feedback to the subsequent opposite phase of ISO, implying a two-way air-sea interaction scenario on the intraseasonal timescale.
Citation: Li, T., F. Tam, X. Fu, et al., 2008: Causes of the intraseasonal SST variability in the tropical Indian ocean, Atmos. Oceanic Sci. Lett., 1, 18-23 |
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| Keywords: | SST ISO shortwave radiation latent heat flux ocean entrainment |
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