| THE WARMING MECHANISM IN THE SOUTHERN ARABIAN SEA DURING THE DEVELOPMENT OF INDIAN OCEAN DIPOLE EVENTS |
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| 作者姓名： | 桂发银 李崇银 谭言科 黎 鑫 夏淋淋 |
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| 作者单位： | College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101 China |
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| 摘 要： | This study aims to explore the relative role of oceanic dynamics and surface heat fluxes in the warming of southern Arabian Sea and southwest Indian Ocean during the development of Indian Ocean Dipole (IOD) events by using National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) daily reanalysis data and Global Ocean Data Assimilation System (GODAS) monthly mean ocean reanalysis data from 1982 to 2013, based on regression analysis, Empirical Orthogonal Function (EOF) analysis and combined with a 2? layer dynamic upper-ocean model. The results show that during the initial stage of IOD events, warm downwelling Rossby waves excited by an anomalous anticyclone over the west Indian Peninsula, southwest Indian Ocean and southeast Indian Ocean lead to the warming of the mixed layer by reducing entrainment cooling. An anomalous anticyclone over the west Indian Peninsula weakens the wind over the Arabian Sea and Somali coast, which helps decrease the sea surface heat loss and shallow the surface mixed layer, and also contributes to the sea surface temperature (SST) warming in the southern Arabian Sea by inhibiting entrainment. The weakened winds increase the SST along the Somali coast by inhibiting upwelling and zonal advection. The wind and net sea surface heat flux anomalies are not significant over the southwest Indian Ocean. During the antecedent stage of IOD events, the warming of the southern Arabian Sea is closely connected with the reduction of entrainment cooling caused by the Rossby waves and the weakened wind. With the appearance of an equatorial easterly wind anomaly, the warming of the southwest Indian Ocean is not only driven by weaker entrainment cooling caused by the Rossby waves, but also by the meridional heat transport carried by Ekman flow. The anomalous sea surface heat flux plays a key role to damp the warming of the west pole of the IOD.
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| 关 键 词： | Arabian Sea summer monsoon Indian Ocean Dipole 2.5 layer dynamic upper-ocean model |
| 修稿时间： | 2016/2/16 0:00:00 |
THE WARMING MECHANISM IN THE SOUTHERN ARABIAN SEA DURING THE DEVELOPMENT OF INDIAN OCEAN DIPOLE EVENTS |
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| GUI Fa-yin,LI Chong-yin,TAN Yan-ke,LI Xin and XIA Lin-lin.THE WARMING MECHANISM IN THE SOUTHERN ARABIAN SEA DURING THE DEVELOPMENT OF INDIAN OCEAN DIPOLE EVENTS[J].Journal of Tropical Meteorology,2016,22(2):159-171. |
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| Authors: | GUI Fa-yin LI Chong-yin TAN Yan-ke LI Xin and XIA Lin-lin |
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| Institution: | College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101 China |
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| Abstract: | This study aims to explore the relative role of oceanic dynamics and surface heat fluxes in the warming of southern Arabian Sea and southwest Indian Ocean during the development of Indian Ocean Dipole(IOD) events by using National Center for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR) daily reanalysis data and Global Ocean Data Assimilation System(GODAS) monthly mean ocean reanalysis data from 1982 to2013,based on regression analysis,Empirical Orthogonal Function(EOF) analysis and combined with a 21/2layer dynamic upper-ocean model.The results show that during the initial stage of IOD events,warm downwelling Rossby waves excited by an anomalous anticyclone over the west Indian Peninsula,southwest Indian Ocean and southeast Indian Ocean lead to the warming of the mixed layer by reducing entrainment cooling.An anomalous anticyclone over the west Indian Peninsula weakens the wind over the Arabian Sea and Somali coast,which helps decrease the sea surface heat loss and shallow the surface mixed layer,and also contributes to the sea surface temperature(SST) warming in the southern Arabian Sea by inhibiting entrainment.The weakened winds increase the SST along the Somali coast by inhibiting upwelling and zonal advection.The wind and net sea surface heat flux anomalies are not significant over the southwest Indian Ocean.During the antecedent stage of IOD events,the warming of the southern Arabian Sea is closely connected with the reduction of entrainment cooling caused by the Rossby waves and the weakened wind.With the appearance of an equatorial easterly wind anomaly,the warming of the southwest Indian Ocean is not only driven by weaker entrainment cooling caused by the Rossby waves,but also by the meridional heat transport carried by Ekman flow.The anomalous sea surface heat flux plays a key role to damp the warming of the west pole of the IOD. |
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| Keywords: | Arabian Sea summer monsoon Indian Ocean Dipole 2 5 layer dynamic upper-ocean model |
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