A zonal domain,primitive equation model is used in this paper to study the influences of the main sea surface tem- perature anomaly(SSTA)areas over the Pacific on precipitation in 1991.Some numerical experiments are m...A zonal domain,primitive equation model is used in this paper to study the influences of the main sea surface tem- perature anomaly(SSTA)areas over the Pacific on precipitation in 1991.Some numerical experiments are made and the mechanisms of the influences are discussed.The results show that the influences of the SSTA are mainly confined within the tropical and the subtropical regions.The direct effect of the SSTA is to change the exchanges of the sensible heat and the water vapour between the air and the sea,through the consequent changes of temperature and the flow fields and the feedback process of condensation,the SSTA finally affects precipitation.展开更多
By prescribing sea surface temperature anomalies(SSTAs)over eastern equatorial Pacific in January—March,the lag influence of ENSO(El Nino and La Nina)on monsoon over East Asia has been studied.The results suggest tha...By prescribing sea surface temperature anomalies(SSTAs)over eastern equatorial Pacific in January—March,the lag influence of ENSO(El Nino and La Nina)on monsoon over East Asia has been studied.The results suggest that,due to the excitation of atmospheric low-frequency oscillation by the SSTA,ENSO has significant lag influence on the monsoon over East Asia. During the summer after E1 Nino,the subtropical high over western Pacific is intensified and shows the northward and westward displacement,meanwhile,the rainfall over East China is below normal,especially in North China:during the winter after E1 Nino,both the Asian trough and the winter monsoon over East Asia are strengthened.During the summer after La Nina,the anomalous subtropical high prevails over the lower reaches of Yangtze(Changjiang)River,the rainfall between Yangtze and Huaihe Rivers is below normal:during the winter after La Nina, both the Asian trough and the winter monsoon over East Asia are weaker.Compared with La Nina,the effect of El Nino is stronger,but it is not always opposite to the one of La Nina.展开更多
Increased evidence has shown the important role of Atlantic sea surface temperature(SST) in modulating the El Nio-Southern Oscillation(ENSO). Persistent anomalies of summer Madden-Julian Oscillation(MJO) act to link t...Increased evidence has shown the important role of Atlantic sea surface temperature(SST) in modulating the El Nio-Southern Oscillation(ENSO). Persistent anomalies of summer Madden-Julian Oscillation(MJO) act to link the Atlantic SST anomalies(SSTAs) to ENSO. The Atlantic SSTAs are strongly correlated with the persistent anomalies of summer MJO, and possibly affect MJO in two major ways. One is that an anomalous cyclonic(anticyclonic) circulation appears over the tropical Atlantic Ocean associated with positive(negative) SSTA in spring, and it intensifies(weakens) the Walker circulation. Equatorial updraft anomaly then appears over the Indian Ocean and the eastern Pacific Ocean, intensifying MJO activity over these regions. The other involves a high pressure(low pressure) anomaly associated with the North Atlantic SSTA tripole pattern that is transmitted to the mid-and low-latitudes by a circumglobal teleconnection pattern, leading to strong(weak) convective activity of MJO over the Indian Ocean. The above results offer new viewpoints about the process from springtime Atlantic SSTA signals to summertime atmospheric oscillation, and then to the MJO of tropical atmosphere affecting wintertime Pacific ENSO events, which connects different oceans.展开更多
A T_(42)L_9 GCM integration is adopted to investigate in detail the effect of Northwest Pacific sea surface temperature anomaly(SSTA)on the Pacific storm track(PST)during winter.Results show that warm(cold)Northwest P...A T_(42)L_9 GCM integration is adopted to investigate in detail the effect of Northwest Pacific sea surface temperature anomaly(SSTA)on the Pacific storm track(PST)during winter.Results show that warm(cold)Northwest Pacific SSTA can give rise to significantly increased (decreased)baroelinicity on the north side of the anomaly area and its downstream in such a way as to make the Pacific storm track strengthen(weaken)in its entrance where the 500 hPa synoptic perturbation height variance,kinetic energy,and low-level upward and poteward transient eddy temperature fluxes who exhibit similar features to those of mid-latitude barolinic waves in their developing phases,show great enhancement for the warm case,suggesting that the Pacific track can be reconstructed in its west side only as a result of an external forcing,viz.,warm Northwest Pacific SSTA during winter.展开更多
By the numerical simulation,the sea surface temperature anomaly(SSTA)of the Pacific and Indian Oceans.being introduced into IAP AGCM,the observed anomalous circulation characteristics on the monthly mean 850 hPa have ...By the numerical simulation,the sea surface temperature anomaly(SSTA)of the Pacific and Indian Oceans.being introduced into IAP AGCM,the observed anomalous circulation characteristics on the monthly mean 850 hPa have been confirmed:during an El Nino episode there appears anomalous westerly flow in the low-level atmosphere over the low-latitude Pacific and the anomalous equatorward air flow over the Southeast Asia coast:during a La Nina episode there appears anomalous easterly flow in the low-level atmosphere over the low-latitude Pacific and the anomalous off-equator air flow over the Southeast Asia coast.If we introduce only Pacific SSTA into or take off orographic forcing from the model,the simulated anomalous air flow in the low- level atmosphere over the low latitudes will be different.The precipitation departure in conformity with the observation over the low latitudes has been simulated with this model as well.展开更多
The SST variation in the equatorial Indian Ocean is studied with special interest in analyzing its dipole oscillation feature. The dipole oscillation appears to be stronger in September-November and weaker in January-...The SST variation in the equatorial Indian Ocean is studied with special interest in analyzing its dipole oscillation feature. The dipole oscillation appears to be stronger in September-November and weaker in January-April with higher SST in the west region and lower SST in the east region as the positive phase and higher SST in the east region and lower SST in the west region as the negative phase. Generally, the amplitude of the positive phase is larger than the negative phase. The interannual variation (4-5 year period) and the interdecadal variation (25-30 year period) also exist in the dipole. The analyses also showed the significant impact of the Indian Ocean dipole on the Asian monsoon activity, because the lower tropospheric wind fields over the Southern Asia, the Tibetan high in the upper troposphere and the subtropical high over the northwestern Pacific are all related to the Indian Ocean dipole. On the other, the Indian Ocean dipole still has significant impact on atmospheric circulation and climate in North America and the southern Indian Ocean region (including Australia and South Africa).展开更多
The study examined effects of sea surface temperature anomalies （SSTAs） off the east coast of Japan on the blocking high over the Okhotsk Sea in June by diagnostic analysis and numerical simulation. Firstly, based o...The study examined effects of sea surface temperature anomalies （SSTAs） off the east coast of Japan on the blocking high over the Okhotsk Sea in June by diagnostic analysis and numerical simulation. Firstly, based on 500-hPa geopotential height fields, the Okhotsk high index （OKHI） for June from 1951 to 2000 is calculated and analyzed. The result indicates that the OKHI has obvious inter-annual and inter-decadal vaxiations, and there are 9 yr of high OKHI and 8 yr of low OKHI in 50 yr. Secondly, by using the OKHI, the relationship between the Okhotsk high and the 500-hPa geopotential height anomaly is investigated. The results indicate that the ＂＋-＋＂ pattern of geopotential height anomaly crossing Eurasia in the mid-high latitudes and the ＂＋-＂ pattern of geopotential height anomaly from high to low latitudes over East Asia are in favor of the formation and maintenance of the Okhotsk high. The relationship between the OKHI and the SSTA over the North Pacific is investigated in early summer by using correlation and composite analysis. We found that when the blocking circulation over the Okhotsk Sea occurs, there is an obvious negative SSTA off the east coast of Japan in early summer. We simulated the effects of the negative SSTA of east coast of Japan on the atmospheric circulation anomaly over East Asia through the control and sensitivity experiments using NCAR CAM3 model in order to confirm our analysis results. The simulation shows that the negative SSTA off the east coast of Japan results in the significant positive 40 gpm 500-hPa geopotential height anomaly over the Okhotsk Sea and the negative anomalies off the east coast of Japan which might contribute to the formation and development of the Okhotsk high in June.展开更多
基金The paper is supported by the National Natural Science Foundation of China.
文摘A zonal domain,primitive equation model is used in this paper to study the influences of the main sea surface tem- perature anomaly(SSTA)areas over the Pacific on precipitation in 1991.Some numerical experiments are made and the mechanisms of the influences are discussed.The results show that the influences of the SSTA are mainly confined within the tropical and the subtropical regions.The direct effect of the SSTA is to change the exchanges of the sensible heat and the water vapour between the air and the sea,through the consequent changes of temperature and the flow fields and the feedback process of condensation,the SSTA finally affects precipitation.
基金国家重点基础研究发展计划(973计划)，Prediction Theory of Severe Climate Disasters in China，科技部"攀登计划"
文摘By prescribing sea surface temperature anomalies(SSTAs)over eastern equatorial Pacific in January—March,the lag influence of ENSO(El Nino and La Nina)on monsoon over East Asia has been studied.The results suggest that,due to the excitation of atmospheric low-frequency oscillation by the SSTA,ENSO has significant lag influence on the monsoon over East Asia. During the summer after E1 Nino,the subtropical high over western Pacific is intensified and shows the northward and westward displacement,meanwhile,the rainfall over East China is below normal,especially in North China:during the winter after E1 Nino,both the Asian trough and the winter monsoon over East Asia are strengthened.During the summer after La Nina,the anomalous subtropical high prevails over the lower reaches of Yangtze(Changjiang)River,the rainfall between Yangtze and Huaihe Rivers is below normal:during the winter after La Nina, both the Asian trough and the winter monsoon over East Asia are weaker.Compared with La Nina,the effect of El Nino is stronger,but it is not always opposite to the one of La Nina.
基金Supported by the National Natural Science Foundation of China(41375059,41690123,41690120,41661144019,and 41375081)China Meteorological Administration(CMA)Special Public Welfare Research Fund(GYHY201306022)+1 种基金State Key Laboratory for Severe Weather Special Fund(2016LASW-B01)Research Fund of CMA Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction
文摘Increased evidence has shown the important role of Atlantic sea surface temperature(SST) in modulating the El Nio-Southern Oscillation(ENSO). Persistent anomalies of summer Madden-Julian Oscillation(MJO) act to link the Atlantic SST anomalies(SSTAs) to ENSO. The Atlantic SSTAs are strongly correlated with the persistent anomalies of summer MJO, and possibly affect MJO in two major ways. One is that an anomalous cyclonic(anticyclonic) circulation appears over the tropical Atlantic Ocean associated with positive(negative) SSTA in spring, and it intensifies(weakens) the Walker circulation. Equatorial updraft anomaly then appears over the Indian Ocean and the eastern Pacific Ocean, intensifying MJO activity over these regions. The other involves a high pressure(low pressure) anomaly associated with the North Atlantic SSTA tripole pattern that is transmitted to the mid-and low-latitudes by a circumglobal teleconnection pattern, leading to strong(weak) convective activity of MJO over the Indian Ocean. The above results offer new viewpoints about the process from springtime Atlantic SSTA signals to summertime atmospheric oscillation, and then to the MJO of tropical atmosphere affecting wintertime Pacific ENSO events, which connects different oceans.
基金National Natural Science Foundation of China with Grant 49475258.
文摘A T_(42)L_9 GCM integration is adopted to investigate in detail the effect of Northwest Pacific sea surface temperature anomaly(SSTA)on the Pacific storm track(PST)during winter.Results show that warm(cold)Northwest Pacific SSTA can give rise to significantly increased (decreased)baroelinicity on the north side of the anomaly area and its downstream in such a way as to make the Pacific storm track strengthen(weaken)in its entrance where the 500 hPa synoptic perturbation height variance,kinetic energy,and low-level upward and poteward transient eddy temperature fluxes who exhibit similar features to those of mid-latitude barolinic waves in their developing phases,show great enhancement for the warm case,suggesting that the Pacific track can be reconstructed in its west side only as a result of an external forcing,viz.,warm Northwest Pacific SSTA during winter.
文摘By the numerical simulation,the sea surface temperature anomaly(SSTA)of the Pacific and Indian Oceans.being introduced into IAP AGCM,the observed anomalous circulation characteristics on the monthly mean 850 hPa have been confirmed:during an El Nino episode there appears anomalous westerly flow in the low-level atmosphere over the low-latitude Pacific and the anomalous equatorward air flow over the Southeast Asia coast:during a La Nina episode there appears anomalous easterly flow in the low-level atmosphere over the low-latitude Pacific and the anomalous off-equator air flow over the Southeast Asia coast.If we introduce only Pacific SSTA into or take off orographic forcing from the model,the simulated anomalous air flow in the low- level atmosphere over the low latitudes will be different.The precipitation departure in conformity with the observation over the low latitudes has been simulated with this model as well.
基金This work was supported by the National Key Basic Science Program in China (Grant No.1998040903) and Chinese NSF (Grant No 498
文摘The SST variation in the equatorial Indian Ocean is studied with special interest in analyzing its dipole oscillation feature. The dipole oscillation appears to be stronger in September-November and weaker in January-April with higher SST in the west region and lower SST in the east region as the positive phase and higher SST in the east region and lower SST in the west region as the negative phase. Generally, the amplitude of the positive phase is larger than the negative phase. The interannual variation (4-5 year period) and the interdecadal variation (25-30 year period) also exist in the dipole. The analyses also showed the significant impact of the Indian Ocean dipole on the Asian monsoon activity, because the lower tropospheric wind fields over the Southern Asia, the Tibetan high in the upper troposphere and the subtropical high over the northwestern Pacific are all related to the Indian Ocean dipole. On the other, the Indian Ocean dipole still has significant impact on atmospheric circulation and climate in North America and the southern Indian Ocean region (including Australia and South Africa).
基金the Major State Basic Research & Development Program under No. 2004CB418300 from the Ministry of Science and Technology of Chinathe NSFC Key Project under No. 40675034the Sino-Japan Research Center for Meteorological Disaster, the JICA project.
文摘The study examined effects of sea surface temperature anomalies （SSTAs） off the east coast of Japan on the blocking high over the Okhotsk Sea in June by diagnostic analysis and numerical simulation. Firstly, based on 500-hPa geopotential height fields, the Okhotsk high index （OKHI） for June from 1951 to 2000 is calculated and analyzed. The result indicates that the OKHI has obvious inter-annual and inter-decadal vaxiations, and there are 9 yr of high OKHI and 8 yr of low OKHI in 50 yr. Secondly, by using the OKHI, the relationship between the Okhotsk high and the 500-hPa geopotential height anomaly is investigated. The results indicate that the ＂＋-＋＂ pattern of geopotential height anomaly crossing Eurasia in the mid-high latitudes and the ＂＋-＂ pattern of geopotential height anomaly from high to low latitudes over East Asia are in favor of the formation and maintenance of the Okhotsk high. The relationship between the OKHI and the SSTA over the North Pacific is investigated in early summer by using correlation and composite analysis. We found that when the blocking circulation over the Okhotsk Sea occurs, there is an obvious negative SSTA off the east coast of Japan in early summer. We simulated the effects of the negative SSTA of east coast of Japan on the atmospheric circulation anomaly over East Asia through the control and sensitivity experiments using NCAR CAM3 model in order to confirm our analysis results. The simulation shows that the negative SSTA off the east coast of Japan results in the significant positive 40 gpm 500-hPa geopotential height anomaly over the Okhotsk Sea and the negative anomalies off the east coast of Japan which might contribute to the formation and development of the Okhotsk high in June.
