By using the monthly average dataset of NCEP/NCAR reanalysis and the monthly average ocean temperature data of NOAA satellite center,we analyzed and probed into the relationship between Siberian high anomaly and SSTA,...By using the monthly average dataset of NCEP/NCAR reanalysis and the monthly average ocean temperature data of NOAA satellite center,we analyzed and probed into the relationship between Siberian high anomaly and SSTA,and found that the sea area anomaly is a bigger area,which have greater effect on the variation of Siberian high.The results indicated that there was a wonderful contemporaneously correlation between the area and intensity index of Siberian high and ocean temperature.The correlation type of the synchronous correlative areas between the central intensity index of Siberian high and ocean temperature have structural similarities with the correlative field's structure of area index,but the positive correlative regions expanded,and the intensity of negative correlative regions weakened significantly.The correlation among the area index of Siberian high and the central intensity index,as well as the ocean temperature anomaly of the North Atlantic during spring,autumn and summer of the same year was remarkable.The area index and the central intensity index of Siberian high anomaly have obvious correlation with the ocean temperature anomaly of Southwest Atlantic Ocean during spring,summer and autumn,however,they have apparent seasonal differences with the prominent negative correlative areas of subtropical South Indian Ocean and tropical South Pacific Ocean as well as Southwest Atlantic Ocean.The correlative index of area anomaly is greater than those of intensity anomaly.Larger impact on the variability of Siberian high anomaly are the SSTA of subtropical South Indian Ocean,mid and high latitudes of North Pacific Ocean,North Atlantic,tropical South Pacific Ocean,Southwest Atlantic Ocean,etc.several areas.展开更多
Using the monthly mean data from NCEP-NCAR reanalysis, through building tropopause pressure index, we investigated the mechanisms of anomalous variations of tropopause pressure over the Tibetan Plateau during summer i...Using the monthly mean data from NCEP-NCAR reanalysis, through building tropopause pressure index, we investigated the mechanisms of anomalous variations of tropopause pressure over the Tibetan Plateau during summer in Northem Hemisphere. For comparative analysis we selected representative years of 1992 and 1998 to study, and they were respectively the highest and the lowest year oftropopause pressure anomaly over the Tibetan Plateau. The results are summarized as follows： （1） Over the Tibetan Plateau, the variations of tropopause pressure are well correlated respectively with anomalous temperature and geopotential height in both troposphere and stratosphere. Besides, the anomalous tropopause pressure has also close relation with anomalous surface temperature in the Tibetan Plateau. In 1992, the surface temperature was anomalously low, correspondingly, the tropopause pressure over the Tibetan Plateau was anomalously high; but in 1998, the opposite was the case. （2） Over the Tibetan Plateau, the correlation of tropopause pressure and OLR （Outgoing Longwave Radiation） is found to be positive. Furthermore, by further diagnosing the circulation fields between 850 hPa and 200 hPa levels and the whole troposphere vapour field, we found out that the anomalously high tropopause pressure in 1992 corresponded to the anticyclonic divergence of low level wind fields and the cyclonic convergence of high level wind fields, and coupled with divergence of the whole troposphere vapour fields along with the South Asian High weakened at the same time. While in 1998, the case was opposite to that in 1992. These facts indicated that the anomalous convection resulted in the significant difference oftropopause pressure in 1992 and 1998 over the Tibetan Plateau. （3） The vertically integrated heat budget anomalies were responsible for explaining tropopause pressure anomalies in 1992 and 1998 over the Tibetan Plateau.展开更多
文摘By using the monthly average dataset of NCEP/NCAR reanalysis and the monthly average ocean temperature data of NOAA satellite center,we analyzed and probed into the relationship between Siberian high anomaly and SSTA,and found that the sea area anomaly is a bigger area,which have greater effect on the variation of Siberian high.The results indicated that there was a wonderful contemporaneously correlation between the area and intensity index of Siberian high and ocean temperature.The correlation type of the synchronous correlative areas between the central intensity index of Siberian high and ocean temperature have structural similarities with the correlative field's structure of area index,but the positive correlative regions expanded,and the intensity of negative correlative regions weakened significantly.The correlation among the area index of Siberian high and the central intensity index,as well as the ocean temperature anomaly of the North Atlantic during spring,autumn and summer of the same year was remarkable.The area index and the central intensity index of Siberian high anomaly have obvious correlation with the ocean temperature anomaly of Southwest Atlantic Ocean during spring,summer and autumn,however,they have apparent seasonal differences with the prominent negative correlative areas of subtropical South Indian Ocean and tropical South Pacific Ocean as well as Southwest Atlantic Ocean.The correlative index of area anomaly is greater than those of intensity anomaly.Larger impact on the variability of Siberian high anomaly are the SSTA of subtropical South Indian Ocean,mid and high latitudes of North Pacific Ocean,North Atlantic,tropical South Pacific Ocean,Southwest Atlantic Ocean,etc.several areas.
基金supported jointly by the National Basic Research Program of China (2010CB428602)the National Natural Science Foundation of China (41005046,40675025)
文摘Using the monthly mean data from NCEP-NCAR reanalysis, through building tropopause pressure index, we investigated the mechanisms of anomalous variations of tropopause pressure over the Tibetan Plateau during summer in Northem Hemisphere. For comparative analysis we selected representative years of 1992 and 1998 to study, and they were respectively the highest and the lowest year oftropopause pressure anomaly over the Tibetan Plateau. The results are summarized as follows： （1） Over the Tibetan Plateau, the variations of tropopause pressure are well correlated respectively with anomalous temperature and geopotential height in both troposphere and stratosphere. Besides, the anomalous tropopause pressure has also close relation with anomalous surface temperature in the Tibetan Plateau. In 1992, the surface temperature was anomalously low, correspondingly, the tropopause pressure over the Tibetan Plateau was anomalously high; but in 1998, the opposite was the case. （2） Over the Tibetan Plateau, the correlation of tropopause pressure and OLR （Outgoing Longwave Radiation） is found to be positive. Furthermore, by further diagnosing the circulation fields between 850 hPa and 200 hPa levels and the whole troposphere vapour field, we found out that the anomalously high tropopause pressure in 1992 corresponded to the anticyclonic divergence of low level wind fields and the cyclonic convergence of high level wind fields, and coupled with divergence of the whole troposphere vapour fields along with the South Asian High weakened at the same time. While in 1998, the case was opposite to that in 1992. These facts indicated that the anomalous convection resulted in the significant difference oftropopause pressure in 1992 and 1998 over the Tibetan Plateau. （3） The vertically integrated heat budget anomalies were responsible for explaining tropopause pressure anomalies in 1992 and 1998 over the Tibetan Plateau.
