In terms of the expansion by extended empirical orthogonal function (EEOF) with data of ECMWF WMO and of outgoing longwave radiation(OLR) furnished by the NOAA polar-orbiting satellite,a study is made of November 1981...In terms of the expansion by extended empirical orthogonal function (EEOF) with data of ECMWF WMO and of outgoing longwave radiation(OLR) furnished by the NOAA polar-orbiting satellite,a study is made of November 1981 to March 1982 low-frequency (30--60 day)summer monsoon activity in the Indone- sian-North Australian zone (INAZ) together with its relation to atmospheric circulations in the Northern and Southern Hemispheres. Results show that at 850 hPa the southward blowing low-frequency NE(SW)wind from the eastern Asian coast changes, after crossing the euqator, to summer NW (SE) monsoon in the INAZ, which, when converging with (diverging from) the western-Australian enforced low-frequency SW (NE) wind, brings about strengthened (weakened) convection in the summer monsoon area and its eastward advance, with corresponding low- frequency variation shown in 850 hPa geopotential height. These outcomes are similar to those from the study of non-filtered actual observations, leading to the conclusion that the component of low-frequency variation illustrates major features characteristic of the variation in the tropical circulation.展开更多
基金The study is jointly supported by National Natural Science Foundation of Chinathe State Meteorological Administration Monsoon Research Funds.
文摘In terms of the expansion by extended empirical orthogonal function (EEOF) with data of ECMWF WMO and of outgoing longwave radiation(OLR) furnished by the NOAA polar-orbiting satellite,a study is made of November 1981 to March 1982 low-frequency (30--60 day)summer monsoon activity in the Indone- sian-North Australian zone (INAZ) together with its relation to atmospheric circulations in the Northern and Southern Hemispheres. Results show that at 850 hPa the southward blowing low-frequency NE(SW)wind from the eastern Asian coast changes, after crossing the euqator, to summer NW (SE) monsoon in the INAZ, which, when converging with (diverging from) the western-Australian enforced low-frequency SW (NE) wind, brings about strengthened (weakened) convection in the summer monsoon area and its eastward advance, with corresponding low- frequency variation shown in 850 hPa geopotential height. These outcomes are similar to those from the study of non-filtered actual observations, leading to the conclusion that the component of low-frequency variation illustrates major features characteristic of the variation in the tropical circulation.
