The summer of 1998 was characterised by a severe flood in East Asia. The possible linkages were examined among the anomalies in the tropics that may be associated with the severe flood. The anomalies of 1998 are obtai...The summer of 1998 was characterised by a severe flood in East Asia. The possible linkages were examined among the anomalies in the tropics that may be associated with the severe flood. The anomalies of 1998 are obtained by removing the climatology, which is the average of the ECMWF (European Centre for Medium Range Weather Forecasts) Re—Analysis (ERA) data over 15 years from 1979 to 1993, from the corresponding fields of 1998, which are obtained from the ECMWF operational analyses. In comparison to the results of Nitta (1990), it was found that there are considerable similarities in the atmospheric circulation anomalies between the summers of 1998 and 1988, in the tropics as well as in middle—high latitudes. It was shown that the atmospheric convection is slightly suppressed over the tropical western Pacific. In general, the suppressed convection corresponds to a negative anomaly of SST in the warm pool region. In the summers of 1998 and 1988, however, there are positive anomalies of SSTs in the tropical western Pacific, corresponding to the suppressed convection over there. This slightly suppressed convection may not provide a viable forcing mechanism for the severe flood in East Asia. It was postulated that the zonal wind anomalies in the tropics, in addition to the atmospheric convection over the tropical western Pacific, influence the position and intensity of the North Pacific subtropical high. In both summers of 1998 and 1988, while the stronger convection occurs over the warmer tropical Indian Ocean, the suppressed convection corresponds to the positive anomalies of SSTs in the tropical western Pacific. A possible explanation was given for the broken relationship between SSTs and OLR, (Outgoing Longwave Radiation) by analyzing the large—scale atmospheric circulation anomalies in the tropics. The heat fluxes at the surface in the warm pool of the tropical western Pacific and tropical Indian Ocean were also examined by using the ERA–15 data. To avoid the inconsistency between the ERA–15 and the op展开更多
基金the National Natural Science Foundation of China ! 49605065"National Key Programme for Developing Basic Sciences"! G19980409
文摘The summer of 1998 was characterised by a severe flood in East Asia. The possible linkages were examined among the anomalies in the tropics that may be associated with the severe flood. The anomalies of 1998 are obtained by removing the climatology, which is the average of the ECMWF (European Centre for Medium Range Weather Forecasts) Re—Analysis (ERA) data over 15 years from 1979 to 1993, from the corresponding fields of 1998, which are obtained from the ECMWF operational analyses. In comparison to the results of Nitta (1990), it was found that there are considerable similarities in the atmospheric circulation anomalies between the summers of 1998 and 1988, in the tropics as well as in middle—high latitudes. It was shown that the atmospheric convection is slightly suppressed over the tropical western Pacific. In general, the suppressed convection corresponds to a negative anomaly of SST in the warm pool region. In the summers of 1998 and 1988, however, there are positive anomalies of SSTs in the tropical western Pacific, corresponding to the suppressed convection over there. This slightly suppressed convection may not provide a viable forcing mechanism for the severe flood in East Asia. It was postulated that the zonal wind anomalies in the tropics, in addition to the atmospheric convection over the tropical western Pacific, influence the position and intensity of the North Pacific subtropical high. In both summers of 1998 and 1988, while the stronger convection occurs over the warmer tropical Indian Ocean, the suppressed convection corresponds to the positive anomalies of SSTs in the tropical western Pacific. A possible explanation was given for the broken relationship between SSTs and OLR, (Outgoing Longwave Radiation) by analyzing the large—scale atmospheric circulation anomalies in the tropics. The heat fluxes at the surface in the warm pool of the tropical western Pacific and tropical Indian Ocean were also examined by using the ERA–15 data. To avoid the inconsistency between the ERA–15 and the op
