By use of the filter analysis technique, the Complex Empirical Othogonal Function (CEOF) method and the ECMWF/WMO 2.5°×2.5°grid data of the geopotential heights during the summer months in 1988, an inte...By use of the filter analysis technique, the Complex Empirical Othogonal Function (CEOF) method and the ECMWF/WMO 2.5°×2.5°grid data of the geopotential heights during the summer months in 1988, an interseasonal process that the western Pacific subtropical high (WPSH) was anomalously far to the north in the first and second ten days of July is studied. It has been found that in the western Pacific subtropical region in the first and second ten days of July,it is the continuous assembly of low frequency geopotential waves (LFGWs) that leads to the abnormality of WPSH. This abnormality emerges with the enhancement of wave assembling and ceases while the wave assembling situation disappears. The structure of the low frequency assembling waves corresponds to the structure of subtropical high in its abnormal period. The effect of the assembling waves on the abnormality of subtropical high can be considered as the accumulation of disturbance energy carried by the low frequency waves from different directions in the western Pacific region.展开更多
Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 &...Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.展开更多
文摘By use of the filter analysis technique, the Complex Empirical Othogonal Function (CEOF) method and the ECMWF/WMO 2.5°×2.5°grid data of the geopotential heights during the summer months in 1988, an interseasonal process that the western Pacific subtropical high (WPSH) was anomalously far to the north in the first and second ten days of July is studied. It has been found that in the western Pacific subtropical region in the first and second ten days of July,it is the continuous assembly of low frequency geopotential waves (LFGWs) that leads to the abnormality of WPSH. This abnormality emerges with the enhancement of wave assembling and ceases while the wave assembling situation disappears. The structure of the low frequency assembling waves corresponds to the structure of subtropical high in its abnormal period. The effect of the assembling waves on the abnormality of subtropical high can be considered as the accumulation of disturbance energy carried by the low frequency waves from different directions in the western Pacific region.
文摘Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.
