Relationship between establishment of South Asia high over the Indo-China Peninsula and splitting of 500 hPa subtropical high over the Bay of Bengal in springtime
Based on the NCEP/NCAR reanalysis and NOAA OLR data, this paper studies the relation- ship between the establishment of South Asian high (SAH) over the Indo-China Peninsula (ICP) and the splitting of 500 hPa subtropical high over the Bay of Bengal ( BOB ) in springtime. Results show that,before the establishment of SAH, the convective activity extends northward from the "Maritime Continent" and establishes initially over the ICP. In concert with this, a local anti-Hadley cell displays in the mid-lower tropospheres over BOB due to the sensible heating induced by the Tibet Plateau. This local meridional cell results in a descending center near the 15°N of BOB from 500 hPa to 700 hPa, which suppresses the development of convective activity and thus becomes unfavorable for the splitting of 500 hPa subtropical high in this region. After the establishment of SAH over ICP, a strong divergence centre shows in the upper troposphere over BOB, accompanied by disappearance of the mid-low tropo- spheres descending center near the 15°N of BOB. Consistent with this, convective activity develops over BOB and coincides with increasing of precipitation and releasing of latent heating. This induces a diabatic maximum center at 500 hPa and thus intercepts the ridge of subtropical high over BOB. There- fore, the divergence effect induced by the upper SAH establishment possibly triggers the establishment of convective activity and the splitting of 500 hPa subtropical high over BOB.
South Asia highsubtropical highBay of BengalIndo-China Peninsulaconvective activity
国家科技期刊平台
NSTL
万方数据
维普
