Moisture transport over the Arabian Sea associated with summer rainfall over Pakistan in 1994 and 2002 |
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| Authors: | Kalim ULLAH GAO Shouting |
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| Institution: | Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, Graduate University of the Chinese Academy of Sciences, Beijing 100049, Department of Meteorology, COMSATS Institute of Information Technology, Islamabad, Pakistan,Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | In this study, we aimed to elucidate the critical role of moisture
transport affecting monsoon activity in two contrasting summers over the Arabian
Sea during the years 1994, a relatively wet year, and 2002, a relatively dry
year. A comprehensive diagnostic evaluation and comparisons of the moisture
fields were conducted; we focused on the precipitation and evaporation as
well as the moisture transport and its divergence or convergence in the
atmosphere. Monthly mean reanalysis data were obtained from the National
Centers for Environmental Prediction (NCEP-I and -II). A detailed evaluation
of the moisture budgets over Pakistan during these two years was made by
calculating the latent energy flux at the surface (E-P) from the
divergence of the total moisture transport. Our results confirm the moisture
supply over the Arabian Sea to be the major source of rainfall in Pakistan
and neighboring regions. In 1994, Pakistan received more rainfall compared
to 2002 during the summer monsoon. Moisture flow deepens and strengthens
over Arabian Sea during the peak summer monsoon months of July and August.
Our analysis shows that vertically integrated moisture transport flux
have a significant role in supplying moisture to the convective centers over
Pakistan and neighboring regions from the divergent regions of the Arabian
Sea and the Bay of Bengal. Moreover, in 1994, a deeper vertically integrated
moisture convergence progression occurred over Pakistan compared to that in 2002.
Perhaps that deeper convergence resulted in a more intense moisture
depression over Pakistan and also caused more rainfall in 1994 during the
summer monsoon. Finally, from the water budget analysis, it has been
surmised that the water budget was larger in 1994 than in 2002 during the
summer monsoon. |
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| Keywords: | moisture flux moisture convergence convection heavy rainfall |
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