Atmospheric Circulation Characteristics of VariType Cold Rainy Weather in Spring Sowing and SeedlingRaising Periods in Hunan Province
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Abstract:
Based on the daily precipitation, temperature and sunshine data from 80 meteorological stations in Hunan, NCEP/NCAR reanalysis data and sea temperature data from 1961 to 2013, the distribution types, the circulation patterns of the same period, and the previous winter SST field characteristics of cold rainy weather during spring sowing and seedlingraising periods in the past 53 years are studied. The results show: (1) There are mainly two anomalous distribution types: above normal (below normal)in whole province; above normal (below normal)in the northern and below normal (above normal) in the southern.(2) When East Asia major trough controls over the Eurasia, coupled with the convergence of lowlevel cold and worm air and the better humidity conditions, the above normal in whole province types is prone to appear. On the contrary, when the Eurasia is controlled by high pressure, coupled with the lowlevel abnormal north winds in the mideastern China and negative relative humidity, the below normal in whole province type is easy to appear. When the northern Hunan is affected by a trough and relative humidity is relatively high, the above normal in the northern province and below normal in the southern province types are easy to appear. When the southern Hunan is affected by a trough and topography and the Nanling stationary front, at the same time, the relative humidity in its south part is relatively high, the below normal in the northern province and above normal in the southern province types are easy to appear.(3) The above normal (below normal) in whole province type is easy to appear if the previous winter SST in the area of the equatorial central and eastern Pacific and Alaska is obviously higher (lower) than normal and that in the area of the Northwest Pacific Ocean and North Atlantic Ocean in the east of North America is obviously lower (higher) than normal. The above normal (below normal) in the northern province and below normal (above normal) in the southern province type is easy to appear if the previous winter SST is obviously higher (lower) than normal in both the area of the equatorial central and eastern Pacific and Alaska and the area of the Northwest Pacific Ocean, and that in the North Atlantic Ocean in the east of North America.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.