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In order to investigate the dew amounts and analysis formation conditions of dew by examining the correlations between dew amounts and meteorological factors in Carex lasiocarpa marsh in the Sanjiang Plain, the dew amounts and several meteorological factors were monitored during the growing season from June to September in 2005 and 2008 at the Sanjiang Mire Wetland Experimental Station, Chinese Academy of Sciences. Dew was collected by woodstick made by poplar tree in Carex lasiocarpa marsh and the amounts were estimated by subtraction method. The results indicated that average daily accumulated dew amounts reached the peak in August. The highest dew amounts in Carex lasiocarpa marsh were 0.201 mm/d, and the most frequent dew volume ranged from 0.08 mm/d to 0.14 mm/d. The amounts correlated positively with relative humidity, dew point temperature, and water vapor pressure. Whereas it correlated negatively with wind speed. The dew production in Carex lasiocarpa marsh more frequently occurred under the conditions of wind speed around 2.0 m/s, the water vapor pressure above 9 hPa; the relative humidity between 90% and 95% and dew point temperature above 6 ℃. 相似文献
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It is generally thought that the influence of comparable track typhoons is approximately similar,
but in fact their wind and especially their rainstorm distribution are often very different. Therefore, a
contrastive analysis of rainstorms by tropical cyclones (TCs) Haitang (0505) and Bilis (0604), which are of
a similar track, is designed to help understand the mechanism of the TC rainstorm and to improve
forecasting skills. The daily rainfall of TC Haitang (0505) and Bilis (0604) is diagnosed and compared.
The result indicates that these two TCs have similar precipitation distribution before landfall but different
precipitation characteristics after landfall. Using NCEP/GFS analysis data, the synoptic situation is
analyzed; water vapor transportation is discussed regarding the calculated water vapor flux and divergence.
The results show that the heavy rainfall in the Zhejiang and Fujian Provinces associated with Haitang
(0505) and Bilis (0604) before landfall results from a peripheral easterly wind, a combination of the
tropical cyclone and the terrain. After landfall and moving far inland of the storm, the precipitation of
Haitang is caused by water vapor convergence carried by its own circulation; it is much weaker than that in
the coastal area. One of the important contributing factors to heavy rainstorms in southeast Zhejiang is a
southeast jet stream, which is maintained over the southeast coast. In contrast, the South China Sea
monsoon circulation transports large amounts of water vapor into Bilis – when a water-vapor transport belt
south of the tropical cyclone significantly strengthens – which strengthens the transport. Then, it causes
water vapor flux to converge on the south side of Bilis and diverge on the north side. Precipitation is much
stronger on the south side than that on the north side. After Bilis travels far inland, the cold air guided by a
north trough travels into the TC and remarkably enhances precipitation. In summary, combining vertical
wind shear with water vapor transportation is a good way to predict rainstorms associated with landing
tropical cyclones. 相似文献