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Huang Y.,Nanjing University of Information Science and Technology | Huang Y.,Anhui Key Laboratory of Atmospheric Science and Satellite Remote Sensing | Huang Y.,Anhui Institute of Meteorology Science | Wang X.,Nanjing University of Information Science and Technology | And 5 more authors.
Journal of Remote Sensing | Year: 2013

Three kinds of satellite infrared imagery from 2001 to 2009, namely, GMS-5, FY-2B, and FY-2C, were used to study the characteristics of convective cloud mergers in summer severe weather in the Huaihe and Yangtze River basin. In the 35 heavy rain and 43 hailstorm cases, the occurrence probabilities of cloud merger were 94% and 65%, respectively. The average cloud merging times were 11.6 and 1.9. In addition, five statistic factors, namely, distance of two clouds (Dis), ratio of two cloud areas (Ar), minimum of two cloud top bright temperature clouds (Tmin), difference of two cloud top lowest bright temperature (dTmin), and change of Tmin (ΔTmin), were calculated and compared in the cases of hailstorm and heavy rain. Three similar points were found for the two kinds of severe weather. The quantities of the four factors comprised the main differences of the merging process in the two kinds of severe weather. Based on the combination of Tmin and dTmin, the cloud top temperature conditions and the statistic probabilities of occurrence with different Ar were analyzed. Finally, three indicators for severe weather forecasting were revealed with Dis and Ar factors.

Qin D.,Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites | Qin D.,Institute of Satellite Meteorology | Li B.,Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites | Li B.,Institute of Satellite Meteorology | And 2 more authors.
Advances in Atmospheric Sciences | Year: 2014

Based on normalized six-hourly black body temperature (TBB) data of three geostationary meteorological satellites, the leading modes of the mei-yu cloud system between 1998 and 2008 were extracted by the Empirical Orthogonal Function (EOF) method, and the transition processes from the first typical leading mode to other leading modes were discussed and compared. The analysis shows that, when the southern mode (EOF1) transforms to the northeastern mode (EOF3), in the mid-troposphere, a low trough develops and moves southeastward over central and eastern China. The circulation pattern is characterized by two highs and one low in the lower troposphere. A belt of low pressure is sandwiched between the weak high over central and western China and the strong western North Pacific subtropical high (WNPSH). Cold air moves southward along the northerly flow behind the low, and meets the warm and moist air between the WNPSH and the forepart of the low trough, which leads to continuous convection. At the same time, the central extent of the WNPSH increases while its ridge extends westward. In addition, transitions from the southern mode to the dual centers mode and the tropical-low-influenced mode were found to be atypical, and so no common points could be concluded. Furthermore, the choice of threshold value can affect the number of samples discussed. © 2014 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

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