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Dong M.-Y.,Zhejiang Institute of Meteorological science | Chen L.-S.,Chinese Academy of Meteorological Sciences | Li Y.,Chinese Academy of Meteorological Sciences | Cheng Z.-Q.,Guangdong Provincial Meteorological Observatory | Zheng P.-Q.,Zhejiang Provincial Meteorological Observatory
Journal of Tropical Meteorology | Year: 2013

In 2005, significant rainfall reinforcement and severe disaster was induced by tropical cyclone (TC) Talim after it made landfall on the east of China. Observational analyses show that it has relationship with cold air intrusion. For investigating the impact of cold air intensity, we make use of Weather Research and Forecasting (WRF) model, the synthesizer of NCEP/NCAR reanalysis data and Japan regional spectral model data, to carry out numerical experiments. Results show that rainfall reinforcement occurs in all experiments. Different intensity of cold air can modify the rainfall distribution and intensity significantly. In the rainfall center, the increment maximum of rainfall is twice as large as that of the minimum. Moderate cold air intrusion may result in the strongest rainfall reinforcement. Different cold air intensity can lead to different motion of low-level convergence lines and fronts. There is a good relationship between the rainfall region and the eastern part of the front. On one hand, strong cold air weakens the TC intensity by its intrusion into the TC center and results in weak convergence and a convergent zone and a rain band shifted southward. On the other hand, weak cold air reduces the convergence and moves the convergent zone and rain band northward. Moderate cold air intrusion maintains strong low-level convergence and high-level divergence, keeping strong upward motion over certain regions. Consequently, the rain band begins to stagnate and rainfall reinforces abruptly therein.

Li F.,Guangzhou Institute of Tropical and Marine Meteorology | Huang X.-Y.,Guangdong Provincial Meteorological Observatory | Zhang Z.-Y.,Guangzhou Institute of Tropical and Marine Meteorology | Liu X.-T.,Guangzhou Institute of Tropical and Marine Meteorology | And 3 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014

Two typical hazy weather events which occurred in the Pearl River Delta (PRD) cities from Mar. 18 to Mar. 21 and from Oct. 13 to Oct. 15, 2012respectively were selected in this paper. A comprehensive analysis of the causes of the events was made by using the in-situ measurement of visibility (VIS), aerosol mass concentration (PM10/PM2.5/PM1), the concentration of black carbon (BC) at an integrated observation base for atmospheric composition in Panyu, Guangzhou, the weather type, meteorological elements and backward airflow trajectory during these events. The results are shown as follows: Daily visibility was as low as 5.3 km, black carbon's hourly concentration value was up to 19.0 μg/m3, PM2.5's hourly concentration was 163.0 μg/m3 at its highest. These two events were affected by the weather conditions which weren't conducive to the transport or spread of pollutants. In PRD, low visibility of haze weather occurs mainly in condition of high relative humidity. It is deduced that aerosol has greater hygroscopicity in the dry season than in the wet season in this region.

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