Freezing Weather Characteristics And Geneticanalysisin Hunan Province

This article is research on the Hunan history records and meteorological data (including 1971～2009 years daily observation data and NCEP/NCAR day average reanalysis data) for statistical analysis, research Hunan freezing weather and climate features. On the basis of Hunan 2011 and 2008 large range freezing weather process for case analysis, do in-depth comparison on 2008 and 2005 Hunan of freezing weather. Revealed out that Hunan freezing weather produced background and formation mechanism, including circulation features, weather situation and temperature,humidity features, and various meteorological factors and the terrain effect, for weather forecast business need, determined Hunan freezing weather especially large range freezing weather forecast of focus and difficulties, and refined out Hunan freezing weather of forecast index, further improve has Hunan freezing weather of better forecast level. Study results showed that:freezing weather has a lot of cizes. Hunan freezing winter is almost every year occurs, from the season distribution, Hunan freezing winter is general from late November to the following year March mid-end. The terrain of distribution on Hunan freezing weather of formation and development has important effect role, in addition, Hunan freezing weather also has obvious of spatio-temporal distribution features, regions frozen of time, and strength,the end time are not as the same.Hunan frozen precipitation and temperature variation are closely related with the strength of Hunan freezing weather, sustainable water supply and low-temperature maintained frozen the greater strength, also performed for the relationship between meteorological elements and frozen strength.In general, Hunan freezing weather forecasting needs to focus on weather factors mainly in atmospheric circulation, moisture conditions, atmospheric condition, followed by the terrain and local effects of meteorological factors. In high latitude in the height field of the Eurasian continent and blocking established, stable or not on the formation of freezing weather in Hunan, sustainable development and is of important guiding significance, the more stable blocking high, the longer duration of freezing weather in Hunan province. In low latitude, the more strong subtropical, the more West of location, Bengal South slots more stability, the more conducive to the continued supply of water vapor, stronger cold air in the North, the principal location on the North, southward diffusion more times be conducive to Hunan low temperature last. Adequate of moisture and sustained low temperature are important guarantee for the freezing weather continued and development in Hunan. Hunan's geographical location makes southward spread of cold air and the Bay of Bengal in the North of the warm, moist air also is conducive to the intersection for a long time in a continuous supply of water vapor is also very beneficial to the lower cold layer of temperature inversion layer and underlying establish and deepen. And middle-level establishment and duration of the temperature inversion layer on the formation and development of Hunan freezing weather has instructed the very important role. According to the development of these systems change,we can reach the basic forecasts of freezing weather forecasting.It is important to consider the wide range of frozen weather forecasting in Hunan province.The difficulties in forecasting is a refinement of the city and County of Hunan province freezing weather forecast.