基于马尔科夫链转移概率极限分布的降水过程持续性研究

各地不同气候条件所具有的天气状态转移概率的极限分布实际上代表了各地天气气候的持续性和转折性特征,同时也表明了它的可预报期限。从马尔科夫链理论出发,初步研究了中国160个代表测站逐日天气状态演变过程的极限分布。结果表明,转移概率的极限分布不但其空间分布有明显差异,而且不同季节的极限分布也有明显差异。例如,有的地区仅有2 d持续期,有的可达4—6 d或更长,充分反映出不同地区因其影响的天气系统差异所造成的逐日天气气候的持续性和转折性特征的差异。其研究意义在于,由此可作为天气气候分型区划的一种理论依据。统计分析结果表明,就全中国平均而言,夏季持续期最短,持续期由北向南、由西向东呈增加趋势,且春季平均降水持续期为5.1 d,夏季平均为5.0 d,秋季平均为6.5d,冬季平均为6.2 d。可见夏半年比冬半年的降水持续期短,这可能是因为春夏季的天气系统比较复杂且中小尺度天气系统较多的缘故。这从另一侧面再次证明,各地逐日降水天气状态演变过程具有一定的天气气候状态自然转折的持续性即自然天气周期的气候状况,从而为短期天气预报提供了气候背景。

An investingation into continuous precipitation based on the Markov transition probability limit distribution

The transition probability limit distribution of weather conditions in a different climate condition actually represents persistence and transition of the climate, at the same time indicates its predictable period. This paper preliminarily studies the limit distribution of the daily weather condition evolution for 160 stations in China, based on the Markov chain theory. The research shows inherent difference of persistence and transition of daily weather conditions caused by the difference in affecting weather system in the different areas. For example, there is continuous raining for two days in some areas. while 4-6 d or longer in other area. The results of statistical analysis show that the nationwide average duration is the shortest in summer and presents an increasing trend from north to south as well as from west to east. The average rainfall duration in spring lasts 5.1 d, 5 d in summer. 6.5 d in autumn and 6.2 d in winter. It means that the rainfall duration in summer half years is shorter than in winter half year. The reason might be that the weather systems are more complicated and meso- and small-scale weather systems are more in spring and summer. It proves once again from another side that the evolution process of the daily precipitation weather conditions in the various regions displays the natural transition sustainability of a certain state of weather and climate, namely the climate condition of natural weather cycle, which provides the climate background for the short-term weather forecast.