关键词: 细胞同步化, 细胞同步化, S期, 羟基脲

Abstract: In order to improve the forecasting and service ability of heavy rainfall in Tianshui area, based on data of surface observation and Micaps observation in Tianshui from 1965 to 2011, the author analyzed the temporal and spatial distribution characteristics, structure characteristics of heavy rainfall in Tianshui area, using statistical methods, the principle of synoptic meteorology and the mesoscale analysis technology. The results showed that the frequency of heavy rainfall was about 2.38 times per year with a slight downtrend of 0.135 times per decade; however, there had no significant trend change in the past 47 years. The heavy rainfall mainly occurred from April to October, especially in July and August. Heavy rainfall frequency increased from Weibei area to Hegu area and Guanshan area. The spatial distribution of heavy rainfall had good relationship with topographic feature. According to the corresponding circulation form, heavy rainfall could be roughly divided into four kinds, which were named as west low east high pattern, southwest airflow around subtropical high northwest edge pattern, low vortex variant cutting pattern, and subtropical high control pattern, respectively. In general, the southwest airflow around subtropical high northwest edge pattern played a dominant part. The other three patterns of heavy rainfall accounted for relatively a small part in the total rainfall. Moreover, the corresponding main weather systems and configuration, heavy rainfall area, and physical indicators varied significantly under the different circulation forms.