Abstract:

Based on the monthly precipitation data from 71 observation stations in Hebei Province from 1961 to 2021 and the NCEP/NCAR reanalysis data, the temporal and spatial variability characteristics and associated factors of precipitation relative variability were analyzed for different climatic subregions of Hebei province through regression analysis and trend analysis. The results indicate that there are significant differences in precipitation relative variabilities across different timescales, with smaller timescales exhibiting larger relative variability. That is, the seasonal precipitation relative variability is greater than that of annual precipitation, which is lower than that of monthly precipitation. The annual precipitation relative variability in Hebei province ranges from 13.5% to 29.8%, with an average of 14.9%. Among the different subregions, the plain areas exhibit greater annual precipitation relative variability, while the Bashang region shows relatively smaller variability. Besides, except for the Bashang region, it shows decreasing trends in the 5 years changes of annual precipitation relative variability over the northern mountainous region, western mountainous region, coastal region, and plain region. Factors such as altitude, urbanization, and atmospheric circulation have significant impacts on the precipitation stability in Hebei province. When the low altitude and low urbanization are accompanied by a westerly wind anomaly at 200 hPa near 40°N and a zonal distribution of cyclonic-anticyclonic-cyclonic systems at 850 hPa, the strong ascending or descending motion circulations may lead to irregular precipitation variability in Hebei province.

Key words: Precipitation, Relative variability, Climatic subregion