Abstract:

In order to explore the fundamental causes of leading to agricultural drought in the northern Shanxi Province and putting forward targeted measures for responding drought, the main climatic factors of affecting evaporation were proposed based on the Penman formulas and Magnus formulas. As well as, the cause of bringing about drought in spring and early summer in the northern Shanxi Province was analyzed based on the methods of the linear trend analysis and polynomial fitting with the meteorological data of the nearly 50 years. The results showed that the fundamental cause of leading to agricultural drought in the northern Shanxi Province was unbalanced between precipitation and evaporation. There were two reasons for the unbalance. On the one hand, the main period of precipitation was in between June and September, and the peak of evaporation appeared in between April and July. On the other hand, the air temperature arised at the rate of 0.33℃/10 a and the saturation deficit increased at the rate of 0.17 hpa/10 a, which directly led to the increase of evaporation. Sunshine duration made a little contribution to evaporation, for the increase rate of evaporation was 5.06 mm/10 a in 50 years and in the same period, the sunshine duration declined at the rate of -2.84 h/10 a, which showed that the sunshine duration was not the main fact of affecting drought. In short, the main climatic factors of affecting drought in the northern Shanxi Province were the same to the most areas of country, but nearly to the northern.