Abstract:

In order to comprehensively grasp the changing law of water and heat resources in Qingyang, improve the level of meteorological forecasting and the ability to guide agricultural production activities, we used the maximum, minimum and average temperature and precipitation data of the 24 solar term days in 8 counties and districts of Qingyang City from 1971 to 2020, and adopted linear trend, polynomial function, correlation analysis, t-test and other methods to study the change rule of climate and response characteristics of Qingyang City based on the 24 solar terms. The results showed that the maximum, minimum and mean temperatures of the 24 solar terms showed an increasing trend and a quasi-normal single-peak distribution, in which the temperatures of the Dashu and Xiaoshu were the highest, and the warming trend was the most significant; the temperature variability and the daily difference of the temperature between the spring and autumn solar terms were large, in which Qingming and Lidong were the two terms with the largest fluctuation of temperature, which was consistent with the period of the early and late frost activities in Qingyang City; the temperature of the phenological solar term, Jingzhe, Qingming, Xiaoman and Mangzhong all showed a fluctuating increase, marking the beginning of different agricultural production periods. After Bailu, the summer heat gradually disappeared, and weather gradually cooled down from Shuangjiang, marking the entry into the wintering period. Qingming-Shuangjiang was Qingyang 's farming period. The precipitation in the 24 solar terms showed a unimodal fluctuation distribution, and the precipitation in Lichun-Dashu gradually increased in one year, and the maximum value appeared in the Liqiu. Guyu-Hanlu solar term was the most precipitation period, accounting for 87% of the total annual precipitation, which was roughly synchronized with the farming period. The precipitation of Chushu-Dahan solar term gradually decreased, and the minimum value appeared in the Winter Solstice; the fastest increase in precipitation was observed in the summer-type solar term, and the fastest decrease in precipitation was observed in the autumn-type solar term. Overall, the increase of heat resources and the fluctuation of precipitation increase, and the same season of rain and heat are conducive to agricultural development; however, the seasonal distribution of precipitation is extremely uneven, and the uncertainty of precipitation in the critical period of crop growth increases the risk of drought. The results of the study are of great practical significance for further improving the forecasting accuracy and guiding agricultural production.

Key words: 24 solar terms, phenological solar terms, hydrothermal resources, climate change, agricultural response, Qingyang