ABSTRACT
Based on data of daily precipitation, temperature, sunshine hours, relative humidity, wind speed and vapor pressure of 70 meteorological stations from 1960 to 2019 in Shanxi Province, the Penman-Monteith model was applied to calculate the reference evapotranspiration (ET0). The spatiotemporal variations of ET0 as well as the ET0 in different climatic zones and at different altitudes were quantitatively analyzed. The results showed that the mean annual ET0 decreased from west to east in 1960-2019. A jumping point was detected in 1982, with the mean annual ET0 increased both in 1960-1982 and 1983-2019. The monthly and ten-day changes of ET0 showed single peak curves. The variation of ET0 in different climatic zones was as follows: ET0 in temperate and semi-arid areas was higher than that in warm temperate and semi-humid areas and warm temperate and semi-arid areas in spring, summer, autumn and the whole year, while in winter, the highest ET0 was in warm temperate and semi-humid areas. ET0 varied with altitudes, with ET0 in <660 m altitude areas being higher than that in other altitudes in summer, autumn, winter and the whole year.
Subject(s)
Crops, Agricultural , Plant Transpiration , China , Temperature , WindABSTRACT
Based on the data of the daily mean air temperature and the minimum soil surface temperature of 70 meteorological stations in Shanxi Province from 1970 to 2012, the heat indices of agricultu-ral resources including accumulated temperatures above 0 °C and 10 °C , the average temperature in July and the annual frost-free duration were calculated. Their variation trends and mutation were analyzed by using linear regression and accumulated anomaly methods. The effect of agricultural heat resource on crop producing area was analyzed. The results showed that the accumulated temperatures for above 0 °C and 10 °C had increased significantly at a rate of about 64.8 and 57.9 °C . d . (10 a) -1, respectively (P<0.001). The average temperature in July and the annual frost-free duration had significantly increased at a rate of about 0.3 °C. (10 a)-1 and 5.9 d . (10 a)-1, respectively. The increasing ranges of heat resource indices had different spatial distribution patterns in Shanxi Province. The accumulated temperatures were greater in the west than that in the east. The average temperature in July was greater in middle and north than that in the south. The annual frost-free duration was greater in the middle than that in the south and north. The accumulated temperatures above 0 °C and 10 °C showed a clear mutation in 1996, so were the average temperature in July in 1993 and the annual frost-free duration in 1997. Compared to the time before mutation, the accumulated temperatures above 0 °C and 10 °C increased by 219.4 °C . d and 196.7 °C . d, respectively, the average temperature in July by 0.8 °C and the annual frost-free duration by 15 d. As a result, hot crop cultivable area and warm crop cultivable area were expanded northward, while the mild crop cultivable area, cool crop cultivable area, cold crop cultivable area and alpine plants area were shrunk. The maximum expansion was of the warm crop cultivable area (by 175.7%). The maximum shrinkage was of the cold area (by 87.9 %). The cultivable area of cotton was expanded by 1.7 x 10(6)hm2(53.5%), and that of potato was shrunk by 8.9 x 10(6) hm2(30.5%).
