1961—2020年华北平原冬小麦-夏玉米生长季内光能资源时空变化特征

利用华北平原具有1961—2020年完整时间序列逐日气象资料的55个常规气象站点及11个辐射观测站点的逐日地面观测资料，建立华北平原冬小麦-夏玉米生长季的太阳总辐射的经验公式，从年代际尺度和年际尺度分析冬小麦-夏玉米周年、生长季和关键生育期辐射资源(总辐射、直接辐射、散射辐射和光合有效辐射)的变化特征。结果表明:华北平原太阳总辐射值分布呈北高南低、东高西低，全年总辐射范围为4 519.26~5 488.30 MJ/m²；冬小麦生长季和夏玉米生长季太阳总辐射分别占全年的58.6%和41.4%；华北平原太阳总辐射呈显著下降趋势，1961—2020年研究区周年太阳总辐射平均减少了14.3%(708.24 MJ/m²)，其中，河南东部以及河北西部地区下降幅度最大，气候倾向率达-210.67 MJ/(m²·10a)；研究时段内冬小麦生长季和关键生育期太阳总辐射平均减少了10.0% 和4.7%，与冬小麦相比，夏玉米生长季和关键生育期的太阳辐射下降幅度更大，分别减少了17.8%和17.7%；年代际尺度上，华北平原冬小麦-夏玉米周年、冬小麦生长季和夏玉米生长季太阳总辐射均呈现出递减的趋势，与1961—1980年相比，2001—2020年的冬小麦-夏玉米周年、冬小麦生长季和夏玉米生长季太阳总辐射分别减少了9.6%、7.7%和12.1%。综上，华北平原的直接辐射、光合有效辐射呈下降趋势，散射辐射呈上升趋势，本研究结果能够为华北平原辐射资源的合理利用以及制定适应气候变化的对策等提供科学依据。

Temporal and spatial variation characteristics of radiation in winter wheat-summer maize growing season in the North China Plain during 1961-2020

Using the complete time series daily meteorological data of 55 meteorological stations and radiation data of 11 radiation observation sites with in North China Plain from 1961 to 2020, an experience formula of the surface solar radiation in the wheat-maize growing season in North China was established in this study. The variation characteristics of radiation resources(total radiation, direct radiation, scattered radiation and photosynthetically active radiation)in annual, growing season and key growth period of winter wheat-summer maize were analyzed at both interdecadal and interannual scales. The results showed that: The surface solar radiation in the North China Plain was high in the north and low in the south, and high in the east and low in the west. The annual total radiation value was between 4 519. 26-5 488. 30 MJ/m². The solar radiation in the growing season of winter wheat and summer maize accounted for 58. 6% and 41. 4% of the whole year, respectively. The surface solar radiation in all regions showed a downward trend throughout the year. The annual global solar radiation in the study area decreased by an average of 14. 3%(708. 24 MJ/m²)during 1961-2020, and the eastern part of Henan and the western part of Hebei had the largest decline, and the climate trend rate was-210. 67 MJ/(m²·10 a). During the study period, the surface solar radiation decreased by 10. 0% and 4. 7% on average in winter wheat growing season and key growth period. Compared with winter wheat, the solar radiation decreased by 17. 8% and 17. 7% in summer maize growing season and key growth period, respectively. The surface solar radiation showed a downward trend in the whole year, the winter wheat and the growing season of summer maize of the three periods. Compared with during 1961-1980, the annual solar radiation in winter wheat and summer maize growth season in 2001-2020 decreased by 9. 6%, 7. 7% and 12. 1%, respectively. In conclusion, the direct radiation and photosynthetically active radiation(PAR)in the study area show a downward trend, while the diffuse radiation shows an upward trend. This study provides scientific basis for the rational utilization of radiation resources in North China and the formulation of countermeasures to adapt to climate change.