Analysis on daily variations and influencing factors of E601B evaporation in the southwest of Anhui Province

LIU Liqun; WANG Xiaolan; ZHENG Yan; DONG Fangyou; FANG Haitao

doi:10.19513/j.cnki.hyqxxb.20250428001

Abstract：Studying the impact of temperature on evaporation observations at automatic meteorological stations is of great significance for climate change research and the assessment of meteorological drought disasters.The diurnal variation characteristics are analyzed using the hourly evaporation and temperature data from Anqing national basic meteorological station(hereinafter referred to as Anqing station)from April to November 2017.The results are as follows.(1)The diurnal variation patterns of hourly evaporation and temperature are similar,both exhibiting one valley and one peak,with the peak hourly evaporation occurring 3 h later than that of the temperature.(2)Through the experimental research on the water temperature in evaporation measurements at Anqing station,it is found that after sunrise,the water temperature in the E601B evaporation pan rises,leading to an increase in volume.Combined with the influence of the operational software's automatic evaporation algorithm,it results in smaller measured hourly evaporation values in the morning but larger values from afternoon to evening on clear days.The analysis on the observation data from two typical warming days shows that the daily evaporation measurements are 7％-26％smaller,while the measurements from two systematic cooling processes are 15％-19％larger.(3)The complete correlation analysis of the hourly evaporation and related meteorological factors at Anqing and Taihu national basic meteorological stations in the southwest of Anhui Province indicates that the thermal factors are the primary drivers for the variations of hourly evaporation.The shallow ground temperatures at 10-20 cm have the most significant impact on hourly evaporation,with the ground temperature at 15 cm showing the strongest correlation with hourly evaporation.