Abstract:In this study, instrument measured evaporation and conventional meteorological observations from 80 stations in Heilongjiang Province from 1961 to 2017 were collected. Using these data, methods such as linear trend estimation, cumulative anomaly, Mann Kendal mutation analysis, mathematical statistics and Marr’s wavelet analysis were employed to analyze the annual and seasonal characteristics of the spatio temporal evolution of instrument measured evaporation in Heilongjiang Province. Additionally, the relationships of the characteristics with climate factors were analyzed. The results show that the geographical correlation of annual evaporation is significant. Annual evaporation decreases as latitude, longitude and altitude increased. The decreasing rates are 55.4 mm/°N, 45.2 mm/°E and 88.8 mm/(100 m), respectively. From 1961 to 2017, annual evaporation in Heilongjiang Province showed a significant downward trend, decreasing at 13.7 mm/(10 a). Annual evaporation had 8 a and 24 a cycles. Statistics show that at up to 70.0% of the stations, the annual pan evaporation show a downward trend, of which 62.5% of the stations have passed the significance test at 0.05 level, which means there is “evaporation paradox” in Heilongjiang Province. Exploring seasonal pan evaporation trend shows that evaporation decreased significantly in spring, having 24 a and quasi 2 a cycles, and 67 stations show a downward trend, 44 of which show a significant downward trend (P<0.05). However, the magnitude of this decrease in summer and fall is relatively small with non significant changes, with 7 a cycles. In winter, evaporation increase slightly having 24 a, 11 a, and 2 a cycles and 23 stations show a significant rising trend. Mutation test shows that there is a significant mutation time of evaporation in year, spring and winter, but no significant mutation in summer and autumn. Additionally, it is found that changes in annual and seasonal pan evaporation are positively correlated with average temperature and wind speed, and negatively correlated with humidity. Our analysis indicates that a significant decrease in wind speed is the dominant factor leading to the decrease in evaporation throughout the year, and the superposition effect of a significant decrease in wind speed and obvious humidification makes the decrease trend of spring evaporation more significant. The higher temperature and lower relative humidity climate may be the cause of the slight increase in evaporation in winter.