Abstract:

Based on the data on soil moisture, precipitation, and temperature at 19 national meteorological stations in Sanjiang Plain from 1982 to 2020, the correlation coefficient and autocorrelation coefficient were used to analyze the soil moisture memory and its relationship with precipitation and temperature in Sanjiang Plain of Heilongjiang province.The results show that the memory time of soil moisture in spring and summer in Sanjiang Plain varies between 10-40 days.The average memory time of soil moisture in different layers is the longest in the middle layer (10-20 cm), and the lower layer shows a decreasing trend.The average memory time of 10-20 cm soil layer in spring and summer in Sanjiang Plain is 20 days and 17 days, respectively.The memory intensity of soil moisture in summer is higher than that in spring, and the memory intensity of soil moisture in the west of Sanjiang Plain is stronger, and the memory intensity of soil moisture tends to increase with the increase of soil layer.Precipitation is the main source of soil moisture in Sanjiang Plain.Under the synergistic effect of precipitation and temperature, soil moisture in summer and autumn has a significant positive correlation with precipitation and temperature and humidity index in the same period.Soil moisture in spring is also positively correlated with precipitation in autumn and winter and negatively correlated with temperature and humidity index in the early period.The increase of temperature in autumn and winter in the early period will promote soil thawing and freezing, thus increasing soil moisture in the spring of that year.Understanding the persistence of soil moisture anomaly is beneficial to climate prediction, drought evaluation, and agricultural production.

Key words: Sanjiang Plain, Soil moisture, Memory, Hydrothermal conditions, Temperature and humidity index