寒区春季融雪期表层土壤湿度变化与影响因素分析

为探究寒区春季融雪期表层土壤湿度时空变化及其影响因素,以松嫩平原黑土区为研究区,利用遥感和GLDAS模拟同化数据集,以温湿指数作为辅助指标,通过一元线性回归、相关分析、滑动平均及相对贡献率法,分析了融雪期表层土壤湿度时空变化特征,揭示了表层土壤湿度变化的具体驱动因素。结果表明：32年来,融雪前期表层土壤湿度空间分布均呈减小趋势,融雪后期则呈南增、北减趋势;整体而言,融雪前期表层土壤湿度主要受积雪影响,后期主要与降雨及总降水变化密切相关,只有在积雪和降雨较少的地区,温度的蒸发作用才会相对明显;融雪前期表层土壤湿度多年变化主要由温度变化趋势驱动,积雪多年变化趋势对土壤湿度变化起到一种限制作用,降雨和总降水变化趋势决定了融雪后期表层土壤湿度的变化方向;从相对贡献率分析可知,融雪前期温度的升高和降雪的减少将导致表层土壤湿度的降低趋势放大一倍,但融雪后期降雨变化趋势的积极作用在一定程度上会影响春播前期土壤湿度暖干化的反馈过程,从而对陆气间水分交换产生积极影响。

Analysis of Surface Soil Moisture Changes and Influencing Factors during Spring Snowmelt in Cold Regions

In order to explore the temporal and spatial variation of surface soil moisture and its influencing factors during the spring snowmelt period in cold regions, the black soil region of Songnen Plain was taken as the research area, remote sensing and GLDAS were used to simulate the assimilation dataset, and the temperature and humidity indexes were used as an auxiliary index to pass the linear regression. Correlation analysis, sliding average and relative contribution rate method were used to analyze the temporal and spatial variation characteristics of surface soil moisture during the snowmelt period, and the specific driving factors of surface soil moisture change was revealed. The results showed that the spatial distribution of soil moisture in the surface of the snowmelt was decreasing in the early stage of snowmelt, and the southward increasing and northward decreasing trend was in the late stage of snowmelt in the past 32 years. On the whole, the surface soil moisture in the early stage of snowmelt was mainly affected by snow, and the latter was mainly related to rainfall and total precipitation changes, the evaporation of temperature in areas with less snow and less rainfall would be obvious;the change of surface soil moisture in the early stage was mainly driven by the trend of temperature change. The trend of years of snow accumulation had a limiting effect on soil moisture change. The trend of rainfall and total precipitation determined the change direction of surface soil moisture in the late stage of snowmelt;from the quantitative contribution results, the change of temperature and snow in the early stage of snowmelt caused the surface soil moisture to be more than doubled, but the positive effect of rainfall trend in the late snowmelt would affect the feedback process of soil moisture warming and drying in the early stage of spring snowing, which would have a positive impact on the water exchange between land and air.