中国东北黑土区地表土壤含水量时空分异特征研究

Spatial and Temporal Variation of Soil Water Content in Phaeozem Region of Northeast China

土壤含水量通过影响土壤养分循环进而控制植被分布格局,量化黑土区土壤含水量空间格局对于理解土地覆被特征及生态系统小气候变化等具有重要意义。本研究以Sentinel-1A双极化合成孔径雷达影像数据为基础,辅助同时段Sentinel-2光学影像数据,基于修正水云模型对东北黑土区不同土地覆被类型下复杂地表土壤含水量进行定量反演;借助MOD11A2和MOD13A3产品计算的温度植被干旱指数,挖掘东北黑土区土壤含水量时空变化特征及其控制因素。研究结果表明,借助VV极化的修正水云模型(R^(2)=0.75,R_(e)=0.015)反演东北黑土区土壤含水量精度最高,研究区内的土壤含水量具有较强的空间分异性,整体呈现偏干旱的状态,其中旱地的干旱现象最为严重,但随着时间的变化,干旱有减轻趋势;土壤含水量变化受降雨的影响高于温度,但研究区内复杂的环境致使干旱情况并不是受单一因素控制。

As a key factor of soil-plant-atmosphere continuum,soil moisture content affects the nutrient circulation and vegetation growth characteristics of soil system,and it is of great significance to quantify the soil moisture spatial pattern in black soil area to understand the characteristics of land cover and the change of ecosystem climate.Based on Sentinel-1A bipolar synthetic aperture radar images,assisted by Sentinel-2 optical image data in the same period,this paper quantitatively inverses the water content of complex surface soil under different land cover types in the northeast black soil area based on the modified water cloud model,and analyzes the characteristics of soil moisture content and its control factors by means of MOD11A2 and MOD13A3 TVDI data.The results show that:The soil moisture content in the northeast black soil area is more accurate by means of the modified water cloud model of VV polarization(R^(2)=0.75;R_(e)=0.015),the soil moisture content in the study area has strong spatial differentiation and overall is in a state of drought of which the drought phenomenon in drylands is the most serious,but with the change of time,the drought has a tendency to decrease.Rainfall influences changes in soil moisture content significantly more than temperature,but the drought situation caused by the complex environment in the study area is not uncontrolled by a single factor.