WATER: Dataset of ground truth measurements synchronizing with Envisat ASAR in the Biandukou foci experimental area on Oct. 17, 2007 during the pre-observation period

The dataset of ground truth measurements synchronizing with Envisat ASAR was obtained in No. 1 and 2 quadrates of the Biandukou foci experimental area on Oct. 17, 2007 during the pre-observation period. The ASAR data were in AP mode and VV/VH polarization combinations, and the overpass time was approximately at 23:04 BJT. Both the quadrates were divided into 3×3 subsites, with each one spanning a 30×30 m2 plot. 25 sampling points were chosen, including centers and corners. Simultaneous with the satellite overpass, numerous ground data were collected: the soil temperature , volumetric soil moisture (cm^3/cm^3), soil salinity (s/m), soil conductivity (s/m) by the Hydra probe, the surface radiative temperature by the handheld infrared thermometer, gravimetric soil moisture, volumetric soil moisture, and soil bulk density by drying soil samples from the cutting ring (100cm^3). Meanwhile, vegetation parameters as height, coverage and water content were also observed. Those provide reliable ground data for the development and validation of soil moisture, soil freeze/thaw algorithms and the forward model from active remote sensing approaches.

本数据集收集于2007年10月17日观测前的预观测期间，具体地点为比安杜口实验区第一、二号象限。数据集包含了与Envisat ASAR卫星同步的地面真实测量值。ASAR数据采集于AP模式，并采用VV/VH极化组合，过境时间约为北京时间23:04。每个象限均被划分为3×3个子区，每个子区覆盖30×30平方米的区域。选取了25个采样点，包括中心点和角落点。与卫星过境同步，收集了多种地面数据：土壤温度、体积土壤湿度（cm³/cm³）、土壤盐分（s/m）、土壤电导率（s/m）由Hydra探头测定，地表辐射温度由手持式红外温度计测定，通过干燥切割环土壤样品（100cm³）得到的重力土壤湿度、体积土壤湿度和土壤容重。同时，还观测了植被参数，如高度、覆盖度和含水量。这些数据为土壤湿度、土壤冻融算法以及从主动遥感方法构建的前向模型的发展与验证提供了可靠的地面依据。