FDR自动土壤水分数据标定问题及解决方法

Problems and Solutions of FDR Automatic Soil-Moisture Data Calibration

针对目前FDR自动土壤水分数据可用性低的实际情况,本文从FDR自动土壤水分站传感器原理出发,结合数据处理流程与方法对湖南60个站点不同层次的标定参数及部分站点的相关观测数据进行了分析,指出目前田间标定法在自然条件下几乎无法得到覆盖土壤各个湿度区间的均匀样本数据,导致二次标定参数不合理是造成FDR自动土壤水分站数据可用性差的根本原因。二次标定方程参数不合理主要表现为方程斜率过大、过小、负值3种情况,导致观测数据增幅过大、常年不变、与实际土壤湿度变化趋势完全相反等问题。最后针对该问题提出了大样本原状取土,实验室标定的解决方法,并对方法进行了初步验证,结果表明该方法能从源头上有效改善土壤水分站观测数据质量。

Aiming at the problem of low data availability of FDR automatic soil-moisture station,based on the working principles of FDR automatic soil moisture sensors,combined with the data processing procedures and methods,about 450secondary-level calibration parameters of 60 station in Hunan and the related observation data are analyzed.It is noted that by the current calibration methods,it is difficult to conducted full scale calibration under natural conditions,and the unreasonable secondary calibration parameters are the root cause of the low data availability of FDR automatic soil-moisture data.The two calibration parameters are not reasonable,for the slope of the equation is too large,too small,or negative values,leading to such problems as too large increase amplitude,unchanging,or opposite to the reality of observation data.The suggestions of large-sample undisturbed soil sampling and laboratory calibration are put forward aiming at the problems of current data calibration method. The method is verified preliminarily,and the results show that the method can effectively improve the quality of soil moisture observation data from the sources.