A method for soil moisture probes calibration and validation of satellite estimates

摘要

class="kwd-title">Keywords: Soil water content, Soil Moisture and Ocean Salinity (SMOS), Land surface processes, Remote sensing class="head no_bottom_margin" id="abs0010title">AbstractOptimization of field techniques is crucial to ensure high quality soil moisture data. The aim of the work is to present a sampling method for undisturbed soil and soil water content to calibrated soil moisture probes, in a context of the SMOS (Soil Moisture and Ocean Salinity) mission MIRAS Level 2 soil moisture product validation in Pampean Region of Argentina. The method avoids soil alteration and is recommended to calibrated probes based on soil type under a freely drying process at ambient temperature. A detailed explanation of field and laboratory procedures to obtain reference soil moisture is shown. The calibration results reflected accurate operation for the Delta-T thetaProbe ML2x probes in most of analyzed cases (RMSE and bias ≤ 0.05 m³/m³). Post-calibration results indicated that the accuracy improves significantly applying the adjustments of the calibration based on soil types (RMSE ≤ 0.022 m³/m³, bias ≤ −0.010 m³/m³). class="first-line-outdent">

• A sampling method that provides high quality data of soil water content for calibration of probes is described.

• Importance of calibration based on soil types.

• A calibration process for similar soil types could be suitable in practical terms, depending on the required accuracy level.