Interpretation of in situ observations in support of P-band radar retrievals

An in situ profile soil water content observation protocol developed at Oregon State University has been deployed in seven of the nine sites of the NASA AirMOSS project. (The other two sites run by USDA already had similar profile monitoring instrumentation installed.) The objective of the project is to develop a calibrated P-band radar which responds to the dielectric constant of the soil profile to produce the regional distribution of soil water content as a function of depth. The overall objective is to reduce the uncertainty in the carbon balance for North America by reducing the uncertainty in soil water content. This article demonstrates an annual time series of soil water content with depth as well as the wet and dry climate driven signals which produce a range of soil water content on which to calibrate the P-band radar. An example of the regional P-band radar retrieval calibrated using the in situ data is presented.