Estimation of vegetation loss coefficients and canopy penetration depths from SMAP radiometer and IceSAT lidar data

TL;DR

This paper develops a framework using the $ au$-$omega$ model to estimate vegetation loss coefficients and canopy penetration depths from SMAP and IceSAT data, aiding in understanding microwave signal attenuation in forests.

Contribution

It introduces a method to derive vegetation loss coefficients and canopy penetration depths globally from combined SMAP and IceSAT data, enhancing forest and soil moisture analysis.

Findings

Vegetation loss coefficients indicate strong microwave attenuation in dense forests.

Canopy penetration depths vary significantly across different forest types.

Soil signal attenuation affects soil moisture retrieval accuracy in densely forested regions.

Abstract

In this study the framework of the $\tau$-$\omega$ model is used to derive vegetation loss coefficients and canopy penetration depths from SMAP multi-temporal retrievals of vegetation optical depth, single scattering albedo and ICESat lidar vegetation heights. The vegetation loss coefficients serve as a global indicator of how strong absorption and scattering processes attenuate L-band microwave radiation. By inverting the vegetation loss coefficients, penetration depths into the canopy can be obtained that is displayed for the global forest reservoirs. A simple penetration index is formed combining vegetation heights and penetration depth estimates. The distribution and level of this index reveal that for densely forested areas the soil signal is attenuated considerably, which can affect the accuracy of soil moisture retrievals.