Global Optimization of Soil Texture Maps from Satellite-Observed Soil
Moisture Drydowns and Its Implementation in Noah-MP Land Surface Model
Abstract
Soil moisture (SM) plays an important role in regulating regional
weather and climate. However, the simulations of SM in current land
surface models (LSMs) contain large biases and model spreads. One
primary reason contributing to such model biases could be the
misrepresentation of soil texture in LSMs, since current available
large-scale soil texture data are often generated from extrapolation
algorithm based on a scarce number of in-situ geological measurements.
Fortunately, recent advancements of satellite technology provide a
unique opportunity to constrain the soil texture datasets by introducing
observed information at large spatial scales. Here, two major soil
texture baseline datasets (Global Soil Datasets for Earth system
science, GSDE and Harmonized World Soil Data from Food and Agriculture
Organization, HWSD) are optimized with satellite-estimated soil
hydraulic parameters. The optimized soil maps show increased (decreased)
sand (clay) content over arid regions. The soil organic carbon content
increases globally especially over regions with dense vegetation cover.
The optimized soil texture datasets are then used to run simulations in
one example LSM, i.e., Noah LSM with Multiple Parameters. Results show
that the simulated SM with satellite-optimized soil texture maps are
improved at both grid and in-situ scales. Intercase comparison analyses
show the SM improvement differs between simulations using different soil
maps and soil hydraulic schemes. Our results highlight the importance of
incorporating observation-oriented calibration on soil texture in
current LSMs. This study also joins the call for a better soil profile
representation in the next generation Earth System Models.