Implementing and Evaluating Variable Soil Thickness in the Community Land Model, Version 4.5 (CLM4.5)
AuthorBrunke, Michael A.
Lawrence, David M.
Leung, L. Ruby
Troch, Peter A.
AffiliationUniv Arizona, Dept Atmospher Sci
Univ Arizona, Dept Hydrol & Water Resources
Univ Arizona, Dept Geosci
MetadataShow full item record
PublisherAMER METEOROLOGICAL SOC
CitationImplementing and Evaluating Variable Soil Thickness in the Community Land Model, Version 4.5 (CLM4.5) 2016, 29 (9):3441 Journal of Climate
JournalJournal of Climate
RightsCopyright © 2016 American Meteorological Society
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractOne of the recognized weaknesses of land surface models as used in weather and climate models is the assumption of constant soil thickness because of the lack of global estimates of bedrock depth. Using a 30-arc-s global dataset for the thickness of relatively porous, unconsolidated sediments over bedrock, spatial variation in soil thickness is included here in version 4.5 of the Community Land Model (CLM4.5). The number of soil layers for each grid cell is determined from the average soil depth for each 0.9 degrees latitude x 1.25 degrees longitude grid cell. The greatest changes in the simulation with variable soil thickness are to baseflow, with the annual minimum generally occurring earlier. Smaller changes are seen in latent heat flux and surface runoff primarily as a result of an increase in the annual cycle amplitude. These changes are related to soil moisture changes that are most substantial in locations with shallow bedrock. Total water storage (TWS) anomalies are not strongly affected over most river basins since most basins contain mostly deep soils, but TWS anomalies are substantially different for a river basin with more mountainous terrain. Additionally, the annual cycle in soil temperature is partially affected by including realistic soil thicknesses resulting from changes in the vertical profile of heat capacity and thermal conductivity. However, the largest changes to soil temperature are introduced by the soil moisture changes in the variable soil thickness simulation. This implementation of variable soil thickness represents a step forward in land surface model development.
VersionFinal published version
SponsorsThis work was supported by DOE (DE-SC0006773), NASA (NNX13AK82A), and NSF (AGS-0944101). L. R. Leung was supported by the DOE Office of Science Biological and Environmental Research Earth System Modeling program. Pacific Northwest National Laboratory is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830. We thank the Jet Propulsion Laboratory for providing the GRACE data, which were processed by Sean Swenson under support from the NASA MEaSUREs Program. High-performance computing support was provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation, through computing time on Yellowstone (http://n2t.net/ark:/85065/d7wd3xhc) and on The University of Arizona Research Computing