Publication Date

Summer 2013

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Meteorology and Climate Science

Advisor

Menglin S. Jin

Keywords

CESM, CLM, Land Surface, Skin Temperature

Subject Areas

Meteorology; Geophysics

Abstract

Hourly ground observations for year 2004 from the Atmospheric Radiation Measurement (ARM) program of the Department of Energy were used to examine the surface and subsurface energy simulations of the Community Land Model version 4 (CLM4). The 2 m air temperature, wind speed, solar radiation, downward longwave radiation, and precipitation observed by the ARM project were used to force the offline CLM4, and the ARM land surface and soil observations including skin temperature (Tskin), soil temperature and moisture, and sensible, latent, and ground heat fluxes were used to evaluate the model outputs. The default and ARM-forced CLM4 runs for 2004 were compared to assess the improvements to the model for hourly, daily, and seasonal timescales. The root mean square error and the Pearson correlation coefficient show that the ARM-forced offline CLM4 leads to improved accuracy in surface and soil energy fluxes in comparison with the default offline CLM4. Nevertheless, a warm bias of 2°C to 3°C was assessed on Tskin in summer due to warm maximum temperatures and in winter due to warm minimum temperatures. To improve CLM4 Tskin simulations, a proposed vegetation emissivity parameterization was evaluated locally and globally using both ARM and Moderate Resolution Imaging Spectroradiometer remote-sensing observations. This new algorithm results in cooling and an improvement of 0.17 K for the ARM site. Global evaluation revealed improvement in areas of intermediate canopy density.

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