The Regional Water Budget and Land-Atmosphere Coupling for Different Convection Regimes at the ARM SGP Site: Comparisons Among Observations, Reanalysis, and Model Simulations

Modelling and observational studies show a discrepancy on the strength of land-atmosphere (L-A) coupling at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site, e.g. a relative strong (weak) signal from model-based (observation-based) studies. One way to characterize the L-A coupling strength is through the analysis of the regional water budget. In this study, we will examine the distributions of the atmospheric water budget for different convection regimes and the interrelations among water budget components to identify the terms that dominate the balance for the net moisture flux and present strong association with precipitation variability at the SGP site. The strength of L-A coupling for different convection regimes will also be quantified by the linear correlation coefficient between selected pairs of land surface and atmospheric variables within the ‘LoCo Process Chain’. Results based 10 years of ARM continuous forcing data will be compared with those derived from the North American Regional Reanalysis (NARR), and cloud-associated parameterizations testbed (CAPT) and Continental United Sates (CONUS) regional-refined model (RRM) simulations. Through the comparisons with observations, we aim to evaluate the performance of reanalysis and model simulations in characterizing the regional water budget at the ARM SGP site, and to investigate the major contributor to the discrepancy in L-A coupling strength between modelling and observational studies.

This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-755408.