Evaluation of warm-rain microphysical parameterizations in mesoscale simulations of the cloudy marine boundary layer
Issue Date
2015-08-31Author
Nelson, Kevin John
Publisher
University of Kansas
Format
51 pages
Type
Thesis
Degree Level
M.S.
Discipline
Atmospheric Science
Rights
Copyright held by the author.
Metadata
Show full item recordAbstract
Marine boundary layer clouds cool the climate system by influencing the shortwave radiation budget, and on shorter timescales can influence marine and aircraft operations. We evaluate the ability of a regional forecast model (NRL COAMPS) to accurately represent marine boundary layer cloud properties, using a number of different microphysical parameterizations. We focus on both the relative performance of the different parameterizations and on how they compare to observations from the VOCALS-REx field campaign conducted over the southeastern Pacific in 2008. We found evidence of a negative model bias on liquid water path (LWP) and marine boundary layer (MBL) depth, and persistent over-estimation of precipitation rates in mesoscale simulations. Certain aspects of the diurnal cycle of cloud systems were also observed. In addition to direct comparisons with the observations to evaluate forecast accuracy, we assess the internal consistency of model microphysical properties by comparing simulation output to a number of observationally derived scalings for precipitation and aerosol scavenging. Model output holds well to the observationally derived scalings, and resolution plays a significant role in determining whether or not the model microphyics is consistent with observations.
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