Evaluation of Warm-Rain Microphysical Parameterizations in Mesoscale Simulations of the Cloudy Marine Boundary Layer

• DOI: 10.1175/mwr-d-15-0266.1
• Publication Date: 2016-03-01T21:12:30Z
• Authors: Kevin J. Nelson; David B. Mechem; Yefim L. Kogan
• Keywords: Cloud condensation nuclei; Liquid water path; Drizzle; Coalescence (physics); Cloud physics

Abstract Several warm-rain microphysical parameterizations are evaluated in a regional forecast model setting (using the Naval Research Laboratory’s Coupled Ocean–Atmosphere Mesoscale Prediction System) by evaluating how accurately is able to represent marine boundary layer (MBL). Cloud properties from large suite of simulations using different and concentrations cloud condensation nuclei (CCN) compared ship-based observations Variability American Monsoon Systems (VAMOS) Ocean–Cloud–Atmosphere–Land Study—Regional Experiment (VOCALS-REx) field campaign conducted over southeastern Pacific (SEP). As previous studies, systematically underestimate liquid water path MBL depth. On other hand, overestimate precipitation rates relative those derived scanning C-band radar on board ship. Most exhibit diurnal cycle, although details differ somewhat recent observational study. In addition direct comparisons with observations, internal consistency simulated assessed comparing simulation output number observationally theoretically scalings for coalescence scavenging. Simulation results broadly consistent these scalings, suggesting COAMPS behaving microphysically fashion. However, as defined analysis highly dependent upon horizontal resolution model. Excessive depletion CCN processing suggests importance parameterizing source term or imposing some form fixed, climatological background concentration.