An evaluation of the Naval Oceanic Vertical Aerosol Model during Key90

Abstract

An experiment was conducted in the Florida Keys from 2 - 19 July 1990 to test the performance of the Naval Oceanic Vertical Aerosol Model (NOVAM) in a weak-convective regime Meteorological data collected by aircraft and boat was used to generate the surface and vertical profile information files required by NOVAM. Using this information, NOVAM predicts the aerosol extinction (km(-1)) for a vertical cross-section of the atmosphere. Aircraft observed aerosol extinction profiles were also obtained. Comparisons between observed and NOVAM aerosol extinction profiles revealed major deviations above the cloud top. From the surface to the top of the cloud layer, NOVAM generally did an excellent job in predicting profile shape, with the magnitude of aerosol extinction tied to the extinction matched at the surface. In a few cases, observed extinction increased more rapidly than NOVAM predicted extinction from the surface to the base of the cloud layer. This is attributed to rain scavenging associated with thunderstorm activity in the area. Comparison between difference aerosol extinction profiles revealed much spatial and temporal variation that was verified by Lidar profiles of atmospheric structure. Thunderstorm activity, multiple cloud-layers, and the spatial variation in the atmospheric structure have led to a hypothesis that deep-convection was responsible for the major differences between observed and predicted aerosol extinction profiles. If this is the case, a simple modification to the weak-convective model may be made to apply to a deep-convection model.