The Navy Oceanic Vertical Aerosol Model

Abstract

ACKNOWLEDGMENTSThe authors wish to express their special thanks to Dr. Juergen Richter of NRaD who has provided both moral and financial support for the development of this program over the time it took to develop and test. We further wish to thank our colleague Ray Noonkester, formerly of NOSC, who was very supportive in the early development of NOVAM. In addition, we wish to acknowledge the contributions of Charles McGrath and Linda Hitney of NRaD who provided support in the development of the code for NOVAM. PS EXECUTIVE SUMMARY OBJECTIVEThe object was the development of the FORTRAN version of the Navy oceanic vertical modcl (NOVAM). The model predicts the vertical distribution of aerosol in the first 6000 meters above the ocean. RESULTSThe NOVAM was developed from extensive marine aerosol studies from different laboratories. The climax was a multimenu-driven interactive program that allows mouse selection of menu items needed for the calculation. It includes graphics and editing capabilities useful to the researcher. When used with an appropriate method to determine the profile parameters, it could be used in a fully automatic mode in which the program could access sets of data and produce an analysis of the data sets in an unattended background mode. The final NOVAM code is intended, however, to be used in conjunction with a LOWTRAN/IMODTRAN program and to supply the electro-optical (EO) propagation characteristics to the calling program that are produced by the unique aerosol found in the marine atmosphere. It is written in FORTRAN so it can be integrated into LOWTRAN/MODTRAN codes to improve model performance in marine environment. RECOMMENDATIONSThe model has several shortcomings that will be addressed in futture modifications. The region of applicability leaves two areas not covered well by the model. First, higher altitudes, various models developed by the U. S. Air Force and included in the LOWTRAN/MODTRAN code will be more accurate. Second, propagation paths that graze the sea surface or pass through the region within a meter or so of the sea surface are not adequately covered by NOVAM. This problem is being remedied by a large-scale experiment off the Dutch coast sponsored by NATO. Another shortcoming is the limited types of weather situations in which it is applicable. Advances in these areas await development of models from the basic research community in the future. Another area of concern is the use of the model in close-in coastal areas. Compensation wasi introduced, but experience has shown this is one of the weakest parts of the model. It is the author's opinion that a special coastal aerosol model needs to be developed that will adequately take into account local sources of aerosol.

Remote Sensing of Tropospheric Aerosols from Space: Past, Present, and Future

“…For ATSR-2, and later for the Advanced Along-Track Scanning Radiometer (AATSR) to be flown on Envisat-1 in 2000, aerosol optical thickness is retrieved separately for nadir and off-nadir measurements and the subsequent results intercompared (Veefkind and de Leeuw 1997). The spectral radiance is inverted using an LUT for two aerosol types, anthropogenic and sea-salt aerosol, based on the Navy Oceanic Vertical Aerosol Model (Gathman and Davidson 1993). The LUT was generated for τ a = 0.0 and 0.1, and the inversion optimized by fitting the four spectral radiances with two free parameters (η, κ) from a mixing model as follows:…”

Satellite retrieved aerosol properties for battlespace characterization and sensor performance

“…The Naval Oceanic Vertical Aerosol Model (NOVAM) [Gathman and Davidson, 1993] 3 calculates the vertical variation of aerosol extinction coefficients across the marine atmospheric boundary layer. The NOVAM approach combines empirical and physical algorithms and requires surface layer meteorological observations as well as a radio sounding to higher elevations.…”

Polarized light scattering by aerosols in the marine atmospheric boundary layer

“…A number of models have been developed to describe the size and composition of marine aerosols. Some are relatively simple, such as those of Diermendjian,12 involving a gamma distribution of a single compo- 36 uses a four-component system, which is a sum of four log normal distributions. This model, not used here, introduces a greater complexity to modeling aerosols in the MABL.…”