A Technique for Estimating Surface Meteorological Ranges Over Oceans from Satellite Measurements of Aerosol Optical Depth
Technical rept. 1 Aug 1989-1 Oct 1990
SPARTA INC LEXINGTON MA
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Measurements of aerosol optical depth obtained from NOAAs Advanced Very High Resolution Radiometers AVHRR aboard polar-orbiting satellites have been used to estimate the surface meteorological range over oceans. To do this, a lookup table of optical depth versus meteorological range had been developed which is based on the aerosol extinction profiles in LOWTRAN 7. To better simulate conditions over oceans, the boundary layer height has been lowered to 0.5 km and an extinction profile corresponding to a 150 km meteorological range has been added. The lookup table has been applied to AVHRR aerosol optical depths near selected island locations where, in turn, the inferred meteorological ranges were validated against surface observations. Results show reasonable success in locating regions where meteorological ranges exceed 30 km, but more precise classification may not be possible due to uncertainties in both the measurements and observations. The algorithm tends to produce higher than observed meteorological ranges when the observed values are less than 30 kilometers. Limited comparisons with SAGE II data, suggest that the assumed model aerosol extinction profiles used by the algorithm may contain too much aerosol loading above the boundary layer, which could account for some, but not all, of this discrepancy. Other explanations include the possibility the island sites have lower visibilities than the surrounding open ocean or the AVHRR optical depths are too small.
- Atmospheric Physics
- Physical and Dynamic Oceanography
- Optical Detection and Detectors