Cloud-free aerosol optical depth determination over oceans from satellite radiometry
- Brookhaven National Lab., Upton, NY (United States)
- Battelle Pacific Northwest Lab., Richland, WA (United States)
Shortwave radiative forcing of climate by anthropogenic sulfate aerosol has been estimated to be of comparable global-average magnitude, but opposite sign, to longwave forcing by greenhouse gases (Charlson et al., 1992). It is therefore important that this forcing be accurately represented in climate models. Sulfate concentrations calculated by a Global Chemistry Model driven by operational meteorological data (GChM; Benkovitz et al., this meeting) exhibit high spatial and temporal variations that closely reproduce observations at continental sites. However, because of the sparsity of sulfate concentration measurements over oceans, aerosol optical depth determinations from satellite data are needed to evaluate the performance of the model over oceans. Previous studies of aerosol optical depths over oceans have employed Advanced Very High Resolution Radiometer Global Area Coverage (AVHRR GAC) data (Rao et al., 1989; Durkee et al., 1991) that should yield the required information, but the emphasis in these studies has been to produce wide spatial coverage by time averaging for periods of a week to a month, thereby masking the high spatial and temporal variability associated with the data and required for model evaluation. The Rao et al. method is employed in the production of the weekly composite aerosol maps by NOAA since June 1987. The authors report results obtained with a modified Durkee algorithm that provides instantaneous optical depths averaged over individual GChM model grid cells (1.125{degrees} x 1.125{degrees}) for comparison with optical depths predicted by the chemistry model at the same times and places (Berkowitz et al., this meeting). The optical depth retrieval is improved by a more accurate removal of sun-glint contamination, using the formulation of (Cox and Munk, 1956) for sun-glint probability as a function of wind speed, together with the wind speeds available from the operational meteorological data used to drive the chemistry model.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States); Pacific Northwest Lab., Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016; AC06-76RL01830
- OSTI ID:
- 10191583
- Report Number(s):
- BNL-49530; CONF-940115-7; ON: DE94001897; TRN: 93:003974
- Resource Relation:
- Conference: 8. Joint conference on applications of air pollution meterology. 74. American Meteorological Society annual meeting,Nashville, TN (United States),23-28 Jan 1994; Other Information: PBD: Jun 1993
- Country of Publication:
- United States
- Language:
- English
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