| Identifying the droplet size distribution, frequency and location of land-based fog is valuable for climate studies, because of the effects on agricultural productivity projections, highway traffic safety, and urban pollution monitoring. It's especially important to the Central Valley of California, which frequently suffers lingering, heavy fog.; Land-based fog plays an important role in surface radiation budgets, by blocking daytime solar heating and nocturnal long wave cooling. The droplet size distribution determines the optical depth and radiative attenuation of fog.; An operational retrieval method for obtaining droplet size and optical depth has been developed for land-based fog from the multichannel NOAA (National Oceanic and Atmospheric Administration) AVHRR (Advanced Very High Resolution Radiometer) digital image data. The visible and near infrared images provide the reflectances of both channels, which vary with droplet microphysical characteristics. The reflectances are interpolated to radiative cloud modeling results.; A new field method has been used for obtaining the measurements of land-based fog microphysical and thermodynamic parameters. A tethered balloon carries a meteorological package and a cloud droplet imaging system which transfer the images to a recording system on the ground. The results from the satellite imagery at Esparto (ESP), California are well matched with field sampling results at the same location. |
