Abstract:
Multi-frequency passive microwave remote sensing affords a unique opportunity
to understand various phenomena; low-frequency microwaves penetrate clouds
and are able to observe Earth surface conditions (,6–18 GHz), while the higher
frequencies are strongly impacted by prevailing atmospheric conditions. By using
these relationships, an atmospheric opacity index (AOI) using Advanced
Microwave Scanning Radiometer on Earth Observing Satellite (AMSR-E)
multi-frequency data is proposed. This index utilizes four AMSR-E frequencies
spanning both high- and low-microwave frequency. This AOI can be used to
discriminate cloudy atmosphere from clear-sky conditions.
This index shows good agreement with current cloud indices. In this research, it
is compared against the Moderate Imaging Spectroradiometer (MODIS) and the
Geostationary Operational Environmental Satellite 9th series (GOES-9) atmosphere
products. It offers the possibility of detecting convective clouds at all
times (day and night) due to the advantage of the independence of the microwave
sensors on the Sun for illumination.
