Investigation of the Influences of Cloud Microphysics and Aerosol-Cloud
Interactions on Solar Irradiance Using WRF-Solar Model
Abstract
Accurate forecast of solar irradiance remains a major challenge,
especially under the influences of aerosols, clouds and aerosol-cloud
interactions due to their inadequate parameterizations in numerical
prediction models. This study focuses on the impacts of cloud
microphysics and the indirect aerosol effect on solar irradiance. The
state of art Weather Research and Forecasting model specifically
designed for simulating and forecasting solar radiation (WRF-Solar) is
employed to investigate the sensitivity of the total solar irradiance
and its partitioning into direct and diffuse irradiances to aerosol and
cloud properties. First, a number of microphysical schemes will be
tested against the measurements of shallow cumulus and stratiform clouds
at the DOE ARM SGP site. Efforts will be made to quantify the
uncertainty spread. The effects of cloud microphysics on surface solar
irradiance will be identified. Second, the indirect aerosol effect on
cloud formation and thus surface solar irradiance will be investigated
by using the Thompson aerosol aware microphysical scheme and different
treatment of aerosols. In particular, we will examine the aerosol
indirect effects in different cloud regimes. To address the
aforementioned problems, we will introduce a new model evaluation
framework based on different WRF-Solar setups (nested WRF, WRF-LES, and
single column WRF). In addition, different evaluation metrics will be
used, including the RMSE, MAPE, and relative Euclidean distance. The
results will provide physical insight into the understanding of
aerosol-cloud-radiation interactions and into improving solar radiation
forecast in cloudy conditions.