Radiative Impacts of Anvil Cloud during the Maritime Continent Thunderstorm Experiment

Abstract

In this study the radiative impact of three separate cirrus anvil systems that occurred during the Maritime Continent Thunderstorm Experiment is investigated. Retrievals of microphysical cloud properties and an independent radar measurement are used to develop an appropriate set of radar reflectivity factor (Z)?ice water content (IWC) parameterizations. This set of parameterizations is then applied to the reflectivity field of a scanning 5.2-cm radar. The three-dimensional ice water structure is used as input to a two-stream radiative transfer model using an independent pixel approximation for several different stages in the life cycle of the cloud system. Peak radiative heating/cooling occurs at many different levels from just below the tropopause down to the freezing level. This behavior is attributed to spatial variability of the anvil cloud?top height. There is a distinct difference between the average radiative heating profile in the presence of island-based convection as compared with oceanic convection. The island-based convection results in a heating profile that concentrates cloud-top solar heating and IR cooling higher in the atmosphere and with a greater magnitude in comparison with studies of oceanic convection. Island-based thunderstorms can play a major role in the large-scale radiative energy balance. The net radiative convergence averaged over a simplified diurnal cycle and over a 120 ? 120 km2 grid box containing an island-based thunderstorm and its associated anvil cloud is near zero. When considering the energy balance over the tropical western Pacific, it is important to consider the ?Maritime Continent? region with all of its small islands separately from the oceanic regime.