Infrared Derived Microphysical Properties of Deep Convection

Infrared measurements can be used to study and monitor deep convection at all times of the day. Deriving cloud microphysical information from infrared measurements, however, is limited in that the effective transmittance (combined effects of transmission and reflection) of the cloud layer must be large enough to detect, since it is the difference in effective transmittance between two infrared channels that contains the cloud microphysical information. The more closely a cloud approximates a blackbody, the less information on cloud microphysics that can be inferred from infrared measurements. Near-infrared derived particle size information is primarily derived from reflected solar radiation and, hence, does not have the same limitations as the infrared with regards to the transmission of radiation near cloud top. Thus, it is instructive to compare near-infrared and infrared derived effective particle radii for deep convective clouds to determine if infrared measurements can be used to derive effective particle radii consistent with the near-infrared. In this study, we will compare near-infrared and infrared derived cloud microphysical information and demonstrate that infrared measurements are useful for studying the microphysics of deep convection. This is important since the cloud top microphysical properties may be related to updraft strength.