Challenges in Assessing Aerosol–Warm Cloud Radiative Interactions with Satellite Observations and Future Directions (Invited Presentation)

Important aerosol-warm cloud radiative interaction problems relevant to climate predic-tion include indirect effects related to changes in cloud microphysics and enhancements to the direct aerosol radiative effect for absorbing aerosol overlying lower level clouds. A number of challenges are obvious in attempting to understand these effects from satellite observations, including: (a) the need to isolate radiative changes due to aerosol perturba-tions from dynamic/thermodynamic changes, and (b) the existence of an observing sys-tem that has the necessary microphysical and radiative retrieval capabilities for under-standing coupled aerosol-cloud processes. While statistical studies over large temporal and/or spatial scales can be filtered to lessen the impact of some of these issues, satellite observations alone do not provide sufficient tools for quantifying aerosol-cloud radiative interactions. For indirect effects in particular, it may be extremely challenging to obtain the necessary information even from in situ observations (e.g., maximum supersaturation experienced by cloud parcels, turbulence/entrainment, etc.).

It is well-recognized that a synergistic observation and modeling approach is needed to advance our understanding of aerosol-cloud interactions and radiative impacts. Therefore, an overarching issue is to what extent current and future observations (satellite and sub-orbital) assist with microphysical and radiative model development.

We provide an overview of the challenges in quantifying the two above-mentioned aero-sol-cloud effects from satellite observations, including experience from our own work on cloud susceptibility and above-cloud absorbing aerosol retrievals. We also discuss future observations and modeling capabilities that would help facilitate progress on the aerosol-warm cloud problem.