An Introduction to the Operational Ground-Based Retrieval Evaluation Framework for Clouds (OGRE-CLOUDS)

Abstract:

The retrieval of cloud properties (e.g., water content, particle size characteristics) using ground-based remote sensing is an important component to the study of cloud processes that include precipitation formation, aerosol-cloud interactions, and cloud radiative effects. These retrievals are challenging to perform and interpret over the entire spectrum of cloud and precipitation conditions due to the natural variability of cloud microphysics and dynamics, the limited information content in the available measurements, the difficulty in maintaining proper measurement quality, and how these factors contribute to retrieval uncertainty.

The Operational Ground-Based Retrieval Evaluation Framework for Clouds (OGRE-CLOUDS) framework effort aims to: 1) produce vertically resolved (time-height) cloud and precipitation properties under various cloud conditions using surface-based remote sensing observations, with initial emphasis on those collected by the DOE Atmospheric Radiation Measurement (ARM) Facility; 2) provide ability to implement new, conditional (i.e., applicable under specified cloud conditions) retrieval techniques; 3) generate a diagnostic package for evaluations of new retrieval options. The first phase of the OGRE-CLOUDS integrated the Continuous Baseline Microphysical (MICROBASE) value-added product cloud property retrievals into the ARM Data Integrator (ADI), and added uncertainty estimates for those retrieved cloud microphysical quantities. In the second phase, a radar-lidar retrieval technique for cloud ice microphysical retrievals was implemented and evaluated through radiative closure. The current phase of this work is aimed at defining metrics for ongoing retrieval evaluation through radiative closure, the implementation of additional cloud retrieval algorithms, and further comparison constraints utilizing in situ measurements. We seek interested scientists to contribute similar cloud retrieval datasets, methods towards a best-estimate microphysical product vetted through this OGRE-CLOUDS framework.