Investigating Biases When Quantifying Aerosol-Cloud-Precipitation Interactions
Abstract
Model representation of the physical processes relating aerosols, clouds, and precipitation is characterized by highly uncertain parameterizations. This study utilizes large eddy simulation, aircraft measurements, and satellite observations to identify factors that bias the absolute magnitude of climate model-related metrics associated with aerosol-cloud-precipitation interactions for warm clouds. Cloud lifetime is shown to potentially result in major differences in metric values relating aerosols to shallow cumulus cloud microphysics and precipitation rate; values of the precipitation susceptibility ("So"; relates rain rate to drop number), which is related to the autoconversion parameterization, are shown at worse to be biased between -186% to 161% over a wide range of cloud liquid water path (LWP). Spatial resolution of measurements is shown to both influence the magnitude (suppression over larger scales) and LWP-dependent behavior of "So" and another cloud-precipitation metric, χ (which relates rain rate to drop size). Other factors shown to be of importance include the choice of how to quantify rain rate, drop size, and the cloud condensation nuclei (CCN) proxy, in addition to using artificially low and high retrieved aerosol concentrations near clouds owing to wet scavenging and above-cloud aerosol layers, respectively. Depending on the use of model, satellite, surface, or aircraft data, these biasing factors will have different levels of impact, which this work will explore.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMIN21C1341D
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0320 ATMOSPHERIC COMPOSITION AND STRUCTURE / Cloud physics and chemistry;
- 1990 INFORMATICS / Uncertainty