5–7 May 2021
virtual
Europe/Copenhagen timezone

Cloud field organisation in trade-wind cumulus: a consequence of precipitation efficiency

7 May 2021, 16:00
1h 45m
virtual

virtual

Interactive presentation Organisation in Shallow Convection Organisation in Shallow Convection

Speaker

Graham Feingold (NOAA ESRL Chemical Sciences Division)

Description

The influence of aerosol on precipitation in shallow clouds is a topic of longstanding interest. We will address the case of aerosol effects on warm trade-wind cumulus and show that the cloud system develops spatial organization structures in such a way as to generate similar amounts of precipitation, regardless of the aerosol input.
In aerosol-poor conditions, precipitation formation is efficient, and the system generates widespread surface rain. As a result, divergent cold pools are small because they encounter adjacent divergent flows within a short distance.
With increasing aerosol there is a reduction in the efficiency by which precipitation is generated and the system has to generate large clusters of clouds in order to achieve a similar amount of surface rain. These large clusters are embedded in extensive, relatively cloud-free areas that are associated with divergent cold pools generated by the precipitating clusters themselves.
Finally we show that these response are not unique to aerosol perturbations; similar changes in organization result from meteorological controls such as wind shear. Thus, we view spatial organisation in trade-wind cumulus fields as a consequence of the efficiency by which rain is produced.

Primary author

Graham Feingold (NOAA ESRL Chemical Sciences Division)

Presentation materials