What causes the weakened convective scavenging of aerosols in E3SMv2?
First Author
Kai Zhang
kai.zhang@pnnl.gov
All Authors
To be confirmed
Topic
Atmospheric aerosols; E3SMv2; model development and evaluation
Project
E3SM
Abstract
Convective clouds can efficiently remove aerosols from the atmosphere. Compared to E3SM version 1, the aerosol wet removal by convective clouds is substantially decreased in v2, while the wet removal by stratiform clouds increased. This shift causes overall weakened aerosol wet removal, larger burden, and longer lifetime for all species (if everything else remains unchanged). Consequently, the simulated aerosol optical depth has large positive biases, especially over regions where convective cloud systems frequently present. To identify the reasons why there is such a shift in aerosol wet removal pathways, we have performed short nudged simulations with individual parameterization modifications reverted to the original v1 settings. We find the modifications that cause 1) a substantial change of the ratio between stratiform and convective precipitation, and 2) a large change in the cloud fields that determine the first-order loss rate (the conversion from cloud condensate to precipitation) can well explain the weakened convective scavenging of aerosols in E3SMv2. These two changes are also expected to happen when the model is running at much higher resolutions or with substantially changed/tuned parameterizations, so this study offers useful information for future model development and evaluations.
In-person
Yes
Poster
Note: This work was performed under phase 2 & 3 water cycle teams, but it’s more relevant to the colleagues who are interested in the atmosphere model development and evaluation. Also, would it be possible to assign this poster next to the other poster Impacts of RRM on aerosols from our group? Thanks!