Moisture Distributions in Tropical Cold Pools

Zuidema, P., University of Miami

Cloud Processes

Convective Processes

Chandra A, P Zuidema, S Krueger, A Kochanski, S de Szoeke, and J Zhang. 2018. "Moisture distributions in tropical cold pools from equatorial Indian Ocean observations and cloud-resolving simulations." Journal of Geophysical Research: Atmospheres, , 10.1029/2018JD028634. ONLINE.

Science

Rain-driven downdraughts (cold pools) occur during conditions unfavorable for deep cloud-cluster formation with a drier mid-atmosphere. Cold pools help explain why cumulus congestus is common in the tropics.

 

Impact

We find that in one cloud-resolving simulation, the rain evaporation is too high, leading to an unrealistic moisture distribution. This may explain why, to date, understandings of cold pool processes through models and observations have not always agreed.

Summary

Cloud-resolving simulations capture realistic rain rates and surface wind changes (and thereby surface fluxes). The evolution in the model near-surface moisture field is unrealistic, however, with an erroneous moisture enhancement inside the cold pool edge that is attributed to rain evaporation. This supports a further focus on the model representation of cold pool frontal dynamics and mixing.