Analysis of Cloud-resolving Simulations of a Tropical Mesoscale Convective System Observed during TWP-ICE: Vertical Fluxes and Draft Properties in Convective and Stratiform Regions

Journal Article · Tue Oct 02 04:00:00 EDT 2012 · Journal of Geophysical Research. D. (Atmospheres), 117:D19201

DOI:https://doi.org/10.1029/2012JD017759· OSTI ID:1057352

Mrowiec, Agnieszka A; Rio, Catherine; Fridlind, Ann; Ackerman, Andrew; Del Genio, Anthony D; Pauluis, Olivier; Varble, Adam; Fan, Jiwen

We analyze three cloud-resolving model simulations of a strong convective event observed during the TWP-ICE campaign, differing in dynamical core, microphysical scheme or both. Based on simulated and observed radar reflectivity, simulations roughly reproduce observed convective and stratiform precipitating areas. To identify the characteristics of convective and stratiform drafts that are difficult to observe but relevant to climate model parameterization, independent vertical wind speed thresholds are calculated to capture 90% of total convective and stratiform updraft and downdraft mass fluxes. Convective updrafts are fairly consistent across simulations (likely owing to fixed large-scale forcings and surface conditions), except that hydrometeor loadings differ substantially. Convective downdraft and stratiform updraft and downdraft mass fluxes vary notably below the melting level, but share similar vertically uniform draft velocities despite differing hydrometeor loadings. All identified convective and stratiform downdrafts contain precipitation below ~10 km and nearly all updrafts are cloudy above the melting level. Cold pool properties diverge substantially in a manner that is consistent with convective downdraft mass flux differences below the melting level. Despite differences in hydrometeor loadings and cold pool properties, convective updraft and downdraft mass fluxes are linearly correlated with convective area, the ratio of ice in downdrafts to that in updrafts is ~0.5 independent of species, and the ratio of downdraft to updraft mass flux is ~0.5-0.6, which may represent a minimum evaporation efficiency under moist conditions. Hydrometeor loading in stratiform regions is found to be a fraction of hydrometeor loading in convective regions that ranges from ~10% (graupel) to ~90% (cloud ice). These findings may lead to improved convection parameterizations.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1057352
• Report Number(s): PNNL-SA-91861; KP1701000
• Journal Information: Journal of Geophysical Research. D. (Atmospheres), 117:D19201, Journal Name: Journal of Geophysical Research. D. (Atmospheres), 117:D19201
• Country of Publication: United States
• Language: English

Related Subjects

TWP-ICE
analysis
cloud-resolving
convective
fluxes
mesoscale
simulations
stratiform
tropical
vertical