Convective Entrainment Rates Estimated from Aura CO and CloudSat/CALIPSO Observations and Comparison with GEOS-5

• Published in: Journal of geophysical research. Atmospheres 2019-09, Vol.124 (17-18), p.9796-9807
• Main Authors: Stanfield, Ryan E, Su, Hui, Jiang, Jonathan H, Freitas, Saulo R, Molod, Andrea M, Luo, Zhengzhao Johnny, Huang, Lei, Luo, Ming
• Format: Article
• Language: English
• Subjects: Atmospheric Infrared Sounder; Carbon monoxide; Carbon monoxide measurements; Computer simulation; Convection; Convective available potential energy; Convective transport; deep convection; Earth; Earth Resources And Remote Sensing; Entrainment; entrainment rates; Geophysics; Height; Humidity; model validation; Parameter sensitivity; Parameter uncertainty; Potential energy; Relative humidity; satellite; Simulation; Statistical methods; Tropical environments; Troposphere
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1029/2019JD030846

Entrainment rate (λ) in convective parameterizations remains a sensitive parameter with much uncertainty in model simulations. This study estimates λ using carbon monoxide (CO) measurements jointly from the Microwave Limb Sounder (MLS) and Tropospheric Emission Spectrometer (TES) onboard the Aura satellite, associated with deep convective cases identified by CloudSat and CALIPSO observations. CO is treated as a conserved quantity over convective transport time scales and a simple entraining-plume model is used to derive entrainment rates. The relationships of the observational estimates of λ as a function of convective height, environmental relative humidity and convective available potential energy (CAPE) derived from Atmospheric Infrared Sounder (AIRS) data are compared with those from Goddard Earth Observing System Model (GEOS-5) simulations. Bulk statistics of λ show that the values of λ are predominately below 20% km(exp-1) for deep convection and the occurrence frequency of any λ decreases with increasing λ. Composite λ values are generally lower in the tropics compared to northern mid-latitudes in both observations and the GEOS-5 model. A decrease of λ with increasing convective height is found in both observations and model simulations. We also find that λ tends to decrease with increasing CAPE in the observation-based λ’s and plume-based GEOS-5 λ’s, although the model given λ’s have a non-monotonic relation with CAPE. The observed λ’s have a weak relation with lower-to-mid tropospheric RH, while both GEOS-5 plume-based and given λ increases with increasing RH.