气候变化领域集成服务门户(CCPortal): An Observational Comparison of Level of Neutral Buoyancy and Level of Maximum Detrainment in Tropical Deep Convective Clouds

CCPortal

DOI	10.1029/2020JD032637
	An Observational Comparison of Level of Neutral Buoyancy and Level of Maximum Detrainment in Tropical Deep Convective Clouds
	Wang D.; Jensen M.P.; D'Iorio J.A.; Jozef G.; Giangrande S.E.; Johnson K.L.; Luo Z.J.; Starzec M.; Mullendore G.L.
发表日期	2020
ISSN	2169897X
卷号	125 期号:16
英文摘要	Tropical deep convective clouds are important drivers of large-scale atmospheric circulation representing the main vertical transport pathway through the depth of the troposphere for heat, momentum, water, and chemical species. The strength and depth of this transport are impacted by the convective updraft size and intensity that are driven by buoyancy, dynamical forcing, and mixing of environmental air, that is, entrainment. In this study, we identify tropical deep convective systems with well-defined forward anvils using Atmospheric Radiation Measurement (ARM) ground-based profiling radars, at three ARM fixed sites in the Tropical Western Pacific (TWP; i.e., Manus, Nauru, and Darwin) and three ARM Mobile Facility deployments in Niamey, Niger; Gan Island, Maldives; and Manacapuru, Brazil. We use the difference between the level of neutral buoyancy (LNB) and the level of maximum detrainment (LMD) as a proxy for the effective bulk convective entrainment (εproxy). The LNB, the theoretical height that a parcel raised above the level of free convection would reach with no mixing, is calculated based on preconvection radiosonde measurements using parcel theory. The LMD is the height of the maximum reflectivity observed in forward anvil clouds by profiling radars. Deep convective systems over the TWP show higher LNBs that extend to 16.3 km on average and larger εproxy (median value of LNB minus LMD up to 6.5 km) compared to their continental counterparts in the Amazon and West Africa. Oceanic conditions show larger convective available potential energy (CAPE) coupled with higher moisture at low levels, which favors larger εproxy. In contrast, continental cases initiate and develop, under high convective inhibition, steeper environmental lapse rate, and high wind shear conditions, which show smaller offset between LNB and LMD. Deep convective cases that promote significant cold pools at the surface experience less εproxy. Using a Random Forest regression algorithm, CAPE is associated with the highest feature importance score for predicting convective εproxy, followed by low-level relative humidity. For continental cases, the low-level wind shear also indicates higher importance. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	ARM profiling radar; CAPE; deep convection; entrainment; level of maximum detrainment; level of neutral buoyancy
语种	英语
来源期刊	Journal of Geophysical Research: Atmospheres
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/185816
作者单位	Department of Environmental and Climate Sciences, Brookhaven National Laboratory, Upton, NY, United States; Department of Meteorology and Atmospheric Science, Pennsylvania State University, University Park, PA, United States; Department of Environmental Science, Colorado College, Colorado Springs, CO, United States; Department of Earth and Atmospheric Sciences, City College of New York, New York, NY, United States; Department of Atmospheric Sciences, University of North Dakota, Grand Forks, ND, United States
推荐引用方式 GB/T 7714	Wang D.,Jensen M.P.,D'Iorio J.A.,et al. An Observational Comparison of Level of Neutral Buoyancy and Level of Maximum Detrainment in Tropical Deep Convective Clouds[J],2020,125(16).
APA	Wang D..,Jensen M.P..,D'Iorio J.A..,Jozef G..,Giangrande S.E..,...&Mullendore G.L..(2020).An Observational Comparison of Level of Neutral Buoyancy and Level of Maximum Detrainment in Tropical Deep Convective Clouds.Journal of Geophysical Research: Atmospheres,125(16).
MLA	Wang D.,et al."An Observational Comparison of Level of Neutral Buoyancy and Level of Maximum Detrainment in Tropical Deep Convective Clouds".Journal of Geophysical Research: Atmospheres 125.16(2020).