气候变化领域集成服务门户(CCPortal): Cloud adjustments from large-scale smoke-circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition

CCPortal

DOI	10.5194/acp-22-12113-2022
	Cloud adjustments from large-scale smoke-circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition
	Diamond, Michael S.; Saide, Pablo E.; Zuidema, Paquita; Ackerman, Andrew S.; Doherty, Sarah J.; Fridlind, Ann M.; Gordon, Hamish; Howes, Calvin; Kazil, Jan; Yamaguchi, Takanobu; Zhang, Jianhao; Feingold, Graham; Wood, Robert
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	12113
结束页码	12151
卷号	22 期号:18 页码:39
英文摘要	Smoke from southern Africa blankets the southeastern Atlantic Ocean from June to October, producing strong and competing aerosol radiative effects. Smoke effects on the transition between overcast stratocumulus and scattered cumulus clouds are investigated along a Lagrangian (air-mass-following) trajectory in regional climate and large eddy simulation models. Results are compared with observations from three recent field campaigns that took place in August 2017: ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES), CLouds and Aerosol Radiative Impacts and Forcing: Year 2017 (CLARIFY), and Layered Atlantic Smoke Interactions with Clouds (LASIC). The case study is set up around the joint ORACLES-CLARIFY flight that took place near Ascension Island on 18 August 2017. Smoke sampled upstream on an ORACLES flight on 15 August 2017 likely entrained into the marine boundary layer later sampled during the joint flight. The case is first simulated with the WRF-CAM5 regional climate model in three distinct setups: (1) FireOn, in which smoke emissions and any resulting smoke-cloud-radiation interactions are included; (2) FireOff, in which no smoke emissions are included; (3) RadOff, in which smoke emissions and their microphysical effects are included but aerosol does not interact directly with radiation. Over the course of the Lagrangian trajectory, differences in free tropospheric thermodynamic properties between FireOn and FireOff are nearly identical to those between FireOn and RadOff, showing that aerosol-radiation interactions are primarily responsible for the free tropospheric effects. These effects are non-intuitive: in addition to the expected heating within the core of the smoke plume, there is also a banding effect of cooler temperature ( similar to 1-2 K) and greatly enhanced moisture ( > 2 g kg(-1)) at the plume top. This banding effect is caused by a vertical displacement of the former continental boundary layer in the free troposphere in the FireOn simulation resulting from anomalous diabatic heating due to smoke absorption of sunlight that manifests primarily as a few hundred meters per day reduction in large-scale subsidence over the ocean. A large eddy simulation (LES) is then forced with free tropospheric fields taken from the outputs for the WRF-CAM5 FireOn and FireOff runs. Cases are run by selectively perturbing one variable (e.g., aerosol number concentration, temperature, moisture, vertical velocity) at a time to better understand the contributions from different indirect (microphysical), large-scale semi-direct (above-cloud thermodynamic and subsidence changes), and local semi-direct (below-cloud smoke absorption) effects. Despite a more than 5-fold increase in cloud droplet number concentration when including smoke aerosol concentrations, minimal differences in cloud fraction evolution are simulated by the LES when comparing the base case with a perturbed aerosol case with identical thermodynamic and dynamic forcings. A factor of 2 decrease in background free tropospheric aerosol concentrations from the FireOff simulation shifts the cloud evolution from a classical entrainment-driven deepening-warming transition to trade cumulus to a precipitation-driven drizzle-depletion transition to open cells, however. The thermodynamic and dynamic changes caused by the WRF-simulated large-scale adjustments to smoke diabatic heating strongly influence cloud evolution in terms of both the rate of deepening (especially for changes in the inversion temperature jump and in subsidence) and in cloud fraction on the final day of the simulation (especially for the moisture banding effect). Such large-scale semi-direct effects would not have been possible to simulate using a small-domain LES model alone.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000855095300001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273815
作者单位	University of Colorado System; University of Colorado Boulder; National Oceanic Atmospheric Admin (NOAA) - USA; University of California System; University of California Los Angeles; University of California System; University of California Los Angeles; University of Miami; National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; University of Washington; University of Washington Seattle; University of Washington; University of Washington Seattle; Carnegie Mellon University; Carnegie Mellon University
推荐引用方式 GB/T 7714	Diamond, Michael S.,Saide, Pablo E.,Zuidema, Paquita,et al. Cloud adjustments from large-scale smoke-circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition[J],2022,22(18):39.
APA	Diamond, Michael S..,Saide, Pablo E..,Zuidema, Paquita.,Ackerman, Andrew S..,Doherty, Sarah J..,...&Wood, Robert.(2022).Cloud adjustments from large-scale smoke-circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(18),39.
MLA	Diamond, Michael S.,et al."Cloud adjustments from large-scale smoke-circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.18(2022):39.