DOI: 10.1002/2016JD025557
论文题名: Low-CCN concentration air masses over the eastern North Atlantic: Seasonality, meteorology, and drivers
作者: Wood R. ; Stemmler J.D. ; Rémillard J. ; Jefferson A.
刊名: Journal of Geophysical Research: Atmospheres
ISSN: 2169897X
出版年: 2017
卷: 122, 期: 2 起始页码: 1203
结束页码: 1223
语种: 英语
英文关键词: aerosols
; Azores
; cloud condensation nuclei
; clouds
Scopus关键词: aerosol
; air mass
; cloud condensation nucleus
; cloud droplet
; coalescence
; cold air
; concentration (composition)
; condensation
; low pressure
; MODIS
; satellite data
; seasonality
; wind velocity
; Atlantic Ocean
; Atlantic Ocean (North)
; Azores
; Graciosa [Azores]
; Portugal
英文摘要: A 20 month cloud condensation nucleus concentration (NCCN) data set from Graciosa Island (39°N, 28°W) in the remote North Atlantic is used to characterize air masses with low cloud condensation nuclei (CCN) concentrations. Low-CCN events are defined as 6 h periods with mean NCCN<20 cm−3 (0.1% supersaturation). A total of 47 low-CCN events are identified. Surface, satellite, and reanalysis data are used to explore the meteorological and cloud context for low-CCN air masses. Low-CCN events occur in all seasons, but their frequency was 3 times higher in December–May than during June–November. Composites show that many of the low-CCN events had a common meteorological basis that involves southerly low-level flow and rather low wind speeds at Graciosa. Anomalously low pressure is situated to the west of Graciosa during these events, but back trajectories and lagged SLP composites indicate that low-CCN air masses often originate as cold air outbreaks to the north and west of Graciosa. Low-CCN events were associated with low cloud droplet concentrations (Nd) at Graciosa, but liquid water path (LWP) during low-CCN events was not systematically different from that at other times. Satellite Nd and LWP estimates from MODIS collocated with Lagrangian back trajectories show systematically lower Nd and higher LWP several days prior to arrival at Graciosa, consistent with the hypothesis that observed low-CCN air masses are often formed by coalescence scavenging in thick warm clouds, often in cold air outbreaks. ©2016. American Geophysical Union. All Rights Reserved. 资助项目: DE SC0006865MOD0002
; DE-SC0013489
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/62730
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Department of Atmospheric Science, University of Washington, Seattle, WA, United States; School of Marine and Atmospheric Sciences, Stony Brook University, New York, NY, United States; Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States
Recommended Citation:
Wood R.,Stemmler J.D.,Rémillard J.,et al. Low-CCN concentration air masses over the eastern North Atlantic: Seasonality, meteorology, and drivers[J]. Journal of Geophysical Research: Atmospheres,2017-01-01,122(2)