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Title: Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores

Abstract

Here, six coupled and decoupled marine boundary layer (MBL) clouds were chosen from the 19 month Atmospheric Radiation Measurement Mobile Facility data set over the Azores. Thresholds of liquid water potential temperature difference ΔθL < 0.5 K (>0.5 K) and total water mixing ratio difference Δqt < 0.5 g/kg (>0.5 g/kg) below the cloud base were used for selecting the coupled (decoupled) cases. A schematic diagram was given to demonstrate the coupled and decoupled MBL vertical structures and how they associate with nondrizzle, virga, and rain drizzle events. Out of a total of 2676 5 min samples, 34.5% were classified as coupled and 65.5% as decoupled, 36.2% as nondrizzle and 63.8% as drizzle (47.7% as virga and 16.1% as rain), and 33.4% as daytime and 66.6% as nighttime. The decoupled cloud layer is deeper (0.406 km) than coupled cloud layer (0.304 km), and its liquid water path and cloud droplet effective radius (re) values (122.1 gm-2 and 13.0 µm) are higher than coupled ones (83.7 gm-2 and 10.4 µm). Conversely, decoupled stratocumuli have lower cloud droplet number concentration (Nd) and surface cloud condensation nucleus (CCN) concentration (NCCN) (74.5 cm-3 and 150.9 cm-3) than coupled stratocumuli (111.7 cm-3 and 216.4 cm-3).more » The linear regressions between re and Nd with NCCN have demonstrated that coupled re and Nd strongly depend on NCCN and have higher correlations (-0.56 and 0.59) with NCCN than decoupled results (-0.14 and 0.25). The MBL cloud properties under nondrizzle and virga drizzle conditions are similar to each other but significantly different to those of rain drizzle.« less

Authors:
 [1];  [1];  [1];  [1]
  1. Univ. of North Dakota, Grand Forks, ND (United States)
Publication Date:
Research Org.:
Univ. of North Dakota, Grand Forks, ND (United States)
Sponsoring Org.:
USDOE Office of Environment, Health, Safety and Security (AU), Office of Environmental Protection and ES&H Reporting
OSTI Identifier:
1440552
Grant/Contract Number:  
SC0008468
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 120; Journal Issue: 12; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; coupled and decoupled boundary layers; CCN; marine boundary layer clouds; cloud microphysical properties; drizzle and nondrizzle

Citation Formats

Dong, Xiquan, Schwantes, Adam C., Xi, Baike, and Wu, Peng. Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores. United States: N. p., 2015. Web. doi:10.1002/2014JD022939.
Dong, Xiquan, Schwantes, Adam C., Xi, Baike, & Wu, Peng. Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores. United States. https://doi.org/10.1002/2014JD022939
Dong, Xiquan, Schwantes, Adam C., Xi, Baike, and Wu, Peng. 2015. "Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores". United States. https://doi.org/10.1002/2014JD022939. https://www.osti.gov/servlets/purl/1440552.
@article{osti_1440552,
title = {Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores},
author = {Dong, Xiquan and Schwantes, Adam C. and Xi, Baike and Wu, Peng},
abstractNote = {Here, six coupled and decoupled marine boundary layer (MBL) clouds were chosen from the 19 month Atmospheric Radiation Measurement Mobile Facility data set over the Azores. Thresholds of liquid water potential temperature difference ΔθL < 0.5 K (>0.5 K) and total water mixing ratio difference Δqt < 0.5 g/kg (>0.5 g/kg) below the cloud base were used for selecting the coupled (decoupled) cases. A schematic diagram was given to demonstrate the coupled and decoupled MBL vertical structures and how they associate with nondrizzle, virga, and rain drizzle events. Out of a total of 2676 5 min samples, 34.5% were classified as coupled and 65.5% as decoupled, 36.2% as nondrizzle and 63.8% as drizzle (47.7% as virga and 16.1% as rain), and 33.4% as daytime and 66.6% as nighttime. The decoupled cloud layer is deeper (0.406 km) than coupled cloud layer (0.304 km), and its liquid water path and cloud droplet effective radius (re) values (122.1 gm-2 and 13.0 µm) are higher than coupled ones (83.7 gm-2 and 10.4 µm). Conversely, decoupled stratocumuli have lower cloud droplet number concentration (Nd) and surface cloud condensation nucleus (CCN) concentration (NCCN) (74.5 cm-3 and 150.9 cm-3) than coupled stratocumuli (111.7 cm-3 and 216.4 cm-3). The linear regressions between re and Nd with NCCN have demonstrated that coupled re and Nd strongly depend on NCCN and have higher correlations (-0.56 and 0.59) with NCCN than decoupled results (-0.14 and 0.25). The MBL cloud properties under nondrizzle and virga drizzle conditions are similar to each other but significantly different to those of rain drizzle.},
doi = {10.1002/2014JD022939},
url = {https://www.osti.gov/biblio/1440552}, journal = {Journal of Geophysical Research: Atmospheres},
issn = {2169-897X},
number = 12,
volume = 120,
place = {United States},
year = {Wed Jun 10 00:00:00 EDT 2015},
month = {Wed Jun 10 00:00:00 EDT 2015}
}

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Works referenced in this record:

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Works referencing / citing this record:

Prognostic Precipitation in the MIROC6‐SPRINTARS GCM: Description and Evaluation Against Satellite Observations
journal, March 2019


Episodes of Warm‐Air Advection Causing Cloud‐Surface Decoupling During the MARCUS
journal, November 2019


Marine boundary layer aerosol in the eastern North Atlantic: seasonal variations and key controlling processes
journal, January 2018