Volume 128, Issue 18 e2022JD037109
Research Article

What Are the Similarities and Differences in Marine Boundary Layer Cloud and Drizzle Microphysical Properties During the ACE-ENA and MARCUS Field Campaigns?

Alexa. R. Marcovecchio

Alexa. R. Marcovecchio

Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ, USA

Contribution: Methodology, Software, Validation, Formal analysis, ​Investigation, Resources, Data curation, Writing - original draft, Writing - review & editing, Visualization

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Baike Xi

Baike Xi

Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ, USA

Contribution: Conceptualization, Methodology, Software, Validation, Formal analysis, ​Investigation, Resources, Data curation, Writing - review & editing, Visualization, Supervision

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Xiaojian Zheng

Xiaojian Zheng

Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ, USA

Contribution: Methodology, Software, Validation, Formal analysis, ​Investigation, Resources, Data curation, Writing - review & editing, Visualization

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Peng Wu

Peng Wu

Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA

Contribution: Methodology, Software, Validation, Formal analysis, ​Investigation, Writing - review & editing, Visualization

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Xiquan Dong

Corresponding Author

Xiquan Dong

Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ, USA

Correspondence to:

X. Dong,

[email protected]

Contribution: Conceptualization, Methodology, Formal analysis, Writing - review & editing, Visualization, Supervision, Project administration, Funding acquisition

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Ali Behrangi

Ali Behrangi

Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ, USA

Contribution: Formal analysis, Writing - review & editing, Supervision, Funding acquisition

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First published: 07 September 2023

Abstract

This study compares macrophysical and microphysical properties of single-layered, liquid-dominant MBL clouds from the Measurements of Aerosols, Radiation, and Clouds over the Southern Ocean (MARCUS) (above 60°S) and the ARM East North Atlantic (ENA) site during the Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA) field campaign. A total of 1,136 (16.5% of clouds) and 6,034 5-min cloud samples are selected from MARCUS and ARM ENA in this study. MARCUS clouds have higher cloud-top heights, thicker cloud layers, larger liquid water path, and colder cloud temperatures than ENA. Thinner, warmer MBL clouds at ENA can contain higher layer-mean liquid water content due to higher cloud and ocean surface temperatures along with greater precipitable water vapor (PWV). MARCUS has a higher drizzle frequency rate (71.8%) than ENA (45.1%). Retrieved cloud and drizzle microphysical properties from each field campaign show key differences. MARCUS clouds feature smaller cloud droplets, whereas ENA clouds have larger cloud droplets, especially at the upper region of the cloud. From cloud top to cloud base, drizzle drop sizes increase while number concentrations decrease. Drizzle drop radius and number concentration decrease from cloud base to drizzle base due to net evaporation, and MARCUS' lower specific humidity leads to a higher drizzle base than ENA. The broader surface pressure and lower tropospheric stability (LTS) distributions during MARCUS have demonstrated that there are different synoptic patterns for selected cases during MARCUS with less PWV, while ENA is dominated by high pressure systems with nearly doubled PWV.

Key Points

  • MARCUS clouds have higher cloud-top heights, thicker cloud layers, & larger liquid water path, but much colder cloud temperature than during Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA)

  • MARCUS clouds feature a much higher drizzle frequency (71.8% vs. 45.1%), lower drizzle LWC, & thinner sub-cloud drizzle layer than ACE-ENA

  • MARCUS has varying synoptic patterns with less precipitable water vapor (PWV), while ARM-ENA is dominated by high pressure systems with nearly doubled PWV

Plain Language Summary

This study analyzes warm, low (below 3 km) clouds that are made up of tiny droplets of liquid water. These clouds are difficult for weather and climate models to predict because they are not well understood at the smallest scale. The MARCUS field campaign observed this type of cloud while taking measurements on a ship that was traveling the Northern Southern Ocean. We study cloud and drizzle drops at a very small scale that is almost invisible to the naked eye. We have a method to separate cloud and drizzle droplets from the same sensor and can learn about these drops at different heights in the atmosphere. We then compare this information to observations from the ACE-ENA field campaign on Graciosa Island in the East North Atlantic (ENA). We found that ENA has thinner and warmer clouds than MARCUS. These ENA clouds can contain more water than those of MARCUS because there are higher cloud and ocean temperatures in the area as well as more water vapor available in the atmosphere. The MARCUS clouds are thicker and drizzle events occur more often even though they contain less liquid water and have less available water vapor.

Data Availability Statement

To access data from the ACE-ENA and MARCUS field campaigns go to https://adc.arm.gov/discovery/#/results and select either “Eastern North Atlantic” or “MARCUS (Shipboard Southern Ocean Campaign); Mobile Facility” from the “Sites” menu in column on the left (See references for Giangrande et al., 2011; Zhang, 1996). For MWR input data, “mwrret2turn” data set is used for ENA and the “mwerret1liljclou” is used for MARCUS. MWRRET version 2 is used and for the MARCUS site, MWERRET version one is used. The “arsclkazr1kollias” data set is used for MARCUS and ENA processed ARSCL data. Data from the SOCRATES airborne field campaign is available from the National Center for Atmospheric Research (NCAR) Earth Observing Laboratory SOCRATES data archive (https://data.eol.ucar.edu/master_lists/generated/socrates/; Wu & McFarquhar, 2019; NCAR/EOL HCR Team, & NCAR/EOL HSRL Team, 2022). ERA5 hourly surface data (https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form; Hershbach et al., 2023b) and ERA5 hourly pressure level data (https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-pressure-levels?tab=form; Hershbach et al., 2023a) can be accessed from the Copernicus Climate Change Service (C3S) Climate Data Store. Retrieval data for each site can be accessed at the University of Arizona Research Data Repository (Marcovecchio et al., 2023).