Observations of Clouds, Aerosols, Precipitation, and Surface Radiation over the Southern Ocean: An Overview of CAPRICORN, MARCUS, MICRE, and SOCRATES

McFarquhar, Greg M.; Bretherton, Christopher S.; Marchand, Roger; Protat, Alain; DeMott, Paul J.; Alexander, Simon P.; Roberts, Greg; Twohy, Cynthia H.; Toohey, D. W.; Siems, Steven T.; Huang, Yi; Wood, Robert; Rauber, Robert M.; Lasher-Trapp, Sonia; Jensen, J. B.; Stith, Jeffrey L.; Mace, Jay; Um, Junshik; Järvinen, Emma; Schnaiter, M.; Gettelman, Andrew; Sanchez, Kevin J.; McCluskey, Christina S.; Russell, Lynn M.; McCoy, Isabel L.; Atlas, R.; Bardeen, Charles G.; Moore, Kathryn A.; Hill, Thomas C. J.; Humphries, Ruhi S.; Keywood, Melita; Ristovski, Zoran; Cravigan, Luke T.; Schofield, Robyn; Fairall, C. W.; Mallet, Marc; Kreidenweis, Sonia M.; Rainwater, Bryan; D'Alessandro, J.; Wang, Yang; Wu, Weihong; Saliba, Georges; Levin, Ezra J. T.; Ding, Saisai; Lang, Francisco; Truong, S. C. H.; Wolff, Cory A.; Haggerty, Julie; Harvey, Mike; Klekociuk, Andrew; McDonald, Adrian

doi:10.1175/bams-d-20-0132.1

Cited by 141 publications

(235 citation statements)

References 123 publications

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“…For the 150 m particles, some variation in composition was seen from case to case (McFarquhar et al, 2020), but in all but one of the six cases, sea-spray was secondary in number to sulfur-based particles. The TWOHY ET AL.…”

Section: Elemental Composition Of Single 01-05 μM Aerosol Particlesmentioning

confidence: 92%

Cloud‐Nucleating Particles Over the Southern Ocean in a Changing Climate

et al. 2021

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Stratocumulus clouds over the Southern Ocean have fewer droplets and are more likely to exist in the predominately supercooled phase than clouds at similar temperatures over northern oceans. One likely reason is that this region has few continental and anthropogenic sources of cloud-nucleating particles that can form droplets and ice. In this work, we present an overview of aerosol particle types over the Southern Ocean, including new measurements made below, in and above clouds in this region. These measurements and others indicate that biogenic sulfur-based particles >0.1 μm diameter contribute the majority of cloud condensation nuclei number concentrations in summer. Ice nucleating particles tend to have more organic components, likely from sea-spray. Both types of cloud nucleating particles may increase in a warming climate likely to have less sea ice, more phytoplankton activity, and stronger winds over the Southern Ocean near Antarctica. Taken together, clouds over the Southern Ocean may become more reflective and partially counter the region's expected albedo decrease due to diminishing sea ice. However, detailed modeling studies are needed to test this hypothesis due to the complexity of oceancloud-climate feedbacks in the region. Plain Language Summary Clouds over the Southern Ocean tend to have less droplets and ice crystals than similar clouds over northern oceans due to fewer sources of cloud-nucleating aerosol particles in the region. In this work, we present an overview of aerosol particle types over the Southern Ocean, including new measurements made below, in and above clouds. These measurements indicate that while sea-spray-derived salts do provide cloud nuclei, the majority of aerosol particles that influence summertime clouds in this region are biogenic-that is, derived from ocean microorganisms, with the ocean region near Antarctica being a large summertime source. These cloud-nucleating particles may increase in a warming climate likely to have less sea ice and more phytoplankton activity near Antarctica. These additional particles could make low clouds reflect more light and offset a portion of the warming expected due to diminishing sea ice in a future climate. TWOHY ET AL.

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Section: Elemental Composition Of Single 01-05 μM Aerosol Particlesmentioning

confidence: 92%

Cloud‐Nucleating Particles Over the Southern Ocean in a Changing Climate

et al. 2021

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“…A comprehensive suite of instrumentation from the second Atmospheric Radiation Measurement (ARM) Mobile Facility (McFarquhar et al., 2020, submitted to BAMS) was deployed aboard the ship. A vertically pointing W‐band (95 GHz) Doppler cloud radar (MWACR) sampling every 2 s and set‐up on a stabilizing platform provided vertical profiles of reflectivity, Doppler velocity and spectral width.…”

Section: Meteorological Setting Observations and Simulationsmentioning

confidence: 99%

Challenging and Improving the Simulation of Mid‐Level Mixed‐Phase Clouds Over the High‐Latitude Southern Ocean

et al. 2021

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Climate models exhibit major radiative biases over the Southern Ocean owing to a poor representation of mixed‐phase clouds. This study uses the remote‐sensing dataset from the Measurements of Aerosols, Radiation and Clouds over the Southern Ocean (MARCUS) campaign to assess the ability of the Weather Research and Forecasting (WRF) model to reproduce frontal clouds off Antarctica. It focuses on the modeling of thin mid‐level supercooled liquid water layers which precipitate ice. The standard version of WRF produces almost fully glaciated clouds and cannot reproduce cloud top turbulence. Our work demonstrates the importance of adapting the ice nucleation parameterization to the pristine austral atmosphere to reproduce the supercooled liquid layers. Once simulated, droplets significantly impact the cloud radiative effect by increasing downwelling longwave fluxes and decreasing downwelling shortwave fluxes at the surface. The net radiative effect is a warming of snow and ice covered surfaces and a cooling of the ocean. Despite improvements in our simulations, the local turbulent circulation related to cloud‐top radiative cooling is not properly reproduced, advocating for the need to develop a parameterization for top‐down convection to capture the turbulence‐microphysics interplay at cloud top.

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“…In this study, the vertical variations of characteristics of the DSDs (i.e., r e , ε , N d ) are presented and the variation of ε with aerosol loading and vertical velocity ( w ) is analyzed and discussed for the prevalent SLW non‐precipitating stratocumulus clouds observed over the SO during the Southern Ocean Clouds Radiation Aerosol Transport Experimental Study (SOCRATES, McFarquhar et al., 2021). SOCRATES was conducted in the region between Hobart, Australia and 62°S, and from 134°E to 163°E.…”

Section: Introductionmentioning

confidence: 99%

Dispersion of Droplet Size Distributions in Supercooled Non‐precipitating Stratocumulus from Aircraft Observations Obtained during the Southern Ocean Cloud Radiation Aerosol Transport Experimental Study

et al. 2021

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These low-level clouds, such as shallow boundary layer clouds (e.g., subtropical stratocumulus and trade-wind cumulus) have significant impacts on the radiation budget and climate change (Bony & Dufresne, 2005). While most past studies have focused on r e and LWC, the relative dispersion (ε), defined as the ratio of the standard deviation of the droplet size distribution (σ) to the number mean radius (r m), represents another DSD parameter which is of great importance to estimate the indirect aerosol effect on the climate system (Peng & Lohmann, 2003).

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Observations of Clouds, Aerosols, Precipitation, and Surface Radiation over the Southern Ocean: An Overview of CAPRICORN, MARCUS, MICRE, and SOCRATES

Cited by 141 publications

References 123 publications

Cloud‐Nucleating Particles Over the Southern Ocean in a Changing Climate

Cloud‐Nucleating Particles Over the Southern Ocean in a Changing Climate

Challenging and Improving the Simulation of Mid‐Level Mixed‐Phase Clouds Over the High‐Latitude Southern Ocean

Dispersion of Droplet Size Distributions in Supercooled Non‐precipitating Stratocumulus from Aircraft Observations Obtained during the Southern Ocean Cloud Radiation Aerosol Transport Experimental Study

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