Ice in Southern Ocean Clouds With Cloud Top Temperatures Exceeding −5°C

Zaremba, Troy J.; Rauber, Robert M.; McFarquhar, Greg M.; DeMott, Paul J.; D'Alessandro, J.; Wu, Weihong

doi:10.1029/2021jd034574

Cited by 6 publications

(8 citation statements)

References 42 publications

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“…The cloud top temperature is higher than −5°C where INP concentrations were previously reported to be the lowest (Kanji et al., 2017), and the liquid/drizzle near cloud base is very likely caused by melting level being located at 1 km above the warm ocean surface. Other studies using satellite observations (Mace, Protat, & Benson, 2021) and airborne observations (Finlon et al., 2020; Zaremba et al., 2021) have also shown possible existence of SIP processes, leading to the high amount of ice over the SO at similar temperature conditions. Several studies mentioned that the warm ocean surfaces over the SO potentially result in stronger updrafts and more turbulence motions, which may be conducive to SIP processes such as rime splintering (Field et al., 2016; Hallett & Mossop, 1974; Korolev & Leisner, 2020; Luke et al., 2021).…”

Section: Discussionmentioning

confidence: 91%

“…In addition to previously reported biases of liquid phase in climate model simulations, several studies have shown that ice phase is likely underestimated in climate model simulations, potentially due to the underestimation of secondary ice production (SIP) processes in model parameterizations (Zhao, Liu, Phillips, et al, 2021;. Other studies using aircraft and satellite observations also indicated that SIP processes likely increase the amount of cloud hydrometeors in ice phase over the SO (Mace, Protat, & Benson, 2021;Zaremba et al, 2021). Several studies evaluated newer versions of climate models with improved representations of SLW in mixed-phase clouds compared with the CMIP5 models and found remaining biases in ice phase.…”

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confidence: 99%

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Ship‐Based Observations and Climate Model Simulations of Cloud Phase Over the Southern Ocean

et al. 2023

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The Southern Ocean (SO) region is characterized by vast open waters and extremely high (80%) annual low-level cloud cover (Hu et al., 2010). These clouds prevent the darker ocean waters below them from considerable warming by reflecting most of the shortwave solar radiation back to space. The SO clouds thereby maintain a delicate surface energy balance which has a cascading effect on global ocean circulations as well as global atmospheric circulation patterns (Hwang & Frierson, 2013). Thus, a number of recent studies have focused their attention on the comparisons between observations and global climate model (GCM) simulations in terms of cloud properties over the SO. Recent modeling efforts showed that SO clouds in GCMs suffered from large uncertainties and biases and improved representations of cloud processes are needed (

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Section: Discussionmentioning

confidence: 91%

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confidence: 99%

Ship‐Based Observations and Climate Model Simulations of Cloud Phase Over the Southern Ocean

et al. 2023

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“…This section discusses methods of identifying cloud phase using both the in situ and remote-sensing data, and compares the identified phases for collocated remote sensing and in situ observations. Detailed information about the in situ and remote probes installed on the NCAR/NSF GV during SOCRATES, their operating characteristics, and the algorithms used to process the data are discussed elsewhere (e.g., D'Alessandro et al, 2021;Järvinen et al, 2022;McFarquhar et al, 2021;Wang et al, 2020;Zaremba et al, 2020Zaremba et al, , 2021. Thus, only a brief summary is provided here together with a focus on unique aspects of the processing required for this analysis.…”

Section: In Situ Datamentioning

confidence: 99%

Characterization of Southern Ocean Boundary Layer Clouds Using Airborne Radar, Lidar, and In Situ Cloud Data: Results From SOCRATES

et al. 2022

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The atmosphere above the Southern Ocean (SO) has very high cloud coverage, with the fraction of clouds below 3 km in altitude approaching 80% (Haynes et al., 2011;Mace et al., 2009). Many of these low boundary layer (BL) clouds are associated with large and complex extratropical cyclones that are prevalent over the SO (McFarquhar et al., 2021), and are one of the largest sources of disagreement among General Circulation Models (GCMs) (Bony et al., 2006;Vial et al., 2013). An understanding of the processes responsible for the complicated structure of SO BL clouds is critical for improving the parameterizations that are used to represent such processes in GCMs that model cloud radiative feedbacks in a rapidly warming global climate (McCoy et al., 2015;Trenberth & Fasullo, 2010), as needed to better project future climate change (IPCC, 2021).Past studies have shown that supercooled liquid water (SLW; liquid water at subfreezing temperatures) is especially common in SO clouds, and more prevalent than at similar latitudes in the Northern Hemisphere (NH), likely due to the lack of ice nucleating particles, which tend to increase glaciation rates, over the SO (Gong

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“…An additional focus was the observation of supercooled liquid water, which is common in the pristine environment of the Southern Ocean (D’Alessandro et al., 2021; Romatschke & Vivekanandan, 2022; Schima et al., 2022). While many of the studies that are based on SOCRATES observations focus on microphysical properties of clouds (D’Alessandro et al., 2021; Efraim et al., 2020; Saliba et al., 2021; Schima et al., 2022; Twohy et al., 2021; Y. Wang et al., 2021; Zaremba et al., 2021; Zhao et al., 2020), few studies (e.g., Truong et al., 2020) have focused on the physical properties of the observed clouds.…”

Section: Introductionmentioning

confidence: 99%

“…While many of the studies that are based on SOCRATES observations focus on microphysical properties of clouds (D'Alessandro et al, 2021;Efraim et al, 2020;Saliba et al, 2021;Schima et al, 2022;Twohy et al, 2021;Y. Wang et al, 2021;Zaremba et al, 2021;Zhao et al, 2020), few studies (e.g., Truong et al, 2020) have focused on the physical properties of the observed clouds.…”

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confidence: 99%

Cloud Properties Derived From Airborne Cloud Radar Observations Collected in Three Climatic Regions

Romatschke

2023

JGR Atmospheres

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Clouds observed by the airborne High‐Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Cloud Radar (HCR) were classified into twelve categories, based on their convective/stratiform nature. Dimensional and convective cloud properties were analyzed in three climatic regions: The subtropical easterlies off the coast of California, the Southern Ocean, and the tropics surrounding Central America. The convective properties of the stratocumulus clouds in the subtropical easterlies are closely related to the degree of boundary layer decoupling. In regions of strong boundary layer coupling, convectivity and updrafts in the clouds are weak and precipitation is light. In regions where the boundary layer is more decoupled, convective properties increase together with cloud top altitudes and cloud depth. Cloud properties of stratocumulus and cumulus clouds over the Southern Ocean show similarities to those observed in the subtropics, but overall they are less convective, indicating a strongly coupled boundary layer. Sea surface temperatures are much lower and the development of clouds is driven by transient synoptic conditions rather than zonal ocean temperature gradients. Clouds observed over the tropical oceans are much more convective in nature. As in the two other regions, they are mostly shallow, but clouds in regions with high sea surface temperatures have high convectivity and reflectivity values and stronger updrafts. Some of them grow to extreme depths (>14 km) and widths (>500 km). They have strong and large updraft regions and are heavily precipitating throughout their life cycle as they transition from the convective to the stratiform stage.

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Ice in Southern Ocean Clouds With Cloud Top Temperatures Exceeding −5°C

Cited by 6 publications

References 42 publications

Ship‐Based Observations and Climate Model Simulations of Cloud Phase Over the Southern Ocean

Ship‐Based Observations and Climate Model Simulations of Cloud Phase Over the Southern Ocean

Characterization of Southern Ocean Boundary Layer Clouds Using Airborne Radar, Lidar, and In Situ Cloud Data: Results From SOCRATES

Cloud Properties Derived From Airborne Cloud Radar Observations Collected in Three Climatic Regions

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