Spaceborne Evidence That Ice‐Nucleating Particles Influence High‐Latitude Cloud Phase

Carlsen, Tim; David, Robert O.

doi:10.1029/2022gl098041

Cited by 21 publications

(7 citation statements)

References 93 publications

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“…Figure 2 (c) underlines the differences in this initial development by emphasising the initial relative lack of mixed-phase clouds early in MCAO (the gradient highlighted as Region A). This gradient in the temperature at which mixed-phase clouds become the majority has previously been observed by Carlsen and David (2022), who found that the temperature at which a cloud regime switched from being liquid-dominant to mixed-phase dominant (which they called T*) increased as a function of distance from the ice edge, until a plateau is reached at about -15°C. They also observed a seasonal dependence; during the summer, there was a slightly weaker gradient in T* from the ice edge (from about -17°C to -15°C) than in the winter (from about -22°C to about -15°C).…”

Section: Cloud Propertiessupporting

confidence: 71%

Air mass history linked to the development of Arctic mixed-phase clouds

Murray-Watson,

Gryspeerdt

2024

Preprint

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Abstract. Clouds formed during marine cold-air outbreaks (MCAOs) exhibit a distinct transition from stratocumulus decks near the ice edge to broken cumuliform fields further downwind. The mechanisms associated with ice formation are believed to be crucial in driving this transition, yet the factors influencing such formation remain unclear. Through Lagrangian trajectories co-located with satellite data, this study investigates into the development of mixed-phase clouds using these outbreaks. Cloud formed in MCAOs are characterized by a swift shift from liquid to ice-containing states, contrasting with non-MCAO clouds also moving off the ice edge. These mixed-phase clouds are predominantly observed at temperatures below -20 °C near the ice edge. However, further into the outbreak, they become the dominant at temperatures as high as -13 °C. This shift is consistent with the influence of biological ice nucleating particles (INPs), which become more prevalent as the air mass ages over the ocean. The evolution of these clouds is closely linked to the history of the air mass, especially the length of time it spends over snow- and ice-covered surfaces, terrains may that be deficient in INPs. This connection also accounts for the observed seasonal variations in the development of Arctic clouds, both within and outside of MCAO events. The findings highlight the importance of understanding both local marine aerosol sources near the ice edge and the overarching INP distribution in the Arctic for modelling of cloud phase in the region.

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Section: Cloud Propertiessupporting

confidence: 71%

Air mass history linked to the development of Arctic mixed-phase clouds

Murray-Watson,

Gryspeerdt

2024

Preprint

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“…The sharp gradient in I in the vicinity of the Antarctic Polar Front (APF; 50–55°S; Freeman & Lovenduski, 2016) is consistent with the previous finding that mixed‐phase clouds become increasingly scarce poleward of that point (Mace et al., 2020, 2021). The causes of low heterogeneity to the south of the APF are likely complex, as changes in sea surface temperature and sea ice coverage are known to have myriad effects on boundary layer clouds (e.g., Carlsen & David, 2022; Eirund et al., 2019; Sotiropoulou et al., 2016; Young et al., 2017). Low I over the SO is also consistent with the fact that, in some models, biases in LCF and absorbed shortwave radiation are larger over the SO than in the extratropical NH (Kay et al., 2016; Tan et al., 2016; Trenberth & Fasullo, 2010).…”

Section: Resultsmentioning

confidence: 99%

“…The spring and summertime maximum in I seen throughout the extratropics is broadly consistent with the idea that INP availability affects phase heterogeneity. Several field‐based studies have found that INP concentrations in the Arctic surge after the springtime thaw of sea ice and land‐based snow (Creamean et al., 2018; Tobo et al., 2019; Wex et al., 2019), and these seasonal fluctuations were recently found to affect cloud glaciation temperatures (Carlsen & David, 2022). In the SO region, I is elevated during the ice‐free time of the year and depressed during the ice‐covered seasons, suggesting that INPs may enhance heterogeneity there.…”

Section: Resultsmentioning

confidence: 99%

The Spatial Heterogeneity of Cloud Phase Observed by Satellite

Sokol,

Storelvmo

2024

JGR Atmospheres

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We conduct a global assessment of the spatial heterogeneity of cloud phase within the temperature range where liquid and ice can coexist. Single‐shot Cloud‐Aerosol Lidar with Orthogonal Polarization lidar retrievals are used to examine cloud phase at scales as fine as 333 m, and horizontal heterogeneity is quantified according to the frequency of switches between liquid and ice along the satellite's path. In the global mean, heterogeneity is greatest between −15 and −4°C with a peak at −5°C, when small patches of ice are prevalent within liquid‐dominated clouds. Heterogeneity “hot spots” are typically found over the extratropical continents, whereas phase is relatively homogeneous over the Southern Ocean and the eastern subtropical ocean basins, where supercooled liquid clouds dominate. Even at a fixed temperature, heterogeneity undergoes a pronounced annual cycle that, in most places, consists of a minimum during autumn or winter and a maximum during spring or summer. Based on this spatial and temporal variability, it is hypothesized that heterogeneity is affected by the availability of ice nucleating particles. These results can be used to improve the representation of subgrid‐scale heterogeneity in general circulation models, which has the potential to reduce longstanding model biases in cloud phase partitioning and radiative fluxes.

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“…Furthermore, we reduce the amount of INPs available across all simulations by a factor of 10 3 (INP factor: 0.001). Observational studies show that INPs are important for controlling cloud phase (Carlsen & David, 2022;Creamean et al, 2022;Sze et al, 2023) and that climate models overestimate the amount of activated INPs in regions with the most frequent MPCs. This is especially pronounced over the Southern Ocean and the Arctic, where model INP concentration can be orders of magnitude too high (Vergara-Temprado et al, 2018;Vignon et al, 2021;Li et al, 2022).…”

Section: Implementation Of Observational Constraints In Noresm2mentioning

confidence: 99%

Realistic representation of mixed-phase clouds increases future climate warming

Höfer

Hahn

Shaw

et al. 2023

Preprint

Self Cite

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Clouds are the main source of uncertainties when projecting climate change. Mixed-phase clouds (MPCs) that contain ice and supercooled-liquid particles are especially hard to constrain, and climate models neither agree on their phase nor their spatial extent. This is problematic, as models that underestimate contemporary supercooled-liquid in MPCs will underestimate future warming. Furthermore, it has recently been shown that supercooled-liquid water in MPCs is not homogeneously-mixed, neither vertically nor horizontally. However, while there have been attempts at observationally constraining MPCs to constrain uncertainties in future warming, all studies only use the phase of the interior of MPCs. Using novel satellite observations, and contrary to current knowledge, we show that MPCs are more liquid at the cloud top globally. We use these observations to constrain, for the first time, the cloud top phase in addition to the interior of MPCs in a global climate model, leading to +1C more 21st century warming in NorESM2 SSP5-8.5 climate projections. We anticipate that the difference between cloud top and interior phase in MPCs is an important new target metric for future climate model development, because similar MPC-related biases in future warming are likely present in many climate models.

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Spaceborne Evidence That Ice‐Nucleating Particles Influence High‐Latitude Cloud Phase

Cited by 21 publications

References 93 publications

Air mass history linked to the development of Arctic mixed-phase clouds

Air mass history linked to the development of Arctic mixed-phase clouds

The Spatial Heterogeneity of Cloud Phase Observed by Satellite

Realistic representation of mixed-phase clouds increases future climate warming

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