In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Pole‐to‐Pole Observation campaigns

Chubb, Thomas; Jensen, J. B.; Siems, Steven T.; Manton, M. J.

doi:10.1002/grl.50986

Cited by 70 publications

(90 citation statements)

References 27 publications

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“…• S in the previous campaign (April 2010) and the subject of Chubb et al (2013), undoubtedly pristine maritime conditions were encountered. Low-level CO concentrations were about 41 ppbv (this may be a seasonal difference compared to HIPPO-4 RF06), but still varied by about 5 ppbv between 5000 and 7000 m a.s.l.…”

Section: Comparison To Clearly Polluted And/or Pristine Casesmentioning

confidence: 89%

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Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

Chubb

Huang

Jensen³

et al. 2016

Atmos. Chem. Phys.

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Abstract. Cloud physics data collected during the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-toPole Observations (HIPPO) campaigns provide a snapshot of unusual wintertime microphysical conditions in the boundary layer over the Southern Ocean. On 29 June 2011, the HIAPER sampled the boundary layer in a region of prefrontal warm air advection between 58 and 48 • S to the south of Tasmania. Cloud droplet number concentrations were consistent with climatological values in the northernmost profiles but were exceptionally high for wintertime in the Southern Ocean at 100-200 cm −3 in the southernmost profiles. Sub-micron (0.06 < D < 1 µm) aerosol concentrations for the southern profiles were up to 400 cm −3 .Analysis of back trajectories and atmospheric chemistry observations revealed that while conditions in the troposphere were more typical of a clean remote ocean airmass, there was some evidence of continental or anthropogenic influence. However, the hypothesis of long-range transport of continental aerosol fails to explain the magnitude of the aerosol and cloud droplet concentration in the boundary layer. Instead, the gale force surface winds in this case (wind speed at 167 m above sea level was > 25 m s −1 ) were most likely responsible for production of sea spray aerosol which influenced the microphysical properties of the boundary layer clouds. The smaller size and higher number concentration of cloud droplets is inferred to increase the albedo of these clouds, and these conditions occur regularly, and are expected to increase in frequency, over windy parts of the Southern Ocean.

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Section: Comparison To Clearly Polluted And/or Pristine Casesmentioning

confidence: 89%

“…Chubb et al (2013) examined two SO flights that encountered low-altitude cloud (i.e. below 2 km) as far south as 67…”

Section: T Chubb Et Al: High Cdnc Observed During Hippo-4mentioning

confidence: 99%

Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

Chubb

Huang

Jensen³

et al. 2016

Atmos. Chem. Phys.

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“…would expect that supercooled liquid water might be more prevalent, especially given that Chubb et al (2013) observed it in situ over the Southern Ocean at temperatures as low as 2228C. Huang et al (2012) found in case studies that the DARDAR v1 algorithm often classified cloud tops as ice when CALIPSO classification suggested liquid or unknown, and DARDAR v2 appears to classify more scenes as ice and fewer scenes as SLW compared to v1 (Ceccaldi et al 2013).…”

Section: Cloud Profilesmentioning

confidence: 99%

A Climatology of Clouds in Marine Cold Air Outbreaks in Both Hemispheres

2016

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A climatology of clouds within marine cold air outbreaks, primarily using long-term satellite observations, is presented. Cloud properties between cold air outbreaks in different regions in both hemispheres are compared. In all regions marine cold air outbreak clouds tend to be low level with high cloud fraction and lowto-moderate optical thickness. Stronger cold air outbreaks have clouds that are optically thicker, but not geometrically thicker, than those in weaker cold air outbreaks. There is some evidence that clouds deepen and break up over the course of a cold air outbreak event. The top-of-the-atmosphere longwave cloud radiative effect in cold air outbreaks is small because the clouds have low tops. However, their surface longwave cloud radiative effect is considerably larger. The rarity of cold air outbreaks in summer limits their shortwave cloud radiative effect. They do not contribute substantially to global shortwave cloud radiative effect and are, therefore, unlikely to be a major source of shortwave cloud radiative effect errors in climate models.

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“…At temperatures greater than about −15 • C, these concentrations remain low: only one particle in every 10 3 or 10 4 will nucleate an ice crystal (Rogers et al, 1998;Chubb et al, 2013;DeMott et al, 2015). However, even when INP concentrations are low at warm subzero temperatures, incloud ice crystal number concentrations (ICNCs) can be orders of magnitude higher (e.g., Hallett and Mossop, 1974;Heymsfield and Willis, 2014;Lasher-Trapp et al, 2016;Taylor et al, 2016;Ladino et al, 2017), particularly in tropical maritime clouds (Koenig, 1963(Koenig, , 1965Hobbs and Rangno, 1990).…”

Section: Introductionmentioning

confidence: 99%

Initiation of secondary ice production in clouds

et al. 2018

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Abstract. Disparities between the measured concentrations of ice-nucleating particles (INPs) and in-cloud ice crystal number concentrations (ICNCs) have led to the hypothesis that mechanisms other than primary nucleation form ice in the atmosphere. Here, we model three of these secondary production mechanisms -rime splintering, frozen droplet shattering, and ice-ice collisional breakup -with a sixhydrometeor-class parcel model. We perform three sets of simulations to understand temporal evolution of ice hydrometeor number (N ice ), thermodynamic limitations, and the impact of parametric uncertainty when secondary production is active. Output is assessed in terms of the number of primarily nucleated ice crystals that must exist before secondary production initiates (N (lim) INP ) as well as the ICNC enhancement from secondary production and the timing of a 100-fold enhancement. N ice evolution can be understood in terms of collision-based nonlinearity and the "phasedness" of the process, i.e., whether it involves ice hydrometeors, liquid ones, or both. Ice-ice collisional breakup is the only process for which a meaningful N INP here suggest that, under appropriate thermodynamic conditions for secondary ice production, perturbations in cloud concentration nuclei concentrations are more influential in mixed-phase partitioning than those in INP concentrations.

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In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Pole‐to‐Pole Observation campaigns

Cited by 70 publications

References 27 publications

Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

A Climatology of Clouds in Marine Cold Air Outbreaks in Both Hemispheres

Initiation of secondary ice production in clouds

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