A numerical study of aerosol influence on mixed-phase stratiform clouds through modulation of the liquid phase

Boer, Gijs de; Hashino, Tempei; Tripoli, Gregory J.; Eloranta, E. W.

doi:10.5194/acp-13-1733-2013

Cited by 13 publications

(14 citation statements)

References 47 publications

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“…The same "high CCN" and "low CCN" cases, with the same initial conditions, were run with different criteria for heterogeneous freezing. Assuming freezing can only occur above water saturation, as in previous studies by de Boer et al (2010) and as observed by Ansmann et al (2008), shows no suppression of ice formation. The number concentration of ice in the "high CCN" and "low CCN" cases is the same.…”

Section: Demonstration Of the Suppression Effectsupporting

confidence: 61%

“…However their explanation of this effect differs from the one put forward here. de Boer et al (2013) explain that the reduction in ice formation in their simulations performed with high CCN concentrations is due to a reduction in drop vol-ume, similar to the Twomey effect (Twomey, 1974). The immersion freezing parameterisation that de Boer employ is a function of drop volume and the production of ice particles through immersion freezing decreases as drop volume decreases.…”

Section: Introductionmentioning

confidence: 93%

“…Even with Morrison et al (2012)'s insight into the nature of mixed-phase Arctic clouds the ability of climate models to simulate them is lacking (Ovchinnikov et al, 2014). More research is required to fully understand the many ways aerosol composition and size distribution can influence mixed-phase clouds (de Boer et al, 2013). The number of ice crystals and liquid drops present in a cloud strongly depends on the size distribution of aerosols (Twomey, 1991;Andreae and Rosenfeld, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore the competition effect needs to be addressed within the models which use these ice nucleation parameterisations. Modelling studies such as that by de Boer et al (2013) do consider the concentration of CCN as having an influence on ice formation in clouds and show that higher concentrations of CCN can reduce ice number concentration. However their explanation of this effect differs from the one put forward here.…”

Section: Introductionmentioning

confidence: 99%

“…In the literature, immersion freezing (which is a type or "mode" of freezing nucleation) has been confined to those particles that have activated in cloud drops (Hoose et al, 2010a;Pruppacher and Klett, 1997) or those drops greater than 2 µm in diameter (Paukert and Hoose, 2014). Diehl and Wurzler (2004) use a water activity, similar to the Koop et al (2000) approach, to calculate the amount of condensed water required to overcome the freezing point depression caused by soluble compounds present as an internal mixture within the INP. However de Boer et al 2013found that the freezing point depression due to soluble compounds was not important for large cloud droplets such as those found in stratiform clouds, since droplets are large enough to overcome the effect.…”

Section: Introductionmentioning

confidence: 99%

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Competition for water vapour results in suppression of ice formation in mixed-phase clouds

2018

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Abstract. The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP), which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN) and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

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Section: Demonstration Of the Suppression Effectsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

2018

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Modeling immersion freezing with aerosol‐dependent prognostic ice nuclei in Arctic mixed‐phase clouds

Paukert

Hoose

2014

JGR Atmospheres

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While recent laboratory experiments have thoroughly quantified the ice nucleation efficiency of different aerosol species, the resulting ice nucleation parameterizations have not yet been extensively evaluated in models on different scales. Here the implementation of an immersion freezing parameterization based on laboratory measurements of the ice nucleation active surface site density of mineral dust and ice nucleation active bacteria, accounting for nucleation scavenging of ice nuclei, into a cloud‐resolving model with two‐moment cloud microphysics is presented. We simulated an Arctic mixed‐phase stratocumulus cloud observed during Flight 31 of the Indirect and Semi‐Direct Aerosol Campaign near Barrow, Alaska. Through different feedback cycles, the persistence of the cloud strongly depends on the ice number concentration. It is attempted to bring the observed cloud properties, assumptions on aerosol concentration, and composition and ice formation parameterized as a function of these aerosol properties into agreement. Depending on the aerosol concentration and on the ice crystal properties, the simulated clouds are classified as growing, dissipating, and quasi‐stable. In comparison to the default ice nucleation scheme, the new scheme requires higher aerosol concentrations to maintain a quasi‐stable cloud. The simulations suggest that in the temperature range of this specific case, mineral dust can only contribute to a minor part of the ice formation. The importance of ice nucleation active bacteria and possibly other ice formation modes than immersion freezing remains poorly constrained in the considered case, since knowledge on local variations in the emissions of ice nucleation active organic aerosols in the Arctic is scarce.

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The atmosphere over sea ice

Persson

Vihma

2016

Sea Ice

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A numerical study of aerosol influence on mixed-phase stratiform clouds through modulation of the liquid phase

Cited by 13 publications

References 47 publications

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

Modeling immersion freezing with aerosol‐dependent prognostic ice nuclei in Arctic mixed‐phase clouds

The atmosphere over sea ice

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