Polluting of winter convective clouds upon transition from ocean inland over central California: Contrasting case studies

Rosenfeld, Daniel; Chemke, Rei; Prather, Kimberly A.; Suski, Kaitlyn J.; Comstock, J. M.; Schmid, Beat; Tomlinson, Jason; Jonsson, Haflidi H.

doi:10.1016/j.atmosres.2013.09.006

Cited by 20 publications

(15 citation statements)

References 43 publications

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“…States is significantly modulated by atmospheric rivers (i.e., narrow bands of enhanced water vapor; see, e.g., Dettinger et al 2011) and perhaps by aerosols (e.g., Rosenfeld et al 2008). Funded by the California Energy Commission, the G-1 aircraft was deployed to Sacramento to support the 2011 intensive observing period of the CalWater field campaign.…”

Section: Calwater Precipitation In the Western Unitedmentioning

confidence: 99%

The DOE ARM Aerial Facility

Schmid¹,

Tomlinson²,

Hubbe³

et al. 2014

Bull. Amer. Meteor. Soc.

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Section: Calwater Precipitation In the Western Unitedmentioning

confidence: 99%

The DOE ARM Aerial Facility

Schmid¹,

Tomlinson²,

Hubbe³

et al. 2014

Bull. Amer. Meteor. Soc.

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“…The percent of days the MSc regime occurs is lower during the other seasons -particularly during fall -but the location is similar. Rosenfeld et al (2014) show that when r e reaches about 14 µm the coalescence accelerates and initiates warm rain. We only focus on non-raining clouds (r e < 14 µm) because, under raining conditions, the relationship between cloud properties and DAOD may be subject to aerosol removal by precipitation and thus more difficult to analyze directly.…”

Section: Study Areamentioning

confidence: 99%

Impact of Saharan dust on North Atlantic marine stratocumulus clouds: importance of the semidirect effect

et al. 2017

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Abstract. One component of aerosol-cloud interactions (ACI) involves dust and marine stratocumulus clouds (MSc).Few observational studies have focused on dust-MSc interactions, and thus this effect remains poorly quantified. These two methods yield similar results of −1.5 ± 1.4 and −1.5 ± 1.6 W m −2 , respectively, for the annual mean aerosol-cloud radiative effect. Thus, Saharan dust modifies MSc in a way that acts to cool the planet. There is a strong seasonal variation, with the aerosol-cloud radiative effect switching from significantly negative during the boreal summer to weakly positive during boreal winter. Method 1 (Method 2) yields −3.8 ± 2.5 (−4.3 ± 4.1) during summer and 1 ± 2.9 (0.6 ± 1) W m −2 during winter. In Method 1, the aerosol-cloud radiative effect can be decomposed into two terms, one representing the first aerosol indirect effect and the second representing the combination of the second aerosol indirect effect and the semidirect effect (i.e., changes in liquid water path and cloud fraction in response to changes in absorbing aerosols and local heating). The first aerosol indirect effect is relatively small, varying from −0.7 ± 0.6 in summer to 0.1 ± 0.5 W m −2 in winter. The second term, however, dominates the overall radiative effect, varying from −3.2 ± 2.5 in summer to 0.9 ± 2.9 W m −2 during winter. Studies show that the semidirect effect can result in a negative (i.e., absorbing aerosol lies above low clouds like MSc) or positive (i.e., absorbing aerosol lies within low clouds) aerosol-cloud radiative effect. The semipermanent MSc are low and confined within the boundary layer. CALIPSO shows that 61.8 ± 12.6 % of Saharan dust resides above North Atlantic MSc during summer for our study area. This is consistent with a relatively weak first aerosol indirect effect and also suggests the second aerosol indirect effect plus semidirect effect (the second term in Method 1) is dominated by the semidirect effect. In contrast, the percentage of Saharan dust above North Atlantic MSc in winter is 11.9 ± 10.9 %, which is much lower than in summer. CALIPSO also shows that 88.3 ± 8.5 % of dust resides below 2.2 km the winter average of MSc top height. During summer, however, there are two peaks, with 35.6 ± 13 % below 1.9 km (summer average of MSc top height) and 44.4 ± 9.2 % between 2 and 4 km. Because the aerosol-cloud radiative effect is positive during winter, and is also dominated by the second term, this again supports the importance of the semidirect effect. We conclude that Saharan dust-MSc interactions off the coast of northern Africa are likely dominated by the semidirect effect.

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“…Rosenfeld et al (2014) showed significantly different supercooled-water (SCW) and precipitation processes in two contrasting cloud cases with air masses containing maritime and continental aerosols, respectively. Many studies have shown that CCN can reduce warm rain precipitation from orographic clouds by reducing the efficiency of cloud droplet conversion into raindrops (e.g., Lynn et al, 2007;Rosenfeld and Givati, 2006;Jirak and Cotton, 2006), and they can also reduce snowfall precipitation due to reduced riming efficiency (Lowenthal et al, 2011;Rosenfeld et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Effects of cloud condensation nuclei and ice nucleating particles on precipitation processes and supercooled liquid in mixed-phase orographic clouds

et al. 2017

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Abstract. How orographic mixed-phase clouds respond to the change in cloud condensation nuclei (CCN) and ice nucleating particles (INPs) are highly uncertain. The main snow production mechanism in warm and cold mixed-phase orographic clouds (referred to as WMOCs and CMOCs, respectively, distinguished here as those having cloud tops warmer and colder than −20 • C) could be very different. We quantify the CCN and INP impacts on supercooled water content, cloud phases, and precipitation for a WMOC case and a CMOC case, with sensitivity tests using the same CCN and INP concentrations between the WMOC and CMOC cases. It was found that deposition plays a more important role than riming for forming snow in the CMOC case, while the role of riming is dominant in the WMOC case. As expected, adding CCN suppresses precipitation, especially in WMOCs and low INPs. However, this reverses strongly for CCN of 1000 cm −3 and larger. We found a new mechanism through which CCN can invigorate mixed-phase clouds over the Sierra Nevada and drastically intensify snow precipitation when CCN concentrations are high (1000 cm −3 or higher). In this situation, more widespread shallow clouds with a greater amount of cloud water form in the Central Valley and foothills west of the mountain range. The increased latent heat release associated with the formation of these clouds strengthens the local transport of moisture to the windward slope, invigorating mixed-phase clouds over the mountains, and thereby producing higher amounts of snow precipitation. Under all CCN conditions, increasing the INPs leads to decreased riming and mixed-phase fraction in the CMOC as a result of liquid-limited conditions, but has the opposite effects in the WMOC as a result of ice-limited conditions. However, precipitation in both cases is increased by increasing INPs due to an increase in deposition for the CMOC but enhanced riming and deposition in the WMOC. Increasing the INPs dramatically reduces supercooled water content and increases the cloud glaciation temperature, while increasing CCN has the opposite effect with much smaller significance.

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Polluting of winter convective clouds upon transition from ocean inland over central California: Contrasting case studies

Cited by 20 publications

References 43 publications

The DOE ARM Aerial Facility

The DOE ARM Aerial Facility

Impact of Saharan dust on North Atlantic marine stratocumulus clouds: importance of the semidirect effect

Effects of cloud condensation nuclei and ice nucleating particles on precipitation processes and supercooled liquid in mixed-phase orographic clouds

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