Characteristics of Supercooled Liquid Water in Clouds at Mountaintop Sites in the Colorado Rockies

Hindman, Edward E.

doi:10.1175/1520-0450(1986)025<1271:coslwi>2.0.co;2

Cited by 22 publications

(20 citation statements)

References 10 publications

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“…Observational and modeling studies have shown that, on average, snowfall amount and local terrain height variability are strongly positively correlated (Wetzel et al 2004;Saleeby et al 2009), such that the highest, steepest mountain ridges tend to accumulate the greatest snowfall totals. Given the high elevation of Colorado topography, the vast majority of wintertime snow and liquid water clouds has temperatures well below freezing, and thus hydrometeor growth evolution is controlled by cold cloud processes (Hindman 1986).…”

Section: Introductionmentioning

confidence: 99%

“…This effect has been observed to enhance surface precipitation amounts by up to 20%-50% near mountaintop (Mitchell et al 1990;Borys et al 2003). An observational study of high-elevation sites in Colorado by Hindman (1986) revealed that supercooled liquid water clouds and rimed snow were most abundant along primary mountain barriers such as Wolf Creek Pass in the southwestern San Juan Range and Steamboat Springs in the northern Park Range. Secondary ranges that are typically blocked by the primary ranges may succumb to subsidence from the primary ranges or a reduction in available moisture that was precipitated upwind.…”

Section: Introductionmentioning

confidence: 99%

“…The amount of riming growth of an individual snow crystal is a function of the trajectory through the cloud, the cloud liquid water content, cloud droplet number concentration (CDNC), cloud droplet sizes, and snow crystal size and habit (Hindman 1986;Hindman et al 1992;Borys et al 2000;Saleeby et al 2009). From observations of supercooled liquid water clouds, it was concluded that riming is reduced as droplet sizes decrease because of a reduction in the collision efficiency between snow crystals and small droplets (Hindman et al 1992;Borys et al 2000Borys et al , 2003.…”

Section: Introductionmentioning

confidence: 99%

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The Cumulative Impact of Cloud Droplet Nucleating Aerosols on Orographic Snowfall in Colorado

Saleeby

Cotton

Fuller

2011

Journal of Applied Meteorology and Climatology

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Hygroscopic pollution aerosols have the potential to alter winter orographic snowfall totals and spatial distributions by modification of high-elevation supercooled orographic clouds and the riming process. The authors investigate the cumulative effect of varying the concentrations of hygroscopic aerosols during JanuaryFebruary for four recent winter snowfall seasons over the high terrain of Colorado. Version 6.0 of the Regional Atmospheric Modeling System (RAMS) is used to determine the particular mountain ranges and seasonal conditions that are most susceptible. Multiple winter seasonal simulations are run at both 3-and 1-km horizontal grid spacing with varying aerosol vertical profiles. Model-predicted snowfall accumulation trends are compared with automated snow water equivalent observations at high-elevation sites. An increase in aerosol concentration leads to reduced riming of cloud water by ice particles within supercooled, liquid orographic clouds, thus leading to lighter rimed hydrometers with slower fall speeds and longer horizontal trajectories. This effect results in a spillover of snowfall from the windward slope to the leeward slope. A snowfall spillover effect is most evident in the southern and western regions of the San Juan Range where high-moisture-laden storms are more prevalent. The effect over the Park Range is also present in each simulated season, but with lower amplitudes and slightly varying magnitudes among seasons. Seasons with greater overall snowfall exhibit a greater response in magnitude and percentage change. The smallest spillover effect occurred downwind of the primary western slope mountain barriers. Although the aerosol effect on snowfall can be locally significant in particularly wet winter seasons, the interseasonal variability in synoptic conditions can impose much larger widespread changes in snowfall accumulation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Cumulative Impact of Cloud Droplet Nucleating Aerosols on Orographic Snowfall in Colorado

Saleeby

Cotton

Fuller

2011

Journal of Applied Meteorology and Climatology

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“…This low-level riming process enhances the precipitation efficiency, such that the amount of rime has been shown to comprise up to 20%-50% of the final snow mass that reaches the surface (Mitchell et al 1990;Borys et al 2003). Enhanced riming will increase the mass of snow crystals as well as the fall speed; this increases the likelihood of higher snow deposits along windward slopes (Hindman 1986). Slowerfalling, unrimed snow crystals are more likely to fall on the leeward slopes where subsidence leads to evaporation, a reduction in surface snowfall, and disappearance of the feeder cloud (Rauber and Grant 1986).…”

Section: Introductionmentioning

confidence: 99%

A Binned Approach to Cloud-Droplet Riming Implemented in a Bulk Microphysics Model

Saleeby

Cotton

2008

Journal of Applied Meteorology and Climatology

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This paper presents the development and application of a binned approach to cloud-droplet riming within a bulk microphysics model. This approach provides a more realistic representation of collision-coalescence that occurs between ice and cloud particles of various sizes. The binned approach allows the application of specific collection efficiencies, within the stochastic collection equation, for individual size bins of droplets and ice particles; this is in sharp contrast to the bulk approach that uses a single collection efficiency to describe the growth of a distribution of an ice species by collecting cloud droplets. Simulations of a winter orographic cloud event reveal a reduction in riming when using the binned riming approach and, subsequently, larger amounts of supercooled liquid water within the orographic cloud.

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“…The microphysical characteristics of wintertime clouds and storms in this region have been discussed in detail by , , and Rauber (1987). The laboratory is frequently enveloped by precipitating, supercooled clouds during the winter (Hindman, 1986) allowing studies of clouds and precipitation to be conducted for periods of hours to days. The clouds studied were essentially stratiform in nature often with embedded cumulus.…”

Section: 1 Location Of Studymentioning

confidence: 99%

The chemical fractionation of atmospheric aerosol as a result of snow crystal formation and growth

1988

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The relationships between the physical and chemical properties of mixed-phase clouds were investigated at Storm Peak Laboratory (3220m MSL) located near the continental divide in northwestern Colorado. Interstitial aerosol particles, cloud droplets and snow crystals were concurrently collected when the laboratory was enveloped by a precipitating cloud. All samples were analyzed for trace elements, soluble anions, electrical conductivity and acidity.The results show average trace constituent concentration ratios of cloud water to snow water range from 0.4 to 26. All but six of the 32 elements and ions measured had ratios greater than one. This result suggests a chemical species dependency of in-cloud aerosol particle scavenging processes. Evidence of a decrease of in-cloud aerosol particle scavenging efficiency by snow due to increases in aerosol concentration is also presented.Differences between the chemical composition of cloud water and snow water are manifested most strongly when snow crystals grow by vapor deposition. In-cloud scavenging efficiencies by snow crystals for most aerosol particle chemical species are dependent on the growth of the snow crystals by accretion of cloud droplets. This chemical fractionation of the atmospheric aerosol by snow crystal formation and growth should be most active where narrow, continental cloud droplet size distributions and low liquid water contents are prevalent, enhancing the probability of snow crystal growth by diffusion.

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Characteristics of Supercooled Liquid Water in Clouds at Mountaintop Sites in the Colorado Rockies

Cited by 22 publications

References 10 publications

The Cumulative Impact of Cloud Droplet Nucleating Aerosols on Orographic Snowfall in Colorado

The Cumulative Impact of Cloud Droplet Nucleating Aerosols on Orographic Snowfall in Colorado

A Binned Approach to Cloud-Droplet Riming Implemented in a Bulk Microphysics Model

The chemical fractionation of atmospheric aerosol as a result of snow crystal formation and growth

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