A Case Study for Aerosol Induced Snowfall

Spillover During Three Sequential Lake-Effect

Events in Upstate NY

By Joshua TobiasMEA 51412/4/13

What is snowfall spillover?

• Considers the presence of aerosols disrupting the riming process of ice particles within a mix phase cloud.

• A larger concentration of aerosols within a mixed phase cloud will delay or suppress snowfall.

• If this occurs on the windward side of a geographic barrier, then ice particles may be advected and precipitate further downstream.

Modeling Study

Lynn, B., A. Khain, D. Rosenfeld, and W. L. Woodley (2007), Effects of aerosols on precipitation from

orographic clouds, J. Geophys. Res., 112.

• Modeled a snowfall event under two separate environmental conditions:

1) Continental Polluted Conditions Caused Snowfall Spillover to occur.

2) Maritime Pristine Conditions Caused snowfall to remain primarily on the windward side of the orographic barrier

Question to ask…

What would happen in a real life scenario, with a land locked, maritime influenced event? (i.e. Lake-Effect Event)

How can aerosols affect lake-effect snow distribution?

Project Focus and Methods

• Focused on three sequential Lake Effect Storms within the Tug Hill Plateau region of Upstate NY

• Lake Storm Dalmatian

( Jan. 19-21 2008)

• Lake Storm English Setter

(Jan 23-24, 2008)

• Lake Storm Fox Hound

(Jan. 25, 2008)

QUALITATIVE ANALYSIS!

• Level 3 Modis Optical Depth Maps (Giovanni)

• AirNow Fine Particle Concentration (EPA/Giovanni)

• Reanalysis Maps from National Operational Hydrologic Remote Sensing Center’s Interactive Snow Mapping Service: Temperature, Average Wind, Snowfall Accumulation during 24 hour period of maximum snowfall.

Lake Storm Dalmatian (January 19-21)

• First and strongest storm of the three, with accumulations of up to 3 feet in some locations.

• Highest snowfall confined to lake shore, with some blow over beyond the plateau.

• Defined by a single band that developed from a westerly flow, with the strongest winds along the southern shore 10 to 15 mph.

• Note: Winds averaged for the 24 hour period of highest snowfall.

Lake Storm Dalmatian (cont.)• MODIS displayed optical

depths between .125 and .155

• Very LOW Maritime

Concentration

• AirNow Concentrations reaching 10.3 μg/ m^3

• Also low by EPA standards• Good Air Quality

Lake Storm Dalmatian (cont.)

• Low concentrations of aerosols confine the bulk the major snowfall to the windward side of the Tug Hill Plateau

• Any spillover displayed may be attributed to the stronger surface winds over the lake.

Lake Storm English Setter (Jan. 23-24, 2008)

• Quickly followed Lake Storm Dalmatian, after the passage of a frontal system. Arctic air reestablished itself over the Tug Hill Region.

• The flow is similar to that of Dalmation, but the winds were much weaker, at 5 to 10 mph.

Lake Storm English Setter (cont.)

• Aerosol optical depth over Lake Ontario proved to be even lower or mixed out after the frontal passage

• However, AirNow fine particle concentration were much higher along the Southern Lake shore during English Setter. Concentrations ranged between 10.4 and 13.1 μg/m^3

Lake Storm English Setter (cont.)

• The narrow band that developed during English Setter can clearly be seen in the 24 hour snowfall map.

• However, unlike in Lake Storm Dalmation, the extension of snowfall is much further inland. Snowfall appears to occur further into the Adirondacks, despite lower average winds off the lake.

Lake Storm Fox Hound (Jan. 25, 2008)

• Represents the weakest of the three storms, with only a narrow band of heavy snow developing over Jefferson and Oswego County (close to the lake shore).

• Winds and temperature were comparable to Lake Storm English Setter.

Lake Storm Fox Hound (cont.)

• Aerosol concentrations prove to low both over Lake Ontario and New York during Fox Hound.

Lake Storm Fox Hound (cont.)

• Despite lower aerosol concentrations during Fox Hound, an extension of snowfall accumulation inland still occurred.

• Unlike in English Setter though, a slight Northwest shift in the prevailing flow occurred. This could have caused the further distribution of snow inward.

Conclusions• All three storms displayed snowfall redistribution that

extended inland to some extent. The general accumulations that occurred within these locations ranged between 3 to 7 inches.

• Lake Storm English Setter displayed the highest aerosol concentrations of the three storms. It also displayed the largest area of displaced accumulations of the three. Possible spillover?

• The snowfall redistribution that occurred within Dalmatian and English Setter could be attributed to more to the changes within the prevailing flow at the time.

• Final Conclusion: The impact of aerosols on these three storms is still ambiguous, but worth further investigation.

• Despite generally low concentrations, it is still possible that aerosols could be playing some role in snowfall distribution

English Setter

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Lynn, B., A. Khain, D. Rosenfeld, and W. L. Woodley (2007), Effects of aerosols on precipitation from orographic clouds, J. Geophys. Res., 112.

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References (cont.)

Saleeby, Stephen M., William R. Cotton, Jamie D. Fuller, 2011: The Cumulative Impact of Cloud Droplet Nucleating Aerosols on Orographic Snowfall in Colorado. J. Appl. Meteor. Climatol., 50, 604–625

Saleeby, Stephen M., William R. Cotton, Douglas Lowenthal, Joe Messina, 2013: Aerosol Impacts on the Microphysical Growth Processes of Orographic Snowfall. J. Appl. Meteor. Climatol., 52, 834–852.

Questions?