Snow Cover
Mountain with snow cover. Photo: Unsplash
The objectives of this study Were to expand past statistical analyses on the role of pre-existing snow cover and the tracking and intensity of mid-latitude cyclones and understand future changes to mid-latitude storm trajectories with retreating snow extent.
Principal investigators
Ankur R Desai
Jonathan Martin
Michael Notaro (CCR)
Steve Vavrus (CCR)
Staff
Ryan Clare
Overview
Weather system implications for a changing climate
Prediction of mid-latitude cyclone trajectories and intensity is a primary occupation of synoptic weather forecasting and understanding its drivers is a fundamental challenge to modeling the impacts of global climatic variability and change on mid-latitude weather dynamics. One long theorized driver of mid-latitude disturbances is the location of southern extent of Northern Hemisphere snow cover. But, while snow cover anomalies have been used as a forecasting rule of thumb for quite some time, neither the validity nor the physical mechanisms underlying this rule have been rigorously investigated. Recent work, by one of the PIs, has shown that, statistically over the past 30 years, antecedent snow cover in North America is a strong predictor of subsequent mid-latitude disturbance locations. The ensuing manuscript hypothesized a mechanism driven by the snow cover albedo gradient, which develops boundary-layer-free-troposphere interaction through enhancing low-level baroclinicity, a dynamical surrogate for boundary layer potential vorticity gradients.
Therefore, building on this work, the objectives of this proposal are to expand the initial retrospective statistical analysis to a greater range of snow and cyclone observations, focus on central/eastern North America where the strength of the relationship was most robust, evaluate the mechanistic basis of the relationship by piece-wise inversion low-level potential vorticity in numerical model case study simulations with altered snow cover, and benchmark the likelihood of this relationship in a large ensemble of climate models to address implications for future changes to the mid-latitude storm trajectories with retreating snow extent.
Intellectual Merit
The intellectual merit of this proposal is new insights and robust testing of mechanisms that drive boundary-layer to free-troposphere interaction through one of the planet’s most notable and temporally variable surface albedo, temperature, and moisture gradients. This proposal will build on preliminary findings with a focused central North American analysis of snow cover, cyclone trajectory, intensity, and potential vorticity relationships. Statistical analysis of mid-latitude weather systems and central North America snow cover, along with mesoscale numerical modeling with altered snow cover extent will be used to evaluate theories of the dynamical impact of lower lever circulation anomalies on synoptic systems as a function of cyclone intensity, position, and external environment. Favored mechanisms will be further evaluated with a large ensemble of modern and future climate simulations to understand the relative impact of this effect on current and future projections of the mid-latitude storm
Broader Impacts
Broader impacts of this research extend to both the weather/climate prediction and boundary-layer meteorology communities. Societal relevance is found in better understanding of how climate change manifests in weather, which could lead to improvements in both weather and climate forecasting and benefit risk management of weather hazards. Numerical mesoscale and climate models will be analyzed for snow cover and storm track variability, contributing a new diagnostic to the modeling community. Quantification of the conceptual theory proposed here would allow for more robust forecasting of changes to cyclone behavior as a function of pre-existing snow cover, which has significant economic implications for warning and mitigation of storm related risk. Further, this project would support a PhD student and undergraduate students who will be trained in the emerging fields of the weather-climate interface and boundary layer-synoptic interaction and recruited from under-represented groups in the sciences. Harmonized databases on snow cover and mid-latitude storm tracks will be made publicly available. Finally, this proposal supports outreach through weather forecaster presentations, public talks, and enhancing classroom education at the undergraduate level.
Project news & events
Project gallery
Award Abstract #1640452
$354,052.00
2017-2021
Positions
This project supported graduate and undergraduate students trained in the emerging fields of the weather-climate interface and boundary layer-synoptic interactions.
Publications and presentations
Clare, R., Desai, A.R., Martin, J.E., Notaro, M., Vavrus, S.J., 2023. Extratropical Cyclone Response to Projected Reductions in Snow Extent over the Great Plains, Atmosphere, 14, 783, doi:10.3390/atmos14050783.
Breeden, M.L., Clare, R.M., Martin, J.E., Desai, A.R., 2020. Diagnosing the influence of a receding snow boundary on simulated midlatitude cyclones using piecewise potential vorticity inversion, Monthly Weather Review, 148, 4479-4495, doi:10.1175/MWR-D-20-0056.1.
Clare, R.M., A.R. Desai, Notaro M, Martin J.E., and Vavrus, S.J., 2020. Projected Snow Cover Reductions and Mid-latitude Cyclone Responses in the North American Great Plains, 1986 - 2005 ver 3. Environmental Data Initiative. https://doi.org/10.6073/pasta/62b867bfd53d3d87ba294564ca363bd4
Rydzik, M. and Desai, A.R., 2014. Relationship between snow extent and midlatitude disturbance centers. J. Climate, 27, 2971–2982, doi:10.1175/JCLI-D-12-00841.1
Bromley, G., 2016. Effects of Snow Boundary Generated Baroclinicity on Middle Latitude Disturbances Undergraduate senior thesis, University of Wisconsin, Madison, WI.
Climatological Snow Cover Feedbacks in the Land-Atmosphere System. American Meteorological Society, 28th Conference on Climate Variability and Change, New Orleans, LA, USA Jan 14, 2016
