Trends in Spatial and Temporal Variability of Snowfall Totals and Events in Wisconsin, 1974 - 2010
Presented by: Daryn HardwickGraduate, Geography Department, Saint Cloud State University Faculty Advisors: Dr. Keith Rice, UWSP Geography Department Eugene Martin, UWSP Geography Department
Purpose o To better understand winter climatology for the state of Wisconsin Hypothesis o Ha = There has been a decrease in both the amount of snowfall and individual snowfall events in the state of Wisconsin between 1974 and 2010. o Ho = There has been no change in the amount of snowfall or individual snowfall events in the state of Wisconsin between 1974 and 2010.
Economic Benefits o Winter Tourism - $7.9 billion annually o Cold Water Fishing - $2.3 billion/year industry o Snowpack Water Storage saves between $2.3 - 348 billion/year Economic Costs o Snow Removal - $2 billion/year o Road Closures - $2.5 billion/year • Lost retail trade, wages, and tax revenue o Damage to Utilities • $2 billion lost in 1994 snow storm in Mississippi o Flooding • $4.7 billion lost in 1997 Red River flooding in ND and MN
The Impact of Snow/Winter Events on Humans: o 23.4 deaths per year caused o 161.7 injuries per year caused o $484 million in damage caused annually Groundwater Recharge o Urie (1966) determined about 2/3 of yearly groundwater recharge contributed by winter precipitation
Decline in snow cover extent and duration o Choi et al. 2010, Davies 1994, Dêry and Brown 2007 Great Lakes studies o Burnett et al. (2003) - increase in snowfall and both the lee and windward sides o Norton and Bolsenga (2007) – increase in lake-effect snowfall Wisconsin snowfall o Kunkel et al. (2009) – slight increase in snowfall
Data o National Weather Service Cooperative Observer Program • Precipitation, Snowfall, and Snow Depth • October – April • 1974/75 – 2009/10 seasons • 152 weather stations, 11 out-of-state Analyses o Station Homogeny o Season Averages and Event Totals o Snowfall/Precipitation Ratio o Regression lines (trends)
Station Homogeny – having <10% missing data over the study period (Kunkel et al. 2009) o 137/152 (90%) determined homogenous for precipitation o 120/152 (79%) determined homogenous for snowfall o 78/152 (51%) determined homogenous for snow depth o Only stations suitable in both precipitation and snowfall were used in final analysis, 117 stations (77%) 2008-2010 Seasons
Increase in Winter Precipitation o Significant at the ≥ 95% confidence level (p = 0.0001) Increase in Winter Snowfall o Not significant at the ≥ 95% confidence level (p = 0.3624) Decrease in Snowfall-to-Precipitation Ratio o Not significant at the ≥ 95% confidence level (p = 0.0526) Increase in Days with Precipitation o Significant at the ≥ 95% confidence level (p = 0.0365) Decrease in Days with Snowfall o Significant at the ≥ 95% confidence level (p = 0.0271) 2008-2010 Seasons o Anomaly or new trend?
Self Critiques o Climate data inherently unreliable? o Number of Events in a given season o Are t-test’s suitable for climatic data? o Is 36 years enough for a climate study? Future Research o Investigate above critiques o Do El Niño or La Niña have an effect? o Spatial and temporal trends in temperature o Trends in Snow Cover and Snow Depth o Snowfall-to-Precipitation Ratio
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