Analysis of the Climatology of Extreme Weather Events affecting Barrow,Alaska

Elizabeth Cassano

Amanda Lynch

Melinda Koslow

Casey Thornbrugh

Outline

• Project background and overview• Introduction to Self-Organizing Maps• General classification• Precipitation, temperature, and high

wind trends at Barrow• Focus study of high wind events at

Barrow• Conclusions

Project Overview and Background

• An Integrated Assessment of the Impacts of Climate Variability on the Alaskan North Slope Coastal Region– Climate variability on the North Slope of

Alaska– Regional impacts of climate variability– Community responses to regional impacts– http://nome.colorado.edu/HARC/index.html

Project Overview and Background• Barrow, Alaska

– Northern most point in US, on the shore of the Arctic Ocean, average elevation less than 10 m

– Majority of residents are Inupiat Eskimos, many still participate in a subsistence lifestyle

– Modernized substantially since 1960s– Orientation of Barrow on coast makes it exposed

and vulnerable to westerly winds, which can lead to flooding and coastal erosion

Credit: Bill Manley and Scott Peckham

Wind directions leading to wave set up

Wind directions leading to wind set up and resultingEkman transport

Self-Organizing Maps

• Unsupervised learning neural network

• No assumptions made as to the final patterns or organization of patterns

• Used to codify SLP patterns over the Western Arctic to create a climatology

General classification figure

North Pacific Storm Track

Migration into Arctic Ocean

Barrow

Trend analysis

0.62 0.15 -0.06 -0.32 0.39

-0.95 -0.56 0.53 0.08 0.46

-2.22 -0.26 0.71 1.54 -0.17

-0.05 0.18 -0.02 -0.51 0.47

• These numbers are the trends in the number of days that map to each node per decade

Temperature anomaly figureTemperature anomalies at Barrow, Alaska associated with each SOM node

Precipitation proportion figureProportion of precipitation that falls as rain at Barrow, Alaska associated with each SOM node

General classification results

• Dominant patterns are high pressure near Barrow, Aleutian Low in southern Alaska

• SOM organizes patterns with similar characteristics together on map

• Patterns that have low to the north of Barrow (and hence produce westerly winds) are increasing

• Some patterns with positive temperature anomalies and more rain are increasing

Multivariate analysis

• The SOM is retrained using not only sea level pressure, but local winds and fetch at Barrow

• High westerly wind events are highlighted by weighting these samples.

Multivariate figure

Results and conclusions

• The SOM is used to classify general circulation patterns in the Western Arctic, and the results agree with previous Arctic climatologies

• Circulation patterns that produce strong, westerly winds at Barrow are increasing, as are, in general, positive temperature anomalies and more rain events

Results and conclusions

• The multivariate SOM, which highlights westerly winds at Barrow, produces a map with more circulation patterns containing a low north of Barrow

• Future work will consist of adding flooding data (modeled and traditional knowledge) to further train the map and use the SOM as a GCM proxy.