Climate Divisions for Alaska Based on Objective Methods

Peter A. Bieniek, University of Alaska Fairbanks
Uma S. Bhatt, University of Alaska Fairbanks
Richard L. Thoman, NOAA/National Weather Service/Weather Forecast Office Fairbanks
Heather Angeloff, University of Alaska Fairbanks
James Partain, NOAA/National Weather Service/Alaska Region
John Papineau, NOAA/National Weather Service/Alaska Region
Frederick Fritsch, NOAA/National Weather Service/Weather Forecast Office Juneau
Eric Holloway, NOAA/Alaska-Pacific River Forecast Center
John E. Walsh, University of Alaska, Fairbanks
Christopher Daly, Oregon State University
Martha Shulski, University of Nebraska–Lincoln
Gary Hufford, NOAA/National Weather Service/Alaska Region
David F. Hill, Oregon State University
Stavros Calos, Oregon State University
Rudiger Gens, University of Alaska Fairbanks

Copyright 2012 American Meteorological Society

Abstract

Alaska encompasses several climate types because of its vast size, high-latitude location, proximity to oceans, and complex topography. There is a great need to understand how climate varies regionally for climatic research and forecasting applications. Although climate-type zones have been established for Alaska on the basis of seasonal climatologicalmean behavior, there has been little attempt to construct climate divisions that identify regions with consistently homogeneous climatic variability. In this study, cluster analysis was applied to monthly-average temperature data from 1977 to 2010 at a robust set of weather stations to develop climate divisions for the state. Mean-adjustedAdvancedVeryHighResolutionRadiometer surface temperature estimates were employed to fill in missing temperature data when possible. Thirteen climate divisions were identified on the basis of the cluster analysis and were subsequently refined using local expert knowledge. Divisional boundary lines were drawn that encompass the grouped stations by following major surrounding topographic boundaries. Correlation analysis between station and gridded downscaled temperature and precipitation data supported the division placement and boundaries. The new divisions north of the Alaska Range were the North Slope, West Coast, Central Interior, Northeast Interior, and Northwest Interior. Divisions south of the Alaska Range were Cook Inlet, Bristol Bay, Aleutians, Northeast Gulf, Northwest Gulf, North Panhandle, Central Panhandle, and South Panhandle. Correlations with various Pacific Ocean and Arctic climatic teleconnection indices showed numerous significant relationships between seasonal division average temperature and the Arctic Oscillation, Pacific–North American pattern, North Pacific index, and Pacific decadal oscillation.