Climatological Characteristics of Historical and Future High-Wind Events in Alaska

Abstract

High winds cause waves, storm surge, erosion and physical damage to infrastructure and ecosystems. However, there have been few evaluations of wind climatologies and future changes, especially change in high-wind events, on a regional basis. This study uses Alaska as a regional case study of climatological wind speed and direction. Eleven first-order stations across different subregions of Alaska provide historical data (1975-2005) for the observational climatology and for the calibration of Coupled Model Inter comparison Project (CMIP5) simulations, which in turn provide projections of changes in winds through 2100. Historically, winds exceeding 25 and 35 knots are most common in the Bering Sea coastal region of Alaska, followed by northern Alaska coastal areas. Autumn and winter are the seasons of most frequent high-wind occurrences in the coastal sites, while there is no distinct seasonal peak at the interior stations where high-wind events are less frequent. An examination of the sea level pressure pattern associated with the highest-wind event at each station reveals the presence of a strong pressure gradient associated with an extratropical cyclone in most cases. Northern coastal regions of Alaska are projected to experience increased frequencies of high-wind events during the cold season, especially late autumn and early winter, when reduced sea ice cover in the late century will leave coastal regions increasingly vulnerable to flooding and erosion.

Increasing coastal exposure to extreme wave events in the Alaskan Arctic as the open water season expands

“…This is especially relevant as winter storm intensity equals or surpasses fall intensity 27,32 , and extratropical cyclones (typically the most impactful synoptic event causing Alaskan Arctic coastal flooding) trend further northward into the Arctic 27 . This threat is compounded as regional winter month storminess is projected to increase in the coming decades 23,33,34 . Thus, the expanding seasonal window of open water in the Alaskan Arctic threatens to not only expose shorelines to an increased number of storm events, but also to leave shorelines exposed to events of increased intensity.…”