Increasing urbanization and development in the Arctic may exacerbate the local impacts of climate warming in areas underlain by permafrost. As part of the Barrow Urban Heat-Island Study (BUHIS), hourly air and near-surface soil temperatures (5 cm depth) were collected at 66 sites in and near Barrow, Alaska. Comparison of near-surface soil temperatures, categorized by land-cover type, revealed that urban temperatures in each category were higher than those in corresponding units of the surrounding undeveloped area. Mean summer soil-surface temperatures within comparable land-cover units were 0.3–2.3°C higher in the urban area. Active-layer thickness was greater by 15–40 cm at the urban sites than at locations with similar vegetation in the rural portions of the study area. Engineering criteria established from measurements made at ‘rural’ meteorological sites or from general maps of a large region may assume colder soils than are actually present, raising the possibility that inappropriate design criteria could be implemented. This risk will continue to grow as urbanization, resource development, and climatic changes increase.

The coastal village of Barrow, Alaska (71.3° N, 156.5° W) is the northernmost settlement in the United States. With 4000 residents, it is also the largest native community in the circumarctic region. Installation of the 67-site Barrow Urban Heat Island Study network in 2001 facilitated a detailed examination of the spatial characteristics of summer air temperature within a 150 km 2 area incorporating Barrow and its surroundings. Although the summers of 2001 and 2002 were climatologically unusual, the record clearly illustrates the control of a local maritime gradient, as well as a close correspondence between temperature distribution and wind regime. In contrast to the situation in winter, the effects of local urban infrastructure on air temperatures were relatively minor during these summers, compared to those of maritime and wind influences.

The maximum depth of seasonal thaw is a critical design factor for civil infrastructure in permafrost regions. Although maps of active-layer thickness (ALT) have been created for localized areas in undisturbed terrain, this has rarely been done within urbanized areas. The modified Berggren solution was used to map ALT at a resolution of 30 × 30 m over the 150-km² Barrow Peninsula in northern Alaska. Emphasis was placed on analyzing differences in accuracy obtained in urbanized and relatively undisturbed tundra. Although the modified Berggren solution is known to provide more accurate estimates of frost and thaw depth than the Stefan solution, it has not been used previously in mapping applications. As part of the Barrow Urban Heat Island Study, seventy-one miniature data loggers were installed in and surrounding the City of Utqiaġvik (formerly Barrow) to measure air and soil temperature. The resulting data were used to calculate air and soil surface temperature fields, as well as summer n-factors, based on nine urban and rural land-cover classes. Regional soil and land-cover maps were used to obtain additional input data. Validation was performed by comparing probed ALT measurements with predicted pixel values. Model results confirm that the presence of urban infrastructure increases both the magnitude and the geographic variability of ALT relative to surrounding undisturbed tundra. The Berggren solution performed well for estimating mean values for land-cover classes in both rural and urban areas and has considerable potential as a tool for mapping ALT in other applications. Key Words: active layer, Alaska, Barrow, frozen ground, geocryology, mapping, permafrost, urban, Utqiaġvik.