The urban heat island in winter at Barrow, Alaska

Abstract

The village of Barrow, Alaska, is the northernmost settlement in the USA and the largest native community in the Arctic. The population has grown from about 300 residents in 1900 to more than 4600 in 2000. In recent decades, a general increase of mean annual and mean winter air temperature has been recorded near the centre of the village, and a concurrent trend of progressively earlier snowmelt in the village has been documented. Satellite observations and data from a nearby climate observatory indicate a corresponding but much weaker snowmelt trend in the surrounding regions of relatively undisturbed tundra. Because the region is underlain by ice-rich permafrost, there is concern that early snowmelt will increase the thickness of the thawed layer in summer and threaten the structural stability of roads, buildings, and pipelines. Here, we demonstrate the existence of a strong urban heat island (UHI) during winter. Data loggers (54) were installed in the ∼150 km 2 study area to monitor hourly air and soil temperature, and daily spatial averages were calculated using the six or seven warmest and coldest sites. During winter (December 2001-March 2002, the urban area averaged 2.2°C warmer than the hinterland. The strength of the UHI increased as the wind velocity decreased, reaching an average value of 3.2°C under calm (<2 m s −1 ) conditions and maximum single-day magnitude of 6°C. UHI magnitude generally increased with decreasing air temperature in winter, reflecting the input of anthropogenic heat to maintain interior building temperatures. On a daily basis, the UHI reached its peak intensity in the late evening and early morning. There was a strong positive relation between monthly UHI magnitude and natural gas production/use. Integrated over the period September-May, there was a 9% reduction in accumulated freezing degree days in the urban area. The evidence suggests that urbanization has contributed to early snowmelt in the village.

Evidence for influence of anthropogenic surface processes on lower tropospheric and surface temperature trends

“…It is possible that the cumulative effects of small-scale human activities could contribute to lower tropospheric heating on regional or even larger scales (e.g. Hinkel et al (2003)). This is not to be confused with the issue of whether the proximity of human activity may affect the local temperature measurement without changing the actual temperature over a larger surrounding (cf Loveland and Belward, 1997;Peterson, 2003).…”

Urban warming in villages

“…Oke, 1982), but observable UHI effects are found in towns (e.g. Magee et al, 1999;Steeneveld et al, 2011) and small villages (Hinkel et al, 2003).…”

Evaluating the Role of Snow Cover in Urban Canopy Layer on the Urban Heat Island in Sapporo, Japan with a Regional Climate Model

“…The contribution of solar insolation to winter heat islands is less than that to summer heat islands (Oleson et al 2010). Moreover, the contribution of anthropogenic heat in winter is larger than in other seasons because of the weaker solar radiation flux (Hinkel et al 2003;Hamilton et al 2009;Malevich and Klink 2011;Bohnenstengel et al 2014). Therefore, the effect of heat storage on maintaining nocturnal urban surface air temperatures is relatively small in winter, indicating that nocturnal temperature distribution depends heavily on nocturnal anthropogenic heat release.…”

“…1a), the daily minimum winter air temperature has increased over 0.06°C yr −1 from 1931 to 2010, which is more than or comparable with other major Japanese cities (e.g., 0.069°C yr −1 in Tokyo, 0.036°C yr −1 in Osaka, and 0.043°C yr −1 in Nagoya) (JMA 2011). The properties of the winter heat island in high-latitude cold regions differ from those of the summer heat island effect because the lower solar radiation flux in winter enhances the contribution of anthropogenic warming to the heat island effect (Hinkel et al 2003;Hamilton et al 2009;Malevich and Klink 2011;Bohnenstengel et al 2014). Snow cover also alters the surface energy budget (DeWalle and Rango 2011), and it is therefore critical to consider the surface energy budget over snow in any evaluation of the winter heat island effect in cold regions.…”