Urban heat island effects on growing seasons and heating and cooling degree days in Madison, Wisconsin USA

Abstract

Urban areas tend to be warmer than their rural surroundings, a phenomenon known as the urban heat island (UHI) effect. UHIs are nearly always described in terms of temperature. However, UHIs can also be described using derived climate indices, including growing season length, growing degree days (GDDs), and heating and cooling degree days, which may have more direct ecological and economic significance than temperature alone. To characterize UHI effects on these basic climate parameters, we used over 3 years of continuously collected temperature data from up to 150 locations in and around Madison, Wisconsin, USA, an urban area of population 402 000 surrounded by lakes and a rural landscape of agriculture, forests, wetlands, and grasslands. Compared to rural areas, Madison's UHI extended the freeze-free season by several weeks each year. However, it only shifted the onset of spring and fall (represented by 10-day moving average temperature crossing seasonal thresholds) by 1 day or less in spring and by a few days to a week in fall. The different effects on freeze dates versus running-mean temperatures were primarily because the UHI could affect temperatures during individual freeze events much more than it could influence regional seasonal temperature trends. Urban effects on the meteorological growing season were nearly always greater in fall than in spring. We hypothesize that this is due to seasonal differences in sub-surface temperatures, with urban and rural areas presumably having more uniform sub-surface temperatures in spring after being frozen throughout the winter, contributing to weaker UHI effects in spring than in fall. In terms of degree days, densely built urban areas averaged 14% (209) more GDDs, 25% (117) more cooling degree days, and 6% (284) fewer heating degree days than rural areas, indicating that the UHI could have significant impacts on energy consumption in Madison.

Examining Spatio-Temporal Characteristics of Urban Heat Islands and Factors Driving Them in Hangzhou, China

“…The NDVI and MNDWI were negatively correlated with UHIs at the level of significant of 1%, indicating that the increase in areas of water and green spaces can inhibit UHIs, which is consistent with most past studies [55], [56]. This is because plants and waterbodies transmit water to the atmosphere through evapotranspiration [57], which increases humidity and reduces heat in the city [58]. The DEM and slope were negatively correlated with UHIs at a significance of 1%, which is consistent with the results reported by Peng et al [32].…”

Life History of Parthenolecanium spp. (Hemiptera: Coccidae) in Urban Landscapes of the Southeastern United States

“…The phenology of many ectothermic species has become earlier owing to climate change in recent decades including many pests (Parmesan and Yohe 2003). The urban heat island effect adds growing degree days and can thus cause insects to develop or become active earlier than in rural areas (Meineke et al 2014, Schatz andKucharik 2016). Future climateinduced changes in pest biology will require vigilance by IPM practitioners to maintain accurate pest forecasting tools.…”

“…The temperature data used to calculate degree-days are the major source of error in DD models (Herms 2004). If the weather station is far from the actual site or is more or less urban than the site, it may not be able to accurately record the temperature experienced by the scale insect population on the site (Schatz and Kucharik 2016). There also could be a potential effect of warmer ambient temperatures due to heat accumulation on paved surfaces in urban areas (i.e.…”

Urban heat island‐induced increases in evapotranspirative demand

“…By demonstrating substantial and predictable variability in RET GS as a function of impervious cover within urban areas, we show that land cover must be considered as a driver of variability in evapotranspirative demand over fine spatial scales. While much previous urban ecological research has focused on the impacts of the UHI on growing season length [ Buyantuyev and Wu , ; Jochner and Menzel , ; Schatz and Kucharik , ; Zipper et al , ], our results suggest that studies focusing solely on UHI‐induced changes in growing season length are inadequate to understand UHI effects on plant water requirements.…”

“…Furthermore, Madison's UHI is well characterized by past studies, providing useful context for interpretation of results. Our sensor network is among the densest currently deployed [ Schatz and Kucharik , ; Smoliak et al , ; Shiflett et al , ] and has been previously used to study the spatial patterns and drivers of Madison's UHI [ Schatz and Kucharik , ], the impact of the UHI on extreme heat and cold [ Schatz and Kucharik , ], and the UHI impacts on growing season heating/cooling degree days [ Schatz and Kucharik , ] and plant phenology [ Zipper et al , ].…”