The urban-parkland nocturnal temperature interface

An urban heat island (UHI) study has been made of the transition between an open park area and an urban environment, mainly through the use of night-time mobile traverses concentrating on still nights at cloudless times. The park areas exhibit lower temperatures than the urban areas, with little extension of the effect into the urban area. The boundary transition proves to be quite sharp at times when wind speeds are low. Through additional measurements of water vapor it was found that there is an inverse relationship between specific humidity and screen temperature along traverses. The park areas have higher humidity levels. Measurements at fixed urban locations exhibit a similar effect with evapotranspiration apparently playing a significant role.