UCLA

Temperature rise, caused by urbanization, increases electricity demand, adversely affects human health, and alters hydrological and ecological patterns. Urban heat islands (UHI) are affected by both complex urban cover as well as surrounding environments. This study describes the variability of temperature and relative humidity as it is (1) influenced by local vegetation and land cover type over neighborhoods and (2) moderated by coastal climate across the urban gradient. Data were collected at four different times of the day during three different weather conditions using mobile transects over four urban neighborhoods in Southern California: Venice, Mid-Wilshire, Pomona, and Riverside. The four neighborhoods also form a climate gradient extending from the Venice (coast) to Riverside (99 miles inland). The influence of urban land cover on local climate proved dependent on the time of day and general atmospheric conditions (sunny, cloudy, etc). Temperature was statistically related to vegetation during cooler or early morning measurements, but less so during midday and extreme heat conditions. Inland neighborhood temperatures and relative humidity showed an increased dependence on vegetation from coastal areas because of the lack of other moisture sources. This study serves as an initial baseline for continued study of the urbanization of coastal and inland areas and relationship to local land cover and vegetation density.