Abstract
Abstract. The Urban Heat Island (UHI) phenomenon is a manifestation of the abnormal amount of heat generated in urban areas and anthropogenic land surface modifications. While urbanization can improve material comfort and be a boon to the economy, the accompanying problems associated with urbanization like the UHI effect has implications on health, demand for water and energy, and impacts the microclimate. Land surface temperature (LST), the Normalized Difference Vegetation Index (NDVI), and the Normalized Difference Built-up Index (NDBI) were calculated from historical remotely-sensed Landsat data from 2013 to present. The global horizontal irradiance (GHI) was computed from the lidar-derived elevation model of Cebu City using the Geographical Resources Analysis Support System (GRASS). It is shown that annual variation in average temperatures in Cebu is generally less than 5 °C. Mean UHI temperatures in Cebu City do not show a clear trend over time, but categorizing data by season, namely the rainy season (June–November), the cool dry season (December–February), and the hot dry season (March–May), permits the emergence of a pattern. Surface temperatures for the cool dry season and hot dry season show a linearly increasing trend with R2 values of 0.916 and 0.514, respectively. This study further investigates the temporal change in the degree and extent of the UHI in Cebu City by analyzing LST maps. Regression analysis is done to determine how LST is affected by the distribution of vegetation (NDVI) and built-up (NDBI), and the seasonal variation in solar radiation through the GHI.
Highlights
The urban heat island (UHI) effect describes the phenomenon in which urbanized areas have comparatively higher air and/or land surface temperatures than the surrounding rural areas (Landsberg, 1981, Oke, Mills, Christen, Voogt, 2017)
We present results of our study of the UHI effect in Cebu City taking into account vegetation, urbanization, and the amount of solar radiation as measured by the global horizontal irradiance (GHI)
The Normalized Difference Built-up Index (NDBI) can be computed from multiband remotely-sensed imagery, this time exploiting the fact that manmade surfaces tend to have higher reflectance in the short wave infrared (SWIR) than in the NIR wavelengths
Summary
The urban heat island (UHI) effect describes the phenomenon in which urbanized areas have comparatively higher air and/or land surface temperatures than the surrounding rural areas (Landsberg, 1981, Oke, Mills, Christen, Voogt, 2017). Memon et al (2008) classified these factors into controllable and uncontrollable factors Controllable factors are those associated with anthropogenic influence such as urban design, building materials, sky view factor, population growth, etc. Uncontrollable factors are those factors that are controlled by nature such as solar radiation, wind speed, cloud cover, etc. Uncontrollable factors are those factors that are controlled by nature such as solar radiation, wind speed, cloud cover, etc. Memon et al (2008) mentioned categorization of these factors into temporary effect factors such as wind and cloud cover, permanent effect factors such as building design and materials and sky view factor, and cyclic effect factors such as diurnal conditions and seasonal meteorological phenomena
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