Distribution of Land Surface Temperature In Yogyakarta Urban Area

Yogyakarta urban area has grown throughout the year as the course of migration and its attraction to tourists and students resulting in the high demand of living space which leads to the increment of the built-up area such as hotels and other supporting-tourism-activity accommodation, so-called urban sprawl. The increase of paved-surface causes the increase of land surface temperature (LST), which may impact to micro-climate in the urban area with adverse consequences, for instance, erratic rainfall and rainstorm in the urban area. Consequently, it triggers new future problems. Therefore, it is necessary to study LST to perceive the state of temperature change in the study area as a preliminary assessment in studying urban climate. This paper attempts to present the distribution of Land Surface Temperature (LST) in Yogyakarta urban area, extracted from remotely-sensed Landsat 8 image acquired from a two-year image. Before the extraction, several variables are incorporated such as Normalized Difference Vegetation Index (NDVI) to calculate emissivity, as well as atmospheric correction parameter transmissivity, upwelling and downwelling radiance. The reflectance values are also corrected to obtain NDVI. Land surface temperature extracted according to the procedures: conversion of the digital number of Landsat image to radiance, correction of radiance value, conversion of the corrected radiance value to brightness temperature, then brightness temperature to land surface temperature. The extracted temperature map then presented into 5 degrees C interval. Consecutively, the two-year of temperature maps are then analyzed to obtain the difference of its spatial distribution. The expected result is the expanding high-temperature distribution in the urban area. The result shows there is an increase in the average land surface temperature by 1,5 degrees C from two different images, 2014 and 2018. The majority value of temperature is between 30 - 40 degrees C, dominated with the built-up area. Two image shows that the respective area spread from 54% to 70%.