A Study on the Thermal Characteristics of Midsummer in Daegu Metropolitan Area

Abstract

This study aims to examine the actual status of the urban heat island in Daegu by analyzing the data of 17 automatic weather stations installed in the Daegu area. And the results can be summarized as follows: First, regarding the temperature distribution in Daegu by summer time zones, for the 31 days(August 1st till 31st), 18 days showed daily maximum temperature over <TEX>$30^{\circ}C$</TEX>, and 11 days indicated daily minimum temperature over <TEX>$25^{\circ}C$</TEX>. The day that showed the highest daily maximum temperature was August 5th, which indicated <TEX>$36^{\circ}C$</TEX>. Second, about the spatial distribution of time ratio exceeding <TEX>$30^{\circ}C$</TEX> and <TEX>$25^{\circ}C$</TEX>, the area with the highest time ratio exceeding <TEX>$30^{\circ}C$</TEX> is mostly the downtown(central area), eastern area, and northern area. Meanwhile, regarding the time ratio exceeding <TEX>$25^{\circ}C$</TEX>, the downtown area centering around the central area were high as over 70%, and the outskirts were low as under 65%. Third, considering the temporal distribution of daily maximum temperature and daily minimum temperature, daily maximum temperature was shown around 14:00 to 15:00 while the daily minimum temperature was indicated around 17:00 to 18:00. Daily maximum and minimum temperature were appeared at northeast and downtown, respectively. Fourth, regarding the spatial distribution of tropical days and tropical night days, tropical days showed 77% and tropical night days indicated 42% before and after the 24th and also the 13th each. Tropical days were occurred up to 24 days at northeastern area. And the southwestern area of Daegu showed under 22 days. The downtown showed the 14 days of the tropical night. However, the outskirts indicated relatively few days as under 10 days. Fifth, about the spatial distribution of the average daily temperature range (the difference between the highest temperature and lowest temperature), the central area, the central part of the city, showed the smallest as <TEX>$7.2^{\circ}C$</TEX>, and as it was closer to the northern area, it became larger, so in the eastern and northern area, it was over <TEX>$8.8^{\circ}C$</TEX> or so.