[A-CG32] Land-Atmosphere interactions and Asian monsoon precipitation (LAMos)

[ACG32-04] The Effect of Urbanization on Extreme Temperature Indices in the Philippines

*John Asaula Manalo^1,2、Jun Matsumoto^1,3、Hiroshi G. Takahashi¹、Marcelino Q. Villafuerte²、Lyndon Mark P. Olaguera^4,5、Guoyu Ren^6,7、Thelma Acebes Cinco² (1.Department of Geography, Tokyo Metropolitan University、2.Department of Science and Technology - Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA-DOST), Quezon City, Philippines、3.Department of Coupled-Ocean-Atmosphere-Land Processes Research, Japan Agency for Marine Earth Science and Technology, Yokosuka, Japan、4.Regional Climate Systems Laboratory, Manila Observatory, Ateneo de Manila University Campus, Quezon City, Philippines、5.Physics Department, Ateneo de Manila University, Quezon City, Philippines、6.Department of Atmospheric Science, School of Environmental Studies, China University of Geosciences, Wuhan, China、7.National Climate Center, China Meteorological Administration, Beijing, China)

キーワード：surface air temperature, extreme temperature indices, urbanization, satellite night-light, the Philippines

This paper presents a comprehensive analysis of the effect of urbanization on the surface air temperature (SAT) from 1951 to 2018 in the Philippines. The daily minimum temperature (Tmin) and daily maximum temperature (Tmax) records from 34 meteorological stations were used to derive extreme temperature indices. These stations were then classified as urban or rural based on satellite night-lights. The results showed a significant difference in the SAT trends between urban and rural stations, indicative of the effect of urbanization in the country. Larger and more significant warming trends were observed in indices related to Tmin than those related to Tmax. In particular, the effects of urbanization were significant in the annual index series of Tmin, diurnal temperature range, minimum Tmin, percentage of days when Tmin was less than the 10th percentile (TN10p), percentage of days when Tmin was greater than 90th percentile (TN90p), and the number of coldest nights. The effects of urbanization were not as clear on the index series of maximum Tmax (TXx), minimum Tmax (TXn), percentage of days when Tmax was less than 10th percentile (TX10p), and the number of hottest days. The effects of urbanization on the annual series of extreme temperature indices were statistically significant at the 95% confidence level, with the exception of Tmax, TXn, TXx, TX10p, and the number of hottest days. Further analysis revealed that the effect of urbanization was the greatest during the winter season. This may be related to the lower urban boundary layer that reduces the urban to rural air exchange during this season. These findings serve as a baseline study that focuses on the countrywide effect of urbanization on SAT trends in the Philippines.