Application of remote sensing on urban heat island effects of the northern Taiwan

Urban heat island effects (UHIE) of the northern Taiwan have been growing concerns due to urbanization in recent years. This study aims to assess the UHIE of the northern Taiwan using remote sensing techniques. The processes include the generation of land-use maps from 1995 and 2002 landsat-5 images for monitoring the land-use change according to the calculated building area and Normalized Difference Vegetation Index (NDVI); the calculation of surface temperature and a comparison among various land-use types; and the assessment of UHIE magnitude in the north of Taiwan. The results showed that the study area was classified into five land-use types (i.e., forest, building, farmland, fallow farmland, and water) with 89.09% classification accuracy. A comparison of land-use between 1995 and 2002 pointed out that building area was increased from 12.99% to 14.05%, and the NDVI was decreased from 0.257 to 0.255. The result implied that the study area had more green cover and less human constructions in 1995 than in 2002. The estimations of surface temperature among land-use types showed that the highest value occurred in building area, and then fallow farmland, farmland, water, and forest was the smallest one. Meanwhile, the surface temperature of the northern Taiwan revealed an increasing trend from 13.49°C (in 1995) to 14.37°C (in 2002). Furthermore, the value in 2002 was significantly greater than that in 1995 according to the t-test value (p << 0.05). From above results, obviously urban sprawl did enhance the UHIE strength of the northern Taiwan. Besides, remote sensing technique can be applied for the UHIE study under a large scale.