Analysis of the Thermal Environment around an Urban Green Area in Seoul, Korea Using Climate Analysis Seoul (CAS)

Climate Analysis Seoul (CAS) which provides gridded data relevant for thermal assessment was applied to one of the urban green areas, the Seonjeongneung, in Seoul, Korea. The thermal environment in the Seonjeongneung was evaluated from the CAS simulation for the five heat- wave issued cases during the last five years (2011 similar to 2015). The CAS has been improved continuously since it was developed. An updated version with a higher resolution of the CAS simulation domain and an addition of the vegetation information was used in this study. The influence of vegetation in the Seonjeongneung is estimated through the amount of the cold air generation (Q(ca)) and air temperature deviation at each grid points, which are calculated by incorporating Geographic Information System (GIS) analysis on the simulation domain and meteorological analysis with the METeorology and atmospheric PHOtochemistry mesoscale MODel (MetPhoMod) in the CAS. The average amount of the cold air generation (Q(ca)) at the Seonjeongneung is about 25.5 m(3) m(-2) h(-1) for the whole cases, and this value is similar to the ones in a forest or a well- wooded region. The average value of the total air temperature deviation (TD) is- 2.54 degrees C at the Seonjeongneung for the five cases. However, this cooling effect of the urban green area disappeared when the region is replaced by high- rise buildings in the CAS simulation. The Q(ca) drastically decreases to about 1.1 m(3) m(-2) h(-1) and the average TD shows an increase of 1.14 degrees C for the same events. This result shows that the vegetation in the Seonjeongneung supposes to keep down temperature during the heat- wave issued day and the average cooling effect of the green region is 3.68 degrees C quantitatively from the TD difference of the two simulations. The cooling effect represented with the TD difference is larger than 0.3 degrees C within 200 m distance from the boundary of the Seonjeongneung. Further improvements of the thermodynamical and advection processes above the model surface are required to consider more accurate assessment of the cooling effect for the urban green area.