Regional Distribution of Perceived Temperatures Estimated by the Human Heat Budget Model (the Klima-Michel Model) in South Korea

The regional distribution of perceived temperatures （PT） for 28 major weather stations in South Korea during the past 22 years （1983-2004） was investigated by employing a human heat budget model, the Klima-Michel model. The frequencies of a cold stress and a heat load by each region were compared. The sensitivity of PT in terms of the input of synoptic meteorological variables were successfully tested. Seogwipo in Jeju Island appears to be the most comfortable city in Korea. Busan also shows a high frequency in the comfortable PT range. The frequency of the thermal comfort in Seoul is similar to that of Daejeon with a relatively low frequency. In this study, inland cities like Daegu and Daejeon had very hot thermal sensations. Low frequencies of hot thermal sensations appeared in coastal cities （e.g., Busan, Incheon, and Seogwipo）. Most of the 28 stations in Korea exhibited a comfort thermal sensation over 40% in its frequency, except for the mountainous regions. The frequency of a heat load is more frequent than that of a cold stress. There are no cities with very cold thermal sensations. In this study, we found the decreasing trend of mortality with an increasing PT. If the PT is over any critical temperature point, however, the mortality rate increases again. The mortality variation with the PT of a station seems to be associated with the latitudinal location of the station, implying that it results from a regional acclimation effect of inhabitants.

Restoration of an Inner-City Stream and Its Impact on Air Temperature and Humidity Based on Long-Term Monitoring Data

Spatiotemporal changes in air temperature and humidity associated with the restoration of an innercity stream in Seoul, Korea, are investigated based on long-term monitoring data. The Cheonggye stream, covered under a concrete structure for 46 years, was restored in 2005 and runs 5.8 km eastward through a central region of Seoul. Long-term monitoring of the air temperature and relative humidity was made along the stream throughout the restoration and across the stream after the restoration. The area along the stream had a higher air temperature than the entire metropolitan area. The temperature anomaly between the monitoring area and the surrounding metropolitan area was 0.13℃ lower on average at the center of the stream after the restoration. The stream＇s effect on the air temperature was also evident in the temperature distribution along a street traversing the stream. The relative and specific humidities were increased due to the restoration. The restored stream modified the nearby urban climate in the opposite direction compared to urbanization. The results could be used as a model case in mitigating urban climate by a stream in future urban planning practices.

Sensitivity of Snowfall Characteristics to Meteorological Conditions in the Yeongdong Region of Korea

This study investigates the characteristics of cold clouds and snowfall in both the Yeongdong coastal and mountainous regions under different meteorological conditions based on the integration of numerical modeling and three-hourly rawinsonde observations with snow crystal photographs for a snowfall event that occurred on 29−30 January 2016.We found that rimed particles predominantly observed turned into dendrite particles in the latter period of the episode when the 850 hPa temperature decreased at the coastal site,whereas the snow crystal habits at the mountainous site were largely needle or rimed needle.Rawinsonde soundings showed a well-defined,two-layered cloud structure along with distinctive wind-directional shear,and an inversion in the equivalent potential temperature above the low-level cloud layer.The first experiment with a decrease in lower-layer temperature showed that the low-level cloud thickness was reduced to less than 1.5 km,and the accumulated precipitation was decreased by 87%compared with the control experiment.The difference in precipitation amount between the single-layered experiment and control experiment(two-layered)was not so significant to attribute it to the effect of the seeder−feeder mechanism.The precipitation in the last experiment by weakening winddirectional shear was increased by 1.4 times greater than the control experiment specifically at the coastal site,with graupel particles accounting for the highest proportion(~62%).The current results would improve snowfall forecasts in complicated geographical environments such as Yeongdong in terms of snow crystal habit as well as snowfall amount in both time and space domains.