A Building Block Urban Meteorological Observation Experiment (BBMEX) over Seoul City, Korea

For the purpose of understanding the detailed distribution of surface and air temperatures in a high-rise building block, a 3-dimensional Building-Block Meteorological observation EXperiment (BBMEX) campaign has been carried out over typical commercial area (Gwanghwamun) in Seoul Metropolitan Area, Korea during the heat-wave and tropical night periods (5-6 August) in 2019. Several types of fixed and mobile instruments were deployed in the experiment domain: A thermal infrared imager (TIR) monitored the surface temperature with 320×240 pixels including building wall, road, sidewalks at every 10 min; 6 automatic weather stations obtained air temperature and relative humidity, and wind speed and direction at every 1 min; a mobile weather vehicle (MOVE4) monitored road surface temperatures and 4-components of radiation at 1 s on roadway; a mobile cart for meteorological observation (MCMO) monitored surface, 0.5m, 1.5m, and 2.5m air temperatures at 1 s on the sidewalk and square. The TIR exhibited that east-face of a building was strongly heated during the morning time, while horizontal surface was strongly heated near noon. Air temperatures at 2 m high in 2×2 km² exhibited 1.5 ℃ temperature range at 06 LST, while 4.0 ℃ temperature range at 15 LST on 6 August 2019, depending on the location of site in building blocks. Air temperatures in Gwanghwamun Square were 1.5-1.7 ℃ and 0.1-2.2 ℃ higher than those observed at the Seoul synoptic station (1 km apart) in night and day, respectively. Surface and 0.5, 1,5, and 2.5m temperatures was 49.1 ℃, 38.7 ℃, 38.1 ℃, and 37.9 ℃, respectively, at 1500 LST on 6 August 2019, when the hottest air temperature in the year 2019 (36.9 ℃) was recorded at the Seoul station. Surface and air temperatures were found to be affected by many factors in a building-block such as shades, trees, building height and density, aspect ratio of building canyon, sky-view, ground-fountain, waterway, etc.