Observations of the Wind Speed Profile over the Seoul Metropolitan Area in Korea Using Doppler Lidar

Wind is one of the most important factors for the improvement thermal environment and air pollution in the city. In addition, the vertical distribution of wind speed also provides information for wind power generation. However, operation weather observations provide little vertical distribution of wind speed around the city. NIMS (National Institute of Meteorological Sciences)/KMA operates urban meteorological sensor network in Seoul (UMS-Seoul) to observe urban meteorological phenomena since year 2013. UMS-Seoul is composed of 14 surface energy balance systems, 2 aerosol lidar systems and ceilometers, 6 wind lidar systems, and 7 microwave radiometers. This study aims to analyze the wind speed characteristics such as temporal variability, profile and impact of roughness length on wind speed profile using the data obtained from wind lidar over Seoul metropolitan area. Three wind lidars which are installed in high-rise building area in the downtown of the city, residential area of the city, and suburban agriculture region around the Seoul are used in this study to consider various kinds of land-use characteristics. Seasonal variation of wind speed indicates that wind is strongest during the spring below 1km, while it peaks during the winter season above 1km. Urban wind speed in the surface layer decreases than suburban due to the roughness effect of urban buildings. Comparing the distribution of wind speed profile between urban and suburban, the wind speed increases remarkably with altitude up to 500m above ground level over urban area, while it tends to increase slowly in the suburban area. The rate of increase of wind speed according to the altitude depends on the magnitude of the wind speed. Wind speed in the surface layer of the suburban area increase rapidly with altitude than urban area, while the rate of increase of wind speed above the surface layer in the urban area is larger than suburban for low wind speed period (less than 0.2m/s at ground level). However, the rate of increase of wind speed shows large value in the urban area regardless of altitude for high wind speed period (above than 5.5 m/s at ground level). Measured wind speed profile is consistent with the distribution of logarithmic law in Seoul, Korea. Comparison of the wind profile between observation and logarithmic law may provide upper wind information in area where wind profile is not observed. Detailed introduction of UMS-Seoul and results including wind profile using doppler lidar will be presented in the conference.