17:15 〜 18:30
[ACG36-P12] Verification of satellite-observed surface temperature in water areas and application to meteorological simulations
キーワード：河川、地表面温度、ASTER、領域気象モデルWRF
It is well known that urban rivers have a moderating effect on the surrounding climate. In order to investigate such an effect using a regional climate model, numerical simulations with a high-resolution are required, and initial and boundary conditions with a high resolution are also required for these simulations. Water temperatures in major rivers are measured by the River Bureau of the Ministry of Land, Infrastructure, Transport and Tourism, and the hourly measured data are open to the public, but these observations do not cover the entire river. The Earth observation satellite Terra passes over the same area at 16 day intervals at the same time, and the surface kinetic temperature is measured with a high resolution of about 90 m by the Thermal Infrared Radiometer (TIR) of the mounted Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). In a large river with a width of 200-300 m, the surface temperature observed by this satellite seems to be available as the river water temperature. In this study, at first, we compare the surface temperature observed by Terra/ASTER (TASTER) with the water temperature measured at River Bureau in Yodogawa River and at water quality monitoring points in Osaka bay. Next, we try to create boundary conditions for the surface temperature of water bodies in Weather Research and Forecasting (WRF) model from the TASTER surface temperature. Then, the effect of incorporating TASTER surface temperature is investigated with the WRF simulations.
The TASTER surface temperature data (AST_08) at 10:52 JST on April 8, 2019 is used, of which the cloud cover rate is 2% and the observation area includes Osaka Bay and Yodogawa River. The accuracy of the TASTER surface temperature is verified by comparing this surface temperature with the water temperature observed at 11:00 on the left bank of Hirakata Bridge at the Yodogawa River Bureau and at four water quality monitoring points in Osaka Bay. The surface temperature of the water area, which is one of the boundary conditions for a WRF simulation, is produced by fitting in the surface temperature of the satellite observation point with the nearest model grid point. Numerical experiments are carried out for the case using the boundary conditions of the surface temperature of water bodies produced from the meso-scale land surface analysis of the Japan Meteorological Agency (JMA), and the case produced from the TASTER surface temperature. We compare the results of these calculations with those of the surface meteorological observations by the JMA and the Atmospheric Environment Measurement Bureau.
The TASTER shows lower surface temperatures in water areas, such as Osaka Bay and the Yodogawa River, than in land areas at this time. The TASTER surface temperatures around the five monitoring points in the Yodogawa River and Osaka Bay are all higher than the water temperatures measured at the monitoring points. Compared with the surface temperature of the water bodies in the JMA meso-scale land surface analysis, the TASTER surface temperature is lower in the ocean and higher in the land water area. Since the observations at the River Bureau and the water quality monitoring points in Osaka Bay show higher surface temperature in the Yodogawa River than in Osaka Bay, the TASTER surface temperature reasonably represents the realistic land water temperatures. The WRF simulations with two different boundary conditions show that the surface wind converges over the Osaka Plain from 13:00 to 18:00, and that there is a relatively large difference in the air temperature, mixing ratio, and relative humidity of the two simulations in the region where the wind converges.
The TASTER surface temperature data (AST_08) at 10:52 JST on April 8, 2019 is used, of which the cloud cover rate is 2% and the observation area includes Osaka Bay and Yodogawa River. The accuracy of the TASTER surface temperature is verified by comparing this surface temperature with the water temperature observed at 11:00 on the left bank of Hirakata Bridge at the Yodogawa River Bureau and at four water quality monitoring points in Osaka Bay. The surface temperature of the water area, which is one of the boundary conditions for a WRF simulation, is produced by fitting in the surface temperature of the satellite observation point with the nearest model grid point. Numerical experiments are carried out for the case using the boundary conditions of the surface temperature of water bodies produced from the meso-scale land surface analysis of the Japan Meteorological Agency (JMA), and the case produced from the TASTER surface temperature. We compare the results of these calculations with those of the surface meteorological observations by the JMA and the Atmospheric Environment Measurement Bureau.
The TASTER shows lower surface temperatures in water areas, such as Osaka Bay and the Yodogawa River, than in land areas at this time. The TASTER surface temperatures around the five monitoring points in the Yodogawa River and Osaka Bay are all higher than the water temperatures measured at the monitoring points. Compared with the surface temperature of the water bodies in the JMA meso-scale land surface analysis, the TASTER surface temperature is lower in the ocean and higher in the land water area. Since the observations at the River Bureau and the water quality monitoring points in Osaka Bay show higher surface temperature in the Yodogawa River than in Osaka Bay, the TASTER surface temperature reasonably represents the realistic land water temperatures. The WRF simulations with two different boundary conditions show that the surface wind converges over the Osaka Plain from 13:00 to 18:00, and that there is a relatively large difference in the air temperature, mixing ratio, and relative humidity of the two simulations in the region where the wind converges.