Measurements of water vapor profiles with compact and mobile lidars for local heavy rainfall prediction
Abstract
Water vapor is the strongest greenhouse gas and controls the Earth's radiation balance. It is also important for cloud formation and precipitation processes. In recent years, the frequency of occurrence of locally heavy rainfall that can cause extensive damages, has been increasing in Japan. For early prediction of heavy rainfall, numerical weather model is employed using the conventional meteorological station radiosonde data. However, the lead time and accuracy of the prediction are limited because of the coarse spatial and temporal resolutions of the data. To improve them, it is useful to measure the water vapor distribution upwind cumulus convection beforehand and assimilate the data into the model. For that purpose, we have developed two compact and mobile lidars that can measure the vertical distribution of water vapor in the lower troposphere. One is the compact diode-laser-based differential absorption lidar (DIAL) and the other is the mobile Raman lidar. The DIAL employs two distributed Bragg reflector (DBR) lasers operating at 829.054 nm for the online wavelength and 829.124 nm for the offline wavelength with a tapered semiconductor optical amplifier (TSOA) in a master oscillator power amplifier (MOPA) configuration. The Raman lidar employs a Nd:YAG laser operating at 355 nm and detects the Raman scattering by water vapor at 408 nm and nitrogen at 387 nm. These lidars can measure the vertical distribution of the water vapor in the lower troposphere with a vertical resolution of 75-300 m and a temporal resolution of 10-60 minutes. We show the results of the measurements with these lidars in summer when the local heavy rainfall frequently occurs in Japan. We also show the preliminary result of the assimilation of the lidar data to the numerical model and impact on the heavy rainfall prediction.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A31G0129S
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE