13:45 〜 15:15
[MIS23-P08] 雲・水蒸気を観測するテラヘルツ二周波気象レーダーとその噴煙観測可能性
キーワード：二周波気象レーダー、テラヘルツ波、火山噴煙
A microwave weather radar is used to observe a distribution of precipitation. However, non-precipitating clouds cannot be observed with the sensitivity of ordinary weather radars, because cloud droplets are much smaller than precipitation particles. Therefore, a cloud radar was developed with higher sensitivity using a shorter wavelength. We describe the configuration and specifications of this cloud radar, and show its case study. In addition, we show the problems of the current cloud radar and propose a dual-frequency terahertz weather radar to solve the problems.
National Research Institute for Earth Science and Disaster Resilience (NIED) developed a Ka-band cloud radar to observe cumulous cloud developing into cumulonimbus. To realize the detectability of such a cloud, 3 kW Extended interaction Klystron (EIK) and pulse compression technology are used. NIED developed the detection system of developed cumuli which will generate rain by the Ka-band cloud radar network in Tokyo metropolitan area. However, some problems become obvious in this radar system.
Recently, the EIK price is increasing and its delivery period is also getting longer. These situations make the operation of EIK radar difficult. X-band dual-polarization weather radar enabled to make an accurate quantitative precipitation estimation (QPE) with a differential phase shift in these ten years. However, the Ka-band cloud radar still uses the radar reflectivity which is not well correlated with a cloud water content. Furthermore, atmospheric attenuation, especially water vapor effect, disturbs the accurate reflectivity observation by the millimeter wavelength radar.
We propose a dual-frequency terahertz (95 GHz and 150 GHz) weather radar with solid-state amplifiers to solve these problems. The radar sensitivity with the solid-state amplifiers may be lower than that with EIK, but it is compensated by using higher frequency than Ka-band. Dual-Wavelength Ratio (DWR) of radar reflectivity is well correlated with cloud and water vapor contents. the cloud and water vapor effects in the DWR are separated by an artificial intelligence (AI) model, which learns the relationship between meteorological parameters and radar reflectivity simulated by meteorological model using the spectral-bin microphysics.
The observability of volcanic smoke with the proposed radar is discussed by referring to the past volcanic smoke observation by Ka-band radar at Sakurajima.
Acknowledgements: The development of the dual-frequency terahertz radar is supported by the commissioned research (No. 06901) by National Institute of Information and Communications Technology (NICT) , Japan.
National Research Institute for Earth Science and Disaster Resilience (NIED) developed a Ka-band cloud radar to observe cumulous cloud developing into cumulonimbus. To realize the detectability of such a cloud, 3 kW Extended interaction Klystron (EIK) and pulse compression technology are used. NIED developed the detection system of developed cumuli which will generate rain by the Ka-band cloud radar network in Tokyo metropolitan area. However, some problems become obvious in this radar system.
Recently, the EIK price is increasing and its delivery period is also getting longer. These situations make the operation of EIK radar difficult. X-band dual-polarization weather radar enabled to make an accurate quantitative precipitation estimation (QPE) with a differential phase shift in these ten years. However, the Ka-band cloud radar still uses the radar reflectivity which is not well correlated with a cloud water content. Furthermore, atmospheric attenuation, especially water vapor effect, disturbs the accurate reflectivity observation by the millimeter wavelength radar.
We propose a dual-frequency terahertz (95 GHz and 150 GHz) weather radar with solid-state amplifiers to solve these problems. The radar sensitivity with the solid-state amplifiers may be lower than that with EIK, but it is compensated by using higher frequency than Ka-band. Dual-Wavelength Ratio (DWR) of radar reflectivity is well correlated with cloud and water vapor contents. the cloud and water vapor effects in the DWR are separated by an artificial intelligence (AI) model, which learns the relationship between meteorological parameters and radar reflectivity simulated by meteorological model using the spectral-bin microphysics.
The observability of volcanic smoke with the proposed radar is discussed by referring to the past volcanic smoke observation by Ka-band radar at Sakurajima.
Acknowledgements: The development of the dual-frequency terahertz radar is supported by the commissioned research (No. 06901) by National Institute of Information and Communications Technology (NICT) , Japan.