5:15 PM - 6:45 PM
[AAS08-P07] Development and experimental observation of a next-generation water vapor lidar to improve forecast skill of SLMCS
★Invited Papers
Keywords:Water vapor lidar, DIAL, Stationary linear mesoscale convective systems
Detailed observations of the vertical profiles of water vapor concentration in the lower atmosphere are important to improve the forecast skill of local severe rainfall associated with stationary linear mesoscale convective systems (SLMCS). However, such observations are lacking. Therefore, we have developed a next-generation water vapor lidar that is capable of continuous observation with high precision and high temporal resolution, and can be operated at low cost for future operational use.
The water vapor lidar being developed in this study is a diode-laser-based differential absorption lidar (DIAL). Compared to the Raman lidar, the DIAL has a more complicated configuration, but it has many advantages, such as low maintenance frequency, no need for calibration, and the use of a diode laser, which makes the device compact and lightweight. We developed a prototype of the DIAL (e.g., Abo et al., 2018). However, there were some issues such as the inability to observe to high altitudes during the daytime due to solar background light and the long time and experience required for the adjustment process. Therefore, based on the prototype, we have developed an instrument that can observe up to 3-4 km altitude throughout the day and night, and has improved workability and operability at the observation sites.
We have simulated the optical path of the receiver system and selected lenses based on the simulation results. We also evaluated the transmittance of etalon and interference filters in the receiver system. On the other hand, the transmitter system was redesigned by adding mirrors for alignment and by effectively using a beam profiler, the time required for alignment was significantly reduced (from half a day to one day to less than one hour). Furthermore, we have implemented a wavelength control function for the transmitting laser.
We moved the DIAL from Tokyo Metropolitan University to Meteorological Research Institute in Tsukuba at the end of September 2023, and have been conducting experimental observations since December 2023. Although further adjustments are needed, the vertical profiles of water vapor concentration observed with the DIAL generally correspond to data from the radiosonde at Tateno and the JMA Meso-scale Analysis, as well as the Raman lidar installed at the same location as the DIAL.
The next step is to improve the stability of the output power of the DIAL. In the near future, we will conduct field observations targeting the SLMCS in Kyushu.
Reference
M. Abo, T. Sakai, P. P. L. Hoai, Y. Shibata, and C. Nagasawa: EPJ Web of Conferences 176 (2018) 04015.
The water vapor lidar being developed in this study is a diode-laser-based differential absorption lidar (DIAL). Compared to the Raman lidar, the DIAL has a more complicated configuration, but it has many advantages, such as low maintenance frequency, no need for calibration, and the use of a diode laser, which makes the device compact and lightweight. We developed a prototype of the DIAL (e.g., Abo et al., 2018). However, there were some issues such as the inability to observe to high altitudes during the daytime due to solar background light and the long time and experience required for the adjustment process. Therefore, based on the prototype, we have developed an instrument that can observe up to 3-4 km altitude throughout the day and night, and has improved workability and operability at the observation sites.
We have simulated the optical path of the receiver system and selected lenses based on the simulation results. We also evaluated the transmittance of etalon and interference filters in the receiver system. On the other hand, the transmitter system was redesigned by adding mirrors for alignment and by effectively using a beam profiler, the time required for alignment was significantly reduced (from half a day to one day to less than one hour). Furthermore, we have implemented a wavelength control function for the transmitting laser.
We moved the DIAL from Tokyo Metropolitan University to Meteorological Research Institute in Tsukuba at the end of September 2023, and have been conducting experimental observations since December 2023. Although further adjustments are needed, the vertical profiles of water vapor concentration observed with the DIAL generally correspond to data from the radiosonde at Tateno and the JMA Meso-scale Analysis, as well as the Raman lidar installed at the same location as the DIAL.
The next step is to improve the stability of the output power of the DIAL. In the near future, we will conduct field observations targeting the SLMCS in Kyushu.
Reference
M. Abo, T. Sakai, P. P. L. Hoai, Y. Shibata, and C. Nagasawa: EPJ Web of Conferences 176 (2018) 04015.