[A-CG30] Extratropical oceans and atmosphere

[ACG30-12] Observation of Maritime Water Vapor by Shipboard Microwave Radiometer

*Akira Kuwano-Yoshida¹, Kosei Komatsu², Yoshihiro Tachibana³, Mikiko Fujita⁴, Yuhei Yamamoto⁵, Yoshimi Kawai⁴, Masaki Katsumata⁴, Kazuyuki Uehara⁶, Masahiro Minowa⁷, Yuya Takashima⁷ (1.Disaster Prevention Research Institute, Kyoto University, 2.Graduate School of Frontier Science, The University of Tokyo, 3.Mie University, 4.Japan Agency of Marine-Earth Science and Technology, 5.Chiba University, 6.Tokai University, 7.FURUNO ELECTRIC CO., LTD.)

Keywords:water vapor, microwave radiometer, atmosphere-ocean interaction, ship observation

Maritime water vapor is important to understand atmosphere-ocean interaction and predict precipitation. However, the vertical profile and minute-scale variation are not clear because of observational difficulty. Although ground-mounted microwave radiometers (MWR) can observe vertical profiles of water vapor above with every few minutes, it is too large to set on ships. Recently, a small MWR, which is easily set on ships, has been developed. We have been observing maritime water vapor using the shipboard MWR since August 2020 to understand maritime water vapor distribution. Two ships, the training vessel (T/V) Seisui-maru of Mie University and the research and training vessel Bosei-maru of Tokai University have observed whole year, and four ships, research vessel (R/V) Hakuho-maru and R/V Shinsei-maru of the University of Tokyo, Mirai of Japan Agency for Marine-Earth Science and Technology, Koyo-maru of National Fisheries University, have observed in their training and/or research cruises. In result, water vapor vertical profiles from tropics to Arctic in Pacific region have been observed (Fig. 1). Sonde observations have been conducted in the several research cruses. The vertical profiles observed by MWR well match with the sonde observation under 5000 m altitude and capture fine-scale water vapor structure due to high-frequent observation over ocean, which has never been observed by sonde. For example, in July 2022, R/V Shinsei-maru observed water vapor profiles crossing the Kuroshio in the East China Sea. Water vapor increase over warm Kuroshio, and its thickness is shallower in upstream than downstream of air flow. The results show that Kuroshio supplies moisture to air mass from south, which will be an origin of precipitation downstream.