- 著者
- Mikiko Fujita Tatsuya Fukuda Iwao Ueki Qoosaku Moteki Tomoki Ushiyama Kunio Yoneyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.16A, no.Special_Edition, pp.19-24, 2020 (Released:2020-11-07)
- 参考文献数
- 34
- 被引用文献数
- 1 4
We report experimental observations of precipitable water vapor (PWV) derived using Global Positioning System/Global Navigation Satellite System (GPS/GNSS) receivers mounted on autonomous surface vehicles (ASVs), which were deployed in the tropical Pacific Ocean from July to September 2018. The GPS atmospheric delay was estimated by precise point positioning and converted to PWV with ASV surface meteorological data. The GPS-PWV was in agreement with the PWV obtained from radiosondes, with a root mean square error of 3.02 mm and a mean difference of 0.16 mm. A similar accuracy was found in a comparison of GPS-PWV with satellite-based microwave measurements. In anticipation of real-time monitoring applications, PWV was also estimated using real-time clock and orbit data. These estimates were in agreement with the post-processing values. High-resolution temporal observations of PWV over the open ocean made possible by ASV technology could greatly improve our understanding of the rapid variations of developing convective systems.
- 著者
- Mikiko Fujita Tatsuya Fukuda Iwao Ueki Qoosaku Moteki Tomoki Ushiyama Kunio Yoneyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.16A-004, (Released:2020-10-13)
- 被引用文献数
- 4
We report experimental observations of precipitable water vapor (PWV) derived using Global Positioning System/Global Navigation Satellite System (GPS/GNSS) receivers mounted on autonomous surface vehicles (ASVs), which were deployed in the tropical Pacific Ocean from July to September 2018. The GPS atmospheric delay was estimated by precise point positioning and converted to PWV with ASV surface meteorological data. The GPS-PWV was in agreement with the PWV obtained from radiosondes, with a root mean square error of 3.02 mm and a mean difference of 0.16 mm. A similar accuracy was found in a comparison of GPS-PWV with satellite-based microwave measurements. In anticipation of real-time monitoring applications, PWV was also estimated using real-time clock and orbit data. These estimates were in agreement with the post-processing values. High-resolution temporal observations of PWV over the open ocean made possible by ASV technology could greatly improve our understanding of the rapid variations of developing convective systems.
- 著者
- Kenji Suzuki Katsuhiro Nakagawa Tetsuya Kawano Shuichi Mori Masaki Katsumata Fadli Syamsudin Kunio Yoneyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.14, pp.148-152, 2018 (Released:2018-10-17)
- 参考文献数
- 20
- 被引用文献数
- 3
Videosonde observations were conducted at the southwestern coastal region of Sumatra Island, Indonesia, as part of a pilot field campaign of the Years of the Maritime Continent project (Pre-YMC), to investigate the role of solid hydrometeor for precipitation processes in clouds. Videosondes were launched into three types of clouds: convective and stratiform clouds, and a thick upper stratiform cloud with shallow convection at lower level. A quantitative evaluation of the graupel shape data obtained from the videosondes showed different graupel formations in different rain systems. For the typical stratiform cloud, almost no graupel was observed. In contrasts, for the thick upper stratiform clouds with shallow convection, large numbers of ice crystals in the upper layer suggested to act as embryos and form a lot of graupel with the riming of the supercooled droplets that was supposed to be provided from the shallow convection. On the other hand, for the convection case, the videosonde observed spherical graupel just above the freezing level. This suggested that frozen drops acting as embryos formed spherical graupel, which were uplifted by the strong updraft in the convective cloud, and were different from the generally irregular-shaped graupel in the thick upper stratiform cloud.
- 著者
- Peiming Wu Dodi Ardiansyah Satoru Yokoi Shuichi Mori Fadli Syamsudin Kunio Yoneyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.13, pp.36-40, 2017 (Released:2017-03-24)
- 参考文献数
- 17
- 被引用文献数
- 9 16
This study examined the impact of an active phase of the Madden–Julian Oscillation (MJO) on a torrential rain event that occurred on the western coast of Sumatra Island on 12 December 2015, using surface meteorological observations, meteorological radar observations, and balloon sounding data obtained from the pre-Years of the Maritime Continent field campaign. Strong MJO activity took place in mid-December 2015 into January 2016. Radar observations revealed that a convergence and convective cloud merger of mesoscale convective systems from an eastward propagating MJO and westward moving diurnal convection over the western coast of the island was the immediate cause of the torrential rain. An investigation of the occurrence of convection over the island showed that both westward moving diurnal convection from the mountains and eastward propagating convection from the Indian Ocean occurred on 12 December, because the westerly winds in the lower troposphere associated with the MJO were only just initiated and were weak on the day. The results suggest that the leading edge of the MJO westerly wind bursts provided favorable conditions for an active phase of the MJO to work with the westward moving diurnal convection and cause torrential rain on the western coast of Sumatra Island.
- 著者
- Ayako Seiki Yukari N. Takayabu Kunio Yoneyama Naoki Sato Masanori Yoshizaki
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.5, pp.93-96, 2009 (Released:2009-06-10)
- 参考文献数
- 26
- 被引用文献数
- 13 14
Oceanic responses to relatively strong Madden-Julian Oscillations (MJOs) and background winds controlled by El Niño-Southern Oscillation (ENSO) are examined. The MJO’s arrival excites dominant downwelling and upwelling Kelvin waves during El Niño developing (pre-El Niño: PEN) and other (non-PEN) phases, respectively. These opposite signals come from background wind directions under different ENSO phases and exert opposite impacts on SST. In addition, MJO convection itself develops accompanied by larger surface wind variations during PEN phases, which can be related to the interactive amplifications of synoptic- and planetary-scale disturbances when westerly wind bursts occur. Consequently, the strength of westerly forcing and its oceanic response during PEN phases are larger than that of the corresponding easterly forcing and its response during non-PEN phases. These results suggest that modulations of MJO amplitude and structure under the background westerly and easterly winds associated with ENSO phases exert opposite but asymmetric impacts on the ocean.