- 著者
- Biao Geng
- 出版者
- 公益社団法人 日本気象学会
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.2023-017, (Released:2023-05-24)
This study investigated the internal precipitation and kinematic structure of the South Pacific convergence zone (SPCZ) observed by the Doppler radar aboard the research vessel Mirai, which passed through the western tropical portion of the SPCZ on December 17-21, 2016. Convective precipitation developed in association with the low-level convergence induced by the monsoon and the upper-level divergence associated with extratropical Rossby wave breaking. Mesoscale convective systems (MCSs) developed from either intersecting (northeast–southwest/northwest–southeast) or zonally oriented convective bands. For the MCS developing from the former mode, the zonal and meridional divergence fields made comparable contributions to convective development. For the MCS developing from the latter mode, the divergence field induced by the meridional wind had the largest contribution to producing convection. The MCS with stronger convective updrafts and higher echo tops and coverage occurred in the region where more intense convergence was observed near the surface. The results of this study highlight the dependence of organizational modes of SPCZ convection on the coupling of the tropical low-level and extratropical upper-level forcings, as well as on the zonal and meridional forcing structures.
- 著者
- Biao Geng Ryuichi Shirooka
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.17, pp.81-87, 2021 (Released:2021-05-07)
- 参考文献数
- 34
The internal structure and evolution of a monsoon trough (MT) and associated mesoscale convective systems (MCSs) in the western North Pacific were investigated, based mainly on radiosonde and a Doppler radar observations in Palau. The MT was observed on 15-16 June 2013, with the pre-existing disturbance of Typhoon Leepi (2013) being embedded in it. The large-scale circulation around the MT featured a pattern representing an active MT. Deep convection developed ahead and at the leading edge of the downward-sloping monsoonal flow, where intense low-level convergence was observed. Stratiform precipitation broadened rearward over the MT axis. A deep and wide layer of warm and moist air over the MT axis was undercut by a layer of cold air sloping downward from the trailing stratiform region to the leading convective region. An intense low-pressure zone formed in the interface between the warm layer above and cold layer below, with the westerly monsoonal and easterly trade flows being enhanced on its west and east sides, respectively, from the low to middle troposphere. The results suggest that a strengthening of the large-scale cyclonic circulation in response to the internal processes of the MCSs triggered by the MT is important for typhoon genesis.
- 著者
- Biao Geng Ryuichi Shirooka
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.2021-013, (Released:2021-03-18)
The internal structure and evolution of a monsoon trough (MT) and associated mesoscale convective systems (MCSs) in the western North Pacific were investigated, based mainly on radiosonde and a Doppler radar observations in Palau. The MT was observed on June 15-16, 2013, with the pre-existing disturbance of Typhoon Leepi (2013) being embedded in it. The large-scale circulation around the MT featured a pattern representing an active MT. Deep convection developed ahead and at the leading edge of the downward-sloping monsoonal flow, where intense low-level convergence was observed. Stratiform precipitation broadened rearward over the MT axis. A deep and wide layer of warm and moist air over the MT axis was undercut by a layer of cold air sloping downward from the trailing stratiform region to the leading convective region. An intense low-pressure zone formed in the interface between the warm layer above and cold layer below, with the westerly monsoonal and easterly trade flows being enhanced on its west and east sides, respectively, from the low to middle troposphere. The results suggest that a strengthening of the large-scale cyclonic circulation in response to the internal processes of the MCSs triggered by the MT is important for typhoon genesis.