- 著者
- Sato Tomonori Tsujimura Maki Yamanaka Tsutomu Iwasaki Hiroyuki Sugimoto Atsuko Sugita Michiaki Kimura Fujio Davaa Gombo Oyunbaatar Dambaravjaa
- 出版者
- American Geophysical Union
- 雑誌
- Journal of geophysical research: Atmospheres (ISSN:2169897X)
- 巻号頁・発行日
- vol.112, no.D17, pp.D17112, 2007-09
- 被引用文献数
- 47
Origin of water vapor, which falls as precipitation over arid/semiarid area in northeast Asia, is investigated by modeling and observational approaches. The regional climate model evaluates the spatiotemporal variations of precipitation and water vapor budget, which are used to drive the single-layer isotope circulation model. Intraseasonal variations of δ 18O in precipitation are well simulated during June-July-August of 2003. The δ 18O in water vapor experiences rapid decreases according to the passage of synoptic-scale disturbances. The rapid decreases of δ 18O are attributed to two processes. (1) The δ 18O in air mass locally decreases over the western mountains associated with the mountain precipitation; the light vapor is advected to eastern Mongolia by the prevailing westerly wind. (2) Convective systems pass by in the vicinity of the observation site, which persistently keep the lower δ 18O in the air mass. Origin of the water vapor during June-July-August in 2003 is evaluated by the colored moisture analysis in which the tracers are assigned depending on the region where the water vapor finally evaporated. Seasonal mean result indicates that the regions contributing to precipitation in Mongolia are not low-latitude regions but central Asia and western Siberia located to the northwest of Mongolia. Observed multilevel isotopic composition supports the model estimation. The moisture transport along the southwesterly wind of the Asian summer monsoon has difficulty reaching Mongolia as a monthly/seasonal mean perspective. However, eastern Mongolia and northeast China are situated on the border area between westerly wind moisture transport (by midlatitude synoptic cyclones) and southerly wind moisture transport (by Asian summer monsoon).
- 著者
- Kawase Hiroaki Yoshikane Takao Hara Masayuki Kimura Fujio Yasunari Tetsuzo Ailikun Borjiginte Ueda Hiroaki Inoue Tomoshige
- 出版者
- American Geophysical Union
- 雑誌
- Journal of geophysical research: Atmospheres (ISSN:2169897X)
- 巻号頁・発行日
- vol.114, pp.D24110, 2009-12
- 被引用文献数
- 130 24
Changes in the Baiu rainband owing to global warming are assessed by the pseudo global warming downscaling method (PGW-DS). The PGW-DS is similar to the conventional dynamical downscaling method using a regional climate model (RCM), but the boundary conditions of the RCM are obtained by adding the difference between the future and present climates simulated by coupled general circulation models (CGCMs) into the 6-hourly reanalysis data in a control period. We conducted the multiple PGW-DS runs using the selected Coupled Model Intercomparison Project Phase 3 (CMIP3) multimodel data set, giving better performance around East Asia in June, and the PGW-DS run using the multiselected CGCM model ensemble mean (PGW-MME run). The PGW-MME and PGW-DS runs show an increase in precipitation over the Baiu rainband and the southward shift of the Baiu rainband. The PGW-MME run has good similarity to the average of all PGW-DS runs. This fact indicates that an average of the multiple PGW-DS runs can be replaced by a single PGW-DS run using the multiselected CGCM ensemble mean, reducing the significant computational expense. In comparison with the GCM projections, the PGW-DS runs reduce the intermodel variability in the Baiu rainband caused by the CGCMs themselves.