Effects of Large-scale Moisture Transport and Mesoscale Processes on Precipitation Isotope Ratios Observed at Sumatera, Indonesia

• FUDEYASU Hironori

  Yokohama National University

• ICHIYANAGI Kimpei

  Kumamoto University

• YOSHIMURA Kei

  University of Tokyo

• MORI Shuichi

  Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

• HAMADA Jun-Ichi

  Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

• SAKURAI Namiko

  National Research Institute for Earth Science and Disaster Prevention (NIED)

• D. YAMANAKA Manabu

  Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

• MATSUMOTO Jun

  Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Tokyo Metropolitan University

• SYAMSUDIN Fadli

  Agency for the Assessment and Application of Technology (BPPT)

Abstract

Isotopic and meteorological observations in November 2006 on the west coast of Sumatera, Indonesia during the intense observation period of the Hydrometeorological ARray for Intraseasonal Variation-Monsoon AUto-monitoring (HARIMAU2006), revealed the impacts of large-scale moisture transport and mesoscale processes on precipitation isotope ratios. Intraseasonal changes in the precipitation δ²H in November had large variability ranging from +10 to -65 per mil, as a result of the changes in the large-scale moisture transport associated with the intraseasonal oscillation with a time-scale of 10-15 day over Sumatera. The isotopic composition of precipitation was independent from difference in precipitation type (convective or stratiform precipitation). An isotope circulation model reproduced the observed isotopic changes, supporting that the isotopic effect of large-scale moisture transport was the main contributor to intraseasonal isotopic changes.<br>In high-frequency samples taken over a shorter time scale, isotopic variability was related to event type classified by the analysis of radar observations, although the isotopic effects of mesoscale processes on the isotopic averages of each precipitation event were almost masked by the isotopic effect of large-scale moisture transport. The precipitation δ²H accompanying the well-organized convection type decreased significantly by about 20 per mil. Drastic changes in isotope ratios could be described by the Rayleigh distillation process. Isotope ratios of precipitation gently decreased and subsequently increased in the unorganized convection type since the water vapor in surrounding convectively rising air isotopically enriched the remaining low-isotope water vapor advected from the precedent clouds. Isotope ratios in the stratiform precipitation remained steady, possibly attributable to the homogeneous moisture of stratiform clouds.

Journal

• Journal of the Meteorological Society of Japan. Ser. II

  Journal of the Meteorological Society of Japan. Ser. II 89A 49-59, 2011

  Meteorological Society of Japan

Keywords

• Atmospheric Science

Details

• CRID: 1390282681482079104
• NII Article ID: 130004788764
• NII Book ID: AA00702524
• DOI: 10.2151/jmsj.2011-a03
• ISSN: 21869057
• ISSN: 00261165
• NDL BIB ID: 11028709
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I11028709
• Web Site: http://www.jstage.jst.go.jp/article/jmsj/89A/0/89A_0_49/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed