Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Frontier Observational Research System for Global Change
) Volume transport of the Ryukyu Current System
southeast of Miyakojima Island was Sv northeastward
in December.
Hydrological Cycle Observational Research Program
The purpose of the Hydrological Cycle Observational
Research Program is to elucidate physical processes
involved in interannual variations in Asian monsoons
which have a major impact on Japan's climatic variability,
and long-term variations in monsoon and water
resources associated with global warming, focusing on
the Asian monsoon region and the Eurasian Continent,
as well as contributing to the development of an integrated
model and observation system for them.
(I) Large-scale Hydrological Cycle and Processes Group
In FY, the Large-scale Hydrological Cycle and
Processes Group continued observations in Indonesia,
Thailand, Tibet and Siberia, with the aim of elucidating
the large-scale energy and water cycles in Monsoon
Asia. The results, obtained since the establishment of
this group in , have been published in international
journals and presented at international meetings, and
some have won prizes from societies. An overview of
our activities and achievements is as follows:
(a) Diurnal, intraseasonal, seasonal and interannual
variability of precipitating cloud systems and
energy/water cycles over the Indonesian maritime
continent
At Kototabang, in West Sumatra, Indonesia, the
major base of observations, continuous measurements
of precipitation characteristics, sensible and latent heat
fluxes, lower-atmospheric winds, rainfall amounts in
the surrounding area and so on have been carried out
automatically. Rawinsondes (meteorological balloons)
were launched intensively ( or times per day) for
weeks in total in this fiscal year. In addition, standard
meteorological observations have been started also at
Padang in the west coast and at Siberut Island off the
coastline, and preliminary site surveys for future
Fig. 11 Maintenance and data recovery from rain gauges in the
West Sumatra (at 12 locations in total).
extension of observations were conducted at Biak,
Papua Province.
Based on the analyses of the data obtained so far,
papers concerning the suppression of diurnal cycle of
precipitating cloud in the westerly phase of intraseasonal
variations and the geographical and interannual
variations of the rainy season over Indonesia and their
link to El Niño-Southern Oscillation (ENSO) have
been published. A gigantic diurnal cycle of cloud formation
and movement has been discovered from the
data of intensive observational periods. Seasonal variations
of the Hadley circulation, tropopause level and
temperature and their relationship with ENSO have
also been analyzed in detail.
(b) Diurnal variations of water and heat transport
processes in Indonesia, Thailand and Tibet
Based on continuous automatic observations of precipitable
water by GPS (Global Positioning System) at
Kototabang (mountainous area near the western coast)
and Jambi (plain near the eastern coast) in Sumatra,
Indonesia since FY, a striking diurnal variation of
water vapor associated with a local circulation has
been analyzed in particular at Kototabang. The paper
about this study was accepted for publication in an
international journal. GPS observations have also been
started at Padang, Siberut Island and Pontianak (west
Kalimantan) from this fiscal year () in order to
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