Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Ocean Observation and Research Department
During the period of September-October , we
conducted the KY- cruise using R/V Kaiyo. The
objective of this cruise was the investigation of oceanic
conditions and maintenance of ADCP and TRITON
buoys. Hydrographic research in the western tropical
Pacific showed that a mixed layer shallower than in
normal years and high salinity in the uppermost layer.
During normal years, there is a deep mixed layer
caused by strong trade winds and low salinity caused
by active convection in the region. This shift of oceanic
condition is a result of El Niño and we succeeded in
capturing the typical feature of El Niño. It is necessary
to advance investigation about the process of this feature
using TRITON data.
In order to further understand the air-sea interaction
in the warm pool region, stationary observation using
the R/V Mirai at N, .E was carried out from
November through December . The main
objective of the cruise was to study the precipitation
mechanism of convective clouds, which plays a key
role as a heat engine of the entire globe. According
to the cloud images from the Geostationary
Meteorological Satellite (GMS) of the Japan
Meteorological Agency, super cloud clusters accompanied
by the equatorial intraseasonal oscillation,
known as Madden-Julian oscillation (MJO), passed
over the observational area in the earlier period.
However, precipitation systems were not frequently
(mm)
70
60
50
40
30
320 325 330 335 340 345 350 355
Fig. 1 Time series observation of the precipitable water vapor
obtained from radiosonde sounding data. DAY326 corresponds
to 22 November 2002. Dashed lines indicate the
stationary observation period.
observed from shipboard systems such as the Doppler
radar. Figure shows the time series observation of
precipitable water vapor. After the passage of the MJO
convective region (after DAY), it decreases with
time. One interesting feature is that sudden drops in
moisture were seen at DAY- and DAY-
. By analysis of other data sets including
NCEP/NCAR reanalysis, it was shown that dry air
intruded into the observational area from the higher
latitudes. Since we conduct similar cruises at the same
location in different years, we will study these to
extract atmospheric features from the viewpoint of the
different ENSO phases.
() Development and maintenance of the TRITON
buoy network
JAMSTEC has developed and been maintaining
the TRITON surface moored-buoy network for
observing oceanic and atmospheric variability in the
western tropical Pacific and eastern Indian Oceans in
cooperation with interested Japanese and foreign
agencies and institutions. The principal scientific
objective is to understand variations of ocean circulation
and heat/salt transports with emphasis on ENSO,
the Asian monsoon, and decadal scale variability that
influences climate change in the Pacific and its adjacent
seas. In its first phase, the buoy network was
established mainly in the western tropical Pacific
Ocean, and harmonized with TAO-ATLAS array,
which is maintained by NOAA's Pacific Marine
Environmental Laboratory.
The fundamental functions of TRITON are ()
basin scale ENSO monitoring, and () measurements
of heat, freshwater, and momentum fluxes for
improving modeling capability. The scientific goals
of the TRITON project address the observational
requirements of the international research program
Climate Variability and Predictability (CLIVAR),
a major component of the World Climate Research
Program sponsored by the World Meteorological
Organization, the International Council of Scientific
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