Marine Ecosystems Research Department - jamstec japan agency ...

Japan Marine Science and Technology Center
Frontier Research System for Global Change
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Fig. 4 a) Trends of potential evaporation during 1971-2000. b) Trends of observed pan evaporation during 1971-2000.
Changes in storm track activity were identified to
examine how these changes affect the seasonal mean
flow over northern Eurasia associated with an interannual
seesaw in summer precipitation between east and west
Siberia (ES and WS). In the two extreme phases of this
oscillation, an east-west dipole pattern of precipitation
anomalies prevails over much of Siberia. We focused on
the years from – when such spatial–temporal
characteristics of the oscillation are clear and consistent,
as noted by Fukutomi et al. (). The two precipitation
regimes that are manifest as out-of-phase dipole
patterns are represented as the ES-wet--WS-dry regime
and the WS-wet--ES-dry regime. We documented largescale
atmospheric patterns and storm track activities
associated with these contrasting regimes using linear
regression and compositing, and highlighted the synoptic-scale
eddy forcing on the mean circulations.
The climatic distribution and its long-term variability
of the low-level cloud observed by the surface
observer over the Eurasian continent were investigated.
The frequency of appearance of low-level clouds
over China and Mongolia obviously decreased during
the last two decades. While the suppressing of cumuliform
clouds was evident over the whole of China,
stratiform clouds increased in the southern China during
the summer season (Fig. ). However these longterm
trends of low-level cloud have small correlation
to the precipitation trends over China.
Decadal-scale SST variations in the mid-latitude
North Pacific were examined to diagnose the relative
importance between surface and subsurface forcing on
FRQ
FRQ
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The Lower Reaches of Yangtze River Valley
The Coastal Region of South China Sea
Cu
Clear
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Fig. 5 Time series data showing the frequency of appearance of
lower-level clouds in the lower reach of Yangtze River valley
(top) and the coastal region of South China Sea (bottom)
from 1971 to 1996. The linear trends which are significant
at the 95% level are also shown (dashed lines).
the variations. For quantitative discussion, a diagnostic
equation based on the annual integration considering
the large seasonal change of ocean mixed layer
was proposed. It was found that ocean dynamics
played an important role for the low-frequency SST
variation in the Kuroshio-Oyashio extension where the
ocean mixed layer is deep.
b. The Hydrological Process on Land Group
Sensitivity of frozen soil permeability and surface
water storage was investigated using a one-dimensional
land surface model that can be implemented in a climate
model. The atmospheric conditions were
assumed to be those in frozen ground regions of
Russia. The results shows that evaporation is quite
sensitive in these processes. The annual evaporation is
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