17 November, 2008
Japan Meteorological Agency
Monthly Highlights on Climate System (October 2008)
Highlights in October 2008
- Monthly mean temperatures were above normal all over Japan.
- Monthly precipitation amounts were extremely heavy from southern China to northern Thailand.
- In the sea level pressure, negative and positive anomalies were observed in the high latitudes and
in the mid latitudes, respectively.
- Convective activities in the tropics were enhanced over the Indian Ocean, Indonesia and from the
eastern Pacific to the Caribbean Sea.
- Positive SST anomalies were found in the western equatorial Pacific, and negative SST anomalies
were found in the central equatorial Pacific.
Climate in Japan (Fig. 1):
Due to weak influence of cold air inflow from north,
monthly mean temperatures were above normal all over
Japan. Anticyclones tended to cover around Northern Japan,
the Sea of Japan side of Eastern and Western Japan, and
Okinawa/Amami. Thus, monthly precipitation amounts
were below normal in Northern Japan and on the Sea of
Japan side of Western Japan. Also, monthly sunshine
duration was above normal on the Sea of Japan side of
Eastern Japan and Okinawa/Amami. On the other hand, on
the Pacific side of Western Japan, monthly sunshine
duration was below normal due to influence of cyclones
and fronts.
World Climate (Figs. 2 and 3):
The anomaly of the monthly global average surface
temperature in October 2008 was +0.34°C (5th highest
since 1891) (Fig. 2). In a longer time scale, the global
average surface temperature has been rising at a rate of
about 0.60°C per 100 years.
- Monthly mean temperatures were extremely high from
Western Japan to eastern China (Fig.3).
- Monthly precipitation amounts were extremely heavy
from southern China to northern Thailand due to Tropical
Storm Higos and the frontal activity.
- It is reported by MOFA of Japan that torrential rains due
to a tropical depression brought 180 fatalities in Yemen.
Extratropics (Figs. 4 and 5):
In the sea level pressure field, negative and positive
anomalies were observed in the high latitudes and in the
mid-latitudes, respectively, and an annular anomaly pattern
was dominant (Fig. 4). In the zonal mean zonal wind field,
easterly wind anomalies and westerly anomalies were
observed in the lower latitudes and in the higher latitude,
respectively, due to the poleward shift of the subtropical jet
in the both hemispheres (Fig. 5). As for the jet streams in
the Northern Hemisphere, the polar front jet was clearer
than its normal from northern Canada to northern Europe.
In the lower troposphere, high temperature anomalies were
observed in northern Canada and from western Russia to
Siberia. High frequency disturbances were active in a
northward shifted position from the North Atlantic storm
track region to western Russia and the high frequency
disturbances were more active than normal from northern
Europe to western Russia. In late October, the propagations
of the remarkable Rossby wave packets were observed in
the mid-latitudes of the Northern Hemisphere. The
meanderings of the westerlies were therefore intensified
through this region. In the Southern Hemisphere, Sudden
Stratospheric Warming was observed.
Tropics (Figs. 6, 7 and 8):
Convective activities were enhanced over the Indian
Ocean and Indonesia (Fig. 6). From the eastern Pacific to
the Caribbean Sea, the convections were enhanced and the
tropical disturbances including hurricanes formed and
developed. The convective activities were suppressed near
the Philippines and from the equatorial western to central
Pacific. The South Pacific Convergence Zone shifted
westward from its normal position. In the lower
troposphere, the equatorial Rossby wave was formed and
propagated westward associated with the active
convections over the Indian Ocean (Fig. 8). Over the
Pacific, the subtropical highs were stronger than normal in
the both hemispheres. The easterly wind anomalies were
clearly observed over the equatorial western Pacific. The
active phase of the Madden-Julian Oscillation (MJO)
slowly propagated eastward and reached the Indian Ocean
in the first half of October (Fig. 7). The eastward
propagation then became clear, and the active phase of
MJO propagated from the Indian Ocean to Indonesia and
the western Pacific.
Oceanographic Conditions (Figs. 9 and 10):
Positive SST anomalies were found in the western
equatorial Pacific. The monthly mean SST anomaly was
-0.1°C in the NINO.3 region (-0.2°C deviated from the
latest sliding 30-year mean SST for the same region
(Fig.10)).
In the North Pacific, negative SST anomalies were found
from around 10°N, 160°E to the vicinity of the west coast
of North America. Positive SST anomalies were found to
the south of Japan and the south of Aleutian. In the South
Pacific, positive SST anomalies were found from 20°S,
170°W to 40°S, 135°W.
In the Atlantic, positive SST anomalies were found in
the tropical region and from 30°N, 30°W to the Labrador
Sea.
In the Indian Ocean, positive SST anomalies were found
from the central tropical region to the Bay of Bengal.
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17 November, 2008
Japan Meteorological Agency
Fig. 1 Monthly climate anomaly / ratio over Japan
(October 2008)
Fig. 2 Long-term changes in monthly
mean surface temperature anomaly
in October over the globe
Bars indicate anomalies of surface
temperature for each year. Blue line
indicates 5-year running means, and red
line indicates a long-term linear trend.
Anomalies are defined as the deviations
from the normal (1971-2000 average).
Fig. 3 Distribution of extreme climate events (October 2008)
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17 November, 2008
Japan Meteorological Agency
Fig. 5 Monthly mean zonal wind speed and its
anomaly in the zonal mean field (October 2008)
Black lines show zonal wind speeds at an interval
of 5 m/s. Shaded patterns show zonal wind speed
anomalies. Base period for the normal is
1979-2004.
Fig. 4 Monthly mean sea level pressure and its
anomaly in the Northern Hemisphere
(October 2008)
Contours show heights at an interval of 4 hPa.
Shaded patterns show pressure anomalies. Base
period for the normal is 1979-2004.
Fig. 6 Monthly mean Outgoing Longwave Radiation (OLR) anomaly (October 2008)
Contour interval is 10 W/m2. Base period for the normal is 1979-2004. Original data are provided by courtesy
of CDC/NOAA.
Fig. 7 Time-Longitude cross section (5°N-5°S) of 5-day mean 200 hPa velocity potential anomaly (left) and 850
hPa zonal wind anomaly (right) (May – October 2008)
Contour interval is 2x106 m2/s (left) and 2 m/s (right). Base period for the normal is 1979-2004.
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17 November, 2008
Japan Meteorological Agency
Fig. 8 Monthly mean 850 hPa stream function and anomaly (October 2008)
Contour interval is 2.5x106m2/s. Base period for the normal is 1979-2004.
Fig. 9 Monthly mean sea surface temperature anomaly (October 2008)
Contour interval is 0.5°C. Base period for the normal is 1971-2000. Maximum coverage with sea ice is shaded
in gray.
Fig. 10 Time series of monthly mean SST departure (°C) from the reference value defined as the
immediate past 30-year mean SST, averaged over the NINO.3 region (upper). Time series of the
Southern Oscillation Index with respect to the 1971-2000 base period (lower).
Thin blue lines represent monthly means, and thick blue lines 5-month running means. Periods of El Niño
and La Niña events are shown as red-colored and blue-colored boxes, respectively.
Detailed information on the climate system is available on the Tokyo Climate Center’s website
(http://ds.data.jma.go.jp/tcc/tcc/index.html)
This report is prepared by the Climate Prediction Division, Global Environment and Marine Department,
Japan Meteorological Agency.
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