Seasonal Highlights on the Climate System (December 2020 - February 2021)
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
15 March 2021 Japan Meteorological Agency
Seasonal Highlights on the Climate System (December 2020 – February 2021)
Highlights (December 2020 – February 2021)
- La Niña conditions have persisted in the equatorial Pacific since boreal summer 2020 (see El Niño Outlook
updated on 10 March 2021).
- Seasonal mean temperatures were significantly above normal in eastern Japan. Seasonal precipitation
amounts were significantly above normal on the Sea of Japan side of eastern Japan. Seasonal sunshine
durations were significantly above normal in western Japan.
- Seasonal mean temperatures were extremely high in eastern China, in the southwestern part of South Asia,
from the northwestern Middle East to southeastern Europe, in the northern part of Northern Africa, from
the western to southern part of Western Africa, in and around Madagascar, in southeastern Canada, from
the Hawaiian Islands to Minamitorishima, and in western Australia.
- Seasonal precipitation amounts were extremely high in and around the southern part of Central Siberia,
from western to southwestern India, and from western Europe to the northwestern Middle East. Seasonal
precipitation amounts were extremely low in and around the southern part of Central Asia, in and around
northern Algeria, and in southeastern Brazil.
- In the equatorial Pacific, remarkably positive SST anomalies were observed west of 150˚E, and remarkably
negative SST anomalies were observed from east of 160˚E to the central part.
- Convective activity was enhanced from the northern Indian Ocean to the Maritime Continent, and
suppressed around the date line in the equatorial Pacific.
- In the 500-hPa height field, the polar vortex in the Northern Hemisphere split into the Siberian part and the
North American part. Positive anomalies were seen over northeastern North America, and negative
anomalies were seen over northwestern Europe and over Central and Eastern Siberia.
- The westerly jet streams shifted northward from its normal position from East Asia to the North Pacific.
Climate in Japan (Fig. S1):
- The winter monsoon was stronger than normal in the first half of winter and weaker than normal in the
second half of winter. These conditions brought a large variation in temperatures all over Japan.
- Seasonal temperatures were significantly above normal in eastern Japan.
- Seasonal precipitation amounts were significantly above normal on the Sea of Japan side of eastern Japan
due to cold air inflow and frequent passage of low pressure systems.
- Seasonal sunshine durations were significantly above normal in western Japan due to frequent passage of
high pressure systems in the second half of winter.
World Climate (Fig. S2):
- Seasonal mean temperatures were extremely high in eastern China, in the southwestern part of South Asia,
from the northwestern Middle East to southeastern Europe, in the northern part of Northern Africa, from
the western to southern part of Western Africa, in and around Madagascar, in southeastern Canada, from the
Hawaiian Islands to Minamitorishima, and in western Australia.
- Seasonal precipitation amounts were extremely high in and around the southern part of Central Siberia,
from western to southwestern India, and from western Europe to the northwestern Middle East.
- Seasonal precipitation amounts were extremely low in and around the southern part of Central Asia, in and
around northern Algeria, and in southeastern Brazil.
Oceanographic Conditions (Fig. S3):
115 March 2021 Japan Meteorological Agency
- In the equatorial Pacific, remarkably positive SST anomalies were observed west of 150˚E, and remarkably
negative SST anomalies were observed from east of 160˚E to the central part.
- In the North Pacific, remarkably positive SST anomalies were observed from south of Japan to the western
coast of North America and in the western tropical region.
- In the South Pacific, remarkably positive SST anomalies were observed in the western tropical region and
around the area near 30°S, 150°W, and remarkably negative SST anomalies were observed in the eastern
tropical region.
- In the Indian Ocean, remarkably positive SST anomalies were observed from the central to eastern part of
the northern tropical Indian Ocean, and from the area near Madagascar to northwest of Australia.
- In the North Atlantic, remarkably positive SST anomalies were observed from the eastern coast of North
America to the area near 30°N, 40°W and from the Caribbean Sea to the eastern tropical region.
Tropics:
- Convective activity was enhanced from the northern Indian Ocean to the Maritime Continent, and
suppressed around the date line in the equatorial Pacific (Fig. S4).
- In the upper troposphere, anti-cyclonic circulation anomalies straddling the equator were seen from the
tropical Indian Ocean to the western tropical Pacific, and cyclonic circulation anomalies straddling the
equator were seen over the central to eastern tropical Pacific (Fig. S5).
- In the lower troposphere, cyclonic circulation anomalies straddling the equator were seen from the tropical
Indian Ocean to the Maritime Continent, and anti-cyclonic circulation anomalies straddling the equator
were seen over the western to central tropical Pacific.
- In the sea level pressure field, in the equatorial area, positive anomalies were seen from the central Pacific
to South America, and negative anomalies were seen from the Indian Ocean to the western Pacific and over
the Atlantic.
Extratropics:
- In the 500-hPa height field (Fig. S6), the polar vortex in the Northern Hemisphere split into the Siberian
part and the North American part, with positive anomalies over the northern polar region and negative
anomalies over Central and Eastern Siberia. A wave train was seen from North America to northern Eurasia,
with positive anomalies over northeastern North America and negative anomalies over northwestern
Europe.
- The westerly jet stream shifted northward from its normal position from East Asia to the North Pacific (Fig. S7).
- In the sea level pressure field (Fig. S8), positive anomalies were seen from the northern polar region to
northwestern Russia, and negative anomalies were seen over northwestern Europe. The southeastward
expansion of the Siberian High was weaker than normal, and the Aleutian Low shifted northwestward from
its normal position.
- Temperatures at 850-hPa were above normal from the northern polar region to northeastern North America
and over southeastern Europe, and below normal over Siberia (Fig. S9).
215 March 2021 Japan Meteorological Agency
Fig. S1 Seasonal climate
anomaly/ratio over Japan
(December 2020 – February 2021)
Top: temperature anomalies (degree C)
Middle: precipitation ratio (%)
Bottom: sunshine duration ratio (%)
The base period for the normal is
1981-2010.
Fig. S2 Three-month mean temperature anomaly (normalized) category ( December 2020 –February
2021)
315 March 2021 Japan Meteorological Agency
Fig. S3 Three-month mean sea surface temperature anomaly (December 2020 – February 2021)
The contour interval is 0.5 degree C. The base period for the normal is 1981 -2010. Maximum coverage with sea ice
is shaded in gray.
Fig. S4 Three-month mean Outgoing Longwave Radiation (OLR) anomaly (December 2020 – February
2021)
The contour interval is 10 W/m 2 . The base period for the normal is 1981 -2010. Original data provided by NOAA.
Fig. S5 Three-month mean 200-hPa stream function and anomaly (December 20201 – February 2021)
The contour interval is 10x10 6 m 2 /s. The base period for the normal is 1981 -2010.
415 March 2021 Japan Meteorological Agency
Fig. S6 Three-month mean 500-hPa height and Fig. S7 Three-month mean 200-hPa wind speed
anomaly in the Northern Hemisphere and vectors in the Northern Hemisphere
(December 2020 – February 2021) (December 2020 – February 2021)
The contours show 500-hPa height at intervals of 60 m. The black lines show wind speed at intervals of 20 m/s.
The shading indicates its anomalies. The base period The brown lines show its normal at intervals of 40 m/s.
for the normal is 1981-2010. The base period for the normal is 1981 -2010.
Fig. S8 Three-month mean sea level pressure and Fig. S9 Three-month mean 850-hPa temperature
anomaly in the Northern Hemisphere and anomaly in the Northern Hemisphere
(December 2020 – February 2021) (December 2020 –February 2021)
The contours show sea level pressure at intervals of 4 The contours show 850-hPa temperature at intervals of
hPa. The shading indicates its anomalies. The base 4 degree C. The shading indicates its anomalies. The
period for the normal is 1981-2010. base period for the normal is 1981-2010.
Detailed information on the climate system is available on the Tokyo Climate Center's website.
https://ds.data.jma.go.jp/tcc/tcc/index.html
This report is prepared by the Tokyo Climate Center, Climate Prediction Division, Atmosphere and Ocean Department,
Japan Meteorological Agency.
5You can also read
