Dec.
2003---Feb. 2004
During
this winter, mean surface air temperatures were above average in much of China.
Positive anomalies above 2¡æ were observed in parts of Northwest China and
North China. In this season, rainfall totals were
30% ~100% more than normal in northern and eastern Northeast¡¡China,
the eastern bend of the Yellow River, eastern Northwest China, northwestern
Xinjiang, the upper and middle reaches of the Yangtze River and parts of the
Tibet Plateau. Meanwhile, precipitation totals were 30~90% less than normal in
most of the Tibet Plateau, southern Xinjiang, the western bend of the Yellow
River, parts of Northeast China and eastern South China. There was no
precipitation in parts of above regions in this winter.
During
this winter, mean surface air temperatures in Eurasia were above average except
northeastern Russia and parts of southern Europe. Temperature anomalies in
western and east-central Russia were more than 4¡æ. Temperatures were about 1~4
¡æ above normal in much of Canada, while temperatures were near or 1¡æ below
normal in the rest region of North America. Temperatures were generally 1¡æ
above normal in South America except that temperatures in the southeastern part
were below normal. In Australia, temperatures in the northwest part were 1¡æ
below normal while in other regions were 1~2¡æ
above normal.
In
this winter, rainfall totals were 30% ~100% more than normal in central Europe,
the eastern coast of the Mediterranean Sea, northeastern India, most of the
Indochina Peninsula and middle Asia, the coast regions in northern and middle
Russia and southeastern Russia, western and northern Australia, mid-western
Africa and most of South America, with 400% more than normal in parts of above
regions. Meanwhile, precipitation totals were 30~90% less than normal in parts
of western and southern Asia, Mongolia, Northwest Africa and northwestern North
America.
Northern
Hemisphere: During
this winter, the mean 500hPa geopotential height field exhibited a 3-wave
pattern at the mid-high latitudes. A wide trough was located in the regions from East Asia to the
middle North Pacific. In the anomaly field, positive anomalies dominated the
Polar regions, the North Atlantic Ocean, West Asia and the eastern Pacific at
low latitudes, with center values above 12 dam over the North Atlantic Ocean.
The Northwest Pacific subtropical high was stronger than normal in this winter.
Southern Hemisphere: In the mean 500hPa geopotential height field during this winter£¬zonal circulation dominated the mid-high latitudes. In the height anomaly field, 4 dam below-normal heights were observed over parts of the South Pacific, while 4 dam above-normal heights were observed over the South Pole and the nearby regions and the west of the South Atlantic Ocean.
Mar.
2004---May 2004
During
this spring, mean surface air temperatures were 1¡æ above average in much of
China. Positive anomalies above 2¡æ were observed in central Northwest China
and western Tibet Plateau. In this season, rainfall totals were 30% ~100% more
than normal in most of Southwest China, southern Northwest China, western and
northern Xinjiang, northern and eastern Northeast China and parts of North
China. Meanwhile, precipitation totals were 30~90% less than normal in the
regions from the western Tibet Plateau to eastern Xinjiang, western Inner
Mongolia, most of the bend of the Yellow River, middle and southern Northeast
China.
During
this spring, mean surface air temperatures were obviously below average at
mid-high latitudes of the Northern Hemisphere, such as much of northern Russia
and middle and eastern Canada, with negative anomalies below -4¡æ
in parts of above regions. At most of the middle latitudes of the Northern
Hemisphere, temperatures were generally 1~2¡æ¡¡above
normal. In northern South America, temperatures were 1¡æ above normal.
Temperatures were generally 1~2¡æ above normal in Australia except the
southwestern part. Temperatures were 1¡æ above normal in parts of West and
South Africa.
In
the spring, rainfall totals were 30% ~100% more than normal in middle and
eastern Europe, parts of Middle Asia, southeastern Russia, most of Southwest
China, southern and eastern North America, most of South America and central
Australia, with totals of 200% more than normal in parts of above regions.
Precipitation
totals were 30~90% less than normal in most of West Asia, West Africa and
eastern Australia, with no rainfall in parts of above regions during this
season.
Northern Hemisphere: During
the spring, the mean 500hPa geopotential height field exhibited that the trough
over Northern America was stronger than normal. Correspondingly, below -4
dam negative anomalies covered middle and northern Canada. Meanwhile, positive
departures above 4 dam controlled most of the North Pole and the nearby regions,
regions from the Northeast Pacific to the western North Atlantic Ocean with
center values above 8 dam. In this season, the Northwest Pacific subtropical
high was stronger than normal.
Southern
Hemisphere: In
the mean 500hPa geopotential height field during this spring£¬zonal
circulation dominated mid-high latitudes. In the height anomaly field, 4 dam
below-normal heights were observed over the southeastern Pacific, and the ocean
south to Africa, while 4 dam above-normal heights were observed over the South
Pole and the nearby regions.
Jun.
2004---Aug. 2004
During
this summer, mean surface air temperatures were near normal in most of China
except that anomalies about 1¡æ observed in northwestern Northeast China and
eastern Xinjiang. In this season, rainfall totals were 30% ~90% less than normal
in northern Northeast China, eastern and middle Xinjiang. Meanwhile,
precipitation totals were 30~60% more than normal in the mid-western Tibet
Plateau, the lower reaches of the Yellow River and middle reaches of the Yangtze
River.
During
this summer, mean surface air temperatures anomalies were above 1¡æin northern
and southwestern Europe, the regions from Mongolia to northwestern Northeast
China, middle Northwest China, Far East in Russia, western North America,
southern South America and parts of Western Africa with maximum above 3¡æ in
Alaska. In mid-northern Russia and middle-eastern North America, temperatures
were generally 1~2¡æ below normal.
In
the summer, rainfall totals were 30% more than normal in western and southern
Europe£¬
middle northern Russia and parts of Far East, most
of Kazakstan, western Africa, southern United States and southwestern Canada,
parts of South America with maximum above 200% in parts of above regions.
Precipitation totals
were 30% more than normal in most of West Asia, southwestern Europe and southern
Russia, northwestern and southwestern North America, eastern South America and
most of Australia. Even no rainfall was observed in parts of above regions
during this season.
Northern Hemisphere: During
the summer, the mean 500hPa geopotential height field was near normal except
that above 4 dam anomalies controlled Bering Sea and nearby regions. In this
season, subtropical high both in the northern hemisphere and in Northwest
Pacific were stronger and larger than normal.
Southern
Hemisphere: the
mean 500hPa geopotential height field exhibited a 4-wave pattern at mid-high
latitudes.
In the height anomaly field, 4 dam below-normal heights were observed over the
ocean south to Australia, while 4 dam above-normal heights were observed over
the southwestern South Atlantic, the eastern South Pacific and parts of
Antarctica coast.
¡¡