Northern Hemisphere: During
the autumn, the mean 500hPa geopotential height field exhibited
a 3-wave pattern at mid-high latitudes. In
the height anomaly field, 4 dam above-normal heights were observed over regions
from eastern China to the northeastern Pacific via Japan, regions between
northeastern America and the North Atlantic, with maximum above 8 dam. Weak
negative anomalies dominated region from Far East of Russia to Alaska and
northwestern Canada. In this season, the Northwest Pacific subtropical high was
stronger and larger than normal and obviously extended more westward than
normal.
Southern
Hemisphere: The
mean 500hPa geopotential height field exhibited a 3-wave pattern at mid-high
latitudes.
In the height anomaly field, 4 dam above-normal heights were observed over the
Polar region while near-normal heights were observed in other regions.
During
this autumn, mean surface air temperatures were near or above normal in most of
China. Above 1¡æ were anomalies observed in Northeast China, northern North
China, southern Xinjiang and western Qinghai, with central values above 2¡æ in
the northern and middle Northeast China. In this season, rainfall totals were
less than normal in most of China except that about 30% more than normal in the
southern Northeast, eastern Sichuan and middle Qinghai. Precipitation totals
were 30% ~90% less than normal in most of South China, Middle and Lower reaches
of the Yangtze River, regions between the Yangtze River and the Huaihe River,
most of Xinjiang, western Tibet, eastern Northeast China and parts of North
China, with no rain in parts of above regions during the season.
During
this autumn, mean surface air temperatures were generally near or above normal.
Above 1¡æ positive anomalies were in most of Eurasia north to 35¡ãN,
eastern and middle part of U.S.A and Alaska, middle South America and parts of
Africa with maximum above 3¡æ.
In
this autumn, rainfall totals were 30% less than average in parts of West Europe,
Indian Peninsula and the northward nearby regions, most of northern China, most
of Australia, parts of Northwest Africa, South Africa and parts of South
America, with no rain in parts of above regions. Precipitation totals were above
30% more than average in most of Russia, western West Asia, parts of middle
Asia, most of U.S.A, western Canada and parts of South America with center value
about 100% ~200%.