Seasonal Highlights

Climate in China

During autumn 2005, mean surface air temperatures were observed obviously above normal all over China. Seasonal mean temperature for China was the second highest since 1951, while temperatures set new records in most of North China and the southeast coast, with 2~3^oC above normal in eastern Inner Mongolia, western Jilin and Heilongjiang, Zhejiang and parts of northern Xinjiang.

During autumn, precipitation totals were less than average in most of China, with 30~80% less than average in much of Northeast China, parts of Northwest China, and most of South China. Meanwhile, precipitations were observed above or near average in the remainder of China, with more than 30% above normal in parts of the upper and lower reaches of the Yellow River, parts of the lower reaches of the Yangtze River, southwestern Tibet and southwestern and northeastern Xinjiang.

Climate in the World

During autumn 2005, while mean surface air temperatures were observed about 1^oC below normal in western Australia, northern Argentina and western Alaska, they were obviously above or near normal in the rest of the world, with more than 2^oC above normal in northern Eurasian, parts of North America, northern West Africa and central Australia, and 4~6^oC abnormally above normal in northwestern Russia.

In the season, precipitation totals were not uniformly distributed in the world. Precipitations were 30~80% less than average in the regions from East Europe to Center Asia, most of the Middle East, Mongolia and the regions east to it, southern America, central-eastern Brazil, most of South Africa and western Australia. Meanwhile, precipitation totals were above or near normal in other regions, with 30~80 % more than average in the regions from the Indian Peninsula to the southwestern Tibet Plateau, the regions north to Stanovoi Range in Russia and central Australia.

General Circulation Features

Northern Hemisphere: During the autumn, the mean 500hPa geopotential height field exhibited a 3-wave pattern at the mid-high latitudes. In the height anomaly field, above 4 dam positive anomalies covered most of Europe, western Russia, the northern North Pacific and eastern Canada, with center value above 12 dam. During the season, the Northwest Pacific subtropical high was larger, stronger and located more westward than normal.

Southern Hemisphere: The mean 500hPa geopotential height field exhibited a 3-wave pattern at the mid-high latitudes. In the height anomaly field, below -4 dam negative anomalies covered the southeastern South Indian Ocean and the southern South Pacific, with center value below -8 dam. Meanwhile, above 4 dam positive anomalies were observed over the southwestern and southeastern South Pacific.