Seasonal Highlights

Climate in China

During Spring 2005, the mean surface air temperatures were observed 1℃ below normal in eastern Heilongjiang. Temperatures were observed 1-3℃ above normal in most Northwest China, the southern Huanghuai， the Jianghuai, the Jianghan and most Jiangnan with positive departures above 3℃ in eastern Xinjiang. For the Spring, precipitation totals were observed 30% -400% more than average in most Northeast China, most Northwest China; precipitations were observed 30-60 % below average in eastern Xinjiang, middle Inner Mongolia, the south Tibet, east Yunnan, part of the middle reaches of the Yellow River and the east lower reaches of the Yangtze River.

Climate in the World

During Spring 2005, except that the mean surface air temperatures were observed 1℃ below normal in eastern America, east Heilongjiang of China, the north coast of Europe and northern Argentina, they were found above or near normal in the rest of the world with 1-3℃ above normal in most mid-north Asia, part of West Africa, northwest America and Alaska, northwest Canada, mid-west Australia.

For the season, rainfall totals were 30-90% less than average in the eastern East Europe Plain, the north Siberia, northern and western South Asia, part of Southwest China and north of east China, most Australia, most America, northwest and south West Africa, and north Argentina. Meanwhile, precipitation totals were 30-50 % more than or near normal in the other regions, with 100-400 % more than average in Northwest China.

General Circulation Features

Northern Hemisphere: During Spring 2005, the mean 500hPa geopotential height field exhibited that the Northern America trough was stronger than normal. Correspondingly, below -4 dam negative anomalies covered the eastern North America and the offing and the northeast Atlantic Ocean. Meanwhile, positive departures above 4 dam controlled northern North America northward to the North Pole with 8 dam in south Greenland and nearby oceans. For the season, the Northwest Pacific subtropical high was stronger than normal.

Southern Hemisphere: The mean 500hPa geopotential height field exhibited that a zonal circulation prevailed at the mid-high latitudes. In the height anomaly field, near-normal heights were observed in most of the Southern Hemisphere except that -4 dam controlled the south end of South America and nearby oceans and southeastern South Indian Ocean.