Seasonal Highlights

1. Climate in China

During winter 2009/2010 (Dec. 2009-Feb. 2010), seasonal surface air temperature averaged over China was -3.6°C, with 0.7°C higher than normal, was the 11^th warm winter since 1951/1952. The temperatures were observed 1-2°C lower than normal in most of Northeast China, eastern Inner Mongolia, northern Xinjiang, with 2-4°C below normal in locations. Meanwhile, temperatures were observed 1-2°C above normal in most of Southwest China and Northwest China, southern Jiangnan, most of South China, with 2-4°C above normal in Qinghai, northern Tibet, eastern Yunnan.

For the season, mean precipitation was 43.7mm in China, with 5.4mm above normal. The precipitations were observed 30-100% more than average in most of Northeast China, western Northwest China, most of the southeast coastal areas, western and northeastern Inner Mongolia, with at least 100% above normal in northern Northeast China, northern Xinjiang, northwestern Gansu, and western Inner Mongolia. Meanwhile, precipitations were observed 30-80% less than average in most of Southwest China, central and southeastern Northwest China, central and southern North China, northwestern Huanghuai region, western Hubei and Hunan provinces, with at least 80% below normal in parts of Yunnan and Sichuan provinces.

2. Climate in the World

During the winter, mean surface air temperatures were observed 1-3℃ below normal in most of the mid-high latitude over Eurasia, central and southern North America, northeastern Australia, with 3-6℃ below normal in central and northern Russia, northeastern Europe. Meanwhile, temperatures were observed 1-2℃ above normal in central and northern Africa, northern North America, most of South America, southwestern Australia, southern Asia, with 4℃ above normal in parts of central and northern Africa, northeastern and northwestern North America, northern South America.

For the season, precipitations were observed 30-100% more than average in central South America, central and southern North America, southern Europe, parts of East Africa, eastern Australia, central and eastern Asia, with over 100% above normal in locations of above regions. Meanwhile, precipitations were observed 30-80% less than average in central Russia, South Asia, Southwest China, western Australia, northwestern Africa, northern South America, northwestern North America, with no precipitations in locations of above regions.

3. General Circulation Features

Northern Hemisphere: During the winter, positive departures covered the regions north to 60°N in the 500hPa geopotential height anomaly field, with central values above 20 dam near the area from Baffin Island to Greenland. Meanwhile, negative anomalies regions looked like annular mode along with the mid-latitudes, and the negative centers were located in the northeastern North Pacific, the North Atlantic to eastern Europe, Lake Baikal, with the values of -12 dam, -12 dam and -4 dam, respectively. The Northwest Pacific subtropical high extended westward and its area was larger than average.

Southern Hemisphere: For the season, the mean 500hPa geopotential height field exhibited a 3-wave pattern at the mid-high latitudes. In the 500hPa geopotential height anomaly field, the anomalies was not significant.