Seasonal Highlights

1. Climate in China

During the winter (Dec. 2011-Feb. 2012), seasonal mean surface air temperature of China was -4.8℃ which is 1.0℃ below normal (-3.8℃), being the coldest winter since 1986. Temperatures were above normal in most of the Tibetan Plateau and Yunnan, with 1-2℃ above normal appearing in north-central Tibet, southern Qinghai, north-central Yunnan and parts of western Sichuan, while temperatures were more than 1℃ below normal in Northeast China, northern North China, most of West China, Eastern Southwest China, Central China, South China and western East China, with over 4℃ below normal in parts of Inner Mongolia.

For the winter, averaged precipitation over China was 38.8 mm, close to the normal (40.5 mm), while precipitation distribution was remarkably uneven. Precipitations were observed generally near or below normal, except most of Fujian, south-central Qinghai, western Xinjiang, east-central Sichuan, parts of Tibet, where precipitations were 30%-100% more than normal. Precipitations were 30-80% less than normal in Northeast China, North China, Huanghuai, Jianghan, northeastern Northwest China, most of Yunnan, southwestern Sichuan and central Tibet, with more than 80% below normal in locations, and Northeast China precipitation was the lowest since 1951.

2. World Climate

During winter 2011, temperatures in most places of the world were colder than normal. Temperatures were 1-4℃ below normal in most Europe and Asia, northern Africa, most Australia and northern South America, with temperatures more than 4℃ below normal in southeastern Europe, southern North Asia and Central Asia. Meanwhile, temperatures were 1-4℃ above normal in central-north Russia, most North America, southern South America and northern Southeast Asia, with temperatures at least 4℃ above normal in most Canada and America, and parts of north-central Russia.

For the winter, precipitations were at least 50% less than normal in western Russia, India, eastern China, western Africa and parts of central Canada, with no precipitation in parts of above regions. Meanwhile, precipitations were observed above 50% more than normal in eastern Europe, West Asia, central America, southern Mexico, north-central South America, central-north Russia, with precipitations at least 200% above normal in locations.

3. General Circulation Features

Northern Hemisphere: During the boreal winter(Dec. 2011-.Feb. 2012), in the field of 500hPa geopotential height anomaly, positive anomalies above 4 dam covered regions over the northern North Atlantic Ocean, the Ural of western Russia, and the northeastern North Pacific, with central values above 12 dam over the Ural region. Negative anomalies of -4 dam covered regions over the high latitudes of the Northwest Pacific.

Southern Hemisphere: During the boreal winter, in the field of 500hPa geopotential height anomaly, it exhibited a significant annular mode, with negative anomalies below -4 dam covering the South Pole and positive anomalies dominating the South Pacific, the South Atlantic Ocean and the South Indian Ocean, with parts over 4 dam.