Seasonal Highlights

1. Climate in China

During summer 2012, the surface air temperature averaged over China was 21.4℃, which was 0.5℃ higher than normal (20.9℃). Seasonal mean surface air temperatures were 0.5-1℃ above normal in northern and eastern Xinjiang, central-eastern Northwest China, Xizang, northeastern and western Inner Mongolia, northern Northeast China, Huanghuai, Jianghuai, part of Yunnan, with 1℃ above normal in locations. While temperatures were 0.5℃ below normal in western Xinjiang, eastern Inner Mongolia, central and southern North China, western and northeastern North China, part of eastern Southwest China, central and southern South China, with 0.5-1℃ below normal in locations.

In Summer, average precipitation over China was 332.9 mm, which was 2.5% above  normal (324.9 mm). Precipitations were observed generally 30-50% above normal in northern  Xinjiang, southwestern and central Northwest China, most Inner Mongolia, southern and northern Northeast China, southeastern North China, Northern Jiangnan, and part of Hainan, with over 50% above normal in locations. Meanwhile, precipitations were observed 30-50% below normal in northeastern Heilongjiang, Jianghan, Chongqing and southeastern South China.

2. World Climate

During summer, monthly mean temperatures were 1-2℃ above normal in most Eurasia, most North America, eastern Australia and its western locations, local eastern South America, northern Africa and its central south, ,with temperatures at least 2℃ above normal in locations.. Meanwhile, temperatures were 1-2℃ below normal in northwestern North Europe, eastern Siberia, southwestern North America, central and Southern South America, southern West Africa, local South Africa, central and northern Australia, with temperatures at least 2℃ below normal in locations.

For the summer, precipitations were at least 50% above normal in eastern Europe, central and eastern Siberia, Central Asia, Northwest China, northern South Asia, northern North America and its western locations, southeastern South America and its north parts, West Africa, South Africa, local eastern Australia. Meanwhile, precipitations were at least 50% below normal in central Siberia, West Asia, western America, western South America, North Africa, western Australia, with no precipitation in locations.

3. General Circulation Features

Northern Hemisphere: During summer, the field of mean 500hPa geopotential height exhibited a 4-wave pattern over the mid-high latitudes. In the field of height anomaly, positive anomalies above 4 dam covered the Greenland, regions from southeastern Europe through northern Central Asia to central Russia, with central values above 8 dam over parts of the Greenland. Meanwhile, negative anomalies below -4 dam covered locations of the northwestern North Atlantic Ocean.

Southern Hemisphere: For the season, in the field of 500hPa geopotential height anomaly, positive anomalies above 4 dam covered the southern of South Pacific Ocean, parts of the southern South India Ocean and the southern South Atlantic Ocean. Meanwhile, negative anomalies below -4 dam mainly covered regions from the Bellingshausen Sea to the Drake Passage, with central values below -8 dam over locations.