Monthly Highlights

1. Climate in China

In November 2011, China monthly mean surface air temperature was 3.9℃. It was 1.8℃ higher than normal (2.1℃), which ranked the 3^rd highest since 1951. Monthly mean surface air temperatures were near or above normal over most China, except that temperatures were observed below normal in northeastern Inner Mongolia, eastern Xizang and western Yunnan. The temperatures were observed 1-2℃ above normal in southwestern Xinjiang, western Xizang, southern Qinhai, mid-northern Sichuan, locations of mid-eastern Inner Mongolia，locations of northern and southern Hebei, eastern Shanxi, Henan, western Shandong, locations of western Anhui, most Heilongjiang, locations of central and southwestern Jilin, and southern Liaoning, with temperatures 2-4℃ above normal in western Inner Mongolia, eastern Southwest China, most North China, Huanghuai, Jianghuai, Jianghan, Jiangnan，most Huanan, eastern Southwest China, western Xizang, eastern and southwestern Xinjiang, most Qinhai and Gansu, with more than 4℃ above normal in locations of above regions.

For the month, the mean precipitation over China was 28.3 mm, with precipitation 57% more than normal (18.0 mm), which ranked the 1^st since 1983. Precipitations were 30%-100% more than normal in northern and southeastern Xinjiang, central Xizang, eastern Southwestern China, central and southwestern Northwest China, eastern Inner Mongolia, southern Northeast China, northeastern North China, southern Huanghuai, northern Jianghan, southeastern Jiangnan and central South China, with precipitations 200% more than normal in eastern Northwest China, central Inner Mongolia, most North China, northern Huanghuai, southeastern Jiangnan, and eastern South China. Meanwhile, precipitations were observed 30-80% less than normal in most southwestern Xinjiang, central Qinhai, western Gansu, northwestern Inner Mongolia, most Jianghuai, northern and western Jiangnan, southeastern Southwest China, western and southeastern Xizang, etc., with less than 80% in locations of above regions.

In November, daily temperature drop extremes, consecutive temperature drop extremes and consecutive rainy days extremes were observed in China. Daily temperature drop extremes occurred in 21 stations, which were located in Inner Mongolia, Heilongjiang, Jilin and other provinces (districts), with widespread daily temperature drops of 10-16℃. During the month, consecutive temperature drop extremes were observed in 9 stations, distributed in Inner Mongolia, Shandong and Guizhou. Consecutive temperature drops ranged between 15℃ and 25℃, with Chenbaerhu (25.4℃) and Manchuria (23.9℃) breaking record. Additionally, consecutive rainy days extremes occurred in 5 stations of Inner Mongolia, Hebei, Henan and Guizhou, with Suiyang (22 days) breaking record.

2. World Climate

During November 2011, monthly mean surface air temperatures were 1-4℃ above normal in mid-northern and western Europe, most Siberia and parts of the Russian Far East, most East Asia, most South Asia, northwestern and parts of eastern Africa, southeastern Australia, mid-eastern North America, central and southeastern South America, with temperatures at least 4℃ above normal in northwestern Europe, locations of northern Russia and eastern North America. Meanwhile, temperatures were 1-4℃ below normal in southeastern Europe, southwestern West Siberian Plain, West Asia, Central Asia, Mongolia, western Southeast Asia, mid-northern and southwestern Africa, western Australia, northwestern North America and eastern South America, with temperatures at least 4℃ below normal in locations.

For the month, precipitations were at least 50% more than normal in parts of northwestern Russia, locations of the Russian Far East, West Asia, western and eastern Central Asia, eastern East Asia, eastern part of the Indo-China Peninsula, northern and eastern coastal areas of Africa, western and central Australia, Alaska, northwestern and southeastern North America, and most northern South America, with precipitations at least 100% above normal in locations. Meanwhile, precipitations were at least 50% less than normal in most Europe, parts of central Russia, central areas of Central Asia, India, western Southeast Asia, mid-western North Africa, locations of southern Australia, and parts of central North America, with no precipitations in locations.

3. General Circulation Features

Northern Hemisphere: During November 2011, the Arctic Oscillation (AO) was basically in the positive phase. The field of mean 500hPa geopotential height exhibited a multi-wave pattern over the mid-high latitudes. In the field of height anomaly, positive anomalies above 4 dam were located in western Europe, northern East Asia, eastern Russia, mid-northern North Pacific and locations of northeastern North America, respectively, with central values above 16 dam over western Europe. Meanwhile, negative anomalies below -4 dam covered eastern Europe, West Asia, Central Asia, northeastern North Pacific and northern Atlantic Ocean, with central values below -12 dam over eastern Europe, Central Asia and northern Atlantic Ocean. For the month, the area and intensity of West Pacific Subtropical High were a bit smaller and weaker than normal, while the western ridge line and ridge point were near normal and a bit more eastern, respectively.

Southern Hemisphere:  For the month, the field of mean 500hPa geopotential height exhibited a 3-wave pattern over the mid-high latitudes. In the field of height anomaly, positive anomalies above 4 dam covered the southeastern South Atlantic Ocean and polar areas, with central values above 16 dam over South Atlantic Ocean. Meanwhile, the negative anomalies belt below -4 dam mainly covered around the middle latitude, with the central values below -8 dam over the southwestern Indian Ocean.

4. Tropical Features

Sea Surface Temperatures (SSTs): During November 2011, the negative SST anomalies were significantly strengthened with the minimum below -2.0℃. NINO 1+2 and NINO 4 indices were -0.9 and -0.5, same as last month. NINO 3, NINO 3.4 and NINO Z indices were -1.1℃,-0.9℃ and -0.8℃, with drops of 0.2℃, 0.1℃ and 0.1℃ from last month, respectively. Meanwhile, SSTs were 0.5~1.0℃ above normal in the equatorial Indian Ocean.

Subsurface Temperatures: During November 2011, anomalously cold subsurface water controlled the equatorial central and eastern Pacific. Negative anomalies strengthened but shrunk evidently, with central value shifting eastward slightly. The intensity and extent of anomalously warm subsurface water in equatorial western Pacific weakened and expanded eastward.

Warm Pools: During November 2011, the area of the Indian Ocean warm pool was slightly larger than normal, and that of the western Pacific warm pool was near normal. Their intensities were both above normal.

Wind Field: In November 2011, at lower troposphere (850hPa), easterly anomalies dominated over the most equatorial Pacific. At upper troposphere (200hPa), westerly anomalies were observed over the most equatorial Pacific, with values above 4 m/s.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was 1.3, with a rise of 0.3 from last month.

Convections over the Tropics: During November, the anomalous outgoing long-wave radiation (OLR) showed that enhanced convection was over regions from the East China Sea to northern Indonesia. Meanwhile, suppressed convection was over the most equatorial Pacific.

In the divergent wind field at lower troposphere (850hPa), the convergent center was around equator 120°E and divergent center was around 5°W, 12.5°S. At upper troposphere (200hPa), the corresponding divergent and convergent centers were near equator 115°E and 5°W, 10°S, respectively.

5. ENSO Monitoring and Outlook

Current monitoring results showed that during November 2011, atmospheric and oceanic conditions in the tropical Pacific still maintained La Niña status. Negative SST anomalies continued to stay in the central-eastern Pacific, but enhanced slowly. The index NINO Z was at -0.8℃ in November away from average with drops of 0.1℃ from last month. Southern Oscillation Index (SOI) was at 1.3 away from average with increased 0.3 from last month.

Based on model predictions and current monitoring of the ocean and atmosphere features, the La Niña conditions will continue enhancing in the central and eastern equatorial Pacific and reach its peak from December 2011 to January 2012. It is predicted that the La Niña conditions may decrease in spring 2012.

We will closely monitor the development of ENSO conditions and update our ENSO wrap-up in time.