Monthly Highlights

1.    Climate in China

During November 2012, the surface air temperature averaged over China was 2.0℃, which was 0.9℃ lower than normal (2.9℃). Surface air temperatures were 1-2℃ above normal in southern Qinghai, most Yunnan, Hainan and locations of Heilongjiang, with 2-4℃ above normal in southeastern Yunnan. While temperatures were 1-2℃ below normal in most Northwest China, most Inner Mongolia, northwestern North China, western Huanghuai, Jianghuai, southern Jianghan and western Jiangnan, with 2-4℃ below normal in northern Xinjiang and central Inner Mongolia.

In November, average precipitation over China was 31.7 mm, which was 68.9% more than normal (18.8mm). Precipitations were observed generally 30-200% above normal in most Northeast China and North China, most of Inner Mongolia, northern and central-southern Xinjiang, most Gansu, locations of southwestern Qinghai, eastern Huanghuai, eastern Jianghuai, most Jiangnan and South China, with over 200% above normal in central-eastern Inner Mongolia, western and eastern Northeast China, most North China, central-southern Xinjiang, southern Jiangnan and eastern South China. Meanwhile, precipitations were observed 30-50% below normal in southeastern and southwestern Xinjiang, most Southwest China, parts of central -eastern Northwest China, western Huanghuai and western Jianghuai, with over 80% below normal in most Southwest China, southwestern and southeastern Xinjiang.

In November, extremes of Daily Temperature Drop (DTD) and Consecutive Temperature Drop (CTD) were observed in China impacted by active cold air masses. DTD extremes occurred in 27 stations, which were located in northeastern Qinghai, central Gansu, southern Shaanxi, northwestern Henan and other provinces (districts), with widespread DTDs of 10-17℃ and new record in Guinan station of Qinghai province (13.5℃). At the same time, CTD extremes occurred in 7 stations of Heilongjiang province and Inner Mongolia, with widespread CTDs of 21-27℃ and new records in Xinlin station (27.1℃) and Wudalianchi station (25.4℃) in Heilongjiang province.

2. Climate in the World

During November 2012, mean temperatures were 1-4℃ above normal in most Europe, western and northeastern West Siberia, northern West Asia, the Indo-China Peninsula, northern Africa, southwestern and northeastern North America, parts of southeastern South America, central and southeastern Australia, with temperatures 4-8℃ above normal in parts of northeastern Siberia and over 8℃ in locations. Meanwhile, mean temperatures were 1-4℃ below normal in central Russia, northern East Asia, northeastern Central Asia, locations of central and southern Africa, northwestern and southeastern North America, with temperatures 4-8℃ below normal in locations of central Russia, most Mongolia and most Alaska.

For the month, precipitations were at least 50% above normal in parts of northeastern Europe, southern and eastern Siberia, eastern Central Asia, northern and eastern East Asia, the western Indo-China Peninsula, northern West Asia, parts of central-western North Africa, parts of northwestern North America, parts of central-eastern and southern South America, locations of northern and southwestern Australia, with precipitations at least 400% above normal in northeastern East Asia, northern West Asia and parts of central-western North Africa. Meanwhile, precipitations were at least 50% below normal in locations of Europe, parts of central Russia, most South Asia, southwestern East Asia, parts of northern Africa, southeastern North America, locations of South America and western Australia, with no precipitation in locations.

3. General Circulation Features

Northern Hemisphere: During November 2012, the Arctic Oscillation (AO) appeared two-stage variations, with the positive phase in the early and mid-month and negative phase in the late month. The field of mean 500hPa geopotential height exhibited a three-wave pattern over the mid and high latitudes. In the field of height anomaly, positive anomalies above 4 dam were located in southern Europe, most Siberia, the northwestern North Pacific Ocean and locations of northeastern North America, respectively, with central values above 18 dam over the northwestern North Pacific Ocean. Meanwhile, negative anomalies below -4 dam covered western Europe, region from northeastern Central Asia to northern East Asia, parts of the northern North Pacific Ocean, southeastern North America and the northeastern North Atlantic Ocean, with central values below -8 dam in locations. For the month, the area and intensity of West Pacific Subtropical High were smaller and weaker than normal. The location of its ridge line was more southward and the west end of its ridge shifted more eastward than normal.

Southern Hemisphere:  For the month, the field of mean 500hPa geopotential height exhibited zonal pattern over the mid and high latitudes. In the field of height anomaly, positive anomalies above 4 dam covered the polar areas and most areas north to 60^o N. Meanwhile, the negative anomalies below -4 dam mainly covered the southern South Pacific Ocean, the southern South Indian Ocean and the parts of southern South Atlantic Ocean, with the central values below -8 dam over the southeastern South Indian Ocean and the values below -12 dam in locations.

4. Tropical Features

Sea Surface Temperatures (SSTs): During November 2012, SSTs were slightly above normal over most of the equatorial central and eastern Pacific, with central anomaly value above 0.5℃ near the dateline. However, negative SST anomalies covered the eastern part of the equatorial eastern Pacific, with central value below -0.5℃. NINO1+2 index was -0.4℃, with a drop of 0.2℃ from last month. However, NINO 3, NINO 3.4, and NINO Z indices were 0.1℃, 0.4℃and 0.3℃, with an increase of 0.1℃ from last month, respectively. NINO 4 was 0.5℃ and the same as last month.

Subsurface Temperatures: During November 2012, anomalously warm subsurface water weakened in the equatorial central Pacific and moved eastward. However, anomalously cold subsurface water in the equatorial central Pacific enhanced obviously, while the anomalously cold subsurface water in the equatorial eastern Pacific weakened significantly.

Warm Pools: During November 2012, the areas of the Indian Ocean warm pool and the western Pacific warm pool were larger than normal slightly. The warm pool intensities were above normal in the Indian Ocean and the western Pacific.

Wind Field: During November 2012, at lower troposphere (850hPa), zonal winds were near normal over most of the equatorial central-eastern Pacific, while easterly anomalies prevailed in region from the equatorial western Pacific to the eastern Indian Ocean. At upper troposphere (200hPa), westerly anomalies controlled the most equatorial eastern Pacific, while, easterly anomalies dominated over the equatorial central and western Pacific.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was 0.5, with an increase of 0.1 from last month.

Convections over the Tropics: During November 2012, the anomalous outgoing long wave radiation (OLR) showed that enhanced convection was observed over regions from the equatorial western Pacific east to the Philippines, while decreased convection covered the regions east to the dateline. At lower troposphere (850hPa) divergent wind field, a convergent center was around 100ºE, 5ºN, and a divergent center was near 115ºW, 5ºS. At upper troposphere (200hPa), the corresponding divergent center was near 100ºE, 0ºN, and a convergent center was around 95ºW, 25ºS.

5. ENSO Monitoring and Outlook

At present, the neutral condition dominates the equatorial Pacific and the heat content anomalies of the Central and Eastern Pacific Upper Ocean (0-300 m) have weakened to near zero. Besides, the atmospheric circulation is near average. We predict that the neutral condition is expected to maintain through the Northern Hemisphere winter 2012-2013.

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