1. Climate in China
During November 2013, the surface air temperature averaged over China was 3.6℃, which was 0.7℃ above normal (2.9℃). The monthly mean surface air temperatures were 1-2℃ below normal in central-western Northwest China, while near or above normal in the rest of China. Positive anomalies of about 1-2℃ were observed in northern Xinjiang, eastern Inner Mongolia, most Northeast China, parts of central Tibet, and regions from eastern Southwest China to western Jiangnan. Temperatures were over 4℃ above normal in locations of northwestern Heilongjiang and northeastern Inner Mongolia.
For the month, the mean precipitation of China was 22.5 mm, which was 19.7% more than normal (18.8 mm). Percentages of precipitation anomalies were over 80% below normal in parts of western Northwest China, western Inner Mongolia, regions from northeastern North China to southwestern Northeast China, most Tibet, and western and southern Southwest China. Precipitations were near or above normal in the rest regions, with 50%-100% above normal in locations of western Xinjiang, central-eastern Northwest China, most Northeast China, northern Huanghuai, and regions from central-southern Jiangnan to most South China, and over 200% above normal in parts of the above regions.
In November, extremes of Daily Temperature Drop (DTD) and Daily Precipitation (DP) were observed in China. DTD extremes occurred in 17 stations, which were located in Heilongjiang, Jilin, Liaoning, Henan and Qinghai, with new records in Yixian (14.7℃) of Liaoning and Xiuwu (11.2℃) of Henan. At the same time, DP extremes were observed in 7 stations of Hainan and Guangxi et al., with new record in Fusui (197.6 mm) of Guangxi.
During November 2013, mean temperatures were close or above normal in most Eurasia-Africa-Australia, with temperatures 2-8℃ above normal in eastern Europe, most Russia and northeastern East Asia, with temperatures over 8℃ above normal in locations of central West Siberia Plain. Mean temperatures were 1-2℃ below normal in the eastern part of the Far East of Russia, parts of China Northwest, location of northeastern South Asia, location of southeastern Australia and locations of northwestern Africa. Meanwhile, mean temperatures were close or below normal in America, with temperatures 1-4℃ below normal in most North America, parts of mid-north and part of southern South America, with temperatures 4-8℃ below normal in location of central Canada. Mean temperatures were 1-2℃ above normal in parts of western North America, with temperatures 2-4℃ above normal in western Alaska.
For the month, precipitations were at least 50% above normal in most northern Eurasia, most West Asia, parts of East Asia, mid-northern Australia, parts of central-eastern and northwestern Africa, southwestern North America and most Alaska, northern and part of southeastern South America, with precipitations at least 200% above normal in locations. Meanwhile, precipitations were at least 50% below normal in locations of South Europe, western Central Asia, most South Asia, northern Southeast Asia, mid-northern East Asia, most eastern and part of southwestern Australia, most northern and locations of southern Africa, parts of central and locations of northern North America, and parts of central South America, with no precipitation in parts of above regions such as northern South Asia, northern Southeast Asia, mid-eastern Australia and most northern Africa.
3. General Circulation Features
Northern Hemisphere: During November 2013, the Arctic Oscillation (AO) was observed in significant positive phase. 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 the northeastern North Atlantic Ocean and regions from the northeastern Europe to the northern North Pacific Ocean, with the central values above 16 dam over the northern North Pacific Ocean. Meanwhile, negative anomalies below -4 dam covered most of the polar region, the Japan Sea and parts of the northeastern North America, with central values below -12 dam in locations of the polar region. For the month, the area and intensity of western North Pacific subtropical high were smaller and weaker than normal. The location of its ridge line was slightly 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 regions from the southern South Pacific Ocean to the southwestern South Indian Ocean and parts of the northern Antarctic Continent. Meanwhile, the negative anomalies below -4 dam mainly covered most of the polar region outside of the northern Antarctic Continent, with the central values below -8 dam in locations.
4. Tropical Features
Sea Surface Temperatures (SSTs): During November 2013, SSTs were above normal over the parts of the western equatorial Pacific to the west of dateline. Except that negative SST anomalies in the eastern equatorial Pacific nearby south America with central value below -0.5℃, SST anomalies were near normal over the most central and eastern equatorial Pacific. Niño1+2, Niño3, Niño4, Niño3.4 and NiñoZ indices were -0.4℃, -0.2℃, 0.3℃, 0.0℃and 0.0℃, with a rise of 0.2℃, 0.3℃, 0.3℃, 0.2℃ and 0.0℃, respectively.
Subsurface Temperatures: During November 2013, anomalously warm subsurface water enhanced and moved eastward in the western equatorial Pacific, with central values above 4℃. Meanwhile, anomalously cold subsurface water enhanced in the central and eastern equatorial Pacific.
Warm Pools: During November 2013, the area of the Indian Ocean warm pool was larger than normal and its intensity was stronger than normal. The area and intensity of the western Pacific warm pool were slightly larger and stronger than normal, respectively.
Wind Field: During November 2013, at lower troposphere (850hPa), the easterly wind anomalies covered the western and central equatorial Pacific, while westerly wind anomalies were observed over the eastern equatorial Pacific. At upper troposphere (200hPa), except the easterly wind anomalies covering the region to the east of the dateline, the westerly wind anomalies covered most equatorial Pacific.
Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was 0.9, with an increase of 1.0 from last month.
Convections over the Tropics: During November 2013, the anomalous outgoing long wave radiation (OLR) showed that convections enhanced from the Indo-China Peninsula to northern Australia, while convections were suppressed in the western and central equatorial Pacific Ocean. At lower troposphere (850hPa) divergent wind field, a convergent center was around 120ºE, 10ºS, and the divergent centers were over 30ºW，10ºS and 30ºW，10ºN respectively. At upper troposphere (200hPa), a divergent center was near 120ºE, 5ºS, and the convergent centers were over 60ºW, 20ºN and 0º，10ºS respectively.
5. ENSO Monitoring and Outlook
At present, the index of SOI turned to positive, while the ENSO-neutral conditions have remained. The sea surface temperature is near the normal, with the temperature colder in the eastern pacific, while warmer in the western. The weak east wind is prevailing and the convection is suppressed in the eastern and middle part of the equatorial Pacific. The heat content of upper layer ocean in the tropic has remained positive anomaly. The ENSO-neutral conditions are expected to persist through the boreal spring according to model forecasts and the diagnostic analysis.
Therefore, we will closely monitor the development of ENSO conditions and update our ENSO wrap-up in time.