Monthly highlights
1. Climate in China
During June 2012, the surface air temperature averaged over China was 20.2℃, which was 0.4℃ higher than normal. The monthly mean surface air temperatures were 1-2℃ below normal in most of central Inner Mongolia and eastern Southwest China. Temperatures were 0-1℃ above normal in the remainder of China, with 1-2℃ higher than normal in northeastern Xinjiang, most Gansu, western Huanghuai, northeastern Jianghan, western Southwest China and northern Northeast China.
In June, average precipitation over China was 108.5 mm, which was 11.2% more than normal. Precipitations were observed 20-100% above normal in central northwest China, Inner Mongolia, most northeast China, central Jiangnan, southwestern South China and parts of Southwest China, and 100-200% above normal in central northwest China and parts of Inner Mongolia. While, precipitations were observed generally 30-80% below normal in southern North China, Huanghuai, Jianghuai, Jianghan, western Southwest China and parts of northern Xinjiang.
In June 2012, extreme events of High Temperature (HT), Consecutive High Temperature Days (CHTD), Daily Precipitation (DP), Three Days Precipitation (TDP), Consecutive Precipitation Days (CPD) and Consecutive Precipitation (CP) were observed in China. Daily maximum temperatures of 68 stations in Shandong, Henan, Anhui, Yunnan et al. reached the threshold of HT extreme event, with 1 station setting new records. Extreme event of CHTD occurred in 68 stations in Hebei, Shandong, Henan et al, with 11 station setting new records. Meanwhile, DP extreme event occurred in 43 stations, with 12 station setting new records. TDP extreme event occurred in 50 stations, with 10 station setting new records. CPD extreme event occurred in 88 stations, with 14 station setting new records. CP extreme event occurred in 30 stations, with 9 stations setting new record. Extreme events of precipitation are located over the whole country, with different events occurred in each area.
2.Climate in the World
During June 2012, monthly mean temperatures were 1-4℃ above normal in most Asia and Europe, parts of northern Africa, most North America and mid-east South America, with temperatures 4-6℃ above normal in mid-north Russia, locations of northeastern Canada. Meanwhile, monthly mean surface air temperatures were observed 1-2℃ below normal in northwestern Europe, most Australia, parts of mid-west and east Africa, Northeast China, northeastern North America, southern and northwestern South America, with temperatures 2-4℃ below normal in locations of northern Australia, northwestern Europe, northwestern Australia, mid-eastern Africa.
For the month, precipitations were at least 50% more than normal in eastern Russia, central and northern Asia, parts of western，central and southern Africa, eastern Australia, northern Canada, parts of central South America, with precipitations at least 200% above normal in locations. Meanwhile, precipitations were at least 50% less than normal in parts of central and eastern Russia, northwestern South Asia, most West Asia, pasts of northwestern and northeastern Africa, western Australia, southern North America and western South America, and with no precipitation in locations.
3. General Circulation Features
Northern Hemisphere: During June 2012, the field of mean 500hPa geopotential height exhibited a five-wave pattern over mid-high latitudes. In the field of height anomaly, positive anomalies above 4 dam covered regions from eastern Europe to Central Asia, regions from eastern Russia to northeastern East Asia, and northern North America, with central values above 12 dam over the Ural Mountains and Greenland. Meanwhile, negative anomalies below -4 dam covered the part of northern North Pacific Ocean and the northern North Atlantic Ocean. During the month, the area of the northwestern Pacific subtropical high was smaller than normal. Its intensity was weaker, and the west end of its ridge shifted more eastward than normal.
Southern Hemisphere: For the month, zonal circulation dominated over mid-high latitudes of the mean 500hPa geopotential height. In the field of height anomaly, positive anomalies above 4 dam covered the southern Atlantic Ocean, the southeastern South Indian Ocean, and the Southwestern South Pacific Ocean, with central values above 8 dam over the southwestern South Pacific Ocean. Meanwhile, negative anomalies below -4 dam covered the southeastern South Atlantic Ocean and the southwestern South Indian Ocean, with central values below -8 dam over the Weddell Sea and the Bellingshausen Sea.
4. Tropical Features
Sea Surface Temperatures (SSTs): During June 2012, except that SSTs were near normal in the western equatorial Pacific, SST anomalies were above 0.5℃ over the most central and eastern equatorial Pacific with central values above 2.0℃. NINO 1+2, NINO 3, NINO 4, NINO 3.4 and NINO Z indices were 1.6℃, 0.7℃, -0.1℃, 0.3℃ and 0.4℃, with an increase of 0.5℃, 05℃,
0.2℃ and 0.4℃, respectively. SSTs were near normal or slightly above normal in the equatorial Indian Ocean.
Subsurface Temperatures: During June 2012, anomalously cold subsurface water weakened and shrank in the central equatorial Pacific. Meanwhile, anomalously warm subsurface water enhanced in the eastern equatorial Pacific and it maintained in the western equatorial Pacific.
Warm Pools: During June 2012, the area and intensity of warm pool were slightly above normal in both the western Pacific and the Indian Ocean.
Wind Field: During June 2012, at lower troposphere (850hPa), weak easterly anomalies dominated near the equatorial deadline, while westerly anomalies controlled the most equatorial Pacific. At upper troposphere (200hPa), easterly anomalies covered the western Pacific, while westerly anomalies above 4m/s covered most of the equatorial central and eastern Pacific Ocean.
Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was -0.8, with an apparent decrease of 0.5 from last month.
Convections over the Tropics: During June 2012, the anomalous outgoing long wave radiation (OLR) showed that enhanced convection was observed over the Pacific Ocean from the South China Sea to eastern Indonesia, while convection was suppressed the equatorial datelines. At lower troposphere (850hPa) divergent wind field, a convergent center was around 130ºE, 20ºN, and a divergent center was near 110ºW, 15ºS. At upper troposphere (200hPa), the corresponding divergent center was near 130ºE, 15ºN, and a convergent center was around 110ºW, 20ºS.
5. ENSO Monitoring and Outlook
At present, sea surface temperatures in the eastern equatorial Pacific were above average and the heat content of subsurface kept increasing. At the same time, the atmospheric condition has transferred to El Niño status. Based on the monitoring and diagnostics of the tropical ocean and atmosphere, and predictions of dynamic and statistical models, there would be a transferring from ENSO-neutral conditions to the El Niño status in the next two months. A weak or moderate El Niño event would be expected with the development of warm condition in the rest of year.
Therefore, we will closely monitor the development of ENSO conditions and update our ENSO wrap-up in time.