Monthly Highlights

Climate in China

The average temperature in June 2010 was 20.5℃, which is the 3rd warmest June since 1951. Temperatures were 1-4℃ warmer than normal in most Northeast China, Inner Mongolia, Shanxi, northern Northwest China and central Tibet, with 4-6℃ higher than normal in most Heilongjiang and northeastern Inner Mongolia. Temperatures were 1-2℃ below normal in southern Jiangnan, northern South China, eastern Southwest China and western part of Southern Xinjiang.

In June, precipitations were at least 30-100% more than normal in southern Jiangnan, most South China, central and southwestern parts of Northwest China, and northern Ningxia, with 100% more than normal in some above regions. Precipitations were 30-80% less than normal in most Northeast China and North China, most Huanghuai, the middle and lower reaches of the Yangtze River, most Shaanxi and Inner Mongolia, center and southern parts of Tibet, central Yunnan and Hainan.

In June, daily maximum temperature extremes occurred in northern North East China, North East of Inner Mongolia, most part of North China, North of Xinjiang, part of South Chinaand South West China. The maximum temperature in 33 stations prompted new records in Mohe, Jiagedaqi, Beian, Yichun station of Helongjiang; Eergunashi, Elunchunzuzizhiqi station of Inner Mongolia, Songyuan, Qianguo station of Jilin and Tuokexun station of Xinjiang, and so on. Daily precipitation extremes of 69 stations occurred in Hunan, Guangxi, Fujian, Jiangxi, Qinghai Ningxia, Yunnan, Heilongjiang and Xinjiang et al. New records of daily maximum precipitation were reported in 21 stations, i.e. Huitong, Liling of Hunan; Dongxiang,Yujiang of Jiangxi; Wuyishan, Shunchang of Fujian. Besides, the number of consecutive precipitation days extremes of 37 stations occurred in Guangxi, Guizhou, Xinjiang, Zhejiang, Hunan, Qinhai, Sichuan and new records were broken in 5stations.

Climate in the World

During June 2010, temperatures were 1-4℃ above normal in most Europe, southwestern and eastern Russia, West Asia, most Central Asia, northern South Asia, central and western parts of China, most northern China, most Indo-China Peninsula, southern North America, locations of western South America, northwestern Australia, with 4-6℃ higher than normal in northeastern East Asia and locations of Central Asia. Meanwhile, temperatures were 1-2℃ below normal in locations of northwestern Russia, the Pamir Plateau, parts of South China, locations of western North America and central Australia.

Precipitations in June were at least 50% more than normal in locations of southern Europe, northern and southeastern parts of West Asia, the Pamir Plateau, northern part of the Tibetan Plateau, northern and eastern parts of Russia, parts of South China, most of northern North America, parts of northern South America, western and eastern parts of Africa, with 200% more than normal in locations. Precipitations were at least 50% less than normal in southwestern Russia, northern South Asia, parts of Northeast China and North China, northeastern and western parts of North America, central South America, locations of western and southern Africa, and most of Australia.

General Circulation Features

Northern Hemisphere: During June 2010, the mean 500hPa geopotential height field exhibited a 4-wave pattern at the mid-high latitudes. In the 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered regions from the northeastern North Atlantic Ocean to the Polar regions, areas from Northwest Europe to Lake Balkhash via Central Asia, northern East Asia, most India and Bay of Bengal, the southeastern North Pacific, southeastern North America, with central values above 8 dam in the Polar regions, most Central Asia and northeastern East Asia. Meanwhile, negative anomalies below -4 dam covered northwestern Russia, northeastern Canada, with central values below -8 dam in northwestern Russia. For the month, the Northwest Pacific subtropical high (NWPSH) was larger and obviously stronger than normal. It extended remarkably westward.

Southern Hemisphere: In the June 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered the central and southern South Pacific and the South Indian Ocean, the southern South Atlantic Ocean, with central values above 12 dam in the central and southern South Pacific Ocean. Meanwhile, negative anomalies covered the Polar Regions, with central values below -20 dam from the southeastern Pacific Ocean to the Ploar regions.

Tropical Features

Sea Surface Temperatures (SSTs): During June 2010, SSTs were generally below normal in the central and eastern equatorial Pacific with minimum below -1.5℃. The negative SST anomalies enhanced and expanded. NINO 1+2, NINO 3, NINO 4, NINO 3.4 and NINO Z indices were -0.4℃，-0.6℃，0℃，-0.5℃ and -0.4℃, with drops of 0.4℃, 0.5℃, 0.4℃, 0.4℃ and 0.5℃ from last month, respectively. Meanwhile, equatorial SSTs were 0.5℃ above normal with maximum above 1.0℃ in the western Pacific and Indian Ocean.

Subsurface Temperatures: During June 2010, anomalously cold subsurface water controlled most of the equatorial central and eastern Pacific. Meanwhile, negative anomalies enhanced significantly, shifted eastward and uplifted obviously, with central values below -4℃.

Warm Pools: During June 2010, both the area and intensity of the western Pacific and the Indian Ocean warm pools were above normal.

Wind Field：For the month, at lower troposphere (850hPa), westerly anomalies covered the equatorial Pacific east of 160ºW, and easterly anomalies prevailed over the equatorial Pacific west of 160ºW. At upper troposphere (200hPa), weak westerly anomalies covered the most equatorial Pacific.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was 0.3, with a drop of 0.5 from last month.

Convections over the Tropics: During June 2010, the anomalous Outgoing Longwave Radiation (OLR) showed that suppressed convection was observed over the western tropical Pacific and the vicinity of Philippines, enhanced convection was observed over Indonesia. In the lower troposphere (850hPa) divergent wind field, a convergent center was around 115ºE, 15ºN, and a divergent center was near 90ºW, 25ºS. At the upper troposphere (200hPa), the corresponding divergent and convergent centers were near 115ºE, 10Nº and 105ºW, 25ºS, respectively.

ENSO Monitoring and Outlook

Monitoring showed that during June 2010, SSTs were below normal in most central and eastern equatorial Pacific. Anomalously cold subsurface water controlled most of the equatorial central and eastern Pacific. Meanwhile, it enhanced significantly, shifted eastward and uplifted obviously, with central values below -4℃. SOI was positive for past three consecutive months. All above tropical atmosphere and ocean features were favorable for a quick transition to La Niña conditions. Meanwhile, most statistical and dynamic climate models predicted La Niña conditions were expected to occur in 1-2months and to continue till early 2011.

Aforementioned analysis indicates that the tropical Pacific features a transition to cold conditions in June. SSTs in the central and eastern equatorial Pacific will continue to decrease in 3 months and La Niña conditions are likely to develop during July-August. Therefore, we will closely monitor the development of ENSO conditions and update our ENSO wrap-up in time.