Monthly Highlights

Climate in China

During March 2010, monthly mean surface air temperatures were 2-4℃ above normal in southern Xinjiang, most of Tibet, western Qinghai, eastern Yunan, southwestern Guizhou and northwestern Guangxi. Meanwhile, temperatures were observed 2-4℃ below normal in most of Northeast China, northern North China, eastern Inner Mongolia and northern Xinjiang, with at least 4℃ below normal in locations.

For the month, precipitations were observed 50-200% more than normal in western Northwest China, most of Northeast and North China, the eastern Huanghuai area, the southwestern Jianghuai area, the northeastern Jiangnan area, southeastern Inner Mongolia，northwestern and southeastern Tibet and western Sichuan, with precipitations at least 200% more than normal in locations. Meanwhile, precipitations were observed 50-80% less than normal in South China and southwestern Guizhou, northern and eastern Yunnan, southern Sichuan, central and northeastern Tibet, southern and eastern Qinghai, Ningxia, western and northeastern Inner Mongolia, and northwestern Heilongjiang, with precipitations at least 80% less than normal in locations.   

    For the month, extreme daily drop of temperature was observed in 18 stations of Fujian, Guangdong, Guizhou, Yunnan, Qinghai and so on, with drops of 14-23℃ in general and broking the historical records in Zhangping station (18.8℃), Jiuxianshan (22.7℃) of Fujian, Heping station of Guangdong (20.9℃), Sansui station of Guizhou (17.8℃) and Yiliang station of Yunnan (14.3℃). During the middle and late March, the number of consecutive precipitation days in 38 stations of northern Xinjiang and most part of Jianghuai exceeded the 95th percentile thresholds and 9 of them broke historical records.

Climate in the World

During March 2010, temperatures were 1-4℃ above normal in central and northern North America, northwestern Africa, West Asia, Central Asia, most of South Asia, southern East Asia, northern central Russia and most of South America, with temperatures at least 8℃ above normal in locations. Meanwhile, temperatures were 1-4℃ below normal in southeastern North America, southern central and parts of northwestern Russia, central and eastern East Asia and northeastern Australia, with temperatures 4-6℃ below normal in locations.

For the month, precipitations were observed at least 50% more than normal in northwestern and parts of southwestern North America, most of Central Asia, western and northeastern East Asia, parts of southwestern and southeastern Europe, the Far East Russia, central Africa, southeastern Australia and parts of central South America, with precipitations at least 100% more than normal in locations. Meanwhile, precipitations were at least 50% less than normal in northwestern, northeastern and parts of southwestern North America, parts of Europe, most of West Africa, West Asia, South Asia, central Russia, South China, central and western Australia and northwestern South America, with no precipitation in parts of above regions.

General Circulation Features

Northern Hemisphere: During March 2010, the mean 500hPa geopotential height field exhibited a 3-wave pattern at the mid-high latitudes. In the 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered regions from the eastern North Atlantic Ocean to the western East Asia and the central North Pacific in the latitudes of 20-40ºN, regions from northern North America to the polar regions, with central values above 12 dam in the polar regions and the central North Pacific. Meanwhile, negative anomalies below -4 dam covered regions from the southeastern North America to the western coasts of the Mediterranean, the central and eastern Europe via Baikal Lake to the northeastern North Pacific, with central values below -12 dam in eastern Europe and the northeastern North Pacific. For the month, the Northwest Pacific subtropical high (NWPSH) was larger and stronger. It was located northward than normal and extended abnormally westward.

Southern Hemisphere: During March 2010, zonal circulation prevailed in the mean 500hPa geopotential height field. In the 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered most of Antarctica, the central South Pacific and the sea south of Australia, with central values above 8 dam in Antarctica and the central South Pacific. Meanwhile, negative anomalies below -4 dam covered the central Indian Ocean and the southwestern and parts of the southeastern South Pacific.

Tropical Features

Sea Surface Temperatures (SSTs): During March 2010, above 0.5℃ positive SST anomalies dominated the most central and eastern equatorial Pacific. The positive anomaly center was located in the central equatorial Pacific, with maximum above 1.5℃. Indices of NINO 1+2, NINO 3 and NINO 3.4 were -0.2℃, 0.6℃ and 1.1℃, with drops of 0.3℃, 0.2℃ and 0.2℃from last month, respectively. Indices of NINO 4 and NINO Z were 1.1℃ and 0.8℃ respectively, the same as ones last month.

Subsurface Temperatures: During March 2010, anomalously warm subsurface water dominated the central and eastern equatorial Pacific. Its positive centers shifted eastward slightly and strengthened. Meanwhile, the west board of anomalously cold subsurface water which controlled the equatorial Pacific west of the date line enlarged eastward.

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

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

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was -0.7, with a rise of 0.5 from last month.

Convections over the Tropics: During March 2010, the anomalous Outgoing Long wave Radiation (OLR) showed that convections were enhanced over the mid-eastern equatorial Pacific, while convections were suppressed over the most maritime continent. In the lower troposphere (850hPa) divergent wind field, a convergent center was at near 145ºE, 5ºS, and a divergent center was near 90ºW, 25^oS over the tropical Pacific. At the upper troposphere (200hPa), the corresponding divergent and convergent centers were near 175ºE, 5ºS and 90ºW, 20ºS, respectively.

ENSO Monitoring and Outlook

 Monitoring showed that SST anomalies were more than 0.5℃ in most of the central and eastern equatorial Pacific during March 2010 and index of NINO Z was the same value as last month, but NINO indices decreased on the whole. Most statistical and dynamic climate models predicted that El Niño will continue to weaken in 1-2 months and return to ENSO-neutral conditions by Northern Hemisphere summer 2010.

Aforementioned analysis indicates that El Niño condition will end in the 1-2 months and transit to ENSO-neutral conditions by Northern Hemisphere summer 2010. We will closely monitor development of ENSO conditions and update ENSO monitoring and forecast in time.