Monthly Highlights

Climate in China

During March, monthly mean surface air temperatures were observed 1℃ above normal in western China, with more than 4℃ above normal in northern Xinjiang. While temperatures were found near or below normal in the remainder region of China. Negative anomalies between -1℃ and -2℃ were observed in eastern Gilin, eastern Liaoning ,southern South China, Guangxi, western Guizhou and eastern Yunnan. For the month, precipitations were found 30-200% more than average in Yunnan, central and eastern Xizang, Qinghai, Gansu, western Xinjiang and parts of northern Northeast China, while precipitations were observed more than 30% below average in central and southern Northeast China, most of North China and the middle and lower reaches of Yangtze Rive, with more than 80% below average in southern Northeast China, most of North China and central Xinjiang.

Climate in the World

During March, monthly mean surface air temperatures were more than 1℃ above normal in most of Asia, northwestern North America, northwestern Africa, most of Australia and central and northern South America, with 4-6℃ above normal in Kazakstan and north Xinjiang of China, northwestern North America. While temperatures were found more than 1℃ below normal in most of Europe, IndoChina Peninsula, eastern and southern United States, with 4-6℃ below normal in northeastern Europe.

During March, precipitations were observed more than 30% above average in eastern Europe, western and northern Russia, western Asia, northern India, the central and western China, IndoChina Peninsula, northwestern North America, parts of South America, with more than 200% above average in east of West Africa, western Russia, southern West Asia, northern South Asia to Qing-Zang Plateau, parts of northeastern South America. Meanwhile, precipitations were found 30-100% below average in the western and southern Europe, central and southern Russia, Mongolia, most of northern China, southern South Asia, most of Australia, central and eastern America, central South America.

General Circulation Features

Northern Hemisphere: During March, the mean 500hPa geopotential height field exhibited a 4-wave pattern at the mid-high latitudes. Troughs developed abnormally over North America, Europe, East Asia and the North Pacific. In the height anomaly field, the regions from Baikal to Lake Balkash and the northern North Atlantic at mid-high latitudes were covered by positive anomalies, with central values above 8 dam over the north of North Atlantic Ocean. The central North Atlantic, East Europe, the central and northern North Pacific and Sea of Japan were covered by negative anomalies below -4 dam, with central values below -16 dam over the central North Atlantic and East Europe. For the month, subtropical high in northern hemisphere and the Northwest Pacific subtropical high were larger and stronger than normal.

Southern Hemisphere: During March at the mean 500hPa geopotential height field, zonal circulation prevailed over the mid-high latitudes. Negative anomalies below -4 dam covered southeastern South Pacific and the southern South Indian Ocean. Meanwhile, positive anomalies above 4 dam covered the central South Pacific and south to Australia to polar region.

Tropical Features

Sea Surface Temperatures (SSTs): During March, above 0.5－1.0℃ SST anomalies still dominated the central equatorial Pacific and the equatorial Indian Ocean; Meanwhile, below -0.5℃ SST anomalies controlled the eastern equatorial Pacific east to 120°W; South China Sea was controlled by SST anomalies below -0.5℃ .The indices of NINO Z , NINO 4 were 0.2℃, 0.8℃, respectively. NINO1+2 were -0.8℃, with decreases 0.3℃from last month. NINO3 was - 0.1℃, which ascended 0.1℃ compared with last month.

Subsurface Temperatures: During March, the abnormally warm water enhanced, extended eastward and upward in the central equatorial Pacific. The abnormally cold water enhanced and shrank in the eastern equatorial Pacific, while the abnormally cold water in the eastern equatorial Pacific enhanced.

Warm Pools: During March, the areas of the western equatorial Pacific warm pool and the equatorial Indian Ocean warm pool were larger than normal, while the intensities were stronger than normal.

Wind Field：During March, at the lower troposphere (850hPa), 2-6m/s westerly anomalies controlled most of the Eastern Equatorial Pacific, weak easterly anomalies controlled the western equatorial Indian Ocean. At the upper troposphere (200hPa), easterly anomalies above 4m/s controlled the equatorial Pacific east to the dateline, and westerly anomalies controlled the western equatorial Pacific and the equatorial Indian Ocean.

Southern Oscillation：During March, the Southern Oscillation Index (SOI) was 0.3,with a increase of 2.7 since last month.

Convection over the Tropics: For the month, the anomalous outgoing longwave radiation (OLR) was near normal over the equatorial Pacific and the equatorial Indian Ocean. In the lower troposphere (850hPa) divergent wind field, a convergent center was near 145°E, 5°S and a divergent center was over the equator at 110ºW. Correspondingly, at the upper troposphere (200hPa), a divergent center was near 150°E, 5°S and a convergent center was observed over the equator at 120ºW.

ENSO Monitoring and Forecasting

①  During March, above 0.5℃ SST anomalies dominated the central equatorial Pacific. Anomalies below -0.5℃ controlled the eastern equatorial Pacific. SSTa indices of NINO Z and NINO 3 were near normal.

②   The abnormally warm water enhanced and extent eastward in the central equatorial Pacific. The abnormally cold water shrank in the eastern equatorial Pacific and the abnormally cold water enhanced in the western equatorial Pacific

③   The Southern Oscillation Index (SOI) was near normal with value 0.3.

④ At the lower troposphere (850hPa), westerly anomalies controlled the eastern equatorial Pacific. The convections along the equator were near normal.

⑤ Results of some statistical models for ENSO show that SSTa index for NINO3 will be near normal in the near futurefollowing months.

Above results show that the tropical atmospheric and oceanic conditions were near normal during March. The evolution will continue to be monitored continuously.