Monthly Highlights

Climate in China

During June 2008, the monthly mean surface air temperatures were observed 1-2℃ above normal in most Northwest China, northern Northeast China, northeastern and western Inner Mongolia and northwestern Tibet, with temperatures 2-4℃ above normal in locations. Meanwhile, temperatures were 1-2℃ below normal in eastern North China, the eastern Huanghuai area and southern Northeast China. Temperatures were near normal in other regions of China.

For the month, precipitations were observed 30-100% more than normal in the eastern Jiangnan area, South China, southern Southwest China, most Tibet, North China, southern Northeast China and eastern Inner Mongolia, with precipitations at least 100% above normal in most Guangdong, eastern Guangxi, Tibet and parts of Inner Mongolia. Meanwhile, precipitations were observed 30-80% less than normal in most Northwest China, western Inner Mongolia, northern Northeast China, the Huanghuai area, the Jianghan area and the western Jiangnan area. Precipitations were near normal in other regions of China.

Climate in the World

During June 2008, the monthly mean surface air temperatures were observed 1-2℃ above normal in western and southern Europe, Siberia, Mongolia, northeastern and northwestern China, central Asia, eastern and southwestern America, eastern Canada, southern Argentina, eastern Australia and most West Africa, with temperatures 4℃ above normal in locations. Meanwhile, temperatures were 1-2℃ below normal in western Russia, eastern and southern China, most India, northwestern North America, northern Argentina and northwestern Australia. Temperatures were near normal in other regions of the world.

For the month, precipitations were observed 30-100% more than normal in parts of southern and northern Europe, most Siberia, southeastern and southwestern China, North China, northern India, Alaska, the regions from central to northeastern America, eastern Canada, northern and southeastern Brazil and eastern Australia, with precipitations at least 100% above normal in locations. Meanwhile, precipitations were observed 30-80% less than normal in eastern Europe, northern West Asia, central Asia, most northwestern China, the regions from northeastern China to southeastern Siberia, Pakistan, western and southern America, central Brazil, most Argentina, southern and northern Australia, northwestern Africa and Tanzania, with no precipitations in parts of above regions.

General Circulation Features

Northern Hemisphere: During June 2008, in the 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered the Far East of Russia, the northern North Pacific and the regions from northeastern North America to Greenland, with central values above 12 dam over northeastern North America. Meanwhile, negative anomalies below -4 dam covered western Russia, East Siberian Sea and central America (Fig.4). For the Northwest Pacific subtropical high (NWPSH), its area was larger and intensity was near normal, and it position was more eastward than normal.

Southern Hemisphere: For the month, in the 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered the oceans south of Africa, the regions from southern Australia to oceans south of Australia and the oceans between 20-40°S and 120-170°W, with central values above 12 dam over the oceans south of Africa. Meanwhile, negative anomalies below -4 dam covered the regions from the southern South Atlantic to parts of Antarctica and the oceans between 50-70°S and 165°E-120°W, with central values below -8 dam.

Tropical Features

Sea Surface Temperatures (SSTs): In June, negative SST anomalies remained over the central equatorial Pacific between 170ºE-160ºW with central value about -1.0℃, while positive SST anomalies mainly dominated the eastern equatorial Pacific. In June, indices of NINO 1+2, NINO 3, NINO 4, NINO 3.4 and NINO Z were 0.5℃, 0.1℃, -0.6℃, -0.3℃ and -0.1℃, with rises of 0.5℃, 0.1℃, 0.2℃, 0.3℃and 0.2℃ from last month, respectively. Meanwhile, SSTs in most of the equatorial Indian Ocean were near or slightly above normal.

Subsurface Temperatures: During June, anomalously cold subsurface water in the central equatorial Pacific further weakened in intensity and shrank in area obviously, while anomalously warm subsurface water in the eastern equatorial Pacific strengthened in intensity and expanded westward distinctly.

Warm Pools: During June, the area of the western Pacific warm pool was near normal and the intensity was slightly below normal. Meanwhile, the Indian Ocean warm pool showed a near normal area and a slightly weaker-than-normal intensity.

Wind Field：For the month, at lower troposphere (850hPa), easterly anomalies covered the central equatorial Pacific between 150ºE-160ºW, with the maximum above 4m/s, while weak westerly anomalies prevailed over the eastern equatorial Pacific. At upper troposphere (200hPa), over the equatorial Pacific, the zonal winds were near normal.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was 0.3, with a rise of 0.6 from last month.

Convections over the Tropics: During June, the anomalous outgoing long wave radiation (OLR) showed that convection was near normal over the western and central equatorial Pacific. For the tropical Pacific, in the divergent wind field at lower troposphere (850hPa), a convergent center and a divergent center were observed over 115ºE, 25º N and 90ºW, 20ºS, respectively. Correspondingly, at upper troposphere (200hPa), the divergent center was over 120ºE, 20º N, and the divergent center was over 110ºW, 20ºS.

ENSO Monitoring and Prediction

(1) During June 2008, the central and eastern equatorial Pacific warmed up across the whole region in anomaly SST field, with NINO Z index being -0.1℃, showing a neutral condition in the tropical Pacific.

(2) For the month, the anomalously cold subsurface water in the central equatorial Pacific weakened in intensity and shrank in area obviously, while the anomalously warm subsurface water in the eastern equatorial Pacific enhanced.

(3) Southern Oscillation Index (SOI) was 0.3.

(4) At lower troposphere (850hPa), the easterly anomalies weakened over the central equatorial Pacific.

(5) Convection was near normal over the western and central equatorial Pacific.

(6) Most ENSO models predicted that a neutral condition in the central and eastern equatorial Pacific would maintain during the subsequent 2 months.

During June, the oceanic and atmospheric status showed neutral conditions in the equatorial Pacific, and the conditions may continue in the subsequent 2 months.