Monthly Highlights

1. Climate in China

During November 2005, monthly mean surface air temperatures were above or near normal in most China, and they were 1~2℃ above normal in eastern China, central Tibet and parts of Xinjiang, with 2~4℃ above normal in most of eastern China. For the month, precipitations were 50~200% more than average in most of Jiangnan, northern Heilongjiang, northen Xinjiang, southwestern An’hui, eastern Hubei, with 100~200% more than average in parts of above regions. Meanwhile, precipitations were 30~80% less than normal in eastern and southern Northeast China, Inner Mongolia, North China, north parts of the regions between Yellow River valley and Huaihe River valley, most of Northwest China, most of Southwest China and Guangdong, and no rainfalls were observed in parts of above regions.

2. Climate in the World

During November 2005, monthly mean surface air temperatures were 1~2℃ below normal in West Europe, South Europe, southern East Europe, northwestern America, southern South America and offshore of western Australia, with 2~6℃ below normal in Alaska. Meanwhile, temperatures were near or above normal in the rest areas, with 2~6℃ above normal in east half of China, most of Russia, northern Mongolia, northeastern Kazakhstan, most of North Europe, west half of America, western Canada, eastern Australia, northern Argentina and central Algeria, with 6~8℃ above normal in parts of Siberia.

During November 2005, total rainfalls were observed more than 50% above normal in Southeast China, parts of Northwest China, parts of Russia, offshore of northern Europe, the region from East Europe to Asia Minor, northern America, Northern Territory in Australia and offshore of the east, Venezuela, southern Brazil, southern Argentina, with 200% above normal in parts of above regions. Precipitations were observed near or below normal in the remainder of the world, with 30~80% below normal in most of China, India, the western Siberia of Russia and its west, parts of West Europe, Alaska, southern America, northern Mexico, western Africa, most of Australia, eastern Brazil, parts of northern Argentina, and no rainfalls were observed in parts of above regions.

3. General Circulation Features

Northern Hemisphere: During November 2005, the mean 500hPa geopotential height field exhibited a 4-wave pattern at the mid-high latitudes, and the polar vortex was weaker than normal. In the 500hPa height anomaly field, positive anomalies above 4 dam dominated the northern North Atlantic, the region from Ural to Far East, the northern North Pacific, and positive anomalies were above 20 dam over Kamchatka. Meanwhile, negative anomalies below -4 dam were observed over the Northwestern Pacific, Alaska, nearby South Europe. For the month, the Northwest Pacific subtropical high was stronger than normal and extended westward compared with normal position.

Southern Hemisphere: During November 2005, zonal circulation prevailed over mid-high latitudes in the mean 500hPa geopotential height field. Negative anomalies below -4 dam were observed over the southwestern South Atlantic, the southeastern South Pacific, the southeastern South Indian Ocean, and parts of Antarctica. Meanwhile, heights were near or above normal over the rest of the mid-high latitudes.

4. Tropical Features

Sea surface temperatures (SSTs): During November 2005, SSTs were found above normal in the central and western equatorial Pacific, with maximums of SST anomalies above 0.5℃. Meanwhile, negative SST anomalies below -0.5℃ were observed in the eastern equatorial Pacific and the offshore of South America. Weak positive anomalies were over the equatorial Indian Ocean. The index of NINO 1＋2 was -1.0℃, with increase of 0.2℃ compared with last month; NINO 3, NINO 4, NINO 3.4 and NINO Z were -0.7℃, 0.3℃, -0.2℃ and -0.3℃, with drops of 0.5℃, 0.2℃, 0.4℃ and 0.3℃ respectively compared with last month.

Subsurface Temperatures: For the month, abnormal subsurface cold water in the equatorial Pacific enlarged and strengthened. Meanwhile, abnormal subsurface warm water maintained in the western equatorial Pacific.

Warm Pools: For the month, the area and the intensity of the western Pacific and Indian Ocean warm pool were larger and stronger than normal.

Wind Field：During November 2005, at the lower troposphere (850hPa), weak easterly anomalies were over most of equatorial Pacific, with central values below -4m/s near dateline. And westerly anomalies were found over the tropical Indian Ocean. At the upper troposphere (200hPa), zonal winds were near normal over most of the tropical Pacific.

Southern Oscillation: During November 2005, Southern Oscillation Index (SOI) was -0.3, and dropped 1.7 from last month.

Convection over the Tropics: For the month, the anomalous outgoing long wave radiation (OLR) showed that active convections were over the western tropical Pacific and suppressed convections were over the date line. In the lower troposphere (850hPa) divergent wind field, convergent centers were over nearby equator of 140°E, and a divergent center was around 110ºW, 5ºS. Correspondingly, at the upper troposphere (200hPa), divergent centers were found around equator of 140°E, and a convergent center was observed over nearby 110ºW, 10ºS.

5. ENSO Monitoring and Forecasting

① During November 2005, positive SST anomalies were observed in the central and western equatorial Pacific, with central values above 0.5℃. Negative SST anomalies below -0.5℃ were persistent in the eastern equatorial Pacific and offshore of South America. Indices of NINO1+2, NINO3, NINO4, NINO3.4, NINO Z were -1.0℃、-0.7℃、0.3℃、-0.2℃ and -0.3℃, respectively.

② During November 2005, abnormal subsurface cold water in the equatorial Pacific enlarged and strengthened. Meanwhile, abnormal subsurface warm water maintained in the western equatorial Pacific.

③ The Southern Oscillation Index (SOI) was -0.3 in November 2005, and dropped 1.7 from last month..

④ During November 2005, at the lower troposphere (850hPa), weak easterly anomalies were over most of the equatorial Pacific.

⑤ About half of ENSO models of NCC showed that SSTA index of NINO 3 could be near normal in the following 5 months.

Above results showed that weak cold phase of tropical oceanic appeared during November 2005 and such status could continue in the following 1~2 months. The air – sea conditions is monitored closely and any significant change is going to be reported.