Highlights

General Circulation Features

Northern Hemisphere

During November, the mean 500hPa geopotential height field exhibited a 4-wave pattern at mid-high latitudes. The polar vortex was weaker than normal. Correspondingly, positive anomalies covered the most of Europe, Taymyr Peninsula and northern North Pacific, with center values above 16 dam over the northern Europe and central North Pacific. Meanwhile, negative anomalies below –8 dam controlled the regions of northern North Atlantic. In this month, Northern Hemisphere subtropical high was obviously stronger than normal, and the Northwest Pacific subtropical high was also stronger than normal and extended westward remarkably.

Southern Hemisphere

In the mean 500hPa geopotential height field during November, zonal circulation dominated the mid-high latitudes. In the height anomaly field, positive anomalies dominated the regions between the southeastern South Pacific and Australia. Negative height anomalies below –4 dam were observed over the southwestern South Atlantic, southwestern South Pacific and central Antarctica.

Climate for China

During November, the mean surface air temperatures were 1~3℃ below normal in the northern most Northeast China and northern most Xinjiang. In the rest regions, the monthly mean surface air temperatures were near or above normal, with 1~3℃above-normal observed in southern Xinjiang, Tibet, Qinghai, southeastern Northeast China and coast of southeast China. In this month, rainfall totals were observed more than normal in the northern and less than normal in the southern of China. The rainfall totals were 100% above normal in the regions such as western Xinjiang, western Gansu, northern Shanxi, most of North China, western Shandong and northwestern Northeast China. Meanwhile, rainfall totals were 80% below normal in the southern Tibet, most of Yunnan and southwestern Guangxi.

Tropical Features

Sea Surface Temperatures(SSTs)

During November, above 0.5℃ positive SST anomalies remained in the most of the equatorial Pacific. SST anomalies enhanced around dateline, with center values above 1.5℃. Correspondingly, the SST indices of NINO 4, NINO 3 and NINO 1+2 regions were 0.9℃, 0.4℃ and 0.3℃, respectively. In addition, positive anomalies around 0.5°C controlled the east-central equatorial India Ocean.

Circulation

Wind Field

In this month, at the lower troposphere (850hPa), weak westerly anomalies about 2~4 m/s mainly covered the western and eastern equatorial Pacific. Weak easterly anomalies dominated the regions nearby dateline and offshore of South America. At the upper troposphere (200hPa), easterly anomalies of 4~8 m/s controlled east-central equatorial Pacific.

Southern Oscillation

During November, the Southern Oscillation Index was -0.4.

Convection over the Tropics

During November, the anomalous outgoing longwave radiation (OLR) distribution exhibited that enhanced convection located the regions east to Indonesia and suppressed convection were nearby the dateline over the equatorial Pacific. In the lower troposphere (850hPa) divergent wind field, the convergent center was nearby 165°E, equatorial, and the divergent center was around 110°W, 12.5°S. Correspondingly, the divergent and convergent centers at the upper troposphere (200hPa) were over 165°E, 2.5°S and around 115°W, 15°S, respectively.