1. Climate in China

In November 2015, the surface air temperature averaged over China was 4.1ºC, with 1.2ºC above normal (2.9ºC). The mean precipitation was 39.4 mm over China, which was 110.0% more than normal (18.8mm). For the month, extremes of Daily Temperature Drop (DTD), Consecutive Temperature Drop (CTD) and Consecutive Precipitation Days (CPD) were observed in China.

2. General Circulation Features

Northern Hemisphere: During November 2015, in the field of mean 500hPa geopotential height anomaly, positive anomalies above 4 dam covered the regions from Mid-latitudes of the eastern North Atlantic to the mid-western Europe, from the northeastern Eurasian continent to the central-northern North Pacific, and the southeastern North America, with central values above 12 dam over the northern Siberia and the northeastern North Pacific. Meanwhile, negative anomalies below -4 dam covered most of Central Asia to the north of the Lake Balkhash, most of the polar region in the Western Hemisphere, and the northwestern North America, with central values below -8 dam in the Greenland Sea, the Chukchi Sea, and the Bering Strait. For the month, the Northwest Pacific subtropical high was stronger than normal, with the area larger than normal. The position of its west ridge shifted further westward than normal.

Southern Hemisphere: For the month, in the field of mean 500hPa geopotential height anomaly, positive anomalies above 4 dam were observed over the southeastern South Pacific, and parts of the northwestern Antarctica. Meanwhile, negative anomalies below -4 dam covered most of the Antarctic and the southwestern South Indian Ocean.

3. Tropical Features

Sea Surface Temperatures (SSTs): In November 2015, SSTs were over 0.5℃ above normal in most of the central and eastern equatorial Pacific, with SSTs 3.5℃above normal around the eastern equatorial Pacific. Indices of Niño1+2，Niño3，Niño4，Niño3.4 and Niño Z were 2.0℃，2.9℃，1.7℃，2.9℃ and 2.3℃, respectively. The Indian Ocean Basin-Wide SSTA variation index (IOBW) was 0.6 and the Indian Ocean Dipole (IOD) index was 0.8. The North Atlantic Triple (NAT) index was 1.0.

Subsurface Temperatures: In the month, the anomalously warm subsurface water located at the central-eastern equatorial Pacific, with the central values above 3.0℃. Meanwhile, the anomalously cool subsurface water controlled  the far eastern equatorial Pacific, with the central value below -1℃.

Warm Pools: For the month, the areas of both the Indian Ocean and the western Pacific warm pools were much larger than normal. Meanwhile, the intensity was above normal in the Indian Ocean and was slightly above normal in the western Pacific Ocean.

Wind Field: For the month, at lower troposphere (850hPa), the westerly anomalies dominated over most of the central and eastern equatorial Pacific, while the easterly anomalies dominated over regions from the most equatorial Indian Ocean to the Maritime continent. At upper troposphere (200hPa), the easterly anomalies prevailed over the central and eastern equatorial Pacific Ocean, while the westerly anomalies were observed over most of the Maritime continent.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was -0.4.

Convections over the Tropics: During the month, the anomalous outgoing longwave radiation (OLR) showed that convections were active over the central equatorial Pacific region, with central values below -45W/m². However, convections were suppressed over the western equatorial Pacific.

4. ENSO Monitoring and Outlook

With the continuous and strong warming over the eastern and central Pacific, the anomalies of both tropical atmospheric and oceanic circulation are well coupled and show a clear El Nino - South Oscillation pattern. The positive heat content anomaly of equatorial upper-ocean began to decrease since early November, accompanied with the eastward propagation of the down-welling Kelvin wave going to the end. The present El Nino event may have reached its peak in November 2015 and may begin to decay from January 2016. The event may last through the boreal spring of 2016.

Therefore, we will closely monitor the development of ENSO conditions and update our ENSO wrap-up in time.