1. Climate in China

In November 2014, the surface air temperature averaged was 3.9ºC in China, which was 1.0ºC above normal (2.9ºC). The mean precipitation was 22.6 mm in China, which was 20.2% more than normal (18.8mm). For the month, extremes of Daily Temperature Drop (DTD) were observed in China.

2. General Circulation Features

Northern Hemisphere: During November 2014, in the 500hPa geopotential height anomaly field, positive anomalies above 4 dam covered the regions from the Greenland Sea to most Europe, the regions from the northeastern Pacific Ocean to parts of the Arctic Ocean via Alaska, the central North Atlantic, with central values above 16 dam in locations of the Arctic Ocean and northwestern Europe. Meanwhile, negative anomalies below -4 dam covered the regions from northeastern North America to northwestern Europe via the northern Atlantic Ocean, regions from central and western Siberia to northeastern Central Asia, the central North Pacific Ocean, with central values below -12 dam in locations. For the month, the northwestern Pacific subtropical high was stronger than normal with its area larger than normal, and its position shifted further westward and southward than normal.

Southern Hemisphere: For the month, in the 500hPa geopotential height anomaly field, positive anomalies above 4 dam were observed over the central and eastern South Atlantic Ocean, the regions from mid-southern South Pacific Ocean to parts of the Antarctica and southeastern Australia. Meanwhile, negative anomalies below -4 dam were observed over southwestern South Atlantic Ocean, the South Indian Ocean, parts of the southwestern and southeastern South Pacific Ocean.

3. Tropical Features

Sea Surface Temperatures (SSTs): In November 2014, SSTs were over 0.5℃ above normal in most of the central and eastern equatorial Pacific, especially above 1℃ in some parts. Indices of Niño1+2，Niño3，Niño4，Niño3.4 and Niño Z were 0.7℃，0.9℃，0.9℃，0.8℃ and 0.9℃, respectively. The Sea Surface Temperature (SSTA) in was above the normal in the equatorial Indian Ocean. The Basin-Wide SSTA variation in the Indian Ocean (IOBW) has kept in the persistent positive phase, with SSTs above normal in the southern Indian Ocean. The IOBW index was 0.3℃. Compared with October, the positive phase of North Atlantic sea surface temperature has developed significantly.

Subsurface Temperatures: In November, anomalously warm subsurface water shifted eastward to the east of the dateline, with the warm center located around 150°W, and the central values was above 3℃. The anomalously cold subsurface water in the eastern equatorial Pacific withdrew eastward, but developed towards the surface, with the cold center located around 100°W, and the central values was below -2℃.

Warm Pools: For the month, the areas of both the Indian Ocean and the western Pacific warm pools were larger than normal, and their intensities were both above normal.

Wind Field: For the month, at lower troposphere (850hPa), westerly anomalies dominated over most equatorial eastern Pacific, with central values above 8 m/s. And the equatorial western Pacific was controlled by easterly anomalies, with central values below -4 m/s. At upper troposphere (200hPa), westerly anomalies prevailed over the equatorial western Indian Ocean, the Maritime Continent and the coastal areas of South America, with central values above 4 m/s. Meanwhile, the equatorial central-eastern Pacific was controlled by easterly anomalies, with central values below -8 m/s.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was -0.7.

Convections over the Tropics: During November 2014, the anomalous outgoing longwave radiation (OLR) showed that convections were active around the equatorial Indian Ocean and western Australia, with central values below -15W/m². However, convections were suppressed near the Maritime Continent and the equatorial western Pacific, with central values above 15W/m².

4. ENSO Monitoring and Outlook

At present, positive equatorial sea surface temperature anomalies have persisted across most of the central and eastern Pacific Ocean. Recently, positive subsurface anomalies in the central Pacific have weakened, and westerly wind anomalies have weakened over the eastern equatorial Pacific. Based on models’ prediction and trend diagnoses of the oceanic variations, the El Nino event will reach a peak on the coming winter and may come to an end in spring/summer 2015.

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