1. Climate in China

In June 2015, the surface air temperature averaged over China was -20.3ºC, with 0.3ºC above normal (20.0ºC). The mean precipitation was 104.8 mm over China, which was 5.5% more than normal (99.3mm). For the month, extremes of Daily Precipitation (DP) and High Temperature (HT) were observed in China.

2. General Circulation Features

Northern Hemisphere: During June 2015, in the field of mean 500hPa geopotential height anomaly, positive anomalies above 4 dam covered West Europe, western Siberia, part of central North Pacific Ocean and western North America. Meanwhile, negative anomalies below -4 dam covered Barents Sea, part of northeastern Pacific. During the month, the northwestern 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 over 4 dam were observed over southwestern Pacific, southeastern Indian Ocean and southern Atlantic Ocean. Meanwhile, negative anomalies below -4 dam covered Antarctica and southeastern Pacific.

3. Tropical Features

Sea Surface Temperatures (SSTs): In June 2015, SSTs were over 0.5℃ above normal in most of the central and eastern equatorial Pacific, especially above 1.5℃ in some locations. Indices of Niño1+2，Niño3，Niño4，Niño3.4 and Niño Z were 2.5℃，1.7℃，1.1℃，1.3℃ and 1.5℃, respectively. The Indian Ocean Basin-Wide SSTA variation index (IOBW) was 0.5. The North Atlantic Triple (NAT) index was 1.9 and kept in the persistent positive phase.

Subsurface Temperatures: In June, the anomalously warm subsurface water shifted eastward to the region around 100°W, with the central values above 6℃. Meanwhile, the anomalously cool subsurface water controlled the equatorial western Pacific, with the central value 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), the westerly anomalies dominated over most equatorial Pacific and western equatorial Indian Ocean, while the easterly anomalies dominated over eastern equatorial Indian Ocean. At upper troposphere (200hPa), the westerly anomalies prevailed over the region from the eastern equatorial Indian Ocean to western equatorial Pacific, while the easterly anomalies were observed over most of the central-eastern equatorial Pacific.

Southern Oscillation: For the month, the Southern Oscillation Index (SOI) was -0.9.

Convections over the Tropics: During June 2015, the anomalous outgoing longwave radiation (OLR) showed that convections were active around the tropical Pacific, with central values below -30 W/m². However, convections were suppressed around the South China Sea, and the tropical eastern Indian Ocean.

4. ENSO Monitoring and Outlook

The equatorial SST in the east-central Pacific was expected increased in the next month. There is a great chance that a strong El Nino will continue through Northern Hemisphere winter of 2015/2016.

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