1.Climate in China
During June,
averaged temperature in China was obviously higher than normal. Monthly mean
surface air temperatures were above or near normal in most of China. Anomalies
about 2~4℃
were in the mid-lower reaches of the Yangtze River, regions between the
mid-lower reaches of Yangtze River and the Yellow River, western North China,
eastern Northwest China and west-central Inner Mongolia and eastern Heilongjiang.
For the month, precipitations were 30~100% above average in most of South China,
northern parts of region between the Yellow River and the Huaihe River, regions
from eastern North China to central Northeast China and northern Xinjiang.
Precipitations were below or near average in the rest of China, with more than
50% below average in mid-lower reaches of the Yangtze River, most of Northwest
China, west-central Inner Mongolia, most of Tibet and eastern Heilongjiang and
no rainfall was in parts of above regions.
2. Climate
in the World
During
June, monthly mean surface air temperatures were above or near normal in the
world except in southeastern Europe, western Africa and western North America.
Anomalies more than 2℃
were in southwestern Europe, north-central Russia, eastern
Mongolia, north-central and eastern China, western Africa, northeastern U.S. and
central South America, with maximum above 4℃
in parts of Northern Russia.
During June, precipitations percentage anomalies exhibited zonal pattern in Eurasia. A wet belt was from southeastern Europe to Kamchatka via Kazakstan and southern Russia where precipitations were more than 50% above normal. One dry belt was from northeastern Europe to Bering Sea via northern Russia, and the other was from southwestern Europe to western China and Mongolia via middle Asia. Precipitations percentage anomalies above 50% were in western Africa, western North America, southwestern South America and east-central Australia. Meanwhile, precipitations were 50～100% below average in southern North America, middle South America and parts of western Australia.
3.
General Circulation Features
Northern Hemisphere: During June, the mean
500hPa geopotential height field exhibited a 5-wave pattern at the mid-high
latitudes. In the height anomaly field, positive anomalies above 4 dam were over
Polar Region, Western Europe, northeastern North America and the northeastern
Pacific with central value above 12 dam in the Polar Region. Negative anomalies
below -4 dam were over the central North Atlantic, western North America and Far
East in Russia. For the month, subtropical high in northern hemisphere and the
Northwest Pacific were larger and stronger than normal. Western subtropical high
in the Northwest Pacific was more southern than normal.
Southern Hemisphere:
During June, the mean 500hPa
geopotential height field exhibited a 3-wave pattern at the mid-high latitudes.
In the height anomaly field, negative anomalies below -4 dam were over the
eastern South Pacific, southwestern Australia and sea south to Africa.
Meanwhile, positive anomalies above 4 dam covered the Polar Region and western
South Atlantic, with maximum above 20 dam in the polar region.
4. Tropical
Features
Sea
Surface Temperatures (SSTs): During June, positive SST anomalies above 0.5℃ dominated most of the east-central equatorial
Pacific and the equatorial India Ocean. SST anomalies below -0.5℃ were over the sea nearby South
America. Compared with last month, SSTA Index of NINO1+2 decreased obviously
from 0.1 to -0.6. The indices of NINO 3, NINO4 and NINO Z were 0.4℃, 0.5℃ and 0.4℃,
same with last month. NINO3.4 was 0.6℃,
which increased 0.2 from last month.
Subsurface
Temperatures: During June, weak positive anomalies of subsurface SST remained in the
western and central Pacific while abnormally subsurface cold water in the
western Pacific enhanced and shifted westward.
Warm
Pools: During June, the areas of warm pool in the western Pacific and in the
Indian Ocean were larger than normal, and the intensities were both stronger
than normal.
Wind Field：During June, at the lower troposphere (850hPa), westerly anomalies were over most of the east-central equatorial Pacific and zonal winds over other equatorial regions were near normal. At the upper troposphere (200hPa), easterly anomalies were over most of the east-central equatorial Pacific and zonal winds over the western Pacific and the India Ocean were near normal.
Southern Oscillation: During June, Southern Oscillation Index (SOI) was 0.4, and increased 1.5 from last month.
Convection
over the Tropics: For the month, the anomalous outgoing longwave radiation (OLR) showed that
active convections were over eastern India Ocean and suppressed convections were
over western Pacific. In the lower troposphere (850hPa) divergent wind
field, no convergent center was over tropical Pacific, and a divergent center
was over near 115ºW, 10ºS.
Correspondingly, at the upper troposphere (200hPa), a divergent center was over
South China Sea and a convergent center was observed over 130ºW,
12.5ºS.
5. ENSO
Monitoring and Forecasting
①
During
June, positive SST anomalies about 0.5℃ dominated most of the east-central equatorial
Pacific and the equatorial India Ocean. Compared with last month, SSTA in
NINO1+2 decreased sharply, SSTA
in NINO3, NINO4 and NINOZ remained and SSTA in NINO3.4 increased 0.2 slightly.
② Weak
Positive anomalies of subsurface SST in western and central Pacific and abnormally
subsurface cold water in eastern Pacific enhanced and shifted westward.
③ The Southern Oscillation Index (SOI) was 0.4
in June and fluctuated during past months.
④
At the lower troposphere
(850hPa), westerly anomalies near normal in the western equatorial Pacific. The
convections were suppressed in the western tropical Pacific.
⑤
Forecasts of most statistical and coupled model for ENSO show
that SSTA index for NINO3 will be near normal in the following months.
Above results show generally tropical atmospheric and oceanic conditions were near normal in June and ENSO cycle will likely be neutral in following months. The evolution will be monitored continuously.