1. Features of climate system since 2016 winter签发
Zunya Wang, Yongguang Wang, Yuan Yuan
National Climate Center, CMA

2. Contents Circulations and East Asian winter monsoon SST Snow cover
Sea ice

3. 500-hPa geo-potential height anomalies
Winter of 2016/2017
3-wave pattern is obvious, with the deep troughs over northern North America, central northern Pacific and Europe.
Deep trough is over the Ural mountain and high ridge covers most of Asia. The straight and smooth airflows prevail over mid-high latitudes of Asia.

4. Positive phase of AO continued. Weak trough controlled most East Asia.
After Mar. 1, 2017
Positive phase of AO continued.
Weak trough controlled most East Asia.
East Asian major trough intensified.

5. AO and blocking Blocking Positive phase of AO dominated.
AO持续正位相，改为AO以正位相为主；增加AAO，最好有指数曲线，不然用环流距平
Positive phase of AO dominated.
Ural blocking was inactive, while Okhotsk blocking was active periodically.

6. 500-hPa geo-potential height anomalies over southern hemisphere
AAO
500-hPa geo-potential height anomalies over southern hemisphere
AAO maintained negative phase during winter and turned to positive phase after early March.

7. Western Pacific subtropical high
Winter of 2016/2017
Intensity
After Mar. 1, 2017
Western position of the ridge

8. The weakest in recent 10 years
Siberian high is weaker than normal
Intensity index of Siberian high
The weakest in recent 10 years

9. Weak southerly anomalies are observed. Cold air is not so active.
850-hPa wind anomalies
Less cold air activities A C
Weak southerly anomalies are observed.
Cold air is not so active.
Winter meridional wind averaged over eastern East Asia
at 850 hPa level

10. Intensity index of East Asian winter monsoon
Intensity of EAWM ranks the weakest in recent 10 years
Intensity index of East Asian winter monsoon
（1951/ /2017）

11. Surface air temperature anomalies during 2016 winter
我拿到服务室的一个材料，冬温-1.5度，偏高1.9度
Most parts of the whole world were warmer than normal；
1-3℃ higher than normal over most parts of East Asia.

12. Anomalies of underlying surface

13. Sea Surface Temperature
NINO 3.4 index reaches 0.11℃
warm conditions dominate central-eastern equatorial Pacific
Variations of Niño 3.4 SSTA indices and SOI
The below-average sea surface temperatures (SSTs) in the central-eastern equatorial Pacific, which began in June 2016, increased gradually after October Since February 2017, above-average SSTs have developed in the central-eastern equatorial Pacific again. Recently, warm conditions dominate most central-eastern equatorial Pacific with the Nino 3.4 index being 0.11℃ in March 2017.
Sea surface temperature anomalies in March 2017

14. Indices of key oceanic regions
IOD可以不要，增加黑潮指数
Weak negative phase of IOBW
Increasing positive SIOD

15. Posititve NAT index is increasing.

16. PDO maintains the positive phase

17. 2016 autumn
Snow cover
Since autumn of 2016, the number of days with snow cover has been more than normal in Eurasia.
In Mar. 2017, snow cover over Europe was below normal.
Mar. 2017
2016 winter

18. Snow Cover in China
The number of days with snow cover is above normal in Xinjiang and Northeast China and near normal in the Tibetan Plateau.
有2月资料吗？高原积雪偏少吗？

19. Sea ice anomalies in 2016 Winter
Northern hemisphere
Southern hemisphere
W90° 0°
E90°
180°
40°S
50°S
60°S
70°N
E90° 0°
W90°
180°
40°N
50°N
60°N
70°N
只有90度（1-180之间）可以标注E
Sea ice concentration was below normal in most parts, except in the southeastern Indian Ocean and some parts of the Weddell Sea and Amundsen Sea.
Below-normal sea ice concentration covered almost all regions.

20. Variation of sea ice during winter
Data source：NCEP
Data source：NSIDC

21. Sea ice anomalies in March 2017
W90°
E90° 0°
180° 0°
180°
W90°
E90°
Below-normal sea ice concentration still persists.

22. Conclusions Positive phase of AO and negative phase of AAO dominate.
Straight and smooth airflows prevail over mid-high latitudes of Asia. Intensity of Siberian high is weak. EAWM ranks the weakest in recent 10 years. It is warmer over most East Asia.
Warm condition dominates most equatorial Pacific. Positive phase of SIOD and NAT both has been developing.
Snow cover is more than normal over northern hemisphere.
Arctic and Antarctic sea ice both rank the least since 1978.

23. Thanks！