The autumn-winter atmospheric response to the projected autumn Arctic sea ice free conditions

Lingling SUO, Yongqi GAO, Dong Guo, Jiping Liu, Huijun Wang, and Ola M. JOHANNESSEN

Motivation

Large Uncertanties !the winter atmosphere circulaiton response to the autumn sea ice retreat

•Negative AO patterns Francis et al., 2009; Liu et al., 2012; Cohen et al., 2012; Li and Wang, 2013

•Positive AO patterns Screen et al., 2013a

•Not classical AO patterns Blüthgen et al., 2012; Screen et al., 2013a; Screen et al., 2013a

Note: Liu etal, 2012 and Screen etal, 2013a obtained the contrary results by the utilization of the same model and different ensembles.Implying the importance of the internal variability!

1970 1980 1990 2000 2010 2020-4

-3

-2

-1

0

1x 10

6

Sep

tem

ber s

ea ic

e ex

tent

(km2 )

Possbile link between Arctic sea ice reteat and the winter climate (snowcover, coldness ……) in northern hemisphere proposed by previous studies (Liu etal, 2012; Yang and Christensen, 2012; Francis and Vavrus, 2012; etal);

Strong snowstorms and coldness hit Europe!

Blue Arctic could appear earlier than expected

What’s the impact on the climate? Not clear…More intense and easier detectable response?

Approach: Using Atmosphere global climate model :Control simulations (CONT) (300 one-year-lasting members ) using the 100 year mean in pre-performed present day simulation by BCM as boundary conditions to force the model.Sensitivity experiments (SENS) (300 one-year-lasting members ) with sea ice removal and future projected SST associated with Arctic sea ice free as boundary conditions during autumn in Arctic. In other regions during the whole year and in Arctic during the other seasons, the boundary conditions are the same as the control run.

The differences between control and sensitibity experiments are caused by autumn extreme sea ice conditions and

associated SST in Arctic.Using ERA Interim for comparison with the model results.

Dailiy sea ice area variation in Control (CONT) and sensitivity (SENS) experiment

sea ice concentration changes between SENS and CONT

Sep-Oct mean Nov Dec

Model validation

Control ERAI

Winter SLP

Winter precipitation

Winter SAT

300 ensembles mean 1979-2000mean

Similar patterns in Oct and Nov. Oct-Nov mean patterns are shown.The significant response basiclly occuly the mid-high latitudes.

SAT

unit:

C

-10

-5

0

5

10

Similar patterns in Oct and Nov. Oct-Nov mean patterns are shown.The significant response basiclly occuly the mid-high latitudes.

PW

unit:

kg/

m2

-5

0

5

snowfall

unit:

mm

/day

-0.5

0

0.5

rainfall

unit:

mm

/day

-0.5

0

0.5

Monthly variation of the zonal mean response

Fractional significant signals, No robust negative or positive AO patterns.

Significant response in the continential region occupy the Europe

Fractional significant signals, No robust negative or positive AO patterns.

Significant response in the continential region occupy the Europe

SLP anomalies (shaded) and 500hPa wave flux anomaliy (vector)

SLP (Model)

0 15

E 30 E 45

E 60

E

45 N

60 N

75 N

unit: hPa-4 -2 0 2 4

0 15

E 30 E 45

E 60

E

45 N

60 N

75 N

SAT (Model)

unit: C-2 0 2

0 15

E 30 E 45

E 60

E

45 N

60 N

75 N

PW (Model)

unit: kg/m2-1 0 1

Rainfall

unit: mm/day-0.5 0 0.5

Total Precipitation

0

15 E 30

E 45

E 60

E

45 N

60 N

75 N

Snowfall (Model)

unit:

mm

/day

-0.5

0

0.5

Conclusion1) The autumn Arctic sea ice free can cause significant local warming,

atmospheric precipitable water increase and total precipitation increase during the autumn.

The SLP over the Arctic Ocean shows negative anomalies while there are three positive anomaly centers over the north west America, the Europe and the north of the East Asia. Which looks more like 2-3 zonal waves pattern rather than the classical AO pattern.

2) The autumn atmospheric response can not persist during the middle and late winter season. The significant winter SLP response is much more local. The robust SLP response basiclly occupy the Europe.

3) The late winter low SLP anomaly over the East Europe could bring the intense snowfall locally and the warming over the mid-Asia.

Ongoing Work

In order to compare with the internal variability

• The signal to noise ratio of the atmospheric response

• For specific response interested, the density distribution of 300 members in CONT and SENS. For example, the SLP and snowfall over the East Europe.

Future Plan

Parallel experiments using ocean-atmosphere oupled model have done.

What are the atmospheric responses when the ocean-atmosphere interaction is included?

•The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2007-2013), under grant agreement n.308299•NACLIM www.naclim.eu