Vladimir A. Alexeev, International Arctic Research Center, UAF. with contributions from V. Ivanov, R. Kwok, I.Ezau, J.Cohen, J.Furtado, M.

Transcription

1 North Atlantic warming, disappearing sea ice and winter cooling Vladimir A. Alexeev, International Arctic Research Center, UAF with contributions from V. Ivanov, R. Kwok, I.Ezau, J.Cohen, J.Furtado, M.Barlow

2 Like us on Facebook

3 Geography of IARC schools Fairbanks, AK Toolik Lake, AK Barrow, AK McCarthy, AK Fedorovskoe, Russia Arc c Ocean Bellingshausen, Antarc ca First summer school, July 2003

4 Geography of IARC schools Map with locations of summer schools (red markers) and (incomplete!) locations of origins of attending students (blue markers).

5 2010: King George Island, Bellingshausen sta on in collabora on with APECS, RAE, RAS, AWI, AARI, IAP

6 Scope Focus on the Arc c (and sub- polar regions) Climate system perspec ve Depending on loca on, some mes more focus on one of the components Students get involved in hands- on ac vi es (seeing is believing)

7 Communications report card, 2013 (Lindsay B)

8 Part 1: North Atlan c warming and Arc c sea ice AMSR2 sea ice conc Sep 2012

9 Sea ice extent ocean heat content (delayed freeze up) Surface-based mechanisms are the most likely contributors to the recent Arctic warming in the summer and fall

10 Atlantic Water in the Arctic Ocean

11

12 Fate of Early 2000s Century Arctic Warm Water Pulse By I.Polyakov, V.Alexeev, I.Ashik, S. Bacon, A.Beszczynska-Möller, E.Carmack, I.Dmitrenko, L.Fortier, J.-C.Gascard, E.Hansen, J.Hölemann, V.Ivanov, T.Kikuchi, S.Kirillov, Y-D.Lenn, F.A.McLaughlin, J.Piechura, I.Repina, L.Timokhov, W.Walczowski, and R.Woodgate Bull. Of the Amer Met Soc, 2011

13 AW significantly contributes to thinning of ice Polyakov, Timokhov, Alexeev, Ivanov JPO 2010

14 Water temperature (ºC) distribution, Laptev Sea, Sep 2013 At cross-slope section along 90ºE) Thick (up to 50 m) warm surface layer, which almost merges with intermediate Atlantic water layer

15 Atlantic Water and arctic sea ice. Winter March Alexeev et al, 2013, submitted

16 Sea ice, February 2, 2014

17 North Atlantic SST

18 Scoresby, W An account of the Arctic regions with a history and description of the Northern whale fishery, (PhD Thesis by S.H.Teigen)

19 AW temperature. Fram Strait and Svalbard Fraction of multi-year ice Alexeev et al, 2013

20 Winter sea ice thickness. Atlantic sector March-April 2005 March-April 2006 February-March 2008 Thinning of ice is local Alexeev et al, 2013

21 Ice concentration anomaly Meridional wind DLW (contours) snow anomalies Feb-Mar2008 Ice thickness and motion vectors, ICESat Ivanov et al, 2012, Alexeev et al 2013

22 How much ice does AW melt? Explains at least 20% of the negative trend (volume-wise) Alexeev et al, 2013

23 Part 2: Is warming in the Arctic causing colder winters?

24 Winter temperature anomalies, NCEP/ NCAR Reanalysis data set Cohen, Barlow, Furtado, Alexeev, Cherry, 2012, ERL 2012

25 (a) [ C] [ C] Northern Hemisphere Land Temperatures DJF Trend = 0.07 C/10 yr MAM Trend = 0.39 C/10 yr** 2 2 JJA Trend = 0.38 C/10 yr** 1 0 SON Trend = 0.49 C/10 yr** % % Time - [year] **p < 0.01 Data: CRU temperature Alexeev et al, 2012, Clim Change; Cohen et al, 2012, ERL [ C] [ C] (b) (c) (d) (e)!!,$ % +!!!($ % +!!!*$ % +!!"#$%&'(&)*+,)&$%)&-.$/ !"#$ % &!!"'$ % &!!"!#$%&'%()*+(%#$(%,-#./012 34/45!!($ % &!!!!$ %!!!!($ % )!!"'$ % )!!"#$ %!!,$ % +!!!($ % +!!!*$ % +!!"#$ % &!!"'$ % &!!!"#$%&'%()*+(%#$(%,-#./012 34/45!!($ % &!!!!$ %!!($ % )!!"'$ % )!!"#$ %!!!,$ % +!!!($ % +!!!*$ % +!!"#$ % &!!"'$ % &!!"#$%&'(&)*+,)&$%)&-.$/ !!($ % &!!!!$ %!!!!($ % )!!"'$ % )!!"#$ %!!!,$ % +!!!($ % +!!!*$ % +!!!!!!!!!!!!!!! $ $ $!"#$ % &!!"'$ % &!!!($ % &!!!!$ %!!!!($ % )!!"'$ % )!!"#$ %! -1 [ C per 10 years] $ $ 0 1 # # # # # #

26 Arctic Trends A JAS Arctic-Mean Temperature Anomaly Warming Arctic Less sea ice More atmospheric moisture Increasing snow cover Decreasing Arctic Oscillation trend [ C] [kg m -2 ] [std] 0 # B C D E Trend = -0.05/10 yr** Fall Arctic-Mean Lower Tropospheric Moisture Obs DJF AO Index Trend = 0.44 C/10 yr** September Arctic Sea Ice Coverage Trend = 0.54 kg m -2 /10 yr** CMIP5 Ens Mean October Eurasian Snow Cover Trend = 1.46x10 6 km 2 /10 yr** Trend = -0.29x10 6 km 2 /10 yr** [10 6 km 2 ] [Frac. Area] -2 Trend = -1.0 std/10 yr** ** p < % % Time - [year] Alexeev et al, 2005, Clim Dyn; Cohen et al, 2012, ERL

27 Tropospheric Winter Trends Negative Phase of the Arctic Oscillation!!"#$%&'$()*+,$-./ ! " # $ # [hpa] "!"#$%&'(%)*+ ', "!!

28 Trend in SLP and zonal wind at 10m (ERA-Interim)!"#$%&'$()*+,$-./ ! U 10m "!"#$%&'(%)*+ ',!

29 Changes in the stratosphere Temp 100mb Geop hgt 100mb Alexeev, Ezau, Polyakov, Byam, Sorokina, 2012

30

31 Barotropic vor city equa on Resonance: ψ s ψ 0 /(U U s ) s, Francis, Vavrus, 2013

32 Z 250, Jan climate Note: weakening of the gradient (warmer Arctic)

33 Z500 trend

34 Z500 and T850, January Climate 2014

35 ECMWF maps, Feb 2, 2014

36

37 One of the first UKMO GCM sensitivity experiments with polar ice replaced by water at 0 C Changes in January surface air temperature. The Arctic becomes warmer by up to 40 C but the latitudinal belt south of 60 N over land becomes colder by up to 8 C. Newson 1973; Nature, 241, 39-40

38 Description of the Numerical Model - Upper mixed layer ocean coupled to a full 3D atmospheric GCM - Seasonal cycle - Albedo feedbacks intentionally omitted (no snow, ice) - Land points have 10 times lower thermal inertia than the ocean

39 Warm Arc c Cold Con nents ( wet con nents, no albedo feebacks) Reduced sea ice increased heat content before cold season Ghost forcing added to Barents and Chukchi seas in summer

40 Summary/conclusions The Arc c is warming, sea ice is disappearing North Atlan c warming and associated increase in the AW temperature are responsible for mel ng of a significant por on of arc c sea ice Delayed freeze- up, more open water and consequent heat input to the atmosphere lead to significant changes in atmospheric circula on, including switching the polarity of the transpolar dri to posi ve phase. Significant nega ve AO/NAO trend in the recent years is a manifesta on of the warming in the Arc c Ocean Negative AO/NAO trends are responsible for the negative winter temperature trends in Northern Eurasia (also in the lower 48)