Sea-Ice Thickness Variability in the North-Western Barents Sea

Right: Sea-ice origin (a,b) and age (c,d) based on low resolution (AMSR-E / AMSR2) ice drift, with Quikscat/ASCAT backscatter in background of a & b. The dates listed below a & b are the range of start (in black) and end (in green, blue and red) dates for the drift. The starting locations for these back trajectories are the corners of selected HEM flights. Note the logarithmic scaling in c) & d).

Below: Sea-ice concentration (AMSR-E/ASI and AMSR2/ASI) in the study region during and one month before the field campaigns:

Conclusions • Two years for which HEM data are available demonstrate two extremes of

the possible sea-ice thickness distribution in the NW Barents Sea; 2003 with a large volume of MYI advected from Arctic Basin, and 2014 with sea-ice growth in-situ.

• Two years of ULS data also show significant variation in ice thickness. • We cannot draw any conclusions about a thinning trend due to the sparsity

of sea-ice thickness information. • Ice age and provenance can be a semi-reliable indicator of relative ice

thickness, with the notable exception of MYI in 2003 that has been in contact with Atlantic Water.

• Satellite remote sensing has the potential to provide sea-ice thickness information with better spatio-temporal coverage than in-situ or airborne data.

Barents Sea winter sea-ice cover shows strong year to year variability

a) Location of Barents Sea. b) Winter sea-ice area* within the box defined in blue in (a), with mean ice thickness marked for those years for which we have data. The Barents Sea has the strongest negative sea ice area trend (-23%/decade; dashed line) of the whole Arctic.

Above Left: Sea-ice thickness from helicoper-bourne electromagnetic sea-ice thickness sounding campaigns in 2003 (regions Storfjorden (SF), south (S) and southwest (SW)); and 2014 (regions northwest (NW), northeast (NE) and south central (SC)) (King at al, submitted). Also shown is the location of the mooring from which ULS data was obtained between 1994-1996 (left). Numbers 1-4 represent locations at which ice cores were taken in 2003 (see below). Above right: Sea-ice thickness distributions for a) all data from 2003 and 2014, b) regional differences in 2003, c) regional differences in 2014.

Sea-ice thickness from Satellite Remote Sensing

Jennifer King1, Gunnar Spreen2, Sebastian Gerland1, Christian Haas3, Stefan Hendricks4, Robert Ricker4, Lars Kaleschke5, & Caixin Wang1. 1 Norwegian Polar Institute, Tromsø, Norway; 2University of Bremen, Germany; 3York University, Toronto, Canada; 4Alfred Wegener Institute for Polar and Marine Research, Germany; 5University of Hamburg, Germany;

Acknowledgements The airborne campaign in March 2014 was supported by the European Space Agency SMOSice project (ESA contract 4000110477/14/NL/FF/lf; PI S.Hendricks)), and part of the project IRO2, funded by the Federal Ministry for Economic Affairs and Energy (BMWi) under the contract 03SX328A (PI P. Jochmann). The 2003 Polarstern cruise Ark19/1 was supported by AWI and the EU SITHOS project.(Sea Ice Thickness Observation System; led by NERSC). Jennifer King is funded by the Norwegian Research Council project 'CORESAT' (NFR project number 222681). We also thank the crews of RV Lance, RV Polarstern, and Airlift helicopter, and engineer Marius Bratrein (Norwegian Polar Institute), for their efforts during the campaigns. Processing of the CryoSat-2 Sea Ice thickness is funded by the German Ministry of Economics Affairs and Energy (grant: 50EE1008). Processing of the SMOS Sea Ice thickness was funded by EU project SIDARUS . These data were obtained from

http://www.meereisportal.de (grant: REKLIM-2013-04). Ice concentration data calculated from AMSR-E (2003) and AMSR2 (2014) was obtained from http://seaice.uni-bremen.de/amsr2data/, and from http://seaice.uni-bremen.de/amsredata/. ASCAT data was downloaded from ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/psi-backscatter/data/ascat/arctic/netcdf/2014 and QuikSCAT from: ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/psi-backscatter/data/quickscat/arctic/netcdf/2003/ NCEP Reanalysis daily air temperature at 2.5°resolution (used for FDD model) provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/ Ice thickness data from 2003 are archived at the PANGAEA Data Publisher for Earth & Environmental Science: https://www.pangaea.de/ Ice thickness data from 2014 are available at the Norwegian Polar Data Centre: https://doi.org/10.21334/npolar.2016.ee8f4f8d

Sea-ice thickness from ULS data 1994-1995 Ice thickness measured by upward looking sonar deployed at 77° 55’ N 28° 20’E. The sea-ice was thicker in spring 1995 than in spring 1996 despite greater ice area in 1996 (Abrahamsen et al 2006).

References Abrahamsen, E.P., Østerhus, S., Gammelsrod, T., (2006) Ice draft and current measurements from the north-western Barents Sea, 1993-96, Polar Research 25(1), 25–37 Cavalieri, D. J., Parkinson, C. L., Gloersen, P., and Zwally H. J.. (1996), updated yearly. Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data, Version 1. [1979–2015]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi:10.5067/8GQ8LZQVL0VL. Haas, C., Alexandrov, V., Kern,S., Lieser,J., Lobach,J., Martin, A., Pfaffling,A., and WillmesS. (2004), Sea ice remote sensing, thickness profiling, and ice and snow analyses during Polarstern cruise Ark 19/1/CryoVex2003 in the Barents Sea and Fram Strait, February 28 -- April 24, 2003: Cruise report. Alfred Wegener Institute Bremerhaven, Germany. King,J., Spreen,G., Gerland,S., Haas, C., Hendricks,S., Kaleschke,L., and Wang,C. : Sea-Ice Thickness from field measurements in the north-western Barents Sea, JGR, in review, 2017 Ricker, R., Hendricks, S., Kaleschke, L., Tian-Kunze, X., King, J., and Haas, C.: A Weekly Arctic Sea-Ice Thickness Data Record from merged CryoSat-2 and SMOS Satellite Data, The Cryosphere Discuss., doi:10.5194/tc-2017-4, in review, 2017.

Field Data: Two HEM campaigns, in context of ice age, origin and concentration, illustrate two extremes of a range of possible ice-thickness distributions

Possible contribution from Thermodynamic Growth

Analysis Sea-ice was thinner in 2014 than in 2003. Ice extent was much greater in 2003 2003: Ice in SF region is heavily deformed MYI 2003: Ice in SW is MYI that has experienced

bottom melt on contact with Atlantic water. 2003: Ice in SF and SW regions is 2-3 years old

originating in Laptev & Kara seas. Salinity measurements in 2003 reveal thin MYI

in support of bottom melt hypothesis. 2003: Ice in S is 3-5 months old originating close

to Franz Joseph Land. 2014: ice in all regions <1 month old,

formed locally. 2014: Ice in NW is slightly older and has

experienced more deformation.

Ice thickness (m) from an FDD model simulation started on 1 January. The measured mean sea-ice thickness plotted in red is the monthly mean calculated from the ULS ice draft from March 1995 and 1996, and the regional mean from the HEM measurements in March 2003 and 2014. The regional mode from the HEM measurements in March 2003 and 2014 is plotted in yellow. No mode is available for March 1995 and 1996.

Salinity proles of four ice cores taken during the field campaign in 2003 (from Haas et al, (2004). See Figure 2 for core locations.

• Thickness data derived from combined CryoSat-2 /SMOS thickness product (Ricker et al, submitted ) is available since 2011.

• Suggests the situation in 2014 was not unusual in recent years. • Sea-ice thickness retrieval from space in this region is complicated

by lack of a reliable snow climatology, and challenging conditions (waves, small floes, and variable ice cover) due to proximity to the ice margin.

*Sea-ice area was calculated from ice concentration with 25 km resolution based on the NASA-Team algorithm (Cavalieri et al , 1996).

Combined CS2/SMOS gridded weekly product for the week of 20 March, 2011-15.