Tracking Sea-Ice Seasonal Cycle, Dynamics, and Hazards at Pt

Tracking sea-ice seasonal cycle, dynamics, and hazards at Pt. Barrow, AK with coastal ice radar

H. Eicken 1, A.R. Mahoney2, J. Jones2, L.H. Shapiro2 1: International Arctic Research Center 2: Geophysical Institute University of Alaska Fairbanks, Fairbanks, AK, USA [email protected]

(1) Arctic coastal sea ice (2) Barrow/Utqiaġvik ice observatory (3) Ice velocity & deformation fields (4) Landfast ice breakouts

Dammann et al. (CRST, submitted) • Large swath of reduced ice concentation in Pacific Arctic sector • Impacts on Pt. Barrow coastal communities & infrastructure • Increased ice velocities & less stable ice threaten maritime & on-ice operations The Pt. Barrow – Utqiaġvik sea-ice observatory

• Remote sensing (km- scale) • Coastal radar (sub-km scale) • Thickness and topography (sub-km scale) • Ice mass-balance site (10s m-scale) • Moored oceanographic instruments (sub-km scale) • Local ice observations (J. Leavitt, B. Adams, and many others)

• www.sizonet.org; M. Druckenmiller et al., CRST, 2009 eloka-arctic.org/sizonet; seaice.alaska.edu/gi Ground-based ice radar

• High spatial resolution  Resolve complicated (<30 m) spatial ice motion & • High sampling rate (<5 deformation patterns min–1)  Capture short- • Near-realtime availability term/high-frequency of data & information (e.g., tidal) forcing products (<20 min lag)  Track vessel/vehicle & • Low cost (<$100k) hazard movement  Utility as hazard assessment & emergency response tool • Ice drift • Shear • Conver- gence • Shorefast ice accre- tion ● ●

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• Mk I – 1973-79: 25kW, • Mk IV – 2006-11: 10kW, 12 m a.s.l.; 35 mm 22 m a.s.l., digital video timelapse camera interface, internet upload photos of screen • Mk V – 2012ff.: Furuno • Mk II – 2002-03: 5kW, X-band FAR2127, 25kW, 10 m a.s.l.; webcam 2.4 m open array, 22 m capture of radar a.s.l.; digital controller screen controller/output, internet • Mk III – 2003-05: 10kW, upload 10 m a.s.l.; PC screen capture, internet upload Near-realtime sea ice velocity from ice radar

• Velocity calculated on 20 x 20 pixel grid (438 m) • Combination of sparse and dense optical flow techniques • Local “similarity filtering” used to exclude spurious results MV, Rohith, et al. (2013), IEEE Transactions on Geoscience and http://seaice.alaska.edu/gi/observatories/ Remote Sensing, 51(5), p2556‐2570 barrow_radar/sea-ice-velocity

November mean (2007- 2015) velocity field

• Onset of stationary/landf ast ice formation • Anomalous ice motion events • Prevailing drift from NE

June mean (2007-2015) velocity field

• Stable landfast ice • Ice speed smaller than in November • Prevailing drift from SW

Annual cycle November mean (2007- 2015) divergence

• Onset of stationary/landf ast ice formation • Anomalous ice motion events • Prevailing drift from NE

June mean (2007-2015) divergence field

• Stable landfast ice • Ice speed smaller than in November • Prevailing drift from SW

Landfast ice break-out event & rescue - 29 April 2014 • Destabilization of shorefast ice as major hazard to communities & industry • Use of radar data: Assess stability & track breakout, support evacuation & rescue • Moored instrument deployments guided by research interests & Oceanographic mooring; Hokkaido local concerns University/UAF – Fukamachi, Oshima et al. Understanding causes of break-out events - March 2010 • Ice deformation can form grounded ridges - tracked with coastal radar • Extent of grounded ridges provides insight into landfast ice strength • Wind & current stress, sealevel & ocean temperature provide insight into causes of breakouts • Collaboration with K.-I. Ohshima & Y. Fukamachi, Hokkaido U. Jones et al. (2016) Continental Shelf Research, 126:50–63 Understanding causes of break-out events - March 2010 • Ice deformation can form grounded ridges - tracked with coastal radar • Extent of grounded ridges provides insight into landfast ice strength • Wind & current stress, sealevel & ocean temperature provide insight into causes of breakouts • Collaboration with K.-I. Ohshima & Y. Fukamachi, Hokkaido U. Jones et al. (2016) Continental Shelf Research, 126:50–63

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° Break-out in • Grounded ridge ( density & anchor a March 2010 strength • Ridge

ungrounding: b Preconditioning & bottom ablation c • Current stress • Wind stress • Pack-ice d shorefast ice interaction Date Figure 3.8. Oceanographic conditions for March 2010. a) Water temperature measured at the Mass Balance Site. b) Seaward/Shoreward current velocity (positive is onshore). c) Alongshore current velocity (positive is to the Northeast). d) Estimated stress on landfast ice with drag coef ficient, cw, as 0.0175 (blackline), and ranging from 0.00780 to 0.0200 (green lines; Reynolds et al., 1985; McPhee 1979). Ice radar

key points • Cost-effective • Information on short-term variability & long-term change in ice dynamics • 00s & 10s coastal ice much more dynamic & less stable than 70s ice • Hazard assessment & emergency

response support Fraction of days w/ ice in motion, % motion, in of % ice, w/ days w/ days of Fraction ice Fraction

Sea ice velocity fields from DOE Atmospheric Radiation Measurement (ARM) X-band radar?

• Low elevation X- band data from ARM XSAPR: Evaluate suitability to detect sea ice & derive velocity fields • Greatly extended range

Sea ice velocity fields from DOE Atmospheric Radiation Measurement (ARM) X-band radar?

• Low elevation X- band data from ARM XSAPR: Evaluate suitability to detect sea ice & derive velocity fields • Greatly extended range

Sea ice velocity fields from DOE Atmospheric Radiation Measurement (ARM) X-band radar?

• Low elevation X- band data from ARM XSAPR: Evaluate suitability to detect sea ice & derive velocity fields • Greatly extended range