Assessment of OIB 2009 Data over Pine Island and Thwaites Glaciers. K. Jezek OIB Science Team Meeting. MCORDS (Left) and ATM (Right) 2009 data distribution after post processing. Surface Topography. Surface topography from post-processed ATM data and a locally adaptive kriging technique.
OIB Science Team Meeting
Surface topography from post-processed ATM data and a locally adaptive kriging technique
Ice thickness from post-processed MCORDS data and a locally adaptive kriging technique
OIB data better capture ice bottom topography details than sparser AGASEA data. OIB ice bottom data consistent with surface topography and mini-MAMM flow field. ASAID grounding line shown for refernce
More comparable Thwaites Glacier coverage results in better comparison between OIB and AGASEA derived ice bottom topographies.
Semivariograms for the ice shelf (red/black) show high spatial correation over lags of 6-10 km. Variance for grounded ice (blue/green) increases rapidly after about 4 km. This indicates that data line spacings should be on the order of 4 km or less.
Water layer thickness generally consistent with ASAID grounding line except in north west where InSAR grounding line better matches
If ice thickness bulge at 35 km is accurate and transient, and bathymetry rise at 45 km is accurate, the glacier will reground shortly. Driving stress suggests grounding line fall close to 40 km. ASAID (blue dash) and InSAR (red and green dash) grounding lines appear to be located upstream of topographic high
Bathymetry and ice thickness consistent with ASAID and InSAR grounding lines. Surface slope seems anomalously low. Average geoid referenced of ice shelf surface is about 55 m.
Slopes from ellipsoid heights – negligible geoid correction.
ASAID and InSAR grounding line consistent in East but may be too far upstream in west . Driving stresses upstream of grounding line comparable to WAIS (10 kPa). Low compared to Jacobshavn (~275 kPa).
Geoid Undulaion ζ = h − HN
(From Jezek and Dhanasekaran. Dhanasekaran M.S Thesis, 2011, The Ohio State University)
Water layer thickness generally consistent with ASAID/InSAR grounding lines except in northwest where InSAR grounding line better matches. Driving stress and topography suggest that the southerly grounding line is downstream of the estimates. However if accurate, then ice thickness suggests a regrounding of the ice shelf in the near future.