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SUMMARY:Filling the polar data gap with harmonic functions - Courtenay Str
 ong (University of Utah)
DTSTART:20170911T143000Z
DTEND:20170911T150000Z
UID:TALK78702@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Coauthors: Elena Cherkaev and Kenneth M. Golden <br><br>The &l
 dquo\;polar data gap&rdquo\; is a region around the North Pole where satel
 lite orbits do not provide sufficient coverage for estimating sea ice conc
 entrations. This gap is conventionally made circular and assumed to be ice
 -covered for the purpose of sea ice extent calculations\, but recent condi
 tions around the perimeter of the gap indicate that this assumption may al
 ready be invalid. We present partial differential equation-based models fo
 r estimating sea ice concentrations within the area of the data gap. In pa
 rticular\, the sea ice concentration field is assumed to satisfy Laplace&r
 squo\;s equation with boundary conditions determined by observed sea ice c
 oncentrations on the perimeter of the gap region. This type of idealizatio
 n in the concentration field has already proved to be quite useful in esta
 blishing an objective method for measuring the &ldquo\;width&rdquo\; of th
 e marginal ice zone&mdash\;a highly irregular\, annular-shaped region of t
 he ice pack that interacts with the ocean\, and typically surrounds the in
 ner core of most densely packed sea ice. Realistic spatial heterogeneity i
 n the idealized concentration field is achieved by adding a spatially auto
 correlated stochastic field with temporally varying standard deviation der
 ived from the variability of observations around the gap. Testing in circu
 lar regions around the gap yields observation-model correlation exceeding 
 0.6 to 0.7\, and sea ice concentration mean absolute deviations smaller th
 an 0.01. This approach based on solving an elliptic partial differential e
 quation with given boundary conditions has sufficient generality to also p
 rovide more sophisticated models which could be more accurate than the Lap
 lace equation version\, and such potential generalizations are explored.<b
 r>
LOCATION:Seminar Room 1\, Newton Institute
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