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Nowcast Products
BOOTSTRAP
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The Bootstrap algorithm uses the 37V and 37H channels are used in high
concentration (greater than 90%) regions of the Arctic and the 19V and
37V channels in lower concentrations in the Arctic and throughout
the Antarctic. The Bootstrap uses the fact that in scatter plots of 37H
vs. 37V (or 19V vs. 37V), open water points tend to cluster around a point
and ice tiepoints tend to cluster along a line of a given slope. The ice
concentration is determined by a linear interpolation between the open
water tiepoint and the line of 100% ice. The algorithm employs seasonal
tiepoints for both the Arctic and Antarctic. This helps account for seasonal
variabilities in the surface properties of the sea ice. Because the 19V
GHz channel is used near the ice edge, the precision of the ice edge is
comparable to the NASA Team (and thus less than the Cal/Val and NIC Hybrid).
However, because no H polarized channels are used near the ice edge, the
algorithm is not as affected by wind over open water. Additionally, a
weather filter using the 19V and 22V GHz channels (different from the NASA
Team GR(19/22) is employed to remove spurious concentration retrievals over
open water. The Bootstrap is similar in many respects to the Cal/Val since
it uses the same channel combinations, although the Cal/Val uses 37V and
37H near the ice edge and 19V and 37V within the ice pack, while the
Bootstrap does the reverse (in the Arctic). The Bootstrap is more sensitive
to thin ice than the NASA Team (although less so than the Cal/Val).
Comiso, J.C., 1995. "SSM/I ice concentrations using the Bootstrap algorithm",
NASA Report 1380. Comiso, J.C., D.J. Cavalieri, C.L. Parkinson, and
P. Gloersen, 1997. "Passive microwave algorithms for sea ice concentration:
A comparison of two techniques", Remote Sens. Env., 60, 357-384.
If you have any comments, please E-mail the National Ice Center Liaison
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