 |
| Titel |
Uncertainties in Arctic sea ice thickness and volume: new estimates and implications for trends |
| VerfasserIn |
M. Zygmuntowska, P. Rampal, N. Ivanova, L. H. Smedsrud |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1994-0416
|
| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 2 ; Nr. 8, no. 2 (2014-04-22), S.705-720 |
| Datensatznummer |
250116096
|
| Publikation (Nr.) |
 copernicus.org/tc-8-705-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Sea ice volume has decreased
in the last decades, evoked by changes in sea ice area and thickness.
Estimates of sea ice area and thickness rely on a number of geophysical
parameters which introduce large uncertainties. To quantify these
uncertainties we use freeboard retrievals from ICESat and investigate
different assumptions about snow depth, sea ice density and area. We find
that uncertainties in ice area are of minor importance for the estimates of
sea ice volume during the cold season in the Arctic basin. The choice of mean
ice density used when converting sea ice freeboard into thickness mainly
influences the resulting mean sea ice thickness, while snow depth on top of
the ice is the main driver for the year-to-year variability, particularly in
late winter. The absolute uncertainty in the mean sea ice thickness is
0.28 m in February/March and 0.21 m in October/November. The
uncertainty in snow depth contributes up to 70% of the total uncertainty
and the ice density 30–35%, with higher values in October/November. We
find large uncertainties in the total sea ice volume and trend. The mean
total sea ice volume is 10 120 ± 1280 km3 in October/November
and 13 250 ± 1860 km3 in February/March for the time period
2005–2007. Based on these uncertainties we obtain trends in sea ice volume
of −1450 ± 530 km3 a−1 in October/November and −880 ±
260 km3 a−1 in February/March over the ICESat period
(2003–2008). Our results indicate that, taking into account the
uncertainties, the decline in sea ice volume in the Arctic between the ICESat
(2003–2008) and CryoSat-2 (2010–2012) periods may have been less dramatic
than reported in previous studies. However, more work and validation is
required to quantify these changes and analyse possible unresolved biases in
the freeboard retrievals. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|