Hj. Zwally et Mb. Giovinetto, ANNUAL SEA-LEVEL VARIABILITY INDUCED BY CHANGES IN SEA-ICE EXTENT ANDACCUMULATION ON ICE SHEETS - AN ASSESSMENT BASED ON REMOTELY-SENSED DATA, Surveys in geophysics, 18(2-3), 1997, pp. 327-340
Changes of mean annual net accumulation at the surface on the grounded
ice sheets of East Antarctica, West Antarctica and Greenland in respo
nse to variations in sea ice extent are estimated using grid-point val
ues 100 km apart. The data bases are assembled principally by bilinear
interpolation of remotely sensed brightness temperature (Nimbus-5 ESM
R, Nimbus-7 SMMR), surface temperature (Nimbus-7 THIR), and surface el
evation (ERS-1 radar altimeter). These data, complemented by field dat
a where remotely sensed data are not available, are used in multivaria
te analyses in which mean annual accumulation (derived from firn emiss
ivity) is the dependent variable; the independent variables are latitu
de, surface elevation, mean annual surface temperature, and mean annua
l distance to open ocean (as a source of energy and moisture). The las
t is the shortest distance measured between a grid point and the mean
annual position of the 10% sea ice concentration boundary, and is used
as an index of changes in sea ice extent as well as of mean concentra
tion. Stepwise correlation analyses indicate that variations in sea ic
e extent of +/-50 km would lead to changes in accumulation inversely o
f +/-4% on East Antarctica, +/-10% on West Antarctica, and +/-4% on Gr
eenland. These results are compared with those obtained in a previous
study using visually interpolated values from contoured compilations o
f field data; they substantiate the findings for the Antarctic ice she
ets (+/-4% on East Antarctica, +/-9% in West Antarctica), and suggest
a reduction by one half of the probable change of accumulation on Gree
nland (from +/-8%). The results also suggest a reduction of the combin
ed contribution to sea level variability to +/-0.19 mm a(-1) (from +/-
0.22 mm a(-1)).