Open AccessObservation of perennial Arctic sea ice melt and freeze‐up using passive microwave data
Author(s) -
Smith Douglas M.
Publication year - 1998
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/98jc02416
Subject(s) - sea ice , brightness temperature , sea ice concentration , snow , geology , arctic ice pack , arctic , special sensor microwave/imager , depth sounding , microwave , microwave radiometer , climatology , sea ice thickness , environmental science , atmospheric sciences , radiometer , remote sensing , oceanography , geomorphology , physics , quantum mechanics
The onset of spring melt and autumn freeze‐up of Arctic sea ice are shown, through comparison with coincident ERS‐1 synthetic aperture radar (SAR) and surface air temperature data, to produce significant and detectable changes in the passive microwave signature. Melt onset is marked by a sharp rise in brightness temperatures resulting from the increased emissivity of moisture in the snow cover. Freeze‐up is accompanied by a sharp drop in brightness temperatures because of volume scattering by bubbles in the upper ice layer. An algorithm is developed to detect melt and freeze‐up from passive microwave data and is applied to the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave/Imager (SSM/I) data from 1979 to 1996. The mean accuracy of melt and freeze‐up dates determined from the SSM/I is estimated to be ±2 and ±3 days, respectively. The reduced temporal sampling of the SMMR degrades the accuracy by 1 day. On average, melt onset varies from late May in the southern Beaufort Sea to mid‐June in the central Arctic north of the Canadian archipelago, while freeze‐up varies between mid‐September and mid‐August. The shortest melt season appears to occur north of the Canadian archipelago rather than at the North Pole, which is consistent with the fact that minimum summer air temperatures are centered over Greenland. The mean standard deviations of the interannual variability of melt and freeze‐up are 6.8 and 11.4 days, respectively.