On the estimation of spring melt in the North Water polynya using RADARSAT‐1

Abstract This paper evaluates the utility of time series RADARSAT‐1 Synthetic Aperture Radar (SAR) to detect melt onset (MO) and pond onset (PO) in the North Water (NOW) Polynya. SAR detected MO was associated with the approach of the daily average near‐surface air temperature (Tair) toward freezing, the beginning of a daily average surplus in the net all‐wave radiation flux (Q*), and a sharp decrease in the integrated shortwave albedo (α) at the surface. Relationships between microwave scattering and air, snow surface and ice surface temperature, up until MO, proved sensitive to the diurnal acquisition times of RADARSAT‐1. Time series results demonstrate that, despite its ‘uncalibrated’ status, RADARSAT‐1 ScanSAR data unambiguously identifies MO and PO over landfast First‐Year Ice (FYI) within the NOW Polynya. Spatially, results suggest a significantly earlier spring melt on the Greenland coast compared to the Ellesmere coast (10 to 15 days for regions between 77°N and 79°N and up to 45 days for regions between 76°N and 77°N). The regional near‐surface air temperature pattern was consistent with the spatial pattern of a SAR detected date of MO and PO.

[1]  K. Steffen,et al.  Heat exchange and surface conditions in North Water, northern Baffin Bay , 1985 .

[2]  F. Huang,et al.  A latent- and sensible-heat polynya model for the North Water, Northern Baffin Bay , 1992 .

[3]  Mark Drinkwater,et al.  Springtime C-band SAR backscatter signatures of Labrador Sea marginal ice: measurements versus modeling predictions , 1991, IEEE Trans. Geosci. Remote. Sens..

[4]  Ron Kwok,et al.  Surface and radiative characteristics of the summer Arctic sea ice cover from multisensor satellite observations , 1996 .

[5]  D. Rothrock,et al.  Thinning of the Arctic sea‐ice cover , 1999 .

[6]  R. Macdonald,et al.  Evidence for warming of Atlantic water in the Southern Canadian Basin of the Arctic Ocean: Results from the Larsen-93 Expedition , 1995 .

[7]  R. Colony,et al.  Observation of melt onset on multiyear Arctic sea ice using the ERS 1 synthetic aperture radar , 1994 .

[8]  David G. Barber,et al.  Sea‐ice and meteorological conditions in Northern Baffin Bay and the North Water polynya between 1979 and 1996 , 2001 .

[9]  Konrad Steffen,et al.  Ice Conditions of an Arctic Polynya: North Water in Winter , 1986, Journal of Glaciology.

[10]  B. Dey.  Applications of Satellite Thermal Infrared Images for Monitoring North Water during the Periods of Polar Darkness , 1980, Journal of Glaciology.

[11]  E. Carmack.  Circulation and Mixing in Ice-Covered Waters , 1986 .

[12]  Moira Dunbar,et al.  The Geographical Position of the North Water , 1969 .

[13]  C. Pease,et al.  The size of wind‐driven coastal polynyas , 1987 .

[14]  E. LeDrew.  Sensitivity of the Arctic Climate: A Factor in Developing Planning Strategies for Our Arctic Heritage , 1986, Environmental Conservation.

[15]  L. Mysak,et al.  A Nonlinear Steady-State Model of the North Water Polynya, Baffin Bay , 1994 .

[16]  David G. Barber,et al.  Melt ponds on sea ice in the Canadian Archipelago: 2. On the use of RADARSAT‐1 synthetic aperture radar for geophysical inversion , 2000 .

[17]  A. Gordon,et al.  Cosmonaut polynya in the Southern Ocean: Structure and variability , 1996 .

[18]  Andrew Thomas,et al.  The influence of cloud cover on the radiation budget, physical properties, and microwave scattering coefficient (σ°) of first-year and multiyear sea ice , 1998, IEEE Trans. Geosci. Remote. Sens..

[19]  John E. Walsh,et al.  Recent decrease of sea level pressure in the central Arctic , 1996 .

[20]  David G. Barber,et al.  The physical, radiative and microwave scattering characteristics of melt ponds on Arctic landfast sea ice , 1999 .

[21]  M. Drinkwater.  LIMEX '87 ice surface characteristics: implications for C-band SAR backscatter signatures , 1989 .

[22]  Stuart D. Smith,et al.  Polynyas and leads: An overview of physical processes and environment , 1990 .

[23]  Son V. Nghiem,et al.  The role of snow on the thermal dependence of microwave backscatter over sea ice , 1999 .

[24]  D. Barber,et al.  An examination of the relation between the spring period evolution of the scattering coefficient (σ) and radiative fluxes over Jandfast sea-ice , 1995 .

[25]  Tamara Shapiro Ledley,et al.  Variations in snow on sea ice: A mechanism for producing climate variations , 1993 .

[26]  Donald J. Cavalieri,et al.  Arctic sea ice extents, areas, and trends, 1978-1996 , 1999 .

[27]  T. Grenfell,et al.  Temporal variations of the microwave signatures of sea ice during the late spring and early summer near Mould Bay NWT , 1985 .