Microwave signatures of first-year and multiyear sea ice

Abstract

A combination of remote sensing from an aircraft and simultaneous surface measurements have confirmed the feasibility of identifying old and new sea ice according to its emission of thermal radiation at wavelengths between 0.3 and 3 cm. Emissivity of first‐year thick ice with a surface temperature of about 260°K is 0.95 or greater for wavelengths between 0.81 and 11 cm; the emissivity of multiyear ice is 0.8 at 0.81 cm and 0.95 at 11 cm, increasing monotonically in this wavelength interval. The ease with which multiyear ice can be distinguished from first‐year ice using a passive microwave radiometer is demonstrated by comparing mosaics prepared both from photographs and images of 1.55‐cm radiation.

Estimating sea-ice volume flux out of the Laptev Sea using multiple satellite observations

“…Assuming ice density, water density and snow depth, ice freeboard can be converted to ice thickness by applying the Archimedes principle (Kwok, Zwally et al 2004). The density of sea ice varies depending on the age of the ice, which is related to the amount of brine and air inclusions (Gloersen et al 1973). FY ice containing a substantial amount of brine water is expected to have a higher density.…”

Satellites—New Global Observing Techniques for Ice and Snow

“…The sea ice surrounding Antarctica appears to have the characteristics of first-year ice, that is, ice with salinity content of 1% or more in the freeboard portion of the ice. The emissivity of such ice is 0.95 or greater at a wavelength of 1.55 cm based on aircraft measurements in the Arctic area (Gloersen et al, 1973 and. The fact that this signature is present in the Weddell Sea is surprising inasmuch as the ice pack in this region persists from one year to the next, according to the ESMR data acquired since November 1972 and the observations of workers in the field (W. F. Weeks, Priv.…”

“…Only under conditions of extensive heavy rainfall does the entire contribution come from the atmosphere. The applications of the ESMR imagery in terms of meteorological phenomena over the oceans have been described by Wilheit et al (1973). The atmospheric contribution is the greatest in the tropical regions.…”

Technology in the advancement of glaciology

“…Sensitive also to the difference in emission between multiyear and first-year sea ice ( Fig. 14; from Gloersen and others, 1973), the passive microwave data also provide unique information on the concentration of multi-year ice (Cavalieri and others, 1984) and the drift, convergence/ divergence, and inter-annual variability of the perennial ice pack on the Arctic Ocean (Zwally and Walsh, 1987).…”

“…Scanning electron micrographs of the 'entrapped dust (Fig. 10) enable the identification of the sources of particles as volcanic, continental, or extra-terrestrial (Mosley- Thompson, 1980 Gloersen and others, 1973. ) particular, recent dust studies indicate that the high concentration of particles in the late Wisconsinan is predominantly due to wind-blown desert dust (Petit and others, 1981).…”