Observations of sea ice ridging in the Weddell Sea

Abstract

Equipment Configuration and Measurements Laser and CamerasThe laser profiler is a Holometrix LRG-90 with a PRAM IV controller (Figure la). This system uses a GaAs pulsed laser 25,735

Morphology of sea ice pressure ridges in the northwestern Weddell Sea in winter

“…The highest ridge frequencies of more than 10/km were found mainly in the northwestern and southeastern Weddell Sea, the Amundsen Sea and the eastern Bellingshausen Sea, while the ice deformation in the central parts and the eastern non-coastal region of the Weddell Sea, the Ross Sea and other parts of the Bellingshausen Sea was distinctly smaller. The mean ridge heights of regimes C 2 and C 3 in the present data set are higher than all those of other studies, and the frequencies are larger than those of the Ross Sea [Weeks et al, 1989] and the eastern Weddell Sea [Lytle and Ackley, 1991;Granberg and Leppäranta, 1999].…”

“…It is clear that the mean ridge heights in the present study with different cutoff heights are larger than the corresponding values in other studies (Figure 11a), while the ridge frequencies and ridging intensities are greatly smaller than the corresponding values in the Amundsen Sea and Weddell Sea presented by Haas et al [1999], but similar to those of others (Figures 11b and 11c). The average thickness of ridged ice is similar to that of Granberg and Leppäranta [1999], but greatly larger than that reported by Weeks et al [1989]. The average thickness of ridged ice given by Lytle and Ackley [1991] seems to be smaller than the present result, intuitively, but it is within the range of uncertainty of the present value, thus there is no significant difference between them.…”

“…For example, Weeks et al [1989] also found the best fit between the Wadhams'80 distribution and the measured ridge height but Lytle and Ackley [1991] found that the Hibler'72 distribution was a better match for the measured ridge height data. For the ridge spacing distribution, the better fit by a lognormal function than a negative exponential function was found by Dierking [1995], while Granberg and Leppäranta [1999] found that the ridge spacing distribution fit neither of the two distributions particularly well but resembled the lognormal distribution more closely in the eastern Weddell Sea.…”

“…Results from different Antarctic areas have been assembled into a ridge frequency‐ height diagram (Figure 12) similar to that in Leppäranta [2011]. All results of these studies have been transformed to a 1‐m cutoff height using the relations 〈 h 〉 = 〈 h 〉 c 0 + h c ‐ h c 0 and 〈 s 〉 = exp[ λ 2 ( h c ‐ h c 0 )] 〈 s 〉 c 0 , where 〈 h 〉 c 0 and 〈 s 〉 c 0 are the mean ridge height and mean spacing at the cutoff height of h c 0 for different data sets [ Dierking , 1995; Granberg and Leppäranta , 1999], to ease comparison. Each of the sea areas appears to occupy its own characteristic region in the ( μ r , 〈 h 〉) space.…”

“…Arctic ridge morphology and distributions have been well documented by laser altimeter surveys [ Wadhams , et al , 1992; Doble et al , 2011] and airborne electromagnetic‐inductive (HEM) methods [ Peterson et al , 2008; Rabenstein et al , 2010]. Researchers have observed the morphology and frequency of pressure ridges in the Antarctic by employing the airborne laser systems [ Weeks et al , 1989; Dierking , 1995; Haas et al , 1999; Granberg and Leppäranta , 1999], ship‐based systems [ Lytle and Ackley , 1991; Haas , 1998], HEM methods [ Haas et al , 2009a] and remote sensing [ Bashmachnikov et al , 2009]. However, to the authors' knowledge, few field observations or quantitative analyses of pressure ridges are available for the northwestern Weddell Sea, which is one of a few regions around Antarctica covered by perennial sea‐ice and plays an important role in the freshwater and energy budget of the Southern Ocean [ Haas et al , 2008].…”