Geographical distribution and volume of Antarctic icebergs derived from ship observation data

Abstract

ABSTRACT. Information on the occurrence, spatial distribution and morphometric characteristics of Antarctic icebergs is needed in a large number of applications including navigation, heat and freshwater balance calculations, biochemistry of the ocean and climatology. Using over 60 000 ship observations of icebergs in the Southern Ocean collected since the end of the 1940s we have produced a detailed map of the distribution of Antarctic icebergs as well as maps of related statistics including the standard deviation, minimum and maximum values of the iceberg concentration and the probability of iceberg-free observations. The study incorporated small and medium-sized icebergs with a length of <10 nautical miles. Most observations were taken during the warm period of the year, from December to April. It is shown that the iceberg distribution across the Southern Ocean is determined by the location of calving regions and peculiarities of the atmospheric circulation and ocean currents. Iceberg concentration data combined with information on the iceberg size and shape distribution have been used to evaluate the area-integrated characteristics of Antarctic icebergs. The instantaneous number of icebergs in the Southern Ocean was estimated as 132 269 with an uncertainty of 7%. The area and volume of icebergs were equal correspondingly to 55 805 km 2 and 16 893 km 3 with uncertainties of 32-33%.

Antarctic petrels ‘on the ice rocks’: wintering strategy of an Antarctic seabird

“…This contradiction requires further investigations. The Polar Front coincides with the northern boundary of the iceberg occurrence [52]. It represents a highly dynamic and heterogeneous region where the ice platform breaks, creating zones of mixing and turmoil, but also a corridor for icebergs that originate mostly from the ice shelves in the Weddell Sea and drift with the Antarctic Circumpolar Current [53,54].…”

Iceberg topography and volume classification using TanDEM-X interferometry

“…in which N L is the independent number of looks and γ is the interferometric coherence (Rosen et al, 2000;Dierking et al, 2017). Based on an average coherence, γ ∼ 0.7 for our study area, this results in a relative height accuracy, σ h ∼ 2.5 m.…”

“…For backscatter, this involved multilooking of 2 × 2 pixels (resulting in resolution of roughly 2.7 m in range and 4.7 m in azimuth) and filtering 5 × 5 pixels using a standard boxcar filter. To obtain phase-derived height (referred to hereafter as the InSAR Digital Elevation Model or InSAR DEM), we followed a standard InSAR processing workflow (Rosen et al, 2000). This processes involves multilooking (2 × 2 pixels) and adaptive phase filtering (Goldstein and Werner, 1998) to reduce phase noise.…”

“…Here, the physical limitations of existing techniques in measuring morphology hamper consistent and accurate iceberg evaluation over large areas (Romanov et al, 2017). TanDEM-X SAR interferometry (InSAR) (Rosen et al, 2000) is a technique to extract topography from the phase information from two complex SAR scenes. This technique has previously been utilized to assess sea ice ridges (Dammann et al, 2017;Dierking et al, 2017;Yitayew et al, 2018).…”

Iceberg topography and volume classification using TanDEM-X interferometry

“…estimate unless the subaerial morphology is measured. The physical limitations of existing techniques in measuring morphology hamper consistent and accurate iceberg evaluation over large areas (Romanov et al, 2017).…”