Frost-table and Thaw Depths in the Littoral Zone near Peard Bay, Alaska

Abstract

ABSTRACT. Measurements were made of thaw depths and of sub-surface temperatures along four beach profiles, between late May and late August. On the upper beach levels, thaw proceeded rapidly following the disappearance of surface snow, but then became much slower. Near the water line, thaw was delayed by the presence of beach-fast ice, but thereafter increased steadily to greater depths than on the upper beach. Greater thaw depths were reached on barrier beaches than on beaches backed by tundra. On the upper beach, thaw depths and zero-degree depths did not differ significantly, but near the water line they were at variance due to the presence of saline pore waters. &UM& Table de gel et profondeurs du dkgel dans la zone du littoral, pr2s dePeard Bay, Alaska. On mesura, sur une p6riode s'Ctendant de la fin mai B la fin aofit et le long de quatre lignes trades en travers des plages, les profondeurs respectives des mnes de dCgel, ainsi que les tempiratures profondes correspondantes. A des niveaux de plage ClevCs, le d6gel se poursuivit rapidement aprBs la disparition de la neige de surface, pour ensuite se ralentir consid6rablement. Par contre, le long du rivage, le dCgel se poursuivit lentement tant qu'il restait de la glace dans la mer, mais ensuite, la profondeur du dCgel augmenta considCrablement pour atteindre des profondeurs plus grandes que celles des niveaux de plage plus ClevCs. Les zones de dCgel atteignirent des profondeurs plus importantes sur les cordons littoraux que sur les plages qui se prolongeaient par la toundra. A des niveaux de plage ClevCs, on n'enregistra pas de diffkrences significatives entre la profondeur des zones de dCgel et de celles de ziro degrC de tempkrature, alors que, prbs du rivage, elles ne co'incidaient pas, B cause de la prhence de pores d'eau salBe entre les grains de sable.

Pathways and transformations of dissolved methane and dissolved inorganic carbon in Arctic tundra watersheds: Evidence from analysis of stable isotopes

“…Liquid active layer water samples were collected from three depths at each location including (1) surface waters, (2) "shallow" subsurface (7.5-15 cm from surface), which was commonly an organic soil horizon, and (3) the bottom of the active layer ("deep"; maximum depth to the frost table < 64 cm, often a mineralrich horizon), which varied with depth across sites from July (33.8 ± 1.7 cm) to September (43.3 ± 2.0 cm) ( Table A1 of the supporting information). We define the frost table as the upper surface of ice-bonded material and the active layer thaw depth as the depth from the soil or water surface to the upper limit of ice-bonded material [Owens and Harper, 1977]. The frost table begins to thaw from the surface in spring and reaches maximum depth in fall just before winter frost, which is consistent with our deeper measurements of the frost table in September than in July for our study.…”

Variability in Rates of Coastal Change Along the Yukon Coast, 1951 to 2015

“…The beach, barrier island, and spit class has the highest peak‐to‐peak variability in rates of shoreline change (−7.2 ± 0.2 to 5.3 ± 0.2 m/a; Figure ). Coastal heights in this class do not exceed 2 m and can thaw to a depth of over 1.5 m during summers (Owens & Harper, ). Thus, the sands, gravels, and cobbles are reworked by waves during the ice‐free season, especially during storms and on a daily basis by longshore currents (Harper, ).…”

Urban–rural contrasts in summer soil-surface temperature and active-layer thickness, Barrow, Alaska, USA

“…Several previous studies in Barrow have direct bearing on the results in the gravel categories. Southwest of Barrow, Owens and Harper (1977) found that the upper beach and mid-spit gravel berms thawed rapidly after snowmelt, which occurred 5Á10 days earlier than on the nearby tundra. Sand and gravel used in the construction of roads and building pads in Barrow is similar to that found on the beaches because it is locally extracted from old beach deposits.…”