The International polar year (IPY) circumpolar flaw lead (CFL) system study: Overview and the physical system

Abstract

The Circumpolar Flaw Lead (CFL) system study is a Canadian-led International Polar Year (IPY) initiative with over 350 participants from 27 countries. The study is multidisciplinary in nature, integrating physical sciences, biological sciences and Inuvialuit traditional knowledge. The CFL study is designed to investigate the importance of changing climate processes in the flaw lead system of the northern hemisphere on the physical, biogeochemical and biological components of the Arctic marine system. The circumpolar flaw lead is a perennial characteristic of the Arctic throughout the winter season and forms when the mobile multi-year (MY) pack ice moves away from coastal fast ice, creating recurrent and interconnected polynyas in the Norwegian, Icelandic, North American and Siberian sectors of the Arctic. The CFL study was 293 days in duration and involved the overwintering of the Canadian research icebreaker CCGS Amundsen in the Cape Bathurst flaw lead throughout the annual sea-ice cycle of 2007-2008. In this paper we provide an introduction to the CFL project and then use preliminary data from the field season to describe the physical flaw lead system, as observed during the CFL overwintering project. Preliminary data show that ocean circulation is affected by eddy propagation into Amundsen Gulf (AG). Upwelling features arising along the ice edge and along abrupt topography are also detected and identified as important processes that bring nutrient rich waters up to the euphotic zone. Analysis of sea-ice relative vorticity and sea-ice area by ice type in the AG during the CFL study illustrates increased variability in ice vorticity in late autumn 2007 and an increase in new and young ice areas in the AG during winter. Analysis of atmospheric data show that a strong northeast-southwest pressure gradient present over the AG in autumn may be a synoptic-scale atmospheric response to sensible and latent heat fluxes arising from areas of open water persisting into late November 2007. The median atmospheric boundary layer temperature profile over the Cape Bathurst flaw lead during the winter season was stable but much less so when compared to Russian ice island stations.RéSuMé [Traduit par la rédaction] L'étude du système du chenal de séparation circumpolaire (CSC) est une initiative de l'Année polaire internationale (API) menée par le Canada et à laquelle 350 participants provenant de 27 pays ont pris part. L'étude, de nature multidisciplinaire, fait appel aux sciences physiques et biologiques ainsi qu'au savoir traditionnel Inuvialuit. L'étude du CSC vise à examiner les répercussions des processus climatiques changeants dans le système du chenal de séparation de l'hémisphère Nord sur les composantes physiques, biogéochimiques et biologiques du système marin arctique. Le CSC est une caractéristique permanente de l'Arctique durant la saison d'hiver et se forme quand la banquise mobile de glace de plusieurs années s'éloigne de la banquise côtière fixe en créant des polynies récurrentes et interconnectées dans les sec...

Physical forcings and intense shelf–slope fluxes of particulate matter in the halocline waters of the Canadian Beaufort Sea during winter

“…Mesoscale eddies in the Beaufort and Chukchi seas are now recognized as an important mechanism for transporting particulate matter from the shelf to the slope and basin environments, thus contributing to both the land-ocean transfer of terrigenous material and to the biological pumping of carbon to depth (Forest et al, 2008;Honjo et al, 2010;O'Brien et al, 2011O'Brien et al, , 2013Watanabe et al, 2014). During winter, the bottom-intensified and slowly-decaying configuration of the shelf-break jet raises the possibility that the Pacific water is mainly routed toward the Canadian Archipelago , thus enhancing the presence of the shelfbreak current and related eddy generation activity to the east -as observed by Barber et al (2010).…”

Modeling and Measurement of C-Band Radar Backscatter From Snow-Covered First-Year Sea Ice

“…Scatterometer and physical data for our study were collected in the southern Beaufort Sea in the winter of 2008 from the research icebreaker CCGS Amundsen as part of the Circumpolar Flow Lead (CFL) system study [29]. Three sites (case studies) representing mobile snow-covered FY sea ice (1.2, 1.2, and 1.1 m thick, respectively) were selected for our analysis (as shown in Table I …”

Integral Profile Estimates of Latent Heat Flux under Clear Skies at an Unconsolidated Sea-Ice Surface

“…b ABL Water Vapour Density Profiles As part of the instrumentation aboard the CCGS Amundsen during the IPY-CFL field campaign (Barber et al, 2010), a Radiometrics MP-3000A © microwave radiometer measured atmospheric temperature and water vapour density profiles (50 m intervals from 0 to 500 m, 100 m intervals from 500 to 2000 m, and 250 m intervals from 2000 to 10,000 m) with high temporal (approximately 1 minute) resolution at various locations over Amundsen Gulf. Temperature and water vapour density profiles were derived using the manufacturer's neural network that had been trained using measurements from the nearest operational upper-air station at Inuvik, Canada (68.30°N; 133.47°W).…”

“…In this study, hour-to-hour changes in near-surface (0-500 m) MWR vapour density profiles observed from January through April 2008 of the International Polar Year, Circumpolar Flaw Lead (IPY-CFL) system study (Barber et al, 2010), and the principle of moisture conservation were used to determine latent heat flux convergence/ divergence profiles. The integral profile method (the vertical integration of latent heat flux convergence or divergence) was then used to estimate the mesoscale latent heat flux (Q E ) at the unconsolidated sea-ice surface of Amundsen Gulf in Canada's western maritime Arctic.…”