16 research outputs found
The Changing Climate of the Arctic
The first and strongest signs of global-scale climate change exist in the high latitudes of the planet. Evidence is now accumulating that the Arctic is warming, and responses are being observed across physical, biological, and social systems. The impact of climate change on oceanographic, sea-ice, and atmospheric processes is demonstrated in observational studies that highlight changes in temperature and salinity, which influence global oceanic circulation, also known as thermohaline circulation, as well as a continued decline in sea-ice extent and thickness, which influences communication between oceanic and atmospheric processes. Perspectives from Inuvialuit community representatives who have witnessed the effects of climate change underline the rapidity with which such changes have occurred in the North. An analysis of potential future impacts of climate change on marine and terrestrial ecosystems underscores the need for the establishment of effective adaptation strategies in the Arctic. Initiatives that link scientific knowledge and research with traditional knowledge are recommended to aid Canadaâs northern communities in developing such strategies.Les premiers signes et les signes les plus rĂ©vĂ©lateurs attestant du changement climatique qui sâexerce Ă lâĂ©chelle planĂ©taire se manifestent dans les hautes latitudes du globe. Il existe de plus en plus de preuves que lâArctique se rĂ©chauffe, et diverses rĂ©actions sâobservent tant au sein des systĂšmes physiques et biologiques que sociaux. Les incidences du changement climatique sur les processus ocĂ©anographiques, la glace de mer et les processus atmosphĂ©riques sâavĂšrent Ă©videntes dans le cadre dâĂ©tudes dâobservation qui mettent lâaccent sur les changements de tempĂ©rature et de salinitĂ©, changements qui exercent une influence sur la circulation ocĂ©anique mondiale â Ă©galement appelĂ©e circulation thermohaline â ainsi que sur le dĂ©clin constant de lâĂ©tendue et de lâĂ©paisseur de glace de mer, ce qui influence la communication entre les processus ocĂ©aniques et les processus atmosphĂ©riques. Les perspectives de certains Inuvialuits qui ont Ă©tĂ© tĂ©moins des effets du changement climatique font mention de la rapiditĂ© avec laquelle ces changements se produisent dans le Nord. Lâanalyse des incidences Ă©ventuelles du changement climatique sur les Ă©cosystĂšmes marin et terrestre fait ressortir la nĂ©cessitĂ© de mettre en oeuvre des stratĂ©gies dâadaptation efficaces dans lâArctique. Des initiatives reliant les recherches et connaissances scientifiques aux connaissances traditionnelles sont recommandĂ©es afin de venir en aide aux collectivitĂ©s du Nord canadien pour que celles-ci puissent aboutir Ă de telles stratĂ©gies
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On sea-ice dynamical regimes in the Arctic Ocean
Central to an understanding of evolution in sea-ice characteristics in response to climate change is an understanding of sea-ice dynamics. In this study, we investigate regional differences in ice dynamics in the Beaufort Sea and High Arctic using high-frequency ice buoy (beacon) data deployed during the SEDNA and IPY-CFL field campaigns from spring 2007 to winter 2008. Examined in particular are scaling laws determined from absolute dispersion statistics. We create temporal scaling maps to determine whether distinct dynamical regimes can be identified with differing scaling properties. The results from this analysis provide an alternative characterization to changes in sea ice based on dynamics rather than concentration and thickness, and thus insight into, and improved understanding of, the connections between sea-ice drift and morphology.This is the publisherâs final pdf. The published article is copyrighted by International Glaciological Society and can be found at: http://orst.library.ingentaconnect.com/content/igsoc/agl/2015/00000056/00000069/art00035?token=004e105a5c5f3b3b4746527666257370507b467a404f582a2f433e402c3568263c2bc5951624c
Landfast Sea Ice Conditions in the Canadian Arctic: 1983 â 2009
We used Canadian Ice Service (CIS) digital charts from 1983 to 2009 to create a climatology of landfast sea ice in the Canadian Arctic. The climatology characterized the spatial distribution and variability of landfast ice through an average annual cycle and identified the mean onset date, breakup date, and duration of landfast ice. Trends in date and duration of onset and breakup were calculated over the 26-year period on the basis of CIS regions and sub-regions. In several sub-regionsâ particularly in the Canadian Arctic Archipelagoâwe calculated significant trends towards later landfast ice onset or earlier breakup, or both. These later onset and earlier breakup dates translated into significant decreases in landfast ice duration for many areas of the Canadian Arctic. For communities located in the most affected areas, including Tuktoyaktuk, Kugluktuk, Cambridge Bay, Gjoa Haven, Arctic Bay, and Pond Inlet, this shorter landfast ice season is of significant social, cultural, and economic importance. Landfast sea-ice duration in the interior of the Northwest Passage has not undergone any statistically significant decrease over the time series.Nous nous sommes appuyĂ©s sur les cartes numĂ©riques du Service canadien des glaces (SCG) pour les annĂ©es 1983 Ă 2009 afin de produire la climatologie de la glace de mer de lâArctique canadien. La climatologie permet de caractĂ©riser la distribution spatiale et la variabilitĂ© de la glace de mer au moyen dâun cycle annuel moyen, et de dĂ©terminer la date moyenne du commencement, la date de la dĂ©bĂącle et la durĂ©e de la glace de mer. Les tendances en matiĂšre de dates et de durĂ©es relativement au commencement et Ă la dĂ©bĂącle ont Ă©tĂ© calculĂ©es sur la pĂ©riode de 26 ans en fonction des rĂ©gions visĂ©es par le SCG et des sous-rĂ©gions. Dans plusieurs sous-rĂ©gions â plus particuliĂšrement dans lâarchipel Arctique canadien â nous avons calculĂ© dâimportantes tendances indiquant des dates de commencement plus tardives de la glace de mer ou des dates de dĂ©bĂącle plus hĂątives, ou les deux. Ces dates plus hĂątives et plus tardives se traduisent par la rĂ©duction considĂ©rable de la durĂ©e de la glace de mer en maints endroits de lâArctique canadien. Pour les localitĂ©s situĂ©es dans la plupart des rĂ©gions touchĂ©es, dont Tuktoyaktuk, Kugluktuk, Cambridge Bay, Gjoa Haven, Arctic Bay et Pond Inlet, cette saison de glace de mer plus courte revĂȘt une grande importance sur les plans social, culturel et Ă©conomique. Du point de vue statistique, la durĂ©e de la glace de mer Ă lâintĂ©rieur du passage du Nord-Ouest nâa pas connu de rĂ©duction importante au cours de cette pĂ©riode
Tropospheric Carbon Monoxide Measurements from the Scanning High-Resolution Interferometer Sounder on 7 September 2000 in Southern Africa During SAFARI 2000
[1] Retrieved tropospheric carbon monoxide (CO) column densities are presented for more than 9000 spectra obtained by the University of Wisconsin-Madison (UWis) Scanning High-Resolution Interferometer Sounder (SHIS) during a flight on the NASA ER-2 on 7 September 2000 as part of the Southern African Regional Science Initiative (SAFARI 2000) dry season field campaign. Enhancements in tropospheric column CO were detected in the vicinity of a controlled biomass burn in the Timbavati Game Reserve in northeastern South Africa and over the edge of the river of smoke in south central Mozambique. Relatively clean air was observed over the far southern coast of Mozambique. Quantitative comparisons are presented with in situ measurements from five different instruments flying on two other aircraft: the University of Washington Convair-580 (CV) and the South African Aerocommander JRB in the vicinity of the Timbavati fire. Measured tropospheric CO columns (extrapolated from 337 to 100 mb) of 2.1 Ă 1018 cmâ2 in background air and up to 1.5 Ă 1019 cmâ2 in the smoke plume agree well with SHIS retrieved tropospheric CO columns of (2.3 ± 0.25) Ă 1018 cmâ2 over background air near the fire and (1.5 ± 0.35) Ă 1019 cmâ2 over the smoke plume. Qualitative comparisons are presented with three other in situ CO profiles obtained by the South African JRA aircraft over Mozambique and northern South Africa showing the influence of the river of smoke
The 2017 reversal of the Beaufort Gyre: Can dynamic thickening of a seasonal ice cover during a reversal limit summer ice melt in the Beaufort Sea?
During winter 2017 the semiâpermanent Beaufort High collapsed and the anticyclonic Beaufort Gyre reversed. The reversal drove eastward ice motion through the Western Arctic, causing sea ice to converge against Banks Island, and halted the circulation of multiyear sea ice via the gyre, preventing its replenishment in the Beaufort Sea. Prior to the reversal, an anomalously thin seasonal ice cover had formed in the Beaufort following iceâfree conditions during September 2016. With the onset of the reversal in January 2017, convergence drove uncharacteristic dynamic thickening during winter. By the end of March, despite seasonal ice comprising 97% of the ice cover, the reversal created the thickest, roughest and most voluminous regional ice cover of the CryoSatâ2 record. Within the Beaufort Sea, previous work has shown that winter ice export can precondition the region for increased summer ice melt, but that a short reversal during April 2013 contributed to a reduction in summer ice loss. Hence the deformed ice cover at the end of winter 2017 could be expected to limit summer melt. In spite of this, the Beaufort ice cover fell to its fourth lowest September area as the gyre reâestablished during April and divergent ice drift broke up the pack, negating the reversal's earlier preconditioning. Our work highlights that dynamic winter thickening of a regional sea ice cover, for instance during a gyre reversal, offers the potential to limit summer ice loss, but that dynamic forcing during spring dictates whether this conditioning carries through to the melt season
On the spatiotemporal behavior of sea ice concentration anomalies in the Northern Hemisphere
Method to characterize directional changes in Arctic sea ice drift and associated deformation due to synoptic atmospheric variations using Lagrangian dispersion statistics
AÂ framework is developed to assess the directional changes in sea
ice drift paths and associated deformation processes in response to
atmospheric forcing. The framework is based on Lagrangian
statistical analyses leveraging particle dispersion theory which
tells us whether ice drift is in a subdiffusive, diffusive,
ballistic, or superdiffusive dynamical regime using single-particle
(absolute) dispersion statistics. In terms of sea ice deformation,
the framework uses two- and three-particle dispersion to
characterize along- and across-shear transport as well as
differential kinematic parameters. The approach is tested with GPS
beacons deployed in triplets on sea ice in the southern Beaufort Sea
at varying distances from the coastline in fall of 2009 with eight
individual events characterized. One transition in particular
follows the sea level pressure (SLP) high on 8Â October in 2009 while the sea ice drift
was in a superdiffusive dynamic regime. In this case, the dispersion
scaling exponent (which is a slope between single-particle absolute
dispersion of sea ice drift and elapsed time) changed from
superdiffusive (αââŒâ3) to ballistic (αââŒâ2) as
the SLP was rounding its maximum pressure value. Following this
shift between regimes, there was a loss in synchronicity between sea
ice drift and atmospheric motion patterns. While this is only one
case study, the outcomes suggest similar studies be conducted on
more buoy arrays to test momentum transfer linkages between storms
and sea ice responses as a function of dispersion regime states
using scaling exponents. The tools and framework developed in this
study provide a unique characterization technique to evaluate these
states with respect to sea ice processes in general. Application of
these techniques can aid ice hazard assessments and weather
forecasting in support of marine transportation and indigenous use
of near-shore Arctic areas
Summer extreme cyclone impacts on Arctic sea ice
In this study the impact of extreme cyclones on Arctic sea ice in summer is investigated. Examined in particular are relative thermodynamic and dynamic contributions to sea ice volume budgets in the vicinity of Arctic summer cyclones in 2012 and 2016. Results from this investigation illustrate that sea ice loss in the vicinity of the cyclone trajectories during each year was associated with different dominant processes: thermodynamic processes (melting) in the Pacific sector of the Arctic in 2012, and both thermodynamic and dynamic processes in the Pacific sector of the Arctic in 2016. Comparison of both years further suggests that the Arctic minimum sea ice extent is influenced by not only the strength of the cyclone, but also by the timing and location relative to the sea ice edge. Located near the sea ice edge in early August in 2012, and over the central Arctic later in August in 2016, extreme cyclones contributed to comparable sea ice area (SIA) loss, yet enhanced sea ice volume loss in 2012 relative to 2016. Central to a characterization of extreme cyclone impacts on Arctic sea ice from the perspective of thermodynamic and dynamic processes, we present an index describing relative thermodynamic and dynamic contributions to sea ice volume changes. This index helps to quantify and improve our understanding of initial sea ice state and dynamical responses to cyclones in a rapidly warming Arctic, with implications for seasonal ice forecasting, marine navigation, coastal community infrastructure, and designation of protected and ecologically sensitive marine zones