International Polar Research Articles

The influence of winds, sea-surface temperature and precipitation anomalies on Antarctic regional sea-ice conditions during IPY 2007

The 2007 International Polar Year (IPY) in the Antarctic was distinguished by strong regional and seasonal ice-atmosphere-ocean anomalies associated with an overall weakening of the prevailing westerly circulation. Here we assess the ice-atmosphere-ocean conditions leading up to and during two IPY field campaigns that took place in early spring (September-October): the U.S.-led Sea Ice Mass Balance Antarctica (SIMBA, 68-72°S, 90-95°W) and the Australian-led Sea Ice Physics and Ecosystems eXperiment (SIPEX, 63-67°S, 115-130°E). Our regional analysis is presented within the context of circumpolar and inter-annual variability relevant to other IPY Antarctic studies. Using satellite-derived and numerically analyzed surface and atmospheric variables, we examine relationships between (i) winds and sea-ice concentration and drift, (ii) sea-surface temperature and ice-edge anomalies, and (iii) precipitation and snow accumulation. Though Antarctic-averaged sea-ice extent in September 2007 was the second highest observed for 1979-2007, the SIMBA and SIPEX studies sampled the two regions showing the largest negative sea-ice anomalies in the Southern Ocean. Maps of sea-surface temperature (SST) and sea-ice concentration (SIC) anomalies revealed distinct regional patterns, showing warm SST/low SIC in the greater SIMBA (including all of the Bellingshausen and Amundsen seas) and western SIPEX regions, versus cool SST/high SIC in the Weddell, Ross and eastern SIPEX regions. In the SIMBA and western SIPEX regions, warm northerly winds in May (overlying the warm SSTs) brought anomalously high precipitation to those regions, but due to the regional delays in sea-ice advance (by up to 2 months), most fell on open ocean, which in turn contributed to negative and near-zero September snow depth anomalies in those two regions, respectively. During autumn (March to May), warm SSTs offshore of those regions extended from mid-to-high latitudes, resulting from meridional advection of heat associated with a wave-3 atmospheric circulation pattern. In the SIMBA and SIPEX regions, the late sea-ice advance followed unusually long ice-free summer periods, which suggests that solar ocean warming was relatively high in those regions. The warm ocean conditions may help to explain why the ice edge remained well south of its mean position despite instances during winter of cold southerly winds and northward sea-ice drift. Finally, with respect to the 1978-2008 record, year 2007 was a continuation of decreasing sea ice in the SIMBA region (e.g., decreased annual sea-ice extent and ice season duration), whereas in the SIPEX region, year 2007 was a negative departure from an otherwise slightly positive trend in annual sea-ice extent and ice season duration.

Hot Arctic—Cold Continents: Global Impacts of Arctic Change: International Polar Year Oslo Science Conference; Oslo, Norway, 8–12 June 2010

A warmer Arctic climate is influencing air pressure over the North Pole and wind patterns over the Northern Hemisphere. In response, recent data and modeling suggest that more cold and snowy winters can be expected in Europe, eastern Asia, and eastern North America. These were some of the issues discussed at the International Polar Year (IPY) conference, the largest polar science meeting ever held, with more than 2400 attendees. More than 80 scientific papers debated the state of the science regarding Arctic amplification and midlatitude connections. Arctic amplification is just that: The Arctic is warming twice as fast as the rest of the planet, caused by unique physical processes related in part to loss of sea ice. Arctic amplification is also a consequence of changes in atmospheric circulation that are anthropogenically forced, part of chaotic variability, or both.

Biology of Salpa thompsoni in waters adjacent to the Ross Sea, Southern Ocean, during austral summer 2008

Depth-stratified vertical sampling was carried out during the New Zealand International Polar Year cruise to the Ross Sea on board the RV Tangaroa in February–March 2008. The distribution (horizontal and vertical), density and population biology of Salpa thompsoni were investigated. Salps were found at two of the four major sampling locations, e.g. near the continental slope of the Ross Sea and in the vicinity of seamounts to the north of the Ross Sea. Both abundance and biomass of S. thompsoni were highest near the seamounts in the Antarctic Circumpolar Current reaching ~2,500 ind 1,000 m−3 and 8.2 g dry wt 1,000 m−3 in the water column sampled. The data showed that S. thompsoni populations were able to utilize horizontal and vertical discontinuities in water column structure, in particular the warm Circumpolar Deep Water (CDW), to persist in the high Antarctic. Although salps appeared to continue migrating to the surface colder layers to feed, both aggregate chain and young embryo release seem to be restricted to the CDW. This study for the first time has provided evidence that low Antarctic salp species may successfully reproduce in the hostile high Antarctic realm.

The gas/particle partitioning of polycyclic aromatic hydrocarbons collected at a sub-Arctic site in Canada

Polycyclic aromatic hydrocarbons (PAH) were measured in air samples at a remote air monitoring site established in the Yukon Territory, Canada as part of a global project (International Polar Year; IPY) to study the potential for atmospheric long-range transport of anthropogenic pollutants to the Arctic. Gas- and particle-phase PAH were collected in polyurethane foam plugs and on glass fibre filters respectively from August 2007 to October 2009. PAH concentrations were found to be highest in the winter months and lowest in summer. The gas/particle partitioning coefficients of 3–5 ringed PAH were computed and seasonal averages were compared. In the summer time, lower molecular mass PAH exhibited relatively higher partitioning into the particle-phase. This particle-phase partitioning led to the shallowest slopes being recorded during summer for the log–log correlation plots between the PAH partition coefficients and their sub-cooled vapour pressures. Air mass back trajectories suggest that local impacts may be more important during the summer time which is marked by increased camping activities at camping sites in the proximity of the sampling station. In conclusion, both summer and wintertime variations in PAH concentrations and gas/particle partitioning are considered to be source- and phototransformation-dependent rather than dependent on temperature-driven shifts in equilibrium partitioning.

Can CAPE Maintain Polar Lows?

Abstract A unique dataset of atmospheric observations over the Nordic Seas has been analyzed to investigate the role of convective available potential energy (CAPE) for the energetics of polar lows. The observations were made during the flight campaign of the Norwegian International Polar Year (IPY) and The Observing System Research and Predictability Experiment (THORPEX) in February and March 2008, which specifically targeted polar lows. The data reveal virtually no conditional instability and very limited CAPE. It is suggested that the significance of CAPE values should be assessed by calculating the time scale tCAPE that is necessary for the heat fluxes from the ocean to transfer the corresponding amount of energy. Even the largest CAPE values have a tCAPE of less than 1 h. These CAPE values are associated with unconditional instability. It is concluded that the observed CAPE should be seen as a temporary stage in an energy flux rather than as an energy reservoir. Based on the findings in this investigation, it is proposed that significant reservoirs of CAPE over the marine Arctic atmosphere are impossible since CAPE production will automatically trigger convection and CAPE is consumed as it is produced.

Distribution, abundance and acoustic properties of Antarctic silverfish ( Pleuragramma antarcticum) in the Ross Sea

Antarctic silverfish ( Pleuragramma antarcticum) is a key link between plankton and the community of top predators in the shelf waters of the Ross Sea. In spite of their abundance and important role in Antarctic food chains, very little is known of many ecological and biological aspects of this species. A combined trawl and acoustic survey of silverfish was carried out on the western Ross Sea shelf during the New Zealand International Polar Year Census of Antarctic Marine Life research voyage on R.V. Tangaroa in February–March 2008. Multi-frequency acoustic data (12, 38, 70, and 120 kHz) allowed discrimination of silverfish marks from those of krill and other associated species. Mark identification was achieved using targeted midwater trawls. Additional midwater and demersal trawls were carried out at randomly selected locations over the shelf as part of the core biodiversity survey. Silverfish were widely distributed over the Ross Sea shelf. Adult silverfish tended to form layers at 100–400 m depth and were sometimes present close to the bottom, where they were frequently caught in demersal trawls shallower than 500 m. A weak layer at about 80 m depth was associated with juvenile silverfish of 50–80 mm standard length. Acoustic backscatter strength from both silverfish and krill marks increased with increasing frequency (i.e., was highest at 120 kHz), which is characteristic of species without an air-filled swimbladder. Acoustic target strengths (TS) for silverfish at 12, 18, 38, 70, and 120 kHz were estimated from anatomically detailed scattering models based on computed tomography (CT) scans of frozen specimens. The relationship between TS and fish length at 38 kHz was sensitive to estimates of density and sound speed contrast within the fish, especially for small specimens (less than 110 mm SL). Our best estimate of the acoustic biomass of silverfish in the study area was 592 000 t (95% confidence interval 326 000–866 000 t). However, the biomass of juvenile silverfish was highly uncertain due to large differences between TS model results.

Satellite Observations From the International Polar Year

To realize the benefit of the growing number of international satellites to the scientific objectives of the 2007–2008 International Polar Year (IPY), the Global Interagency IPY Polar Snapshot Year (GIIPSY) was established in November 2005 to develop a consensus on polar science requirements and objectives for IPY that could best and perhaps only be met using the Earth‐observing satellites. Requirements focused on all aspects of the cryosphere and ranged from sea ice and ice sheets to permafrost and snow cover. Individual topics included how best to develop high‐resolution digital elevation models of outlet glaciers using stereo‐optical systems, measure ice sheet surface velocity using interferometric synthetic aperture radar (InSAR), and repeatedly measure sea ice motion using optical and microwave imaging instruments.Because of this foresight, several IPY science objectives were well met using satellite observations, allowing a wealth of valuable data to be collected on cryospheric processes (Figure 1). Further, the framework for coordinating these remote sensing efforts serves as a valuable model for future coordinated efforts to monitor cryospheric dynamics.

Thermal state of permafrost in Russia

AbstractThe results of the International Permafrost Association's International Polar Year Thermal State of Permafrost (TSP) project are presented based on field measurements from Russia during the IPY years (2007–09) and collected historical data. Most ground temperatures measured in existing and new boreholes show a substantial warming during the last 20 to 30 years. The magnitude of the warming varied with location, but was typically from 0.5°C to 2°C at the depth of zero annual amplitude. Thawing of Little Ice Age permafrost is ongoing at many locations. There are some indications that the late Holocene permafrost has begun to thaw at some undisturbed locations in northeastern Europe and northwest Siberia. Thawing of permafrost is most noticeable within the discontinuous permafrost domain. However, permafrost in Russia is also starting to thaw at some limited locations in the continuous permafrost zone. As a result, a northward displacement of the boundary between continuous and discontinuous permafrost zones was observed. This data set will serve as a baseline against which to measure changes of near‐surface permafrost temperatures and permafrost boundaries, to validate climate model scenarios, and for temperature reanalysis. Copyright © 2010 John Wiley & Sons, Ltd.

The role of arctic zooplankton in biogeochemical cycles: respiration and excretion of ammonia and phosphate during summer

The study of the structural and functional properties of key components of polar marine ecosystems has received increased attention in order to better understand the ecological consequences of future sea temperature rise and seasonal ice retraction. Owing to this purpose, during the ATOS-Arctic cruise, held in July 2007 in the framework of the 2007–2008 International Polar Year, we studied the respiratory carbon demand of mesozooplankton as well as their contribution to the regeneration of inorganic nitrogen and phosphorus (NH4-N and PO4-P) via excretion. The studied area comprised several stations along a latitudinal gradient in the East Greenland current, plus a network of stations NW of the Svalbard islands. The specific respiratory carbon losses and phosphorus (PO4-P) excretion rates were similar or slightly higher than some reports for Arctic mesozooplankton, but the nitrogen (NH4-N) excretion rates were higher by a factor of 3 when compared with previous data sets. The mesozooplankton respiratory losses were equivalent to 23% of primary production, and at turn zooplankton contributed by excretion to more than 50% of the N and P required by phytoplankton. Although C:N, C:P and N:P metabolic atomic quotients almost coincided with the average Redfield’s stoichiometric ratios, the low C:N values when compared to previous reports suggested a predominance of protein-related metabolic substrates. The potential consequences of changes observed in the C:N, N:P and C:P metabolic ratios of mesozooplankton for Arctic marine ecosystems are discussed.

Forty-seven Years of Research on the Devon Island Ice Cap, Arctic Canada

The Devon Island ice cap has been the subject of scientific study for almost half a century, beginning with the first mass balance measurements in 1961. Research on the ice cap was the first to investigate (1) the role of meltwater in seasonal ice-velocity variations on a polythermal Arctic ice cap, (2) the use of air temperature rather than net radiation as a proxy for the energy driving surface melt, and (3) the influence of the changing frequency of specific synoptic weather configurations on glacier melt and mass balance. Other research has included investigations of ice cap geometry, flow dynamics, and mass balance; ice core analyses for records of past climate and contaminant deposition; and studies of changes in ice cap area and volume and their relationship to surface mass balance and ice dynamics. Current research includes ground studies connected to efforts to calibrate and validate the radar altimeter that will be carried by the European Space Agency’s (ESA) CryoSat2 satellite, and a major collaborative Canadian International Polar Year (IPY) project focused on the Belcher Glacier, on the northeast side of the ice cap, that examines hydrodynamics of large tidewater glaciers. This paper summarizes our current knowledge of the Devon Island ice cap and identifies some of the outstanding questions that continue to limit our understanding of climate-ice cap interactions in Arctic regions.

IPY observations of ionospheric yearly variations from high‐ to middle‐latitude incoherent scatter radars

Upper atmospheric research during the 2007 International Polar Year features unprecedented yearlong observations by incoherent scatter radars. This valuable data set, collected under very low solar and magnetic activity conditions from a set of four radars spanning middle (Millstone Hill), auroral (Poker Flat), and higher latitudes (Sondrestrom and Svalbard), enables us to address a fundamental question of background climatology on ionospheric yearly variations. The main focus of this paper is on the noon‐time baseline annual and semiannual variations, with an emphasis on the less‐known height dependency, for those geophysically important areas. The radar measurements of ion drifts allow us to examine dynamic effects which have not been well addressed previously. High‐latitude ionospheric climatology shows some interesting features, in particular, the two semiannual peaks of electron density Ne. The two peaks, neither of which is near summer solstice, are essentially of equinoctial symmetry at very high latitude sites, where downward ion drifts are strong in summer thus causing Ne reduction. The symmetry vanishes at the midlatitude site. Clear phase progression is seen from the topside to the F2 peak at the midlatitude site. Comparisons of Millstone Hill data from this period and prior solar minima indicate decreases in the ion temperature throughout the F2 peak and the topside ionosphere. These decreases do not seem to be associated with solar flux and magnetic activity effects.

IPY 2007–08 and the Resurgence of Northern (& Polar) Research in Canada

THE FIRST INTERNATIONAL POLAR YEAR (IPY) in 1882 – 83 was one of the earliest globally coordinated scientific efforts, and its success provided a model for subsequent programs of coordinated international research. The coming IPY in 2007 – 08 (actually extending to 2009) will be a major event that contributes to the advancement of polar knowledge, research and technology and establishes a new foundation and legacy for future decades of work. Canada has recognized that indigenous and non-indigenous residents of polar regions must participate directly in defining the IPY research programs.

IPY 2007–08 and the Resurgence of Northern (& Polar) Research in Canada

THE FIRST INTERNATIONAL POLAR YEAR (IPY) in 1882 – 83 was one of the earliest globally coordinated scientific efforts, and its success provided a model for subsequent programs of coordinated international research. The coming IPY in 2007 – 08 (actually extending to 2009) will be a major event that contributes to the advancement of polar knowledge, research and technology and establishes a new foundation and legacy for future decades of work. Canada has recognized that indigenous and non-indigenous residents of polar regions must participate directly in defining the IPY research programs.

Understanding Antarctic Climate and Glacial History: First Antarctic Climate Evolution Symposium; Granada, Spain, 7–11 September 2009

Antarctic Climate Evolution (ACE; http://www.ace.scar.org), a scientific research project of the Scientific Committee on Antarctic Research and a core International Polar Year project, held its first international symposium in Spain in September 2009. ACE's mission is to facilitate the study of Antarctic climate and glacial history through integration of numerical modeling with geophysical and geological data. Nearly 200 international scientists from the fields of climate, ocean, and ice modeling joined geologists, geophysicists, and geochemists for 5 days of intense interaction. Oral sessions were plenary and were limited to allow time for poster viewing, discussion, and workshops (http://www.acegranada2009.com/).

On the relationship between snow grain morphology and in-situ near infrared calibrated reflectance photographs

Seasonal and permanent snow cover a significant portion of our planet, and its impact on climate is significant. Through specific thermophysical properties, snow controls radiative and turbulent fluxes between the ground and the atmosphere, but many aspects of the energy balance are poorly understood due to lingering uncertainties regarding snow properties, such as grain size in particular. Rapid and accurate measurement method has yet to be developed given the reality of field and laboratory logistical constraints, and the sensitivity of snow to any sort of manipulation. In this paper, we investigate the relationship between snow grain morphology parameters measured from visible (traditional) snow grain photography and optical diameter estimated from Near-InfraRed (NIR) reflectance photographs of snow walls. A total of 51 snowpits were analyzed during our International Polar Year field campaign across a 1000 km South-to-North transect over Eastern Canada. We compared the NIR measurements with the theoretical snow albedo model of Kokhanovsky and Zege (2004). Results show the large difference between the snow specific surface area (SSA) of snow grains derived from snow albedo model and the geometrical (visual) diameter. From three different snow grain classes which can be distinguished from traditional photography, linkages can be made with shape factors required in the optical model in order to retrieve optical grain size from NIR photography.

An 860 km surface mass-balance profile on the East Antarctic plateau derived by GPR

AbstractSnow accumulation and its variability on the East Antarctic plateau are poorly understood due to sparse and regionally confined measurements. We present a 5.3 GHz (C-band) ground-penetrating radar (GPR) profile with a total length of 860 km recovered during the joint Norwegian–US International Polar Year traverse 2007/08. Mean surface mass balance (SMB) over the last 200 years was derived from the GPR data by identifying the volcanic deposition of the Tambora eruption in 1815. It varies between 9.1 and 37.7 kg m−2 a−1 over the profile, with a mean of 23.7 kg m−2 a−1 and a standard deviation of 4.7 kg m−2 a−1. The 200 year SMB estimated is significantly lower than most of the SMB estimates over shorter time periods in this region. This can be partly explained by a SMB minimum in the vicinity of the ice divide. However, it is more likely that a recent increase in SMB observed by several studies is largely responsible for the observed discrepancy.

Recent ice-surface-elevation changes of Fleming Glacier in response to the removal of the Wordie Ice Shelf, Antarctic Peninsula

AbstractRegional climate warming has caused several ice shelves on the Antarctic Peninsula to retreat and ultimately collapse during recent decades. Glaciers flowing into these retreating ice shelves have responded with accelerating ice flow and thinning. The Wordie Ice Shelf on the west coast of the Antarctic Peninsula was reported to have undergone a major areal reduction before 1989. Since then, this ice shelf has continued to retreat and now very little floating ice remains. Little information is currently available regarding the dynamic response of the glaciers feeding the Wordie Ice Shelf, but we describe a Chilean International Polar Year project, initiated in 2007, targeted at studying the glacier dynamics in this area and their relationship to local meteorological conditions. Various data were collected during field campaigns to Fleming Glacier in the austral summers of 2007/08 and 2008/09. In situ measurements of ice-flow velocity first made in 1974 were repeated and these confirm satellite-based assessments that velocity on the glacier has increased by 40–50% since 1974. Airborne lidar data collected in December 2008 can be compared with similar data collected in 2004 in collaboration with NASA and the Chilean Navy. This comparison indicates continued thinning of the glacier, with increasing rates of thinning downstream, with a mean of 4.1 ± 0.2 m a−1 at the grounding line of the glacier. These comparisons give little indication that the glacier is achieving a new equilibrium.

ARENA Public Outreach

In the frame of ARENA and in the spotlight of the 2007–2008 International Polar Year (IPY) and the 2009 International Year of Astronomy (IYA), two extremely visible opportunities to focus public interest and participation were/are to highlight: - Antarctica as a most remote and fascinating continent dedicated to science and - Astronomy & astrophysics as a most profound and enthralling science. Developed by the ARENA consortium since its creation in 2006, the ARENA public outreach web site (European audience EN/FR), the ARENA leaflet (EN/FR)are both telling about the importance of maintaining and expanding programmes to answer astrophysical fundamental questions regarding the origin and evolution of the Universe.

Strong bottom currents and cyclogenesis in Drake Passage

Observations from 38 bottom‐moored Current and Pressure Recording Inverted Echo Sounders (CPIES) deployed in Drake Passage during the 2007–2008 International Polar Year provide unprecedented coverage of near‐bottom currents and pressures spanning the entire Antarctic Circumpolar Current. Year‐long‐mean currents exceed 10 cm s−1 north of the Polar Front, and mean directions are not, in general, aligned with the surface fronts. Topographic steering is most evident at the continental margins. Deep eddy kinetic energy (EKE) is maximum at about 200 cm2 s−2 between the Subantarctic and Polar Fronts, coinciding with the location but about one quarter of the value of a maximum in surface EKE. Multiple high‐speed current events, with peak speeds of 60–70 cm s−1 and lasting 30 to 70 days, are coherent across sites separated by 45 km. The observed spinup of eddies coinciding with meanders in the surface fronts is consistent with deep cyclogenesis.

Visualizing Population Dynamics of Alaska’s Arctic Communities

Arctic demography has previously been reviewed on a large scale, across the circumpolar nations. We look instead at some recent population dynamics on sub-regional to community scales, focusing on Arctic Alaska. Detailed graphics depicting yearly population changes from 1990 to 2006 in 43 selected Arctic Alaska towns and villages and all 27 of the state’s “county-equivalent entities” (e.g., boroughs) have been published online in connection with two International Polar Year projects. Seemingly comparable places within the same borough have taken widely divergent paths. Birth rates generally exceed death rates, although both are high. Year-to-year and place-to-place variations are dominated not by natural increase, but by differences in net migration. Population changes influence demand for resources such as water, electricity, fuel, and capital improvements, and probably for subsistence resources as well. Migration rates provide sensitive indicators that integrate diverse internal and external pressures.