We present an update of the ‘key points’ from the Antarctic Climate Change and the Environment (ACCE) report that was published by the Scientific Committee on Antarctic Research (SCAR) in 2009. We summarise subsequent advances in knowledge concerning how the climates of the Antarctic and Southern Ocean have changed in the past, how they might change in the future, and examine the associated impacts on the marine and terrestrial biota. We also incorporate relevant material presented by SCAR to the Antarctic Treaty Consultative Meetings, and make use of emerging results that will form part of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report

Antarctic Climate Change and the Environment: an Update.

https://www.public.asu.edu/~wenwenl1/papers/5_Semantic_based_web_service_discovery_and_chaining_for_building_an_Arctic_Spatial_Data_Infrastructure.pdf

Semantic-based web service discovery and chaining for building an Arctic spatial data infrastructure

This is the first (Paper I) of three companion papers focused respectively, on the estimates of the errors in ice thickness retrieved from pulsed ground-penetrating radar (GPR) data, on how to estimate the errors at the grid points of an ice-thickness DEM, and on how the latter errors, plus the boundary delineation errors, affect the ice-volume estimates. We here present a comprehensive analysis of the various errors involved in the computation of ice thickness from pulsed GPR data, assuming they have been properly migrated. We split the ice-thickness error into independent components that can be estimated separately. We consider, among others, the effects of the errors in radio-wave velocity and timing. A novel aspect is the estimate of the error in thickness due to the uncertainty in horizontal positioning of the GPR measurements, based on the local thickness gradient. Another novel contribution is the estimate of the horizontal positioning error of the GPR measurements due to the velocity of the GPR system while profiling, and the periods of GPS refreshing and GPR triggering. Their effects are particularly important for airborne profiling. We illustrate our methodology through a case study of Werenskioldbreen, Svalbard.

/pdf/on-the-errors-involved-in-ice-thickness-estimates-i-ground-1m6kch7uf9.pdf

On the errors involved in ice-thickness estimates I: ground-penetrating radar measurement errors

. Previous studies of Totten Ice Shelf have employed surface velocity
measurements to estimate its mass balance and understand its sensitivities to
interannual changes in climate forcing. However, displacement measurements
acquired over timescales of days to weeks may not accurately characterize
long-term flow rates wherein ice velocity fluctuates with the seasons.
Quantifying annual mass budgets or analyzing interannual changes in ice
velocity requires knowing when and where observations of glacier velocity
could be aliased by subannual variability. Here, we analyze 16 years of
velocity data for Totten Ice Shelf, which we generate at subannual resolution
by applying feature-tracking algorithms to several hundred satellite image
pairs. We identify a seasonal cycle characterized by a spring to autumn
speedup of more than 100 m yr −1 close to the ice front. The amplitude
of the seasonal cycle diminishes with distance from the open ocean,
suggesting the presence of a resistive back stress at the ice front that is
strongest in winter. Springtime acceleration precedes summer surface melt and
is not attributable to thinning from basal melt. We attribute the onset of
ice shelf acceleration each spring to the loss of buttressing from the
breakup of seasonal landfast sea ice.

/pdf/seasonal-dynamics-of-totten-ice-shelf-controlled-by-sea-ice-2gnvlkr4w5.pdf

Seasonal dynamics of Totten Ice Shelf controlled by sea ice buttressing

Recent warming of the Antarctic Peninsula during austral autumn, winter, and spring has been linked to sea surface temperature (SST) trends in the tropical Pacific and tropical Atlantic, while warming of the northeast Peninsula during summer has been linked to a strengthening of westerly winds traversing the Peninsula associated with a positive trend in the Southern Annular Mode (SAM). Here we demonstrate that circulation changes associated with the SAM dominate interannual temperature variability across the entire Antarctic Peninsula during both summer and autumn, while relationships with tropical Pacific SST variability associated with the El Nino-Southern Oscillation (ENSO) are strongest and statistically significant primarily during winter and spring only. We find the ENSO-Peninsula temperature relationship during autumn to be weak on interannual timescales, and regional circulation anomalies associated with the SAM more important for interannual temperature variability across the Peninsula during autumn. Consistent with previous studies, western Peninsula temperatures during autumn, winter, and spring are closely tied to changes in the Amundsen Sea Low (ASL) and associated meridional wind anomalies. The interannual variability of ASL depth is most strongly correlated with the SAM index during autumn, while the ENSO relationship is strongest during winter and spring. Investigation of western and northeast Peninsula temperatures separately reveals that interannual variability of northeast Peninsula temperatures is primarily sensitive to zonal wind anomalies crossing the Peninsula and resultant lee-side adiabatic warming rather than to meridional wind anomalies, which is closely tied to variability in the zonal portion of the SAM pattern.

The Relative Influence of ENSO and SAM on Antarctic Peninsula Climate

Variations in Antarctic Peninsula snow liquid water during 1999–2017 revealed by merging radiometer, scatterometer and model estimations

Pedersenbreen is a small valley glacier (ca. 6 km 2 in 2009), ending on land, located in north-western Spitsbergen, Svalbard. Ground-based radio-echo sounding in April 2009, using a 100-MHz commercial radar and a self-made low-frequency radar, revealed a polythermal structure. The radar was coupled with a global positioning system device to geo-reference the traces. Each radar profile was manually edited to pick the reflection arrival time from the interface between ice and bedrock. Travel times were converted to ice thickness using a velocity of 0.165 m/ns, which was estimated from common mid-point measurement. Then the surface topography, bedrock topography, ice thickness contours and ice volume were derived using interpolation methods. Because it was difficult to distinguish the reflection wave from the background with the 100-MHz radar in some of the thickest areas of Pedersenbreen, we used a 5-MHz radar of our own design to fill in this gap. The maximum thickness of Pedersenbreen reaches 183±9 m, and the ice volume is 0.393±0.047 km 3 in 2009. Comparing these data with the surface topographical data available for 1936 indicates a mass loss of nearly 12% during the past 73 years. Keywords: GPR; GPS; glacier topography; ice volume; ice thickness; Pedersenbreen (Published: 20 February 2014) Citation: Polar Research 2014, 33 , 18533, http://dx.doi.org/10.3402/polar.v33.18533

https://www.tandfonline.com/doi/pdf/10.3402/polar.v33.18533

Topography, ice thickness and ice volume of the glacier Pedersenbreen in Svalbard, using GPR and GPS

We present a study of seasonal and interannual ice velocity changes at Polar Record Glacier, East Antarctica, using ERS-1/2, Envisat and PALSAR data with D-InSAR and intensity tracking. Ice flow showed seasonal variations at the front of the glacier tongue. Velocities in winter were 19% less than velocities during summer. No significant interannual changes were detected. Ice velocities in the grounding zone and grounded glacier did not show clear seasonal or interannual changes. The distribution of the seasonal variations suggests that the cause for the changes should be localized. Possible causes are seasonal sea-ice changes and iceberg blocking. Satellite images show that the sea ice surrounding Polar Record Glacier undergoes seasonal changes. Frozen sea ice in winter slowed the huge iceberg, and provided increased resistance to the glacier flow. The interaction between the glacier tongue, iceberg and sea ice significantly influences their flow pattern.

/pdf/seasonal-and-interannual-ice-velocity-changes-of-polar-35p0wjsqkm.pdf

Seasonal and interannual ice velocity changes of Polar Record Glacier, East Antarctica

Enhanced winter snowmelt in the Antarctic Peninsula: Automatic snowmelt identification from radar scatterometer

https://www.earth.ox.ac.uk/~yuz/zhou_etal_rse15.pdf

Chunxia Zhou

Papers

Variations in Antarctic Peninsula snow liquid water during 1999–2017 revealed by merging radiometer, scatterometer and model estimations

Topography, ice thickness and ice volume of the glacier Pedersenbreen in Svalbard, using GPR and GPS

Seasonal and interannual ice velocity changes of Polar Record Glacier, East Antarctica

Enhanced winter snowmelt in the Antarctic Peninsula: Automatic snowmelt identification from radar scatterometer

Improving InSAR elevation models in Antarctica using laser altimetry, accounting for ice motion, orbital errors and atmospheric delays