scholarly journals Spatial and Temporal Variability of Glacier Surface Velocities and Outlet Areas on James Ross Island, Northern Antarctic Peninsula

Geosciences ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 374 ◽  
Author(s):  
Lippl ◽  
Friedl ◽  
Kittel ◽  
Marinsek ◽  
Seehaus ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Glacier Surface ◽  
Local Climate ◽  
Climate Conditions ◽  
Radar Sensors ◽  
James Ross Island ◽  
Almost All

The northern Antarctic Peninsula was affected by a significant warming over the secondhalf of the 20th century and the collapse of several ice shelves. Local climate conditions on James RossIsland on the northeastern coast can differ strongly from the main part of the Antarctic Peninsula.This paper reports the spatial and temporal variability of glacier surface velocities and the area oftheir outlets throughout James Ross Island, and evaluates potential relationships with atmosphericand oceanic conditions. Velocity estimates were retrieved from intensity feature tracking of scenesfrom satellite synthetic aperture radar sensors TerraSAR-X and TanDEM-X between 2014 and 2018,which were validated against ground observations. Calving front positions back to 1945 were usedto calculate outlet area changes for the glaciers by using a common-box approach. The annualrecession rates of almost all investigated glacier calving fronts decelerated for the time periods2009–2014 and 2014–2018 in comparison to the period 1988–2009, but their velocity patterns differed.Analysis of atmospheric conditions failed to explain the different patterns in velocity and areachanges. We suggest a strong influence from local bathymetric conditions. Future investigations ofthe oceanic conditions would be necessary for a profound understanding of the super-position ofdifferent influencing factors.

Large-Scale Atmospheric Drivers of Snowfall on Thwaites Glacier

2020 ◽  
Author(s):  
Michelle Maclennan ◽  
Jan Lenaerts
Keyword(s):  
Temporal Variability ◽  
Large Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Regional Climate ◽  
Southern Annular Mode ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Amundsen Sea ◽  
Weather Patterns

<p>High snowfall events on Thwaites Glacier are a key influencer of its ice mass change. In this study, we diagnose the mechanisms for orographic precipitation on Thwaites Glacier by analyzing the atmospheric conditions that lead to high snowfall events. A high-resolution regional climate model, RACMO2, is used in conjunction with MERRA-2 and ERA5 reanalysis to map snowfall and associated atmospheric conditions over the Amundsen Sea Embayment. We examine these conditions during high snowfall events over Thwaites Glacier to characterize the drivers of the precipitation and their spatial and temporal variability. Then we examine the seasonal differences in the associated weather patterns and their correlations with El Nino Southern Oscillation and the Southern Annular Mode. Understanding the large-scale atmospheric drivers of snowfall events allows us to recognize how these atmospheric drivers and consequent snowfall climatology will change in the future, which will ultimately improve predictions of accumulation on Thwaites Glacier.</p>

scholarly journals Wildfires in the Campanian of James Ross Island: a new macro-charcoal record for the Antarctic Peninsula

2021 ◽  
Author(s):  
Flaviana Jorge de Lima ◽  
Juliana Manso Sayão ◽  
Luiza C. M. de Oliveira Ponciano ◽  
Luiz C. Weinschütz ◽  
Rodrigo Figueiredo ◽  
...  
Keyword(s):  
Plant Communities ◽  
Antarctic Peninsula ◽  
Taxonomic Affinity ◽  
Global Event ◽  
New Information ◽  
Affected Plant ◽  
First Occurrence ◽  
James Ross Island ◽  
Almost All ◽  
The Antarctic

The Cretaceous “high-fire” period was a global event that reached almost all continental masses during that period in Earth’s history. The extensive wildfires directly affected plant communities. Significant palaeobotanical records in the Antarctic Peninsula have been studied from the James Ross Sub-Basin, especially from the Santa Marta Formation. However, there is no described evidence for palaeo-wildfires in the area so far. Here, we present the first occurrence of fossilized macro-charcoal coming from James Ross Island, confirming that palaeo-wildfires occurred in the Campanian vegetation preserved in the Santa Marta Formation. The new charcoal material has a gymnospermous taxonomic affinity, more specifically with the Araucariaceae, which is in accordance with previous palaeobotanical records from James Ross Island. This occurrence adds new information to the construction of the palaeo-wildfire scenario for Gondwana.

scholarly journals Estimation of turbulence parameters from scanning lidars and in-situ instrumentation in the Perdigão 2017 campaign

2019 ◽  
Author(s):  
Norman Wildmann ◽  
Nicola Bodini ◽  
Julie K. Lundquist ◽  
Ludovic Bariteau ◽  
Johannes Wagner
Keyword(s):  
Temporal Variability ◽  
Shear Zones ◽  
Spectral Width ◽  
Early Morning ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Sonic Anemometers ◽  
Spatio Temporal ◽  
Lifting System

Abstract. The understanding of the sources, spatial distribution and temporal variability of turbulence in the atmospheric boundary layer (ABL) and improved simulation of its forcing processes require observations in a broad range of terrain types and atmospheric conditions. In this study, we estimate turbulence kinetic energy (TKE) dissipation rate using multiple techniques, including traditional in-situ measurements of sonic anemometers on meteorological towers, a hot-wire anemometer on a tethered lifting system (TLS), as well as remote-sensing retrievals from a vertically staring lidar and two lidars performing range-height indicator (RHI) scans. For the retrieval of ε from the lidar RHI scans, we introduce a modification of the Doppler Spectral Width (DSW) method. This method uses spatio-temporal averages of the variance of the line-of-sight (LOS) velocity and the turbulent broadening of the Doppler backscatter spectrum. We validate this method against the observations from the other instruments, also including uncertainty estimations for each method. The synthesis of the results from all instruments enables a detailed analysis of the spatial and temporal variability of ε across a valley between two parallel ridges at the Perdigão 2017 campaign. We find that the shear zones above and below nighttime low-level jets (LLJ) experience turbulence enhancements, as does the wake of a wind turbine (WT). We analyze in detail how ε varies in the early morning of 14 June 2017, when the turbulence in the valley, approximately eleven rotor diameters downstream of the WT, is still significantly enhanced by the WT wake.

scholarly journals Dynamics and GPR stratigraphy of a polar rock glacier on James Ross Island, Antarctic Peninsula

2008 ◽  
Vol 54 (186) ◽  
pp. 445-451 ◽  
Author(s):  
Kotaro Fukui ◽  
Toshio Sone ◽  
Jorge A. Strelin ◽  
Cesar A. Torielli ◽  
Junko Mori ◽  
...  
Keyword(s):  
Internal Structure ◽  
Antarctic Peninsula ◽  
Ice Core ◽  
Field Measurements ◽  
Geodetic Survey ◽  
Rock Glacier ◽  
Glacier Surface ◽  
Valley Glacier ◽  
Movement Mechanism ◽  
James Ross Island

AbstractWe describe field measurements (ground-penetrating radar (GPR), geodetic survey and ice-core drilling) to provide new information on the movement mechanism and internal structure of a polar rock glacier on James Ross Island, Antarctic Peninsula. We collected GPR data along longitudinal and transverse profiles. The longitudinal GPR profiles identify inter-bedded debris-rich layers that dip up-glacier, similar to the thrust structures in the compression zone of a valley glacier. The transverse GPR profiles indicate a syncline structure inclined towards the central part of the rock glacier, resembling the transverse foliation of a valley glacier. The stratigraphy of two boreholes shows that the rock glacier consists primarily of bubbly ice with thin debris-rich layers, an internal structure similar to the ‘nested spoons’ structure common in the interior of valley glaciers. These results indicate that the glacier motion is controlled by shear movement, common in valley glaciers. The geodetic survey confirms that flow velocities decrease towards the lower part of the rock glacier. Such heterogeneous movement causes longitudinal compression and forms thrusts which then create the debris-rich layer by uplifting basal ice and debris. Pushing of the upstream ice against the downstream ice bends the surface layers, forming transverse ridges on the rock glacier surface.

scholarly journals Estimation of turbulence dissipation rate from Doppler wind lidars and in situ instrumentation for the Perdigão 2017 campaign

2019 ◽  
Vol 12 (12) ◽  
pp. 6401-6423 ◽  
Author(s):  
Norman Wildmann ◽  
Nicola Bodini ◽  
Julie K. Lundquist ◽  
Ludovic Bariteau ◽  
Johannes Wagner
Keyword(s):  
Wind Turbine ◽  
Temporal Variability ◽  
Dissipation Rate ◽  
Shear Zones ◽  
Spectral Width ◽  
Energy Dissipation Rate ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Sonic Anemometers

Abstract. The understanding of the sources, spatial distribution and temporal variability of turbulence in the atmospheric boundary layer, and improved simulation of its forcing processes require observations in a broad range of terrain types and atmospheric conditions. In this study, we estimate turbulence kinetic energy dissipation rate ε using multiple techniques, including in situ measurements of sonic anemometers on meteorological towers, a hot-wire anemometer on a tethered lifting system and remote-sensing retrievals from a vertically staring lidar and two lidars performing range–height indicator (RHI) scans. For the retrieval of ε from the lidar RHI scans, we introduce a modification of the Doppler spectral width method. This method uses spatiotemporal averages of the variance in the line-of-sight velocity and the turbulent broadening of the Doppler backscatter spectrum. We validate this method against the observations from the other instruments, also including uncertainty estimations for each method. The synthesis of the results from all instruments enables a detailed analysis of the spatial and temporal variability in ε across a valley between two parallel ridges at the Perdigão 2017 campaign. We analyze in detail how ε varies in the night from 13 to 14 June 2017. We find that the shear zones above and below a nighttime low-level jet experience turbulence enhancements. We also show that turbulence in the valley, approximately 11 rotor diameters downstream of an operating wind turbine, is still significantly enhanced by the wind turbine wake.

Mass balance study of the Znosko glacier, Antarctica, using remote sensing and in situ measurements

2021 ◽  
Author(s):  
Cinthya Bello ◽  
Wilson Suarez ◽  
Fabian Brondi ◽  
Gilbert Gonzales
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Antarctic Peninsula ◽  
Austral Summer ◽  
In Situ Measurements ◽  
Glacier Mass Balance ◽  
Atmospheric Conditions ◽  
Glacier Surface ◽  
Balance Study

<p>Glaciers are a key indicator of climate change. Since the second half of the 20th century several glaciers in Antarctica have retreated. In situ measurements of glacier mass balance in the Antarctic Peninsula and its surrounding islands are very scarce because this area is inaccessible due to rough terrain and inhospitable atmospheric conditions, but there is a necessity in study peripheral glaciers dynamics to know their future contribution to sea level rise. To fill this gap, remote sensing is an alternative tool to enable timely monitoring of dynamic glaciers and quantifying spatial-temporal changes. Here we combine remote sensing (satellite imaginary and aerial photos) and in situ measurements to calculate mass balance for the Znosko glacier (King George Island, Antarctic Peninsula) and compare the accuracy of this methods. Two field campaigns were carried out during the XXVI and XXVII Peruvian Antarctic Operation (austral summer 2018/19 and 2019/20). 19 stakes were fixed on the glacier surface, in situ mass balance data were collected from yearly stake measurements. Also, digital elevation models were generated through aerial photogrammetry and auxiliary data from the ICESat-2 mission were included into the analysis.  We find that mass balances estimated with these methods are consistent and confirm the mass loss (heterogeneous pattern between accumulation and ablation zone) and retreat of Znosko glacier. We illustrate how participatory mapping (interdisciplinary team) can complement initial remote sensing land cover classification and assist ground checks.</p>

20th century droughts in southern Africa: spatial and temporal variability, teleconnections with oceanic and atmospheric conditions

2001 ◽  
Vol 21 (7) ◽  
pp. 873-885 ◽  
Author(s):  
Yves Richard ◽  
Nicolas Fauchereau ◽  
Isabelle Poccard ◽  
Mathieu Rouault ◽  
Sylwia Trzaska
Keyword(s):  
20Th Century ◽  
Southern Africa ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions

scholarly journals Spatial and temporal variability of ozone deposition

2009 ◽  
Vol 3 (1) ◽  
pp. 5-7 ◽  
Author(s):  
Cs. Czender ◽  
E. Komjáthy ◽  
R. Mészáros ◽  
I. Lagzi
Keyword(s):  
Soil Moisture ◽  
Temporal Variability ◽  
Deposition Velocity ◽  
Spatial And Temporal Variability ◽  
Climate Conditions ◽  
Ozone Deposition ◽  
Interaction Processes ◽  
Atmosphere Interaction ◽  
The Relationship ◽  
Continental Climate

Abstract. Soil moisture and ozone deposition velocity under continental climate conditions were estimated using a newly developed algorithm. The relationship between soil moisture and deposition velocity was investigated and analysed. These results emphasize the importance of a sophisticated parameterization of soil moisture in surface-atmosphere interaction processes.

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