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Author Topic: Antarctica Surface Imagining  (Read 3027 times)

AbruptSLR

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Antarctica Surface Imagining
« on: August 21, 2014, 04:30:45 PM »
Due to a technical glitch, I cannot get into the "Mosaic" folder therefore, I will repost those links and add more information:

In the "Mosaic" folder, posted some similar to:

"A newly released image of Antarctica offers the most complete, detailed view of the continent since 1997. The map is a mosaic of more than 3,150 individual, high-resolution readings, taken in the Southern Hemisphere's autumn of 2008, and tiled together into a coast-to-coast view of the entire continent with its coastal waters (see the following links and the first attached image of the PIG/Thwaites area):

https://www.polardata.ca/
https://www.polardata.ca/pdcsearch/

However, as indicated by the second attached image of the Thwaites area in April 2012, and in the third and fourth image of Thwaites both in April of 2014, there has been a remarked change in this area since 2008.  Therefore, the linked "Mosaic" should be used with caution.
« Last Edit: August 21, 2014, 04:38:47 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Antarctica Surface Imagining
« Reply #1 on: August 21, 2014, 04:48:26 PM »
The linked reference provides new maps of the elevation and elevation change of Greenland and Antarctica from CryoSat-2:

Helm, V., Humbert, A., and Miller, H., (2014), "Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2", The Cryosphere Discuss., 8, 1673-1721, doi:10.5194/tcd-8-1673-2014

http://www.the-cryosphere-discuss.net/8/1673/2014/tcd-8-1673-2014.html

Abstract: "The ESA satellite CryoSat-2 has been observing Earth's polar regions since April 2010. It carries a sophisticated radar altimeter and aims for the detection of changes in sea ice thickness as well as surface elevation changes of Earth's land and marine ice sheets. This study focuses on the Greenland and Antarctic ice sheets, considering the contemporary elevation of their surfaces. Based on 2 years of CryoSat-2 data acquisition, elevation change maps and mass balance estimates are presented. Additionally, new digital elevation models (DEMs) and the corresponding error maps are derived. Due to the high orbit of CryoSat-2 (88° N/S) and the narrow across-track spacing, more than 99% of Antarctica's surface area is covered. In contrast, previous radar altimeter measurements of ERS1/2 and ENVISAT were limited to latitudes between 81.5° N and 81.5° S and to surface slopes below 1°. The derived DEMs for Greenland and Antarctica have an accuracy which is similar to previous DEMs obtained by satellite-based laser and radar altimetry (Liu et al., 2001; Bamber et al., 2009, 2013; Fretwell et al., 2013; Howat et al., 2014). Comparisons with ICESat data show that 80% of the CryoSat-2 DEMs have an error of less than 3 m ± 30 m. For both ice sheets the surface elevation change rates between 2011 and 2012 are presented at a resolution of 1 km. Negative elevation changes are concentrated at the west and south-east coast of Greenland and in the Amundsen Sea embayment in West Antarctica (e.g. Pine Island and Thwaites glaciers). They agree well with the dynamic mass loss observed by ICESat between 2003 and 2008 (Pritchard et al., 2009). Thickening occurs along the main trunk of Kamb Ice Stream and in Dronning Maud Land. While the former is a consequence of an ice stream stagnated ∼150 years ago (Rose, 1979; Retzlaff and Bentley, 1993), the latter represents a known large-scale accumulation event (Lenaerts et al., 2013). This anomaly partly compensates for the observed increased volume loss in West Antarctica. In Greenland the findings reveal an increased volume loss of a factor of 2 compared to the period 2003 to 2008. The combined volume loss of Greenland and Antarctica for the period 2011 and 2012 is estimated to be −448 ± 122 km3 yr−1."

As this article cites that elevation changes in the Antarctic are concentrated in the ASE (eg PIG and Thwaites Glaciers), I also attached an image should the change in elevation in the Thwaites Glacier from January 2012 to January 2013, during which time a "surge" of the Thwaites Ice Tongue occurred.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Antarctica Surface Imagining
« Reply #2 on: August 22, 2014, 11:50:07 PM »
The accompanying image is from the reference cited in Reply #1, and shows the extensive drop in surface elevation in the ASE area between January 2011 and January 2014:
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

nukefix

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Re: Antarctica Surface Imagining
« Reply #3 on: October 24, 2014, 01:28:23 PM »
Here's another view, Sentinel-1 on 22.10, very different from 2008. Note the recent disintegration of part of the ice-shelf in the lower right corner.

AbruptSLR

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Re: Antarctica Surface Imagining
« Reply #4 on: November 07, 2014, 04:39:27 AM »
I believe that the attached high definition image shows a 2002 image of iceberg B-22 recently calved from the Thwaites Ice Tongue (see the following NOAA announcement):


3/18/02   NOAA News Releases 2002
NOAA Home Page
NOAA Public Affairs
ICEBERG B-22 CALVES OFF THWAITES ICE TONGUE
The National Ice Center (NIC) confirms an iceberg newly calved from the Thwaites Ice Tongue, a large sheet of glacial ice and snow extending from the Antarctic mainland into the southern Amundsen Sea.

This new iceberg, named B-22, is currently located at 74.56S/ 107.55W. Iceberg B-22, roughly 46NM long and 35NM wide, covers an area of approximately 2,120 square statute miles. Dr. Ted Scambos of the National Snow and Ice Data Center notified NIC of a large crack in the Thwaites Tongue, discovered by Jennifer Bohlander using NASA's MODIS data from February 10, 2001. The crack was found to have significantly widened in MODIS data from March 8, 2001. Analyst Judy Shaffier of the National Ice Center confirmed the calving of Iceberg B22 using satellite images shown below from the Defense Meteorological Satellite Program's (DMSP) Operational Line Scan (OLS) Visible sensor and NOAA's AVHRR sensor.

Iceberg names are derived from the Antarctic quadrant in which they were originally sighted. The quadrants are divided counter-clockwise in the following manner:

A = 0-90W (Bellinghausen/Weddell Sea)
B = 90W-180 (Amundsen/Eastern Ross Sea)
C = 180-90E (Western Ross Sea/Wilkesland)
D = 90E-0 (Amery/Eastern Weddell Sea).

When an iceberg is first sighted, NIC documents its point of origin. The letter of the quadrant, along with a sequential number is assigned to the iceberg. For example, B-22 is sequentially the 22nd iceberg tracked by the NIC in Antarctica between 90W-180 (Quadrant B).
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Wipneus

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Re: Antarctica Surface Imagining
« Reply #5 on: January 13, 2015, 10:46:52 AM »
Sentinel-1A images from the Weddell Sea today.
Here is a "panorama" composed of 4 quick-look images. Left/west is the Antarctic Peninsula. A rather big iceberg makes it an interesting image.

(click for the big picture)
« Last Edit: January 13, 2015, 11:02:07 AM by Wipneus »