Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

Abstract

Abstract. We report changes in ice velocity of a 6.5 million km 2 region around South Pole encompassing the Filchner-Ronne and Ross Ice Shelves and a significant portion of the ice streams and glaciers that constitute their catchment areas. Using the first full interferometric synthetic aperture radar (InSAR) coverage of the region completed in 2009 and partial coverage acquired in 1997, we processed the data to assemble a comprehensive map of ice speed changes between those two years. On the Ross Ice Shelf, our results confirm a continued deceleration of Mercer and Whillans Ice Streams with a 12-yr velocity difference of −50 m yr −1 (−16.7 %) and −100 m yr −1 (−25.3 %) at their grounding lines. The deceleration spreads 450 km upstream of the grounding line and more than 500 km onto the shelf, beyond what was previously known. Ross and Filchner Ice Shelves exhibit signs of pre-calving events, representing the largest observed changes, with an increase in speed in excess of +100 m yr −1 in 12 yr. Other changes in the Ross Ice Shelf region are less significant. The observed changes in glacier speed extend on the Ross Ice Shelf along the ice streams' flow lines. Most tributaries of the Filchner-Ronne Ice Shelf show a modest deceleration or no change between 1997 and 2009. Slessor Glacier shows a small deceleration over a large sector. No change is detected on the Bailey, Rutford, and Institute Ice Streams. On the Filchner Ice Shelf itself, ice decelerated rather uniformly with a 12-yr difference in speed of −50 m yr −1 , or −5 % of its ice front speed, which we attribute to a 12 km advance in its ice front position. Our results show that dynamic changes are present in the region. They highlight the need for continued observation of the area with a primary focus on the Siple Coast. The dynamic changes in Central Antarctica between 1997 and 2009 are generally second-order effects in comparison to losses on glaciers in the Bellingshausen and Amundsen Seas region and on the Antarctic Peninsula. We therefore conclude that the dynamic changes shown here do not have a strong impact on the mass budget of the Antarctic continent.

Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

“…Apparent upstream slowing of Bindschadler and MacAyeal ice streams are at the limit of detectability and difficult to interpret. Recent assessments show varying changes in ice stream velocities for this region (Hulbe et al, 2016;Scheuchl et al, 2012), suggesting that measured trends may be influenced by rapid changes in the sub-ice-stream hydrology (Hulbe et al, 2016).…”

“…Mass budget and change in discharge for the 27 basins defined by Zwally et al (2002). Mass budget is calculated as described in Table 2 Scheuchl et al, 2012) with a correction for acquisition time differences to provide an estimate of total discharge for the interior basins (2, 17 and 18; see Table 2). Flux gates FG1 and FG2 are shown with solid green and dashed blue lines, respectively.…”

“…auto-RIFT uncertainties are lowest for the 2015 mapping simply due to a much larger number of available image pairs. The reason for higher uncertainties of the LISA products is not entirely known but is likely due to differences in geolocation offset correction and merging proce- Scheuchl et al, 2012). Much of the difference between velocity mappings can be attributed to product errors.…”

Stochastic ice stream dynamics

“…Centennialand subcentennial-scale variability has taken place in Antarctica over the last 1,000 y (6). Variability on a decadal time scale includes the ongoing deceleration and widening of Whillans Ice Stream (7,8) and velocity changes in its tributaries (9,10), as well as subsequent deceleration and speedup of MacAyeal and Bindschadler Ice Streams (11), and centennial-scale stagnation and reactivation cycles have been inferrered for Whillans, Kamb, and MacAyeal Ice Streams (12). The slowdown of Whillans, along with the shutdown of Kamb Ice Stream ca.…”

A Systematic Study of the Fracturing of Ronne - Filchner Ice Shelf, Antarctica, Using Multisource Satellite Data from 2001 to 2016

“…Therefore, monitoring the stability of the ice shelves is an integral part of the study of AIS mass changes and the associated sea level rise. As some smaller sized ice shelves in the lower latitude and warmer Antarctic Peninsula region, such as the Larsen B ice shelf, experienced collapses (Scambos 5 et al, 2004;Braun et al, 2009), changes of the two largest ice shelves, Ross Ice Shelf (RIS) and RonneFilchner Ice Shelf (RFIS), have also been intensely studied (Hulbe et al, 1998;Larour et al, 2004;Joughin and MacAyeal, 2005;Makinson et al, 2011;Scheuchl et al, 2012;Marsh et al, 2015).…”