Annual cycle in flow of Ross Ice Shelf, Antarctica: contribution of variable basal melting

Abstract

Ice shelves play a critical role in modulating dynamic loss of ice from the grounded portion of the Antarctic Ice Sheet and its contribution to sea-level rise. Measurements of ice-shelf motion provide insights into processes modifying buttressing. Here we investigate the effect of seasonal variability of basal melting on ice flow of Ross Ice Shelf. Velocities were measured from November 2015 to December 2016 at 12 GPS stations deployed from the ice front to 430 km upstream. The flow-parallel velocity anomaly at each station, relative to the annual mean, was small during early austral summer (November–January), negative during February–April, and positive during austral winter (May–September). The maximum velocity anomaly reached several metres per year at most stations. We used a 2-D ice-sheet model of the RIS and its grounded tributaries to explore the seasonal response of the ice sheet to time-varying basal melt rates. We find that melt-rate response to changes in summer upper-ocean heating near the ice front will affect the future flow of RIS and its tributary glaciers. However, modelled seasonal flow variations from increased summer basal melting near the ice front are much smaller than observed, suggesting that other as-yet-unidentified seasonal processes are currently dominant.

Unsupervised Deep Clustering of Seismic Data: Monitoring the Ross Ice Shelf, Antarctica

“…Although class 6 has elevated activity during the summers, it maintains activity throughout the winter months, suggesting that gravity wave activity is not the dominant forcing. The persistence of class 1 signals, which often consist of impulse trains, suggests they may be caused by icequakes resulting from the motion of the ice shelf itself (Klein et al., 2020), as the ice flow velocity in the vicinity of station DR02 is among the highest observed on the RIS. Class 5 (Figure 11h) is more active during the coldest periods of the year (April–September), suggesting that these signals may be associated with extremely cold temperatures or strong wind events.…”

Icequake‐Magnitude Scaling Relationship Along a Rift Within the Ross Ice Shelf, Antarctica

“…Seismic data used in this manuscript were collected through the NSF Office of Polar Programs project titled “Collaborative Research: Dynamic Response of the RIS to Wave‐Induced Vibrations” (network code XH; http://www.fdsn.org/networks/detail/XH_2014/). The GNSS data are available in Klein et al., 2020. ITS_LIVE contains NASA products (https://its-live.jpl.nasa.gov/).…”

“…D. Bromirski and Gerstoft, 2017). We adopt the displacement time series solutions from Klein et al (2020). In a 20-day time window of one GNSS station, there is up to 0.5 m of vertical displacement during diurnal tidal cycles (U-D in Figure 3b).…”

Massive GNSS Network Analysis Without Baselines: Undifferenced Ambiguity Resolution

“…The first module carries out data cleaning and parameter estimation, and the second is used for IAR at a single station. Several geophysical studies have used the software to analyze GNSS data (e.g., Goldberg et al., 2020; Klein et al., 2020; Melgar et al., 2019; Zhang et al., 2020).…”