Version: 1

Gridded 18-year height-change time series for Antarctic ice shelves.

The complete description of processing steps is described by Paolo et al. (2016).

Time series were derived from 18 years (1994-2012) of continuous satellite radar-altimeter measurements of changes in ice-shelf surface height (European Space Agency (ESA) ERS-1, ERS-2 and Envisat missions). 

Time series are average height changes [m] with respect to 1994 every three months (72 time steps).

The time series have been corrected for ocean tides, atmospheric pressure (inverse barometer), regional sea-level trends, and surface scattering variation.

Filtered time series were smoothed (seasonality was removed) using a Hodrick-Prescott filter (see Paolo et al., 2016).

Values are only available for ice-shelf areas north of the maximum latitude (-81.5 degrees) of the altimeter satellites.

Error bars [m] in the height time series are two standard errors,
which account for variance, number of observations, and backscatter correction.

The dataset is a rectangular grid (480 points in x, 80 points in y) with x- and y-axes being longitude and latitude, respectively.

Longitude/latitude coordinates refer to the center of the grid cells.

The grid has a resolution of lon x lat: 0.75 x 0.25 deg (~27 km at latitude -71).

Files are (two options: HDF5 and ASCII):

ice_shelf_dh_v1.h5          # Gridded product in HDF5 format
ice_shelf_dh_v1_raw.txt     # Raw time series (one per column) in ASCII format
ice_shelf_dh_v1_filt.txt    # Filtered time series (one per column) in ASCII format
ice_shelf_dh_v1_err.txt     # 2-standard-error time series (one per column) in ASCII format
ice_shelf_dh_v1_time.txt    # Time [year] for all time series in ASCII format
ice_shelf_dh_v1_lonlat.txt  # x and y coordinates for each time series in ASCII format
ice_shelf_dh_v1_raw.png     # Example figure showing raw time series
ice_shelf_dh_v1_filt.png    # Example figure showing filtered time series

Data are (grids in HDF5):

time         # time coordinate [year; 72 values at 3-month time step]
lon          # x-coordinate [degrees east; range 0/360]
lat          # y-coordinate [degrees north; range -82/-62]
height_raw   # Raw time series of height change [m]     
height_filt  # Filtered time series of height change [m]
height_err   # 2-standard-error time series [m]

Notes:

Due to the wide radar altimeter (pulse-limited) footprint (~3-5 km), there is limited coverage near the grounding lines. This can potentially underestimate changes near some of the rapidly-changing grounding lines (e.g. Pine Island); see references for detailed information.

This is the full "raw" dataset. For further analysis some time series might need to be removed if they show evidence of poor-quality data. This will depend on the criteria applied for quality control. Satellite altimeter measurements over snow/ice are inherently noisy.

References:

Paolo F.S, H.A. Fricker, L. Padman, Constructing improved decadal records of Antarctic ice-shelf height change from multiple satellite radar altimeters, Remote Sensing of Environment, vol.177, pp.192-205 (2016). doi:10.1016/j.rse.2016.01.026

Paolo F.S., H.A. Fricker, L. Padman, Volume loss from Antarctic ice shelves is accelerating, Science, vol.348, pp.327-331 (2015). doi:10.1126/science.aaa0940


Fernando Paolo <fspaolo@gmail.com>
Jan 26, 2017