Products

Product Overview

EOLIS (Elevation Over Land Ice from Swath) is part of the ESA CryoSat ThEMatic PrOducts (CryoTEMPO) initiative, that aims to support a wide variety of end-users working in the areas of sea ice, polar oceans, land ice, coastal areas and hydrology. The EOLIS products exploit CryoSat’s SARIn mode and the novel Swath processing technique to deliver increased spatial and temporal coverage of time-dependent elevation over land ice, a critical metric for tracking ice mass trends. The CryoTEMPO EOLIS products are the operational result of research and development projects CryoTop and CryoTop-Evolution

Products available are:

  1. SWATH THEMATIC POINT PRODUCT (EOLIS POINTS)
  2. SWATH THEMATIC GRIDDED PRODUCT (EOLIS DEM)

current release - version 1.2

Both the point and gridded products are now available for all months back to 2010 for both Greenland and Antarctica.

The Glacier regions are now live with point products available over Arctic Canada, Svalbard, Iceland, Russian Arctic, Southern Andes, Alaska from July 2021, and Asia from October 2021. Gridded products are also available for Iceland and Svalbard from August 2021.

1) Swath Thematic Point Product (EOLIS POINTS)

Description: The EOLIS point product contains a dense set of elevation measurements for individual observations. Due to the high volume of data, the data has been split into tiles of 100x100km in size.

The point product contains the attributes:

  • Time (time in seconds)
  • X (polar coordinate) or lon (degrees)
  • Y (polar coordinate) or lat (degrees)
  • Elevation (metres)
  • Uncertainty (metres)
  • isSwath (1 for Swath, 0 for POCA)
  • fields (id of L1b and L2 underlying products)

Coordinate reference system
Greenland, Iceland, Svalbard, Canadian Arctic, Russian Arctic, Alaska:

  • EPSG:3413 || +proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs

Antartica:

  • EPSG:3031 || +proj=stere +lat_0=-90 +lat_ts=-71 +lon_0=0 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs
Southern Andes and Asia:
  •  ESPG:4326 || +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs

The folder structure on the ESA Science Server is: TEMPO_SWATH_POINT/YYYY/MM/<ZONE>

The file naming convention is: CS_OFFL_THEM_POINT_<ZONE>_<YYYY>_<MM>_<X>_<Y>_<VERSION> where ZONE is currently either GREENLAND, ANTARCTIC, ICELAND__, SVALBARD_ or CANADIANA. Note that X and Y are polar coordinates.

Data tile locations: A Shapefile (.shp) containing the data tile locations is available in each monthly folder in tar file format: CS_OFFL_THEM_POINT_<ZONE>_<YYYY>_<MM>.tgz

Map of the 100km grid cells over Greenland for 2011 (CRS: EPSG 3413)

2) Swath Thematic Gridded Product (EOLIS DEM)

Description: The EOLIS DEM is a monthly 2km resolution DEM with the data sourced from a rolling 3 month window, e.g. February 2020 will use data from a window starting on the 1st January 2020 and finishing on the 31st March 2020.

The folder structure on the ESA Science Server is:  TEMPO_SWATH_GRID/YYYY/MM/<ZONE> where ZONE is either GREENLAND, ANTARCTIC, ICELAND__, SVALBARD_

Coordinate reference system
Greenland, Iceland, Svalbard:

  • EPSG:3413 || +proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs

Antartica:

  • EPSG:3031 || +proj=stere +lat_0=-90 +lat_ts=-71 +lon_0=0 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs
Extents of each region can be found in the product handbook.
Example DEM created over Greenland for January 2020.

SUPPORTING DOCUMENTS

Product Handbook

The product handbook acts as a user guide and contains high level algorithm descriptions as well as an overview of file structure: 

Algorithm Technical Baseline Document

For more in-depth explanations of underlying algorithms, please refer the Algorithm Technical Baseline Document (ATBD):

How to cite

The recommended citation for the EOLIS product is:

“EOLIS elevation data generated using swath processing of CryoSat data (Gourmelen et al., 2018) and provided by the ESA CryoTEMPO project (https://cryotempo-eolis.org/).”

Gourmelen, N., Escorihuela, M., Shepherd, A., Foresta, L., Muir, A., Garcia-Mondejar, A., Roca, M., Baker, S., & Drinkwater, M. R. (2018). CryoSat-2 swath interferometric altimetry for mapping ice elevation and elevation change. Advances in Space Research, 62(6), 1226-1242. https://doi.org/10.1016/j.asr.2017.11.014

Feedback and Queries

Feedback or questions about the CryoTEMPO-EOLIS Thematic Products is welcomed. Please use the following contact details:

E-mail: support@cryotempo-eolis.org