Sea ice deformation and rotation rates (SIDRR) from the ECCC-ASITS

v1.3 update: Extension of the dataset to 2025-08-31.

Description:

This dataset offers pan-Arctic sea ice deformation and rotation rates (SIDRR) computed from Sentinel1 (S1) or the Radarsat Constellation Mission (RCM) Synthetic Aperture Radar (SAR) imagery, based on Sea Ice Motion (SIM) vector outputs from the Environment and Climate Change Canada Automated Sea Ice tracking System (ECCC-ASITS, Howell et al., 2022). 

The ASITS produces lists of sea ice motion vectors derived by tracking recognizable features in overlapping pairs of SAR images (Komarov and Barber, 2014). The tracked features from each SAR image pair are triangulated, and the SIDRRs computed using a line integral method (Bouchat et al., 2020, 2022) based on the velocity and start location of each vertex.

Format:

The raw SIDRR data from multiple SAR images are stacked in daily netcdf output files, based on the acquisition time of the earliest image in the pair. The netcdf files thus include data from variable time and space resolutions depending on the triangulation and images acquisition time, in the ranges of 4 - 20 km and 12 h - 6 days. Each file is named with the convention “SIDRR_YYYYMMDD.nc”. For example, “SIDRR_20210101.nc” contains data from pairs with the first image acquisition time on January 1^st, 2021.

Dimension and variable names:

Dimensions:         n                           triangle ID number

                             npts                     number of triangulated tracked points

Variables:              idpair (n)                  SAR scene pair ID number

                             pts_idpair (npts)       SAR scene pair ID number

                             ids1 (n)                     ID of triangle vertex 1

                             ids2 (n)                     ID of triangle vertex 2

                             ids3 (n)                     ID of triangle vertex 3

                             start_time (n)            Acquisition time, SAR image #1                    (hrs since ref. time)

                             end_time (n)             Acquisition time, SAR image #2                    (hrs since ref. time)

                             start_lat (npts)          Tracked points start latitude                          (ºN)

                             start_lon (npts)         Tracked points start longitude                       (ºE)

                             end_lat (npts)           Tracked points end latitude                            (ºN)

                             end_lon (npts)          Tracked points end longitude                         (ºE)

                             A (n)                          Start triangle Area                                          (m²)

                             errA (n)                     Propagation of tracking error on A                (m²)

                             dudx (n)                    x-direction divergence rate                            (day^-1)

                             dvdy (n)                    y-direction divergence rate                            (day^-1)

                             dvdx (n)                    x-direction shear rate                                     (day^-1)

                             dudy (n)                    y-direction shear rate                                    (day^-1)

                             vrt (n)                        vorticity                                                         (day^-1)

                             err_vrt (n)                  Propagation of tracking error on vrt             (day^-1)

                             div (n)                       Divergent deformation rate                           (day^-1)

                             err_div (n)                 Propagation of tracking error on div             (day^-1)

                             shr (n)                       Shear deformation rate                                 (day^-1)

                             err_shr (n)                 Propagation of tracking error on shr            (day^-1)

                             s2n (n)                      Total deformation’s signal to noise ratio