This data set contains velocity and strain rate fields over the northeast Tibetan Plateau, which are derived from Sentinel-1A and -1B synthetic aperture radar satellite data (SAR) and stored in GeoTIFF (.tif) or NETCDF (.grd) formats.
The velocities in the line-of-sights (LOS) of the satellites were processed at ~100 m resolution from time series in ~250km x 250km frames. The data set consists of velocities from 10 frames in ascending tracks and 13 frames in descending tracks of the satellites' orbits. The spatial extent of the velocities spans 96E-108E and 32N-43N, covering an area of 660,000 km^2. The temporal coverages of the data span from October 2014 to December 2019 across 65-110 acquisition epochs. The uncertainties of the velocities average to <1 mm/yr. The time series are inverted from fully-connected networks of short-temporal-baseline interferograms which are generated from interfering and unwrapping pairs of SAR imagery. The velocities represent the average velocity through the displacement time series.
The LOS velocities were decomposed into east and vertical velocities which are also archived with associated uncertainties. These Cartesian fields cover the overlapping areas between ascending and descending tracks and total 440,000 km^2. By combining the horizontal gradients of the filtered east velocities and interpolated north velocities from Global Navigational Satellite System, we derive second invariant, maximum shear, and dilatation strain rate fields for the same area with 1 km sampling intervals.
These strain rate fields highlight creeping sections and strain concentration on faults and fault junctions. The velocity fields reveal fault kinematics in terms of slip rates and partitioning. The vertical velocities also show non-tectonic signals such as subsidence related to permafrost melting, groundwater extraction, and reservoir loading, as well uplift from blocked drainages.
The data are collected and processed by Qi Ou with the automatic processing tools developed by Milan Lazecky. Velocity and strain rate fields were interpreted by all authors. By default, interferograms were generated from each epoch to six consecutive epochs and between acquisition pairs with six-month and nine-month temporal baselines. Interferograms with the unwrapping error were removed from the network and all networks were continuous and fully connected.
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Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence: http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.
Data were produced by the project team and supplied for archiving at the Centre for Environmental Data Analysis (CEDA).
The quality of interferogram phase unwrapping was checked by the NSBAS method. The uncertainties of the velocities are on average below 1 mm/yr. The uncertainties of the strain rate fields are on average below 10 nst/yr. Data are as given by the data provider, no quality control has been performed by the Centre for Environmental Data Analysis (CEDA).
These data are provided in GeoTIFF (.tif) or NETCDF (.grd) formats.
Computation Element: 1
|Computation for the velocity and strain rate fields of the Northeast Tibetan Plateau
|The interferograms are processed from Sentinel-1 Level 1 (L1) Synthetic Aperture Radar (SAR) imagery using the Looking Into Continents from Space with Synthetic Aperture Radar (LiCSAR) routine. The average line-of-sight (LOS) velocities and associated uncertainties are derived from frame-based five-year time series, which are inverted from networks of short temporal baseline interferograms using the New Small Baseline Subset (NSBAS) method. The scaled uncertainties are the LOS uncertainties with referencing effects corrected by fitting a spherical model to the scatter points between uncertainty and distance from the reference. The stitched LOS velocities in the reference frame of the Global Navigational Satellite System (GNSS) velocities are the results of mosaicking frame-sized LOS velocities into tracks by adding a planar ramp per frame to close the differences between overlapping pixels in consecutive LOS frames and between InSAR and GNSS LOS velocities. The stitched LOS velocities in two line-of-sights were then decomposed into Cartesian velocities in two steps, first into an east component and a combination of the north and vertical components, and then resolving the vertical component from the combination component using an interpolated north component from the GNSS velocities. The strain rate fields are calculated from the horizontal gradients of the filtered InSAR east velocities and interpolated GNSS north velocities.