Principal Investigator (PI): Alex Gardner, NASA's Jet Propulsion Laboratory (JPL)

The core goal of this MEaSUREs project is to put high quality, low latency, high temporal frequency, easy-to-use observations into researchers’ hands to reduce the effort required to make scientific discoveries from these data.

We are generating a globally comprehensive and temporally dense record of land ice and ice shelf velocity and elevation, to be updated continuously. Such a harmonized record will support a fundamental shift in research by the polar ice and glacier community. A continuous multi-parameter data stream will help researchers characterize the underlying mechanisms that link Earth’s ice to its atmosphere and ocean; it will also help prepare the community for future observables from NASA’s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) and the NASA-Indian Space Research Organisation Synthetic Aperture Radar (NISAR) missions by facilitating a transition from analyzing infrequent single-instrument datasets to working with the large continuous data streams that will soon flow.

Our products will synthesize ice velocity grids from the available large data streams: Optical data from Landsat 8 and Landsat 9 (2021) and Sentinel-2 (A and B); and Synthetic Aperture Radar (SAR) from Sentinel-1A/B. These will be processed to a near-continuous velocity product for all land ice (>100 km2), to be delivered within weeks of acquisition as Level 2 scene-pair velocity fields on a common 240 m grid, at the highest practical temporal and spatial sampling for these data. The Level 2 products will be synthesized, in an error-weighted sense, to produce Level 3 quarterly and annual ice-sheet (Greenland and Antarctica) and regional (Alaska, Canadian Arctic, Russian Arctic, Svalbard, High Mountain Asia, Patagonia) velocity mosaics to support large-area studies.

Records of ice flow will be accompanied by a growing 30-year time series of ice sheet and ice shelf elevation changes from 1993 through to 2023, synthesizing data from two NASA and six ESA satellite altimeters. These will be validated against NASA IceBridge laser altimetry through the end of that mission. A standardized record of quarterly elevation change rates (dh/dt) for both ice sheets and Antarctic ice shelves on a compatible 960 m grid will be produced by leveraging JPL infrastructure generating elevations from CryoSat-2 radar waveforms and two other NASA-funded efforts refining laser and radar altimetry.

Our previous project, Global Land Ice Velocity Extraction project (GoLIVE), distributed a first release of all possible Level 2 scene pair velocities from the Landsat 8 archive six months after funding started, and continues to update monthly

This project expands the GoLIVE processing chain to deliver products from all Sentinel-2A and 2B acquisitions. Higher spatial resolution and more frequent coverage will greatly improve records in mountainous terrain and cloudy areas.

We are processing Sentinel 1 SAR scene pairs over land-ice areas globally, providing all-weather all season sampling that complements the optical record. This is only possible because we leverage the InSAR-processing infrastructure that has been built at JPL over the past decade in preparation for NASA’s NISAR mission. This infrastructure is already generating large volumes of Sentinel-1 interferograms with low latency for disaster response through the NASA-funded Advanced Rapid Imaging and Analysis (ARIA) project. We will optimize this infrastructure to produce ice sheet velocities.

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