Mission Objectives: The Surface Water and Ocean Topography (SWOT) mission aims to provide valuable data and information about the world's oceans and its terrestrial surface water such as lakes, rivers, and wetlands. SWOT is being developed jointly by NASA and Centre National D'Etudes Spatiales (CNES), with contributions from the Canadian Space Agency (CSA) and United Kingdom Space Agency (UKSA).

Mission Objectives

Mission Objectives

The Surface Water and Ocean Topography (SWOT) mission aims to provide valuable data and information about the world's oceans and its terrestrial surface water such as lakes, rivers, and wetlands. SWOT is being developed jointly by NASA and Centre National D'Etudes Spatiales (CNES), with contributions from the Canadian Space Agency (CSA) and United Kingdom Space Agency (UKSA).

SWOT will measure ocean surface topography and land surface water elevation with great accuracy, using interferometry to achieve two-dimensional mapping. Observations from SWOT can be used to better understand ocean currents and processes happening at spatial scales on the order of 15-150 km, something that has not been done before. SWOT will enable high resolution (within 1 km from land) monitoring of coastal regions, including coastal currents, storm surges, and regional sea level change. On land, SWOT will provide measurements of water storage changes (surface water area and water depth) of major lakes, reservoirs, rivers, and wetlands, and support derived estimates of river discharge, which aid in assessing water resources. SWOT will observe rivers wider than 100 m and lakes with a surface area of 15 acres or more (i.e., an outline of 250 m x 250 m or 820 ft x 820 ft).

SWOT launched successfully on December 16, 2022!

Datasets Information

Recommended User Documentation

    1 "Version C" KaRIn products are distributed in the "Version 2.0" SWOT collections at PO.DAAC
    2 "Version D" KaRIn products are distributed in the "Version D" SWOT collections at PO.DAAC

Datasets Information

Standard Data Products

The table below summarizes SWOT data products, along with product descriptions and sample data products where available. The release note for these sample files is SWOT Sample Data Products v1.2 and all samples can be downloaded here.

Please refer to “Mission Events” for relevant information about spacecraft events that impact data quality and availability. This page includes links to the downlink masks for the KaRIn high-rate data.

Dataset Description Coverage Format Product Description Document (PDD) Algorithm Theoretical Basis Document (ATBD) Sample Data Products v1.2
L2_LR_PreCalSSH Pre-crossover sea surface height data product with data from the KaRIn swath spanning 60 km on both sides of nadir with a nadir gap. Product provides sea surface height, sea surface height anomaly, wind speed, and significant waveheight, on a geographically fixed, swath-aligned 2x2 km2 grid, as well as sea surface height on a 250x250 m2 native grid. This product is identical to the L2_LR_SSH product except that the crossover calibration correction is not reported. This product is only available in forward processing and not available in reprocessed products. Gridded; full swath for each half orbit netCDF L2_LR_PreCalSSH Product Description Document L2_LR_SSH Algorithm Theoretical Basis Document L2_LR_SSH.tar.gz Sample Data
L2_LR_SSH Sea surface height data product with data from the KaRIn swath spanning 60 km on both sides of nadir with a nadir gap. Product provides sea surface height, sea surface height anomaly, wind speed, significant waveheight, on a geographically fixed, swath-aligned 2x2 km2 grid, as well as sea surface height on a 250x250 m2 native grid. Gridded; full swath for each half orbit netCDF L2_LR_SSH Product Description Document L2_LR_SSH Algorithm Theoretical Basis Document L2_LR_SSH.tar.gz Sample Data
L2_HR_PIXC Point cloud of water mask pixels (“pixel cloud”) with geolocated heights, backscatter, geophysical fields, and flags. Point cloud over tile (approx 64x64 km2); half swath (left or right side of full swath) netCDF L2_HR_PIXC Product Description Document L2_HR_PIXC Algorithm Theoretical Basis Document L2_HR_PIXC.tar.gz Sample Data
L2_HR_RiverSP Shapefiles of river reaches (approximately 10 km long) and nodes (approximately 200 m spacing) identified in prior river database. Reach attributes include water surface elevation, slope, width, derived discharge. Full swath covering individual continents for each half orbit shapefile L2_HR_RiverSP Product Description Document L2_HR_RiverSP Algorithm Theoretical Basis Document L2_HR_RiverSP.tar.gz Sample Data
L2_HR_RiverAvg Cycle average and aggregation of river reach pass data within predefined hydrological basins. Basin for each cycle shapefile L2_HR_RiverAvg Product Description Document   Not available at this time.
L2_HR_LakeSP Shapefiles of lakes identified in prior lake database and detected features not in the prior river or lake databases. Lake attributes include water surface elevation, area, derived storage change. Full swath covering individual continents for each half orbit shapefile L2_HR_LakeSP Product Description Document L2_HR_LakeSP Algorithm Theoretical Basis Document L2_HR_LakeSP.tar.gz Sample Data
L2_HR_LakeAvg Cycle average and aggregation of lake pass data within predefined hydrological basins. Basin for each cycle shapefile L2_HR_LakeAvg Product Description Document   Not available at this time.
L2_HR_PIXCVec Auxiliary information for pixel cloud product indicating to which water bodies the pixels are assigned in river and lake products. Also includes height-constrained pixel geolocation after reach- or lake-scale averaging. Point cloud over tile (approx 64x64 km2); half swath (left or right side of full swath) netCDF L2_HR_PIXCVec Product Description Document   L2_HR_PIXCVec.tar.gz Sample Data
L2_HR_Raster Rasterized water surface elevation and inundation extent in geographically fixed tiles at resolutions of 100 m and 250 m in a Universal Transverse Mercator projection grid. Provides rasters with water surface elevation, area, water fraction, backscatter, geophysical information. On-demand processing available to users for different resolutions, sampling grids, scene sizes, and file formats. Gridded scene (approx 128x128 km2, georeferenced); full swath netCDF L2_HR_Raster Product Description Document L2_HR_Raster Algorithm Theoretical Basis Document L2_HR_Raster.tar.gz Sample Data
L2_HR_FPDEM Flood Plain Digital Elevation Map in raster format, derived from multiple cycles of SWOT acquisitions. Final resolution is not fixed yet (approx 50m). A large portion of the raster pixels will be void. Provides height and quality flag for each pixel. Gridded scene (approx 1°, georeferenced); geographically fixed tiles (not aligned with SWOT swath). netCDF (to be confirmed) L2_HR_FPDEM Product Description Document   Not available at this time.
L1B_LR_INTF Interferograms for each of the 9 Doppler beams formed and spatially averaged (low rate) by the On Board Processor, corrected on the ground for phase biases (inherent to the processing applied on board). The geometry of the measurements is also reported for use in subsequent processing. Gridded; full swath for each half orbit netCDF L1B_LR_INTF Product Description Document L1B_LR_INTF Algorithm Theoretical Basis Document Not available at this time.
L1B_HR_SLC High rate data processed to single-look complex SAR images for each antenna. Gridded tile (approx 64x64 km2); half swath (left or right side of full swath) netCDF L1B_HR_SLC Product Description Document L1B_HR_SLC Algorithm Theoretical Basis Document Not available at this time.
L2_NALT_GDR Nadir Altimeter Geophysical Data Record (GDR) products similar to those from ongoing nadir altimeter missions such as Jason-3. Provide sea surface height, significant wave height and wind speed measurements from the nadir altimeter. GDR using restituted auxiliary data Uses the Precise Orbit Ephemeris (POE). Available with latency of < 90 days. Discrete measurements at nadir for each half orbit, along the ground track. netCDF L2_NALT_GDR Product Description Document   Identical format to L2_NALT_IGDR
L2_NALT_IGDR Same as L2_NALT_GDR, using preliminary values for some auxiliary data. Uses Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at nadir for each half orbit, along the ground track. netCDF L2_NALT_IGDR Product Description Document   L2_NALT_IGDR.tar.gz Sample Data
L2_NALT_OGDR Same as L2_NALT_GDR using predicted values for some auxiliary data, and does not have GIM ionosphere model values. Uses the onboard DORIS orbit ephemeris. Available with latency of < 7 hours. Discrete measurements at nadir for each data downlink, along the ground track. netCDF L2_NALT_OGDR Product Description Document   L2_NALT_OGDR.tar.gz Sample Data
L2_RAD_GDR Radiometer Geophysical Data Record (GDR) product with values are based upon analyzed calibrations. Provides radiometer measurements of wet troposphere content, atmospheric attenuation to backscatter, cloud liquid water, water vapor content, and wind speed. Available with latency of < 90 days. Discrete measurements at ~30 km on each side from nadir for each half orbit, along the ground track. netCDF L2_RAD_GDR Product Description Document L2_RAD_GDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
L2_RAD_IGDR Same as L2_RAD_GDR with values based upon preliminary calibrations and Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at ~30 km on each side from nadir for each half orbit, along the ground track. netCDF L2_RAD_IGDR Product Description Document L2_RAD_IGDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
L2_RAD_OGDR Same as L2_RAD_GDR with values based upon preliminary calibrations and onboard DORIS orbit ephemeris. Available with latency of < 7 hours. Discrete measurements at nadir for each data downlink, along the ground track. netCDF L2_RAD_OGDR Product Description Document L2_RAD_OGDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
POE Precise Orbit Ephemeris (POE) providing position and velocity vectors of satellite center of mass. Available with latency of < 35 days. Daily 26-hour files centered at 12:00:00 (TAI). netCDF POE Product Description Document   POE.tar.gz Sample Data
MOE Medium-accuracy Orbit Ephemeris (MOE) providing position and velocity vectors of satellite center of mass. Available with latency of < 1.5 days. Daily 26-hour files centered at 12:00:00 (TAI). netCDF MOE Product Description Document   MOE.tar.gz Sample Data
ATTD_RECONST Satellite attitude reconstructed from combination of onboard gyro and star tracker data. Available with latency of < 1.5 days. Daily 26-hour files centered at 12:00:00 (TAI). netCDF ATTD_RECONST Product Description Document   ATTD_RECONST.tar.gz Sample Data
SAT_COM Satellite center of mass position with respect to satellite reference point. Available with latency of < 1.5 days. Duration of mission. netCDF SAT_COM Product Description Document   SAT_COM.tar.gz Sample Data
L1_DORIS_RINEX Tracking data from onboard Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) instrument. Available with latency of < 2 days. One file per day RINEX L1_DORIS_RINEX Product Description Document   Not available at this time.
L1_GPSP_RINEX Tracking data from onboard Global Positioning System Payload (GPSP). Available with latency of < 2 days. One file per data downlink. RINEX L1_GPSP_RINEX Product Description Document   Not available at this time.

The following table describes the SWOT data products (collection shortnames*) listed above that are expected to be found at the PO.DAAC: the products received from the mission (in bold) and the same products but separated into corresponding sub-collections. Note: these are the same data, but separated into smaller collections to facilitate easier data access for specific products.

Data Product Collection Shortname Format  
Land-based KaRIn (HR mode)
SWOT_L2_HR_PIXC netCDF parent collection
SWOT_L2_HR_PIXCVec netCDF parent collection
SWOT_L2_HR_Raster netCDF parent collection
SWOT_L2_HR_Raster_100m netCDF sub-collection
SWOT_L2_HR_Raster_250m netCDF sub-collection
SWOT_L2_HR_RiverSP shapefile parent collection
SWOT_L2_HR_RiverSP_node shapefile sub-collection
SWOT_L2_HR_RiverSP_reach shapefile sub-collection
SWOT_L2_HR_LakeSP shapefile parent collection
SWOT_L2_HR_LakeSP_obs shapefile sub-collection
SWOT_L2_HR_LakeSP_prior shapefile sub-collection
SWOT_L2_HR_LakeSP_unassigned shapefile sub-collection
SWOT_L2_HR_RiverAvg shapefile parent collection
SWOT_L2_HR_LakeAvg shapefile parent collection
Ocean-based KaRIn (LR mode)
SWOT_L2_LR_SSH (2 km grid) netCDF parent collection
SWOT_L2_LR_SSH_BASIC netCDF sub-collection
SWOT_L2_LR_SSH_WINDWAVE netCDF sub-collection
SWOT_L2_LR_SSH_EXPERT netCDF sub-collection
SWOT_L2_LR_SSH_UNSMOOTHED (250m) netCDF sub-collection
Continuation of nadir altimetry
SWOT_L2_NALT_OGDR netCDF parent collection
SWOT_L2_NALT_OGDR_SSHA netCDF sub-collection
SWOT_L2_NALT_OGDR_GDR netCDF sub-collection
SWOT_L2_NALT_IGDR netCDF parent collection
SWOT_L2_NALT_IGDR_SSHA netCDF sub-collection
SWOT_L2_NALT_IGDR_GDR netCDF sub-collection
SWOT_L2_NALT_IGDR_SGDR netCDF sub-collection
SWOT_L2_NALT_GDR netCDF parent collection
SWOT_L2_NALT_GDR_SSHA netCDF sub-collection
SWOT_L2_NALT_GDR_GDR netCDF sub-collection
SWOT_L2_NALT_GDR_SGDR netCDF sub-collection

*Shortnames in bold are those products received from the mission, herein referred to as “parent collection”. Those not in bold, are PO.DAAC sub-collections that separate different file types from the original product named in bold. 

*All shortnames will have a version number such as “_1.0” appended as a suffix.

For tips on file naming conventions and wildcard searches, visit our Tips for SWOT HR Spatial Search located in the SWOT Chapter of the PO.DAAC Cookbook.

Acronyms

  • L1: Processing Level 1
  • L2: Processing Level 2
  • HR: High rate
  • LR: Low rate
  • SLC: Single-look complex
  • PIXC: Pixel cloud
  • MOE: Medium-accuracy Orbit Ephemeris
  • POE: Precision Orbit Ephemeris
  • GIM: Global Ionosphere Maps
  • SSH: Sea Surface Height
  • KaRIn: Ka-band Radar Interferometer
  • RINEX: Receiver INdependent Exchange
  • TAI: Temps Atomique International (International Atomic Time)
  • GDR: Geophysical Data Record
Spatial Coverage

Spatial Coverage

SWOT Spatial Coverage for Beta Pre-Validated Products v1.1

To identify spatial coverage/search terms for the Beta Pre-Validated products (v1.1), PO.DAAC has created a KMZ file that has layers of the SWOT passes, tiles, scenes, and basins covered in this product release. Spatial coverage will expand for the pre-validated product release. Each layer has direct links to Earthdata Search (the ‘Open URL’ link) and CMR (the ‘Get CSV’ link) results for the corresponding files. The passes layer has useful information for all SWOT products, the tiles layer is useful for the L1B_HR_SLC, L2_HR_PIXC, and L2_HR_PIXCVec products, the scenes layer is useful for the L2_HR_Raster product (screenshot below), and the basins layer gives the L2_HR_RiverSP and L2_HR_LakeSP product coverages for each continent/pass combination.

Click here to download Beta Pre-Validated HR Product KMZ file. The file can be opened in the Google Earth desktop application and viewed like the following:

https://podaac.jpl.nasa.gov/sites/default/files/mission/SWOT/SWOT-Spatial-Coverage-Beta-Pre-Validated-Products

 

SWOT will provide Low Rate (LR) data with low spatial resolution globally, and High Rate (HR) data with high spatial resolution for the terrestrial and coastal environments.

HR measurements will not be taken everywhere, due to bandwidth issues of downlinking the data. To resolve that, an HR mask will be used. Figure 1 below shows, in yellow, where the HR data will be made available. The areas not covered by the mask will be preprocessed to LR data. Figure 2 below shows the coverage and swath geometry of LR data at high and low latitudes. HR data will have terrestrial corrections applied, whereas LR data will only have oceanic corrections applied.

This is a figure of SWOT High Rate (HR) spatial coverage mask. Areas in yellow will have HR measurements. The HR mask extends a few kilometers off the coast. a) Spatial coverage for terrestrial water features and coastal areas. b) Cook Inlet, AK. c) Amazon River Delta.
Figure 1. SWOT High Rate (HR) spatial coverage mask. Areas in yellow will have HR measurements. The HR mask extends a few kilometers off the coast. a) Spatial coverage for terrestrial water features and coastal areas. b) Cook Inlet, AK. c) Amazon River Delta.

 

This figure illustrates SWOT satellite spatial coverage, including the KaRIn swaths and the Nadir altimeter track. It depicts (a) global coverage, (b) coverage and swath geometry over high latitudes (here Yukon Peninsula is shown), and (c) coverage and swath geometry over lower latitudes (here Mississippi Delta).
Figure 2. This illustrates SWOT satellite spatial coverage, including the KaRIn swaths and the Nadir altimeter track. It depicts (a) global coverage, (b) coverage and swath geometry over high latitudes (here Yukon Peninsula is shown), and (c) coverage and swath geometry over lower latitudes (here Mississippi Delta). Note the coverage difference between (b) and (c). SWOT has a 21-day cycle. Note: this image is for illustration purposes only. Check out the SWOT Visualizer to see how your geographic region of interest might be cover by SWOT observations. KMZ and SHP files of nadir and swath will be provided here (coming soon).

 

Instruments

Instruments

Primary

  • KaRIn – Ka-band Radar Interferometer will measure the elevation of ocean surface topography and land surface water over a 120-km (75-mi) wide swath with a ~20 km (~12 mi) gap along nadir. It will operate in two modes: 1) Low-Resolution over the ocean with onboard processing to reduce data volume and 2) High-Resolution over broad, primarily continental, regions defined by the SWOT Science Team, focusing on hydrology studies.
  • Poseidon-3C Altimeter – Ku and C band nadir altimeter, similar to that of the Jason series, to complement the KaRIn with nadir measurements of ocean surface topography. It measures altimeter range, radar backscatter (sigma0), significant wave height and range delay due to the ionosphere electron content in the nadir gap between the left and right KaRIn swaths.

Additional     

  • AMR – Advanced Microwave Radiometer will provide measurements of the range delay due to water vapor and liquid water content in the atmosphere by measuring the 18.7 GHz, 23.8 GHz and 34.0 GHz sea surface microwave brightness temperatures. The 18.7 GHz channel provides the wind induced effects in the sea surface background emissions correction. The 23.8 GHz channel measures water vapor. The 34.0 GHz channel measures the cloud liquid water to be corrected. The AMR has two simultaneously operating strings that facilitate measurements on each of the left and right sides of the satellite nadir point, approximately half way across each of the two KaRIn swaths.
  • DORIS – Doppler Orbitography and Radiopositioning Integrated by Satellite is a tracking system that facilitates computation of the satellite orbit ephemeris. It receives signals from globally distribute ground beacons at the 401.25 MHz and 2036.25 MHz frequencies.
  • GPSP – Global Positioning System Payload is a tracking system that facilitates computation of the satellite orbit ephemeris. It receives signals from the constellation of Global Positioning System satellites.
  • LRA – Laser Reflector Assembly is a passive array of mirrors that provides a target for laser tracking measurements from ground stations. It supports the calibration and validation for the satellite orbit ephemeris that is computed from the DORIS and GPS tracking measurements, but can also be used to suppose computation of the satellite orbit ephemeris.
Mission Characteristics

Mission Characteristics

Altitude 890.582 km
Inclination 77.6°
Mean Eccentricity 0.00105
Number of Orbits per Cycle 292
Number of Passes per Cycle 584
Nodal Period 6173.62 sec
Duration of one pass 3086.81 sec
Exact repeat cycle duration 20.86455 days
Longitude gap between tracks at the Equator 1.233°
Repeat orbit parameters (N+P/Q) 13+19/21
Mean semi-major axis 7268.72 km

To learn more about the mission, go to SWOT Mission page. 

Mission Events and KaRIn High Rate Masks

Mission Events

Please refer to “Mission Events” for relevant information about spacecraft events that impact data quality and availability. This page includes links to the downlink masks for the KaRIn high-rate data.

The SWOT mission launched successfully on December 16, 2022. The table below details SWOT-relevant datasets currently at PO.DAAC. Please refer to “Mission Events” for relevant information about spacecraft events that impact data quality and availability. This page includes links to the downlink masks for the KaRIn high-rate data.

Ocean
Objectives

SWOT Ocean Objectives

SWOT will revolutionize oceanography by detecting ocean features with 10 times better resolution than present technologies. The higher resolution of SWOT is required to distinguish structures that occur on scales of 100 kilometers or shorter, where most of the ocean's energy is mixed and transported. Such small-scale ocean features contribute to the ocean-atmosphere exchange of heat and carbon, major components in global climate change. Moreover, SWOT's detailed information on ocean circulation will improve understanding of the ocean environment including motion of life-sustaining nutrients and harmful pollutants. To learn more about the mission go to SWOT Mission page. 

The SWOT Ocean objective is to characterize the ocean mesoscale and sub-mesoscale circulation (15 – 200 km or about 9 – 124 mi) at spatial resolutions of 15 km (9 mi) and greater.

Animation. Beginning in 1978 with the first Earth orbiting ocean observing satellite, Seasat, continuing with Geosat, ERS-1,TOPEX/Poseidon, ERS-2, Jason-1, Envisat and Jason-2 missions and looking ahead to the SWOT mission scheduled to launch in 2022 the improvement of the spatial resolution in NASA and partners altimetric missions is dramatic. This animation illustrates this progression of improved data resolution. SWOT will provide sea surface height and hydrography measurements at very high spatial and temporal resolutions unlike anything that has ever been available.

 

 

This graph shows Gulf Stream Eddy at Two Scales. Seen in Sea surface temperature of Mesoscale and Sub-mesoscale.
Figure 1. Sea surface temperature of a Gulf Stream eddy at mesoscale (50 km and greater) and submesoscale (less than 50 km) resolutions. SWOT will be able to observe eddies that are 15 km wide and greater. https://swot.jpl.nasa.gov/oceanography.htm
Datasets Information

SWOT Ocean Datasets

The table below summarizes the SWOT data products, along with product descriptions and sample data products where available. The release note for these sample files is SWOT Sample Data Products v1.2 and all samples can be downloaded here.

Dataset Description Coverage Format Product Description Document (PDD) Algorithm Theoretical Basis Document (ATBD) Sample Data Products v1.2
L2_LR_SSH Sea surface height data product with data from the KaRIn swath spanning 60 km on both sides of nadir with a nadir gap. Product provides sea surface height, sea surface height anomaly, wind speed, significant waveheight, on a geographically fixed, swath-aligned 2x2 km2 grid, as well as sea surface height on a 250x250 m2 native grid. Gridded; full swath for each half orbit netCDF L2_LR_SSH Product Description Document L2_LR_SSH Algorithm Theoretical Basis Document L2_LR_SSH.tar.gz Sample Data
L1B_LR_INTF Interferograms for each of the 9 Doppler beams formed and spatially averaged (low rate) by the On Board Processor, corrected on the ground for phase biases (inherent to the processing applied on board). The geometry of the measurements is also reported for use in subsequent processing. Gridded; full swath for each half orbit netCDF L1B_LR_INTF Product Description Document L1B_LR_INTF Algorithm Theoretical Basis Document Not available at this time.
L2_NALT_GDR Nadir Altimeter Geophysical Data Record (GDR) products similar to those from ongoing nadir altimeter missions such as Jason-3. Provide sea surface height, significant wave height and wind speed measurements from the nadir altimeter. GDR using restituted auxiliary data Uses the Precise Orbit Ephemeris (POE). Available with latency of < 90 days. Discrete measurements at nadir for each half orbit, along the ground track. netCDF L2_NALT_GDR Product Description Document   Identical format to L2_NALT_IGDR
L2_NALT_IGDR Same as L2_NALT_GDR, using preliminary values for some auxiliary data. Uses Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at nadir for each half orbit, along the ground track. netCDF L2_NALT_IGDR Product Description Document   L2_NALT_IGDR.tar.gz Sample Data
L2_NALT_OGDR Same as L2_NALT_GDR using predicted values for some auxiliary data, and does not have GIM ionosphere model values. Uses the onboard DORIS orbit ephemeris. Available with latency of < 7 hours. Discrete measurements at nadir for each data downlink, along the ground track. netCDF L2_NALT_OGDR Product Description Document   L2_NALT_OGDR.tar.gz Sample Data
L2_RAD_GDR Radiometer Geophysical Data Record (GDR) product with values are based upon analyzed calibrations. Provides radiometer measurements of wet troposphere content, atmospheric attenuation to backscatter, cloud liquid water, water vapor content, and wind speed. Available with latency of < 90 days. Discrete measurements at ~30 km on each side from nadir for each half orbit, along the ground track. netCDF L2_RAD_GDR Product Description Document L2_RAD_GDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
L2_RAD_IGDR Same as L2_RAD_GDR with values based upon preliminary calibrations and Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at ~30 km on each side from nadir for each half orbit, along the ground track. netCDF L2_RAD_IGDR Product Description Document L2_RAD_IGDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
L2_RAD_OGDR Same as L2_RAD_GDR with values based upon preliminary calibrations and onboard DORIS orbit ephemeris. Available with latency of < 7 hours. Discrete measurements at nadir for each data downlink, along the ground track. netCDF L2_RAD_OGDR Product Description Document L2_RAD_OGDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data

Acronyms

  • L1: Processing Level 1
  • L2: Processing Level 2
  • HR: High rate
  • LR: Low rate
  • SLC: Single-look complex
  • PIXC: Pixel cloud
  • MOE: Medium-accuracy Orbit Ephemeris
  • POE: Precision Orbit Ephemeris
  • GIM: Global Ionosphere Maps
  • SSH: Sea Surface Height
  • KaRIn: Ka-band Radar Interferometer
  • RINEX: Receiver INdependent Exchange
  • TAI: Temps Atomique International (International Atomic Time)
  • GDR: Geophysical Data Record
Spatial Coverage

SWOT Ocean Coverage

The ocean will be observed at a Low Rate (LR) with low spatial resolution. The LR data will have oceanic corrections applied. Figure 1 below shows the coverage and swath geometry of LR data at high and low latitudes.

This fifure illustrates SWOT satellite spatial coverage, including the KaRIn swaths and the Nadir altimeter track. It depicts (a) global coverage, (b) coverage and swath geometry over high latitudes (here Yukon Peninsula is shown), and (c) coverage and swath geometry over lower latitudes (here Mississippi Delta). Note the coverage difference between (b) and (c). SWOT has a 21-day cycle.
Figure 1. This illustrates SWOT satellite spatial coverage, including the KaRIn swaths and the Nadir altimeter track. It depicts (a) global coverage, (b) coverage and swath geometry over high latitudes (here Yukon Peninsula is shown), and (c) coverage and swath geometry over lower latitudes (here Mississippi Delta). Note the coverage difference between (b) and (c). SWOT has a 21-day cycle. Note: this image is for illustration purposes only. Check out the SWOT Visualizer to see how your geographic region of interest might be cover by SWOT observations. KMZ and SHP files of nadir and swath will be provided here (coming soon).

 

The SWOT mission is targeted to launch in 2022. Please visit this page with latest updates on dataset release timelines. The table below details SWOT-relevant datasets currently at PO.DAAC.

Mission Theme Image: 
Terrestrial Hydrosphere
Objectives

SWOT Hydrosphere Objectives

SWOT will provide the very first comprehensive view of Earth's surface inland water bodies from space and will allow scientists to determine changing volumes of inland water across the globe at an unprecedented resolution. Hydrologists will use the data to calculate the rate of water gained or lost in lakes, reservoirs, and wetlands as well as discharge variations in rivers, globally. These measurements are key to understanding surface water availability and in preparing for important water-related hazards such as floods and droughts. To learn more about the mission go to SWOT Mission page.

The SWOT Hydrology objectives are to 1) provide a global inventory of all terrestrial water bodies (lakes, reservoirs, wetlands) whose surface area exceeds 250 m by 250 m (~820 ft by ~820 ft) and rivers whose widths exceed 100 m (~330 ft); 2) Measure the global storage change in freshwater bodies at sub-monthly, seasonal, and annual time scales; 3) Estimate the global change in river discharge at sub-monthly, seasonal, and annual time scales.

Datasets Information

SWOT Terrestrial Hydrology Datasets

The SWOT satellite will survey rivers wider than 100 m (328 ft). Three datasets will be available to users, including pixel cloud, raster, and vector. They will only be generated for rivers recorded in an existing database and will cover reaches of approximately 10 km (6 mi).

This Figure demonstrated a new database of rivers and their widths will be used to interpret data from SWOT, which will measure changes in river and lake heights globally. Note that there are certain regions of the globe where SWOT will not be measuring such as the Sahara dessert.

Figure 1.  A new database of rivers and their widths will be used to interpret data from SWOT, which will measure changes in river and lake heights globally. Note that there are certain regions of the globe where SWOT will not be measuring such as the Sahara dessert. To see if your region of interest will be observed by SWOT, check out the SWOT swath visualizer. Image credit: NASA Earth Observatory

The table below summarizes the SWOT data products, along with product descriptions and sample data products where available. The release note for these sample files is SWOT Sample Data Products v1.2 and all samples can be downloaded here.

Dataset Description Coverage Format Product Description Document (PDD) Algorithm Theoretical Basis Document (ATBD) Sample Data Products v1.2
L2_HR_PIXC Point cloud of water mask pixels (“pixel cloud”) with geolocated heights, backscatter, geophysical fields, and flags. Point cloud over tile (approx 64x64 km2); half swath (left or right side of full swath) netCDF L2_HR_PIXC Product Description Document L2_HR_PIXC Algorithm Theoretical Basis Document L2_HR_PIXC.tar.gz Sample Data
L2_HR_RiverSP Shapefiles of river reaches (approximately 10 km long) and nodes (approximately 200 m spacing) identified in prior river database. Reach attributes include water surface elevation, slope, width, derived discharge. Full swath covering individual continents for each half orbit shapefile L2_HR_RiverSP Product Description Document L2_HR_RiverSP Algorithm Theoretical Basis Document L2_HR_RiverSP.tar.gz Sample Data
L2_HR_RiverAvg Cycle average and aggregation of river reach pass data within predefined hydrological basins. Basin for each cycle shapefile L2_HR_RiverAvg Product Description Document   Not available at this time.
L2_HR_LakeSP Shapefiles of lakes identified in prior lake database and detected features not in the prior river or lake databases. Lake attributes include water surface elevation, area, derived storage change. Full swath covering individual continents for each half orbit shapefile L2_HR_LakeSP Product Description Document L2_HR_LakeSP Algorithm Theoretical Basis Document L2_HR_LakeSP.tar.gz Sample Data
L2_HR_LakeAvg Cycle average and aggregation of lake pass data within predefined hydrological basins. Basin for each cycle shapefile L2_HR_LakeAvg Product Description Document   Not available at this time.
L2_HR_PIXCVec Auxiliary information for pixel cloud product indicating to which water bodies the pixels are assigned in river and lake products. Also includes height-constrained pixel geolocation after reach- or lake-scale averaging. Point cloud over tile (approx 64x64 km2); half swath (left or right side of full swath) netCDF L2_HR_PIXCVec Product Description Document   L2_HR_PIXCVec.tar.gz Sample Data
L2_HR_Raster Rasterized water surface elevation and inundation extent in geographically fixed tiles at resolutions of 100 m and 250 m in a Universal Transverse Mercator projection grid. Provides rasters with water surface elevation, area, water fraction, backscatter, geophysical information. On-demand processing available to users for different resolutions, sampling grids, scene sizes, and file formats. Gridded scene (approx 128x128 km2, georeferenced); full swath netCDF L2_HR_Raster Product Description Document L2_HR_Raster Algorithm Theoretical Basis Document L2_HR_Raster.tar.gz Sample Data
L2_HR_FPDEM Flood Plain Digital Elevation Map in raster format, derived from multiple cycles of SWOT acquisitions. Final resolution is not fixed yet (approx 50m). A large portion of the raster pixels will be void. Provides height and quality flag for each pixel. Gridded scene (approx 1°, georeferenced); geographically fixed tiles (not aligned with SWOT swath). netCDF (to be confirmed) L2_HR_FPDEM Product Description Document   Not available at this time.
L1B_HR_SLC High rate data processed to single-look complex SAR images for each antenna. Gridded tile (approx 64x64 km2); half swath (left or right side of full swath) netCDF L1B_HR_SLC Product Description Document L1B_HR_SLC Algorithm Theoretical Basis Document Not available at this time.
 
Acronyms
  • L1: Processing Level 1
  • L2: Processing Level 2
  • HR: High rate
  • LR: Low rate
  • SLC: Single-look complex
  • PIXC: Pixel cloud
  • MOE: Medium-accuracy Orbit Ephemeris
  • POE: Precision Orbit Ephemeris
  • GIM: Global Ionosphere Maps
  • SSH: Sea Surface Height
  • KaRIn: Ka-band Radar Interferometer
  • RINEX: Receiver INdependent Exchange
  • TAI: Temps Atomique International (International Atomic Time)
  • GDR: Geophysical Data Record

 

Passes and Tiles

A pass is half an orbit/revolution that starts and ends at the poles. Shown in Figure 2a below are three different passes (purple, green, and yellow) that would observe the Mississippi River, USA, as it drains into the Gulf of Mexico.

The data gathered by the satellite will be divided into tiles (Figure 2b), the spatial granule used for distributing the data. Each tile extends approximately 64 km along-track and 64 km perpendicular to the pass.

Note: the tiles shown are not the same as what SWOT will observe, as their along-track locations and extents were chosen for illustration purposes only.

This Figure is an illustration of three different passes observing the Mississippi River as it drains into the Gulf of Mexico, in North America.

Figure 2a

This Figure is an illustration of a data tile that is 64 km by 64 km, the spatial granule used for distributing certain SWOT hydrology data products.

Figure 2b

(a) Illustration of three different passes observing the Mississippi River as it drains into the Gulf of Mexico, in North America.
(b) Illustration of a data tile that is 64 km by 64 km, the spatial granule used for distributing certain SWOT hydrology data products. Images are for illustration purposes only; actual exact SWOT tracks may not match what is shown here.

Images are for illustration purposes only; actual exact SWOT tracks may not match what is shown here.

 

For more details on the SWOT terrestrial hydrology datasets, and other SWOT mission information, go to SWOT Mission page.

 

SWOT River Datasets

SWOT - The Lake Surveyor

SWOT video: River Datasets

SWOT video: The Lake Surveyor
Video Credit: JPL SWOT Mission Page (Click on image to play video) Video Credit: JPL SWOT Mission Page (Click on image to play video)
Spatial Coverage

SWOT Terrestrial Coverage

Terrestrial water features (rivers, lakes, reservoirs) will be observed at a High Rate (HR) with high spatial resolution. HR measurements will not be taken everywhere, due to bandwidth issues of downlinking the data. To resolve that, an HR mask will be used. The areas not covered by the mask will be preprocessed to a Low Rate (LR) with low spatial resolution. Figure 1 below shows, in yellow, where the HR data will be made available. The HR data will have terrestrial corrections applied.

SWOT: About Hydrosphere: this is a Figure of Spatial Coverage: SWOT High Rate (HR) spatial coverage mask. Areas in yellow will have HR measurements. The HR mask extends a few kilometers off the coast. a) Spatial coverage for terrestrial water features and coastal areas. b) Cook Inlet, AK. c) Amazon River Delta.

Figure 1. SWOT High Rate (HR) spatial coverage mask. Areas in yellow will have HR measurements. The HR mask extends a few kilometers off the coast. a) Spatial coverage for terrestrial water features and coastal areas. b) Cook Inlet, AK. c) Amazon River Delta.

The SWOT mission is targeted to launch in 2022. Please visit this page with latest updates on dataset release timelines. The table below details SWOT-relevant datasets currently at PO.DAAC.

Mission Theme Image: 
Coast
Objectives

SWOT Coast Objectives

SWOT will make continuous measurements, regardless if over land or ocean. So the transitional areas between land and sea will be measured, whether it is an estuary, river delta, or coast from the surf zone to the continental shelf. The spatial resolution of measurements will differ depending on how far away from land the satellite is. See the Spatial Coverage section for more information.

To find out more about SWOT and coastal areas, the mission wrote a white paper on estuaries and near shore processes  and coastal seas and shelf processes.

Datasets Information

SWOT Coastal Datasets

The table below summarizes the SWOT data products, along with product descriptions and sample data products where available. The release note for these sample files is SWOT Sample Data Products v1.2 and all samples can be downloaded here.

Dataset Description Coverage Format Product Description Document (PDD) Algorithm Theoretical Basis Document (ATBD) Sample Data Products v1.2
L2_LR_SSH Sea surface height data product with data from the KaRIn swath spanning 60 km on both sides of nadir with a nadir gap. Product provides sea surface height, sea surface height anomaly, wind speed, significant waveheight, on a geographically fixed, swath-aligned 2x2 km2 grid, as well as sea surface height on a 250x250 m2 native grid. Gridded; full swath for each half orbit netCDF L2_LR_SSH Product Description Document L2_LR_SSH Algorithm Theoretical Basis Document L2_LR_SSH.tar.gz Sample Data
L1B_LR_INTF Interferograms for each of the 9 Doppler beams formed and spatially averaged (low rate) by the On Board Processor, corrected on the ground for phase biases (inherent to the processing applied on board). The geometry of the measurements is also reported for use in subsequent processing. Gridded; full swath for each half orbit netCDF L1B_LR_INTF Product Description Document L1B_LR_INTF Algorithm Theoretical Basis Document Not available at this time.
L2_NALT_GDR Nadir Altimeter Geophysical Data Record (GDR) products similar to those from ongoing nadir altimeter missions such as Jason-3. Provide sea surface height, significant wave height and wind speed measurements from the nadir altimeter. GDR using restituted auxiliary data Uses the Precise Orbit Ephemeris (POE). Available with latency of < 90 days. Discrete measurements at nadir for each half orbit, along the ground track. netCDF L2_NALT_GDR Product Description Document   Identical format to L2_NALT_IGDR
L2_NALT_IGDR Same as L2_NALT_GDR, using preliminary values for some auxiliary data. Uses Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at nadir for each half orbit, along the ground track. netCDF L2_NALT_IGDR Product Description Document   L2_NALT_IGDR.tar.gz Sample Data
L2_NALT_OGDR Same as L2_NALT_GDR using predicted values for some auxiliary data, and does not have GIM ionosphere model values. Uses the onboard DORIS orbit ephemeris. Available with latency of < 7 hours. Discrete measurements at nadir for each data downlink, along the ground track. netCDF L2_NALT_OGDR Product Description Document   L2_NALT_OGDR.tar.gz Sample Data
L2_RAD_GDR Radiometer Geophysical Data Record (GDR) product with values are based upon analyzed calibrations. Provides radiometer measurements of wet troposphere content, atmospheric attenuation to backscatter, cloud liquid water, water vapor content, and wind speed. Available with latency of < 90 days. Discrete measurements at ~30 km on each side from nadir for each half orbit, along the ground track. netCDF L2_RAD_GDR Product Description Document L2_RAD_GDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
L2_RAD_IGDR Same as L2_RAD_GDR with values based upon preliminary calibrations and Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at ~30 km on each side from nadir for each half orbit, along the ground track. netCDF L2_RAD_IGDR Product Description Document L2_RAD_IGDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data
L2_RAD_OGDR Same as L2_RAD_GDR with values based upon preliminary calibrations and onboard DORIS orbit ephemeris. Available with latency of < 7 hours. Discrete measurements at nadir for each data downlink, along the ground track. netCDF L2_RAD_OGDR Product Description Document L2_RAD_OGDR Algorithm Theoretical Basis Document L2_RAD_OIGDR.tar.gz Sample Data

Acronyms

  • L1: Processing Level 1
  • L2: Processing Level 2
  • HR: High rate
  • LR: Low rate
  • SLC: Single-look complex
  • PIXC: Pixel cloud
  • MOE: Medium-accuracy Orbit Ephemeris
  • POE: Precision Orbit Ephemeris
  • GIM: Global Ionosphere Maps
  • SSH: Sea Surface Height
  • KaRIn: Ka-band Radar Interferometer
  • RINEX: Receiver INdependent Exchange
  • TAI: Temps Atomique International (International Atomic Time)
  • GDR: Geophysical Data Record
Spatial Coverage

SWOT Coastal Coverage

Coastal areas will be observed at a High Rate (HR) with high spatial resolution. HR measurements will not be taken everywhere, due to bandwidth issues of downlinking the data. To resolve that, an HR mask will be used. The areas not covered by the mask will be preprocessed to a Low Rate (LR) with low spatial resolution. Figure 1 below shows, in yellow, where the HR data will be made available. HR data will have terrestrial corrections applied. If oceanic corrections are needed, users will need to add those themselves.

About Hydrosphere: SWOT High Rate (HR) spatial coverage mask. Areas in yellow will have HR measurements. The HR mask extends a few kilometers off the coast. a) Spatial coverage for terrestrial water features and coastal areas. b) Cook Inlet, AK. c) Amazon River Delta.

Figure 1. SWOT High Rate (HR) spatial coverage mask. Areas in yellow will have HR measurements. The HR mask extends a few kilometers off the coast. a) Spatial coverage for terrestrial water features and coastal areas. b) Cook Inlet, AK. c) Amazon River Delta.

The SWOT mission is targeted to launch in 2022. Please visit this page with latest updates on dataset release timelines. The table below details SWOT-relevant datasets currently at PO.DAAC.

Mission Theme Image: 
SWOT
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