SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record with Waveforms Version D

(SWOT_L2_NALT_IGDR_D)
VersionD
Processing Level2
Start/Stop Date2022-Dec-16 to Present
Short NameSWOT_L2_NALT_IGDR_D
DescriptionThe SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record (IGDR) Version D dataset produced by the Surface Water and Ocean Topography (SWOT) mission provides sea surface height, significant wave height and wind speed measurements from the Poseidon-3C nadir altimeter, a Jason-class dual frequency (Ku/C) altimeter. SWOT is a joint mission between NASA and CNES that launched on December 16, 2022. It aims to measure ocean surface topography with unprecedented resolution and accuracy, as well as map inland water bodies globally. The IGDR dataset consists of discrete measurements along the nadir track with sampling resolutions of approximately 6-km and 300-m at 1Hz and 20Hz, respectively. The data were processed using the Medium-accuracy (preliminary) Orbit Ephemeris (MOE) and preliminary values for certain auxiliary data. The IGDR data are distributed as one file per half orbit in netCDF-4 file format with a nominal latency of < 1.5 days.
This collection is the parent collection to the following sub-collections:
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_NALT_IGDR_SSHA_D
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_NALT_IGDR_GDR_D
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_NALT_IGDR_SGDR_D
DOI10.5067/SWOT-NALT-IGDR-D
MeasurementOCEANS > SEA SURFACE TOPOGRAPHY > SEA SURFACE HEIGHT
OCEANS > OCEAN WAVES > SIGNIFICANT WAVE HEIGHT
OCEANS > SEA SURFACE TOPOGRAPHY > DYNAMIC TOPOGRAPHY
OCEANS > SEA SURFACE TOPOGRAPHY > DYNAMIC TOPOGRAPHY
OCEANS > SEA SURFACE TOPOGRAPHY > MEAN SEA SURFACE
OCEANS > SEA SURFACE TOPOGRAPHY > SEA LEVEL
OCEANS > SEA SURFACE TOPOGRAPHY > SEA LEVEL
OCEANS > SEA SURFACE TOPOGRAPHY > SEA SURFACE HEIGHT
OCEANS > SEA SURFACE TOPOGRAPHY > SEA SURFACE SLOPE
Platform/Sensor
SWOT
Platform
Name: Surface Water Ocean Topography (SWOT)
/
Jason-class Altimeter
SENSOR
Name: Jason-class Altimeter (Jason-class Altimeter)

SWOT
Platform
Name: Surface Water Ocean Topography (SWOT)
/
AMR
SENSOR
Name: Advanced Microwave Radiometer (AMR)
Swath Width: 18.7 ghz
Description: The operating frequency which is aimed towards recovery of atmospheric attenuation due to sigma0
Swath Width: 23.8 ghz
Description: The operating frequency which is aimed towards recovery of atmospheric attenuation due to water vapor
Swath Width: 34.0 ghz
Description: The operating frequency which is aimed towards recovery of atmospheric attenuation due to cloud liquid water.

ProjectSurface Water Ocean Topography (SWOT)
Data ProviderPublisher: NASA/JPL/PODAAC
Creator: Surface Water Ocean Topography (SWOT)
Release Date: 2025-May-06
Resource: https://swot.jpl.nasa.gov

FormatnetCDF-4
Keyword(s)sea level, SWOT, Surface Water Ocean Topography, sea level anomaly, sla, sea surface height, ssh, sea surface height anomaly, ssha, significant wave height, swh, wave height, along-track, nadir, altimeter Jason-class, Poseidon-3C
Questions related to this dataset? Contact podaac@podaac.jpl.nasa.gov
Resolution
Spatial Resolution: 300 Meters x 300 Meters
 
Coverage
Region: GLOBAL
North Bounding Coordinate: 77.6 degrees
South Bounding Coordinate: -77.6 degrees
West Bounding Coordinate: -180 degrees
East Bounding Coordinate: 180 degrees
Time Span: 2022-Dec-16 to Present
 
NameLong NameUnit
/data_01/alt_qualaltimeter quality flag
/data_01/altitude1 Hz altitude of satellitem
/data_01/dacdynamic atmospheric correctionm
/data_01/depth_or_elevationocean depth/land elevationm
/data_01/geo_qualgeophysical quality flag
/data_01/ice_flagice flag
/data_01/internal_tide_hretinternal tide heightm
/data_01/inv_bar_corinverted barometer height correctionm
/data_01/ku/iono_cor_alt_filteredfiltered altimeter ionospheric correction on Ku bandm
/data_01/ku/iono_cor_alt_filtered_mle3filtered altimeter ionospheric correction on Ku band (MLE3 retracking)m
/data_01/ku/range_ocean1 Hz Ku band corrected altimeter rangem
/data_01/ku/range_ocean_mle31 Hz Ku band corrected altimeter range (MLE3 retracking)m
/data_01/ku/sea_state_biassea state bias correction in Ku bandm
/data_01/ku/sea_state_bias_mle3sea state bias correction in Ku band (MLE3 retracking)m
/data_01/ku/sig0_oceanKu band corrected backscatter coefficientdB
/data_01/ku/sig0_ocean_mle3Ku band corrected backscatter coefficient (MLE3 retracking)dB
/data_01/ku/sshasea surface height anomalym
/data_01/ku/ssha_mle3sea surface height anomaly (MLE3 retracking)m
/data_01/ku/swh_oceanKu band corrected significant waveheightm
/data_01/ku/swh_ocean_mle3Ku band corrected significant waveheight (MLE3 retracking)m
/data_01/ku/wvf_main_class1 Hz Ku band waveform main class
/data_01/latitudelatitudedegrees_north
/data_01/longitudelongitudedegrees_east
/data_01/mean_dynamic_topographymean dynamic topography above geoidm
/data_01/mean_sea_surface_cnesclsmean sea surface height (CNES/CLS solution) above reference ellipsoidm
/data_01/meteo_map_availability_flagECMWF meteorological map availability
/data_01/model_dry_tropo_cor_zero_altitudemodel dry tropospheric correction at zero altitudem
/data_01/ocean_tide_fesgeocentric ocean tide height (FES solution)m
/data_01/pole_tidegeocentric pole tide heightm
/data_01/rad_cloud_liquid_waterradiometer liquid water contentkg/m^2
/data_01/rad_qualradiometer quality flag
/data_01/rad_side_1_rain_flagradiometer rain flag from first radiometer
/data_01/rad_side_1_sea_ice_flagradiometer sea-ice flag from first radiometer
/data_01/rad_side_1_surface_type_flagradiometer surface type from first radiometer
/data_01/rad_side_2_rain_flagradiometer rain flag from second radiometer
/data_01/rad_side_2_sea_ice_flagradiometer sea-ice flag from second radiometer
/data_01/rad_side_2_surface_type_flagradiometer surface type from second radiometer
/data_01/rad_water_vaporradiometer water vapor contentkg/m^2
/data_01/rad_wet_tropo_corradiometer wet tropospheric correctionm
/data_01/rad_wet_tropo_cor_interp_qualradiometer wet tropospheric correction interpolation quality flag
/data_01/rain_flagrain flag
/data_01/solid_earth_tidesolid earth tide heightm
/data_01/surface_classification_flagsurface classification
/data_01/timetime in UTCseconds since 2000-01-01 00:00:00.0
/data_01/time_taitime in TAIseconds since 2000-01-01 00:00:00.0
/data_01/wind_speed_altaltimeter wind speedm/s
/data_01/wind_speed_alt_mle3altimeter wind speed (MLE3 retracking)m/s
Citation is critically important for dataset documentation and discovery. Please cite the data as follows, and cite the reference papers when it is appropriate.
Citation Surface Water Ocean Topography (SWOT). 2025. SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record with Waveforms Version D. Ver. D. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/SWOT-NALT-IGDR-D

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For more information see Data Citations and Acknowledgments.
Journal Reference Shailen Desai, 2018. Surface Water and Ocean Topography Mission (SWOT) Project: Science Requirements Document. Jet Propulsion Laboratory, JPL D-61923, Rev. B. https://swot.jpl.nasa.gov/system/documents/files/2176_2176_D-61923_SRD_Rev_B_20181113.pdf

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