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Full catalog/SWOT_L2_NALT_IGDR_D
SWOT_L2_NALT_IGDR_D·vD·dataset

Sea and lake surface height, interim version D (SWOT)

SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record with Waveforms Version D
ocean NASA POCLOUD Level 2 netCDF-4
In plain English

What it measures. Measurements of sea surface height taken straight down beneath the satellite, along with wave height and wind speed, recorded as points along the flight track rather than a full map.

How it's made. Collected by the Poseidon-3C radar altimeter on the NASA/CNES SWOT satellite; this interim 'Version D' is processed quickly with preliminary orbit information, available in under about 1.5 days.

How & where you'd use it. Supports monitoring of ocean topography and inland water bodies, with the fast turnaround making it suitable for time-sensitive work, while a more precise final version comes later.

What's measured

OCEANS › SEA SURFACE TOPOGRAPHY › SEA SURFACE HEIGHTOCEANS › OCEAN WAVES › SIGNIFICANT WAVE HEIGHTOCEANS › SEA SURFACE TOPOGRAPHY › DYNAMIC TOPOGRAPHY › ABSOLUTE DYNAMIC TOPOGRAPHYOCEANS › SEA SURFACE TOPOGRAPHY › DYNAMIC TOPOGRAPHY › MEAN DYNAMIC TOPOGRAPHYOCEANS › SEA SURFACE TOPOGRAPHY › MEAN SEA SURFACEOCEANS › SEA SURFACE TOPOGRAPHY › SEA LEVEL › MEAN SEA LEVELOCEANS › SEA SURFACE TOPOGRAPHY › SEA LEVEL › SEA LEVEL ANOMALYOCEANS › SEA SURFACE TOPOGRAPHY › SEA SURFACE HEIGHT › SEA SURFACE HEIGHT ANOMALY (SSHA)OCEANS › SEA SURFACE TOPOGRAPHY › SEA SURFACE SLOPE

Coverage & cadence

  • Time span2022-12-16 → ongoing
  • Measured bySWOT (Jason-class Altimeter, AMR)
  • Processing levelLevel 2
  • Spatial extent-180, -77.6, 180, 77.6
  • FormatsnetCDF-4
  • StatusACTIVE

What you can do with it

  • Watch sea-surface temperature and marine heatwaves
  • Spot algal blooms and ocean-colour shifts
  • Support fisheries and coastal monitoring
Official description

The 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

Get the data

swot_l2_nalt_igdr_d_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="SWOT_L2_NALT_IGDR_D",
    version="D",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from POCLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.