Earth Data School
About
Full catalog/S104
S104·dataset

Standardized water level forecasts for ships (NOAA)

NOAA S-104 Water Level Data
ocean NOAA NOAA active
In plain English

What it measures. Forecasts of how high the water will be, combining tides and storm effects, delivered as map tiles matched to electronic nautical charts.

How it's made. NOAA draws water level guidance from its global surge-and-tide model and encodes it in the international S-104 standard format out to 7.5 days.

How & where you'd use it. It plugs directly into electronic chart systems so mariners can see expected water levels for the exact areas they're navigating.

What's measured

aws-pdsmarine navigationhydrographyoceanscoastalwater

Coverage & cadence

  • Time span— → ongoing

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

S-104 is a data and metadata encoding specification that is part of the S-100 Universal Hydrographic Data Model, an international standard for hydrographic data. This collection of data contains water level forecast guidance from NOAA's Global Surge and Tide Operational Forecast System 2-D (STOFS-2D-Global), an operational hydrodynamic nowcast and forecast modeling system for global water level conditions. These datasets are encoded as HDF-5 files conforming to the S-104 specification, and are geospatially subset into individual tiles conforming to the NOAA/OCS Nautical Product Tiling Scheme, with filenames indicating the corresponding NOAA Electronic Navigational Chart (ENC) Cell Identifier. A set of prototype S-104 tiles has been created for the Charleston, SC area for a select model run cycle. Each individual S-104 (HDF-5) file contains all forecast projections from a single model run for that geographic area. A single S-104 file will contain multiple gridded arrays each containing a forecast valid at a distinct time in the future, out to the forecast horizon of STOFS-2D-Global, which is 180 hours or 7.5 days. The water level forecast guidance includes the combined effects of storm surge (sub-tidal) and tides (astronomical tide predictions).

Get the data

noaa_access.py
# NOAA Open Data on AWS — public S3, no login
import s3fs

fs = s3fs.S3FileSystem(anon=True)
# find this dataset's bucket in the docs link in the sidebar, then:
# files = fs.ls("noaa-<bucket>/...")
# open NetCDF/GRIB with xarray, COGs with rioxarray
NOAA Open Data is on public AWS S3 — no login at all (anonymous access).