About WEMo
Version 1.1 (October 2026)
WEMo puts the Wave Exposure Model in your browser: draw an area of water and get wave height, wave energy and seabed forces for every site, with bathymetry and decades of hourly wind built in.
The model
The Wave Exposure Model was formulated at NOAA's National Centers for Coastal Ocean Science, at the Center for Coastal Fisheries and Habitat Research in Beaufort, North Carolina, by Amit Malhotra and Mark S. Fonseca. It was published in 2007 as NOAA Technical Memorandum NOS NCCOS 65, WEMo (Wave Exposure Model): Formulation, Procedures and Validation.
WEMo was designed to answer a practical question for estuaries and other sheltered waters: how much wave energy reaches a given spot? It has since been used for siting seagrass restoration, designing living shorelines and assessing shoreline erosion, and NOAA now publishes an open-source R version.
This app
What's different
The original WEMo ran inside desktop GIS software and needed you to prepare your own shoreline, bathymetry and wind data. This app does that for you: draw an area on the map, and it gathers depth (GEBCO 2026, or your own survey) and up to decades of hourly wind for that place, or the measured wind of a nearby buoy or weather station, and runs the model on our servers, from a handful of sites to 50,000. Ocean swell, vegetation and coastal structures can be added to a run.
What's the same, and what's been added
WEMo still grows waves along fetch rays from each site and weights them by the wind climate, as in the original formulation, and with the "Original 2007 model" setting the engine reproduces NOAA's WEMo implementation exactly. By default it adds what a spectral wave model would include in shallow, sheltered water: growth limited by the depth, bottom friction (the formula SWAN uses), breaking on the local bed slope, wave energy spread over neighbouring directions, three rays per direction, and wind blended between neighbouring cells. These defaults were tuned against SWAN and tested in four basins and against three years of buoy data. The model's assumptions and limits still apply; see How it works and its limitations.
Geo Horizons
WEMo is built by Geo Horizons, a geospatial company working on marine industry and natural resource management. The team combines GIS, environmental modelling, remote sensing and AI in work that includes spatial planning, aquaculture planning, offshore wind, coastal ecosystem management, decision-support tools and harmful algal bloom monitoring.
Geo Horizons was founded in 2007 by Amit Malhotra, one of the two original developers of WEMo. Amit is a certified GIS Professional with 25 years of experience in geospatial and hydrodynamic modelling. Bringing WEMo to the web is a way to put the model he helped create in the hands of anyone working on sheltered coastal waters.
Data and credits
- Bathymetry: GEBCO Bathymetric Compilation Group (2026), The GEBCO_2026 Grid. Not for navigation.
- Wind: Open-Meteo historical weather, containing modified Copernicus Climate Change Service information (ERA5, ERA5-Land). Measured wind: NOAA National Data Buoy Center and Integrated Surface Database; Environment and Climate Change Canada and Fisheries and Oceans Canada (Open Government Licence – Canada); E.U. Copernicus Marine Service Information.
- Swell: Open-Meteo marine data (Météo-France MFWAM, ERA5).
- Maps: Sentinel-2 cloudless by EOX IT Services GmbH; Esri; U.S. Geological Survey; OpenFreeMap © OpenMapTiles, data © OpenStreetMap contributors. World shoreline © OpenStreetMap contributors (ODbL).
- Model: Malhotra & Fonseca (2007), NOAA Technical Memorandum NOS NCCOS 65.
WEMo (this web app) is an independent product of Geo Horizons. It is not affiliated with or endorsed by NOAA.
Contact
Questions, feedback, or interested in using WEMo for a project? Email [email protected] or visit geohorizons.co.