The Gulf of Maine Operational Forecast System (GoMOFS)

Effective on May 20, 2020 beginning at 18z Coordinated Universal Time (UTC), two major changes for NOS OFS datasets on THREDDS will be implemented. Please see the Service Change Notice for details

https://www.weather.gov/media/notification/scn20-43nos_ofs.pdf

1. Retention period change - Only the most recent 31 days of OFS output files will be available on CO-OPS THREDDS.

2. File structure changes - To improve THREDDS performance related to file access and data aggregation

Oceanographic nowcasts and forecast guidance are scientific predictions about the present and future states of a water body (generally including water levels, currents, water temperature and salinity). These predictions rely on either observed data or forecasts from large-scale numerical models. A nowcast incorporates recent (and often near real-time) observed meteorological, oceanographic, and/or river flow rate data and/or analyzed (e.g. gridded) meteorological and oceanographic products. A nowcast covers the period of time from the recent past (e.g., the past few days) to the present, and it can make predictions for locations where observational data are not available. Forecast guidance incorporates meteorological, oceanographic, and/or river flow rate forecasts and makes predictions about the future states of a water body. A forecast is usually initiated by the state of a nowcast.

GoMOFS surface meteorological forcing conditions are based on the National Weather Service (NWS) North American Mesoscale (NAM) weather prediction model (for both nowcast and forecast). The National Centers for Environmental Prediction (NCEP)'s operational meteorological forecast products of Global Forecast System (GFS) are used as a backup while NAM products are not available.

GoMOFS relies on NCEP's Global Real-Time Ocean Forecast System (G-RTOFS) to provide lateral ocean open boundary conditions of water temperature, salinity and sub-tidal water levels, and Navy's operational global HYCOM is used as a backup of RTOFS while RTOFS is not available. ADCIRC 2001 Tidal Database is used to generate GoMOFS tidal open boundary forcing. Additionally, USGS Real-time river discharge observations from 7 major river gauges are provided to drive the model.

The GoMOFS orthogonal grid has 1132 x 777 horizontal points with roughly 700m as resolution. The vertical grid follows the terrain and consists of 30 model levels. The bathymetry of the Gulf of Maine is indicated on your left, and it is populated from the best available data, which include NOS sounding data, NGDC and NGS shoreline data, and USGS topography gridded product. Note that the water depth along the southern boundary can reach up to 4,000m.

GoMOFS runs on NOAA's High Performance Computer Systems (HPCS), the Weather Climate Operational Supercomputer System (WCOSS) under the NOS shared standard Coastal Ocean Modeling Framework (COMF) developed by CO-OPS. As a result, GoMOFS has direct access to NWS operational meteorological products and real-time observations that are required to run GoMOFS reliably. GoMOFS runs four times (00z, 06z, 12z, and 18z UTC) per day with 6-hour nowcasts and 72-hour forecasts for each cycle.

The GoMOFS graphics archive is located at: ftp://tidepool.nos.noaa.gov/pub/outgoing/ofs/gomofs/graphics/

GoMOFS output is in NetCDF format and available for selected locations (stations) and whole model domain (fields). The station output is named as nos.gomofs.stations.{nowcast|forecast}. YYYYMMDD.tCCz.nc where nowcast/forecast denotes either the nowcast or forecast results; YYYYMMDD is the date of the model run, tCCz is the cycle of the day. The 3-D field output is written every 3 hours and named as nos.gomofs.fields.nNNN.YYYYMMDD.tCCz.nc for nowcast and nos.wcofs.fields.fFFF.YYYYMMDD.tCCz.nc for forecast, where NNN and FFF is the record number in nowcast and forecast, respectively. An archive of WCOFS NetCDF nowcast and forecast files can be accessed from CO-OPS THREDDS server.

All CO-OPS official real-time products, including nowcast and forecast guidance from GoMOFS are monitored by the CO-OPS's Continuous Operational Real-Time Monitoring System (CORMS). CORMS provides 24 hour per day, 7 days per week monitoring and quality control of sensors and data in order to ensure the availability, accuracy, and quality of tide, water level, current, and other marine environmental information. CORMS is intended to identify invalid and erroneous data and information before application of the data by real-time and near real-time users.