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This nowCOAST™ time-enabled map service provides maps of NOAA/NOS' latest forecast guidance on the probability of occurrence of Vibrio vulnificus (Vv), a marine pathogen which can cause illness and hospitalization. The forecast guidance is issued once per day for Chesapeake Bay and includes predictions for the present day (Day 1) and the next day (Day 2). The Day 1 forecast guidance is based on a daily average of temperature and salinity to remove tidal effects and diurnal changes and is valid around 06 UTC (2:00 AM EDT) of the present day and the Day 2 guidance is valid centered at 06 UTC for the next day. A color scale from dark blue to yellow is used to depict the probability of occurrence from 0 to 100% at 2% increments. For more detailed information about layer update frequency and timing, please reference the nowCOAST™ Dataset Update Schedule.
The probability of occurrence forecast guidance for Vv is generated by the model of Jacobs et al., 2014. The model predicts the probability of Vv occurrence based on nowcasts and forecast guidance of water temperature and salinity from the 0000 UTC forecast cycle of the NOS Chesapeake Bay Operational Forecast System (CBOFS). The CBOFS temperature and salinity predictions are averaged over a 24-hour period and over the top 1 meter to provide averages centered around 0600 UTC. This is accomplished by using the hourly nowcasts valid from 1900 UTC to 2300 UTC from the previous day and the hourly forecast guidance valid at forecast projections 0- to 18-hr (i.e. valid for hours 0000 to 1800 UTC) of the present day. These 24-hour averages of temperature and salinity for the present day are then used by the Vv model to generate the Day 1 predictions. CBOFS' hourly guidance for forecast projections 19- to 42-hr are used to calculate average temperatures and salinities centered at the 30-hr forecast projection. These averages are used by the Vv model to generate its Day 2 predictions. Due to a bias in CBOFS' salinity predictions, the salinity predictions are automatically corrected based on near-real-time observations from several buoys in the bay before the predictions are used by the Vv model.
The Vv pathogen model was developed and evaluated by NOAA/NOS National Centers for Coastal Ocean Science (NCCOS). The model was implemented operationally and made available on nowCOAST™ through a collaborative effort between NCCOS, NWS/NCEP Ocean Prediction Center, NOS/Center for Operational Oceanographic Products and Services (CO-OPS), and NOS/Coast Survey Development Laboratory (CSDL). The Vv pathogen model became operational at CO-OPS in April 2018. The model runs on CO-OPS servers and CBOFS runs on the NOAA Weather and Climate Operational Supercomputer System (WCOSS) operated by NCEP Central Operations (NCO).
This map service is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.
In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.
This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.
This service is configured with time coverage support, meaning that the service will always return the most relevant available data, if any, to the specified time value. For example, if the service contains data valid today at 12:00 and 12:10 UTC, but a map request specifies a time value of today at 12:07 UTC, the data valid at 12:10 UTC will be returned to the user. This behavior allows more flexibility for users, especially when displaying multiple time-enabled layers together despite slight differences in temporal resolution or update frequency.
When interacting with this time-enabled service, only a single instantaneous time value should be specified in each request. If instead a time range is specified in a request (i.e. separate start time and end time values are given), the data returned may be different than what was intended.
Care must be taken to ensure the time value specified in each request falls within the current time coverage of the service. Because this service is frequently updated as new data becomes available, the user must periodically determine the service's time extent. However, due to software limitations, the time extent of the service and map layers as advertised by ArcGIS Server does not always provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time extent of the service: