Example Scenario with Manual Setup

Sample Files

This example will use the following files. These files were all obtained through the GNOME Data Server GOODS at http://gnome.orr.noaa.gov/goods

Incident

On May 10, 2017 at approximately 3 PM, a platform west of the Mississippi River Delta at:

29° 6.5’ N, 89° 40.1’ W

experienced a crude oil discharge from a production pipeline. Pipeline pressure at the time was 70 psi. The maximum potential for this leak is 460 barrels of LA medium crude oil. Sheen was observed and the pipeline was shut in. USCG is requesting a 48-hour fate and trajectory analysis.

Get Started

Since we’re starting from scratch in this example, we’ll begin in WebGNOME’s “Setup View”. If you are on the WebGNOME landing page click on “Manual Setup”. If you have already started WebGNOME, you can select Manual Setup from the “New” pull down menu on the menubar.

Once you are in Setup View, you will see a number of panels which are used to interact with various model components. For example, these panels can be used to change basic model parameters (the model start time or run duration within the “Model Settings” panel) or to load or create movers (e.g. the “Wind” and “Current” panels).

Begin by entering data in the Model Settings panel. You can give the incident a name and set the model start time and duration. Leave the “Include uncertainy in particle transport” box unchecked for now.

Load a Map

Next, create a map in WebGNOME. The default map is an “infinite ocean” - a water world. This is useful for idealized scenarios or cases where you only want to consider oil weathering. But in most cases, you’ll upload shoreline data to create a map.

On the Map panel, click on the + sign on the upper right hand corner to add a map. (WebGNOME only supports the use of one map at a time, so adding a map will replace the current map.) Navigate to your saved sample file or drag it onto the form to create a map.

Add Wind Data and Current Data

The wind file provided is a NOAA marine point forecast. This is loaded as a “Point Wind” in WebGNOME (“Gridded Wind” is used for loading model wind products in NetCDF format). In the Point Wind panel, clicking on the + sign will allow you to upload the wind data. You’ll see various options that are available, e.g. manually entering data or automatically retrieving the most recent NWS forecast. But in this case, use the provided sample file by choosing Upload File.

Follow the same procedure to add the current data, in this case choose Load NetCDF Surface Currents from the form. It may take a little longer to load the currents as it is a much bigger file.

WebGNOME allows you to upload or create multiple wind and current movers. This is handy if you have more than one data source for a region and you want to see how they differ. Each mover will appear in a list at the bottom of the panel. In this case, you should only have one wind and one current in your list.

Add Horizontal Mixing (Diffusion)

Small scale turbulent wind and currents act to spread oil on the water surface and result in an increasingly patchy oil distribution. To simulate this, the model uses a random walk based on a specified diffusion coefficient. To create a horizontal diffusion mover in WebGNOME, click the + icon on the Horizontal Diffusion panel. The default value is 100,000 cm2s-1

Add the Spill

To add the spill, once again you will click on the + icon, this time in the spill panel. Assume the spill happened very quickly (in less than an hour) and choose “Instantaneous Spill”. If you set the model start time earlier, the spill should already be initialized to the correct time. If not, you can set it here, and when you hit Save, you’ll automatically be prompted to change the model start time to match. Enter the amount released and the spill location. For now, leave the substance as non-weathering (we will consider transport only for this example).

Run the Model

Once everything is setup, it’s time to run the model. To switch to Map View, select Map View under Views or use the globe icon on the upper right of the menu bar. Use the controls on the upper left part of the map to play, pause, rewind, or step through the model. The icons on the upper right of the menu bar can be used to switch back to the Setup View, or go to Fate View (note, since the scenario used a non-weathering substance, output in Fate View will be unavailable).

Explore

There are many other WebGNOME features to explore. For instance:

  • Use the Layers menu on the right hand side of Map View to change background imagery.

  • Use the Layers menu on the right hand side of Map View to visualize currents (you’ll need to rerun the model)

  • Export the output as a KMZ for Google Earth or shapefile for GIS applications

  • Change the substance from non-weathering to an oil from the ADIOS oil database and explore Fate View – note, you’ll also need to add data in the Water panel to compute weathering