Time Varying Fields

1. Introduction

This tutorial will provide step-by-step guidance on how to generate time and space wind forcing data for the Katrina hurricane (August 2005) in Florida Bay. DSI has developed a script to generate Wind Field and Pressure from storm track data as inputs of EFDC+ and then show wind field vector and pressure results in EE. Based on the format described below users can develop their own scripts. 

2. Data processing

To generate field files, we need to prepare a storm track record file. In this case, the storm track recorded for the Katrina hurricane (August 2005) is downloaded from the Weather Underground website (https://www.wunderground.com/hurricane/atlantic/2005/Major-Hurricane-Katrina).

Figure 1. Storm track data file format.

3. Generate field files

Recorded storm track data will be processed by a script to generate field files for EE. Normally, field files will be generated in a text file format (*fld.inp), but sometimes, the data size is very large. EE allows saving field files in binary format (*fld.fld) to save memory and read files faster. Examples of code to create the binary files are provided in Appendix B - Data format B-26.

Generated field files will have a format as shown in Figure 2 below. See  Appendix B - Data format B-26 for more details on the fields data format.

Figure 2. Field files format.

4. Import field files to EEMS

After field files are generated, the user can import them as input of EFDC+ in EE. From Model Control form, expand External Forcing Data tab, go to Time Varying Fields sub-tab. From Time Varying Fields menu, RMC on Pressure Field as shown in Figure 3 below.

Figure 3. Import field files to EEMS (1).

Time Variable Data Field: Air Pressure form open (Figure 4). From this form, click on Import button and browse to the pressure field file generated earlier to import pressure field data to EEMS, then click OK button to save settings.

Figure 4. Import field files to EEMS (2).

Carry out the same steps with Wind Velocity field file to import wind field to EEMS.

5. Visualize field files in EEMS

Once the field is generated, EFDC will use this field in place of the other forcings defined by the user to simulate. The user may review the forcing fields in 2DH View by selecting Forcing Fields from the 2DH View Option as shown in Figure 5 below.

Figure 5. 2DH View Option form.