The Grid tab provides the options by which the user may set the vertical layering system as well as modify the horizontal grid , set masks, and also set the model position at its center as shown in Figure 1. The Sigma Zed (SGZ) vertical layering option is implemented with EFDC+ alongside the previous option of Standard Sigma grid (SIG). A dropdown option for the Water Layers is provided and each option the options described below.
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Figure 1 Domain Tab: Grid
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The Standard Sigma option for Water Layers is the previous option provided in all versions of EFDC_DSIEFDCPlus. When this is selected the SGZ options are not displayed.
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Care should be exercised in using channel modifiers as model instability is sometimes increased and mass balance errors can occur.
Model Position at Center
Latitude and longitude settings the center of model are accessed in Domain | Grid | Model Position at Centre as shown in Figure 1 above. These settings are required for EFDC+ to calculate solar radiation as well as mapping features in EE. The user should select the Modify button to update these values. If the user has not entered a UTM zone for the model the default will be UTM zone 10 and the Northing and Easting will be set to the model centroid. EE reads the UTM zone from C91 (netCDF settings) in the EFDC.INP and updates to the latitude and longitude are stored in C46C (atmospheric location and wind function coefficients). Northing and Easting values are calculated based on the UTM and lat/long values.