The Wind Data frame provides access to create and edit wind series (WSER.INP). The wind sheltering coefficient can be assigned using the Sheltering button and/or edited in ViewPlan. If more than one wind series is being used it is necessary to distribute the wind field assignments. This is done using the Series Weighting function described below.

Wind Series

EE has the ability to add multiple wind, atmospheric and ice stations. Stations may be defined and edited with the Edit button shown in Figure 1.  The user may also set a number of wind drag options from the Drag Options dropdown box, including Original, Original Relative U/V, Hersbach 2011 (ECMW), and COARE3.6 Simplified.   The Original Relative U/V option computes wind drag using the original EFDC wind drag approach but takes into account the surface water velocities.  The other two show the technical reference for their respective approaches.

Figure 1  Hydrodynamics Tab: General.

The user may set the coordinates of the wind series with the Show Params button in the Wind BC Time Series Editing as shown in Figure 2. EE will use the X, Y coordinates in the value column for display purposes. If the user has not entered the X, Y values then EE will automatically calculate X,Y coordinates based on the lat/long values provided. However, if both are entered it should be noted that EE will use the X, Y coordinates.

Figure 2  Wind Data Series: Station Coordinate Setting.

Series Weighting

EE and EFDC+ have been updated to provide a more flexible station weighting methodology for map files when handling multiple the atmospheric series, wind series and ice series. Each of these time series has a corresponding map files when there are multiple series. In EE8.1 a change was made to the EFDC input file for these map files so that station weighting would be handled in EFDC. While the overall approach provided users with a simpler methodology, having the station weighting calculated by EFDC removed the level of use control, and made support of legacy models more difficult. For this reason, the calculation of the station weighting is now handled by EE and the input files for EFDC  have reverted to the previous format as described below. 

The approach that was adopted from EE8 onward is to provide users with a simple tool for managing the data and stations for wind, ice and atmospheric data. This approach allows EE to display the stations in a grid format with a quality index that indicates how the user rates each time series and time block within that series.

An example of a model domain with three wind stations is shown in Figure 3. This example has three stations WSER_1, WSER_2 and WSER_3. These have a total of of five time series for wind as shown in Figure 4.

Figure 3   Wind stations and time series.

Figure 4   Wind Map: Default quality indexes for wind stations and time series.

In Figure 4. the default quality indexes have been set by EE after selecting the Generate by Time Series Data button. EE automatically generates the quality index with the maximum value of one for the defaults, which is 1.  The user now needs to provide each time series with a quality index from 0 to 1. This weighting is based on users judgment of the quality of this data series based on various factors. If the user knows of no problems with the series then they would give it a rating of 1. However, often various factors which will influence the quality of a time series and cause the user to downgrade the series such as the distance from the model domain, or an intervening geographical feature. In this case a lower value for the quality index will be selected, and if another times series is available for that period with a higher weighting it will have a greater impact on the model. 

Each time series can be separated into many parts to set different quality/influence levels if necessary.  EE will use the values provided in the Wind Map Spatial Rating table to generate the WNDMAP.INP file, an example of which is provided in the appendix. This file contains the calendar interval (Julian day) for which the following map is valid, and then the on each row is  I, J, and weighting for each  time series. This makes the format similar to EFDC GVC WNDMAP.INP file, however it should be noted that GVC has certain requirements for this header files (six comment lines only). In a similar way, atmospheric series (ASER.INP), and ice series (ISER.INP) have map files which are ATMMAP.INP and ICEMAP.INP respectively.

The weighting map that EE generates is calculated based on the inverse squared distances from the cells to the stations and the qualitative coefficients for each time series. It includes the number of maps and the corresponding blocks of weighting coefficients. The first row of each block is beginning time, ending time and the qualitative coefficients. The remaining part of the block is the map of true weighting coefficients, including LA-1 data rows (L=2, LA). The true weighting coefficients are calculated as follows:

Where

N is the total number of time series (N  the number of stations),

N=NASER for ASER.INP; N=NWSER for WSER.INP N=NISER for ISER.INP

XS(n), YS(n)    UTM coordinates of one station to get time series,

XC(L), YC(L)    UTM coordinates of the cell L.

L = index of cell,

α_n is qualitative coefficient of each time series

EFDC then reads the true weighting coefficients from the map file to calculate the averaged value V(L) of each cell for every time step by:

Wind Rose Plotting

A wind rose plotting function is now available within the Data series editing forms for winds. The winds data series form may be accessed in the Domain | Boundary Conditions | Number of Input Table and Series form and pressing the E button, or from Hydrodynamics tab | Wind data | Edit. Selecting the Wind Rose button shown in Figure 6 prompts the user the start and end time for the rose data set to be displayed. After entering these data wind rose is displayed as shown in Figure 7.

Figure 6  Boundary Conditions: Rose Plots for Winds.

Figure 7  Example of a Wind Rose Plot.

A number of export functions are provided including metafile, bitmap and ASCII. The user user can also customize the rose format by RMC on the rose or selecting Format | Scale in the menu as shown in Figure 8.

Other options in the Format dropdown include editing the wind rose labels and setting the number of sectors. When setting the sector options the user can select the number of sectors, the number of degrees for the gap between sections and switch on and off the outline of the sectors.

Figure 8  Rose Plot Category Options.