Edit and Weighting Wind Series

EE supports to add multiple wind series and provides a flexible station weighting methodology for map files ( as shown in Figure 1).

Figure 1. Edit and Weighting Wind Series.

The time series may be defined and edited with the Edit button ( Figure 1) . Figure 2 shows the wind data series. The user may add new, copy or delete time series. The coordinates of the wind station is presented in Parameters tab as shown in Figure 2. EE will use the X and Y coordinates in the value column for display purposes. If the user has not entered the X and Y values, then EE will automatically calculate X and Y coordinates based on the lat/long values provided. However, if both are entered, it should be noted that EE will use the X and Y coordinates.

Figure 2. Wind Data Series.

Figure 3 show the station weighting handled by EE.  The function provides users with a simple tool for managing the multiple time series 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.

Figure 3. Set Wind Map Spatial Weighting.

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 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. If another time 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 these 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 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 the 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: the total number of time series (N the number of stations) where MASER represents in ASER.INP, WSER.INP, and 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 a cell,

α_n: 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: