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Extracting data for an area from a grid time series (available since build 18645)
It For certain types of data it is possible to extract time series data for a specific part of a grid and show this in a separate graph. This is only possible for scalar data with dimension L3/T, L3, L/T, L or 'amount of substance' and for horizontal flow data with dimension L3/T or L/T. The specific part of the grid is defined by drawing an area sketch (a closed polygon surrounding the desired area). Start drawing an area sketch either by right clicking and selecting 'Start Drawing Area' from the pop-up menu or by Shift+left clicking on an edge for the desired area. A coloured dot will be drawn to indicate the selected point. Add additional line segments along the edge of the desired area by left clicking in the display. Finish drawing by double-clicking. The last point in the sketch will be connected to the first point automatically to create a closed polygon that surrounds the desired area. Each grid cell inside the area is marked with a green dot.
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- For dimensions L3/T (e.g. flow in m3/s), L3 (e.g. volume in m3) and 'amount of substance' the calculation will be 'volume summation'. This calculates the sum of the values inside the area. This uses all grid cells that are (partially) inside the area. The value of each grid cell is weighted using the fraction of the grid cell that is inside the area.
- For dimensions L/T (e.g. velocity in m/s) and L (e.g. water level in m) the calculation will be 'area times average level'. This calculates the average level inside the area multiplied by the size of the area. This uses all grid cells that are (partially) inside the area. The value of each grid cell is weighted using the fraction of the grid cell that is inside the area.
- If the selected data has another dimension, or no dimension, is configured for the selected data, then the options 'Start Drawing Area' and 'Calculate Budget' are not available.
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- For dimension L3/T (e.g. flow in m3/s) the calculation will be 'mass balance horizontal flux'. This calculates the net horizontal flow into/out of the area. This uses all grid cells that are for at least 50% inside the area.
- For dimension L/T (e.g. velocity in m/s) the calculation will be 'mass balance horizontal velocity'. This multiplies First for each grid cell the value for of u, respectively v, with is multiplied by the height of the gridcell, respectively the width of the grid cell, to get flow values (The height of the flowing water mass is taken to be 1). Then the net horizontal flow into/out of the area is calculated. This uses all grid cells that are for at least 50% inside the area.
- If the selected data has another dimension, or no dimension, is configured for the selected data, then the options 'Start Drawing Area' and 'Calculate Budget' are not available.
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