Grid Manager Operations


Select Weather Element and TimeRange
Copy from Derived Model Grids
Interpolate Grids
Copy Grid
Paste Grid
Stretch a Grid's Valid Time Period
Create Grid from Scratch
Delete Grids
Split Grids
Fragment Grids
Assign Default Value
Run Smart Tools

Grid Manager Operations

This section of the training guide covers grid operations that are performed on the Grid Manager.

Select Weather Element and TimeRange

In this section we discuss how to populate your forecast by copying weather element grids based on model output and how to temporally interpolate, which fills in time gaps between grids. But first you need to know how to identify the weather element and time range over which these operations will be performed.
  1. Press and drag MB1 over any time period of your choice inside one of the weather element panes of the Grid Manager.
  2. Release MB1.
As you drag the mouse cursor you should see blue hatched shading appear inside the weather element pane. This is how you identify a time period and weather element to which you will later apply an edit operation. Later, you will encounter exercises that show you how this selected time period and weather element are used in Grid Manager edit operations.
You can also select a time period in a slightly different way using the Time Scale (located just above the Grid Manager). After selecting a time period in the Time Scale by dragging MB1, MB1 click in the small box located in the upper-left of each weather element pane. Note that the time period for that pane now becomes selected. Using this method, you can select the same time period for many different weather elements.

There is also a way to extend the currently selected TimeRange by performing a MB1-SHIFT click operation anywhere on the Grid Manager. Hold down the shift key while clicking MB1. The currently selected TimeRange will be extended to the time on which you SHIFT-clicked. If you SHIFT-MB1-click insider the currently selected TimeRange it will have no effect. This works for any WE pane or the TimeScale.

  1. Press and hold MB3 over the Grid Manager and pick Deselect All from the pop-up menu. Note that your previously selected Weather Elements/ Time Ranges are now deselected.
  2. Select another set of Weather Elements over any time period.
  3. Next, press the button Deselect all in the button bar to deselect. Note that you can deselect the set of Weather Elements from both the button bar and the pop-up menu.

Copy from Derived Model Grids

One of the GFESuite of programs derives surface-based weather elements from numerical models such as NAM. Since it would be too time consuming for forecasters to create all forecast grids from scratch, these derived model grids provide a starting point on which your gridded forecast is based. The next section shows you how to copy these model-based grids into your forecast.
Select a time period and one or more weather elements using the technique described in the previous exercise.
  1. Select from the main menu Bar: Populate->Copy Selected Grids From...
  2. Select one of the model sources listed in the dialog, such as NAM12.
  3. Select OK.
You should see new grids appear in your forecast. If not, make sure that you have selected a time period that matches at least a portion of the time period of the model you desire and repeat until new grids have been copied into your forecast. Click MB1 on one of the grids in the Grid Manager. The grid will appear in the Spatial Editor.

Note that there are some gaps in your forecast. Because models provide snapshots of the state of the atmosphere, for some weather elements, the system (arbitrarily) assigns a one-hour duration to most grids. However, this duration is model and weather element dependent. For example, a grid representing 6-hour QPF has a 6-hour time duration.

If you want to initialize your entire forecast from a particular model, you are not required to select every weather element for the entire time period of the model. The next exercise shows you how to copy all the grids derived from a model in to your forecast.
  1. From the main menu bar select Populate->Copy All Grids From...
  2. Select one of the model sources listed in the dialog.
  3. Select OK.
Note that Copy All Grids From... ignores the selected time range and the selected weather elements. All of the grids available from that model are copied into your forecast overwriting any grids that existed previously.

Interpolate Grids

Since copying grids from the model-based databases leaves temporal gaps in the forecast, the GFE provides you a way to fill in those gaps. This next exercise show you how to interpolate over a time period and weather element that you select.
  1. Select any time period and weather element that contains gaps in the forecast (except Wx).
  2. From the main menu bar, select Grids->Interpolate... The Interpolate Dialog is displayed. Choose "By Gaps" and click on OK.
You should see new grids that appear and fill in the gaps that you identified in step 1. If you visualize these grids in sequence by stepping through them using an MB1 click (or the animator), you will notice that the values at each grid point progressively change in time to provide a smooth transition from one original grid to the next.

Interpolating By Gaps uses all grids in the selected time range to calculate new grids to fill the gaps. The other method of interpolation uses only the grids that you modified to calculate the new grids and replaces any grids you did not modify with interpolated grids (grids that you have modified are identified in the grid block by an "m"). For example, if you edit two of three grids copied from a model, select these grids in the Grid manager and choose Grids->Interpolate... and then the "Based on Editing Data" from the Interpolation Dialog, new interpolated grids will fill the gaps, the unedited model grids will be replaced by interpolated grids, and the edited grids will remain unmodified.

The interpolation algorithm may be changed through the GFE->Editing Preferences->Interpolation Algorithm... menu entry.  This brings up the Interpolation Algorithm Dialog, from which the type of interpolation may be selected.

Copy Grid

Now and then it is useful to copy a grid from one time period to another. The next exercise shows you how to copy individual grids from one time to another.
The method described in this exercise allows you to copy any grid that is in the Grid Manager to any other weather element, provided that the destination weather element shares the same units (e.g., Temperature and Dew Point) or the units can be converted automatically.
  1. Make sure there is a weather element with at least one grid block and one gap visible.
  2. MB3 press over the grid you wish to copy and select from the pop-up menu Copy Grid.
  3. Now move your cursor to a gap in the same Weather Element. Press and hold down MB3 again, and this time select Paste Grid.
When you executed the Copy Grid operation, a copy of that grid was place in a paste buffer. Selecting Paste Grid over a gap or another grid replaces that gap or grid with the contents of the copy buffer.
Load T (temperature) and Td (dewpoint) into the GFE (if they are not already loaded). Repeat this exercise using one of the T grids as the source and Td as the destination. Note that you may copy a grid from one weather element to a different weather element as long as they both share the same units (in this case degrees F) or the units can be converted automatically.

Paste Grid

Now that you learned to copy a grid, you can paste the same grid into a gap or over an existing grid.
  1. Perform the Copy Grid exercise above, if you have not already done so.
  2. Move the cursor over to a gap in the same weather element.
  3. MB3 press and select Paste Grid.
Note the the grid that you copied in the previous exercise has now been pasted into a different time period.

Stretch a grid's valid time period

Some weather elements such as Wx, frequently change very little over long time periods. In this case, rather than repeating the same grid over and over, it is useful to define a single grid that is valid over the entire (longer) time period. This operation shows you how to extend the time period over which a grid is valid.
  1. Press and hold MB2 over a grid block that is adjacent to a gap.
  2. While holding down MB2, drag the cursor to the left or right until you see the grid block stretch.
  3. Release MB2
As you drag MB2 left and right, you should notice that you are extending the end time of the grid forward in time (right) or extending the start time backwards in time (left). There is no way to directly shrink a grid block in time. An indirect method is to Split the grid, and then delete the unneeded grid.
Repeat this exercise, but this time stretch the grid block so that it overlaps into one or more existing grid blocks. Once you release the mouse button, any grid blocks that overlapped the new grid block (or portions thereof) are removed from the inventory. This is one way to shorten the time over which a grid block is valid.

Create Grid from Scratch

Occasionally, you may want to create a new grid from scratch instead of copying one from a model, or another parameter, or by using interpolation. The Create From Scratch feature was made for this situation.
  1. Press and hold MB3 over a gap (a place with no grid block) within an editable weather element.
  2. Select Create From Scratch from the pop-up menu.
A new grid should appear over the gap block that you selected. This new grid has the minimum time period allowed for that weather element, but it can always be stretched or copied to a new time period. The default value of this grid varies by parameter, but is usually the minimum value allowed (e.g., temperature, value = -30F). Generally the next step is to define the values of the grid points using one of the Spatial Editor tools described in the Spatial Edit tools section.

Note that you can also create grids from scratch through the GFE Main Menu's Grid's entry.

Delete Grids

  1. Using MB1, select a time period for any weather element that contains some grid blocks.
  2. From the main menu bar select Grids->Delete Grids.
Note that the grids that you identified were removed from that weather element's inventory. Now try a variation on the previous exercise.
  1. Find a grid block and stretch it until its duration is many hours long.
  2. Select a time period that corresponds to a portion of that same time block using MB2,
  3. From the main menu bar select Grids->Delete Grids.
This time, since you only selected a portion of the grid block, only that portion was deleted. This is another way that you can shorten the time period over which a grid is valid.

Another technique can be used to delete a single grid.

  1. Find a grid block.
  2. MB3 popup over the grid block and select Delete Grid from the popup.

Split Grids


The Split operation is used to divide a single grid into two or three parts in time. The resulting parts may then be edited independently, providing more temporal detail to the forecast. This particular split operation is invoked from the GFE main menu by selecting
Grids->Split Grids. There is another Spilt Grids operation that can be executed from the MB3 Pop-up menu as well. See the section
Split Grids to learn how to split grids using the MB3 Pop-up option.
  1. Select a new time period over a single grid with such that only a portion of the grid is selected.
  2. From the main menu select Grids->Split Grids.
 
You should end up with something that looks like the figure to the right.
Note that the grid was severed at the edges of the selection. There are three separate grids now, each of which have gridded values identical to the original grid.

Fragment Grids

The Fragment Grids operation also splits grids into smaller temporal parts. But Fragment differs from Split in that it divides grids into their smallest possible time blocks.
  1. Find or make a long duration T (temperature) time block as in the previous exercise and select it using the MB1 drag operation. It should look something like this.
  2. From the main menu select Grids->Fragment Grids.
You should now see that over the time period that was selected, many smaller duration grids have replaced the long duration grid.  If you
select just a portion of the grid, only that portion will be fragmented. Each of the grids has the same gridded values as the original. The result should look something like this:

Another technique can be used to fragment a single grid from the MB3 Pop-up menu. See the section on the Grid Manager Button 3 Pop-up options for more information on how to Fragment grids using the MB3 Pop-up Menu.

Assign Pickup Value

Occasionally you might find it useful to set the gridded values of a group of grids to the pickup value, as if you were starting from scratch. The Assign Pickup Value function was made for this situation.
  1. Select one or more grids using the MB1 drag operation.
  2. From the main menu select Grids->Assign Pickup Value. Note that the menu doesn't actually say "Pickup Value". The actual pickup value is displayed instead of the words.
All of the gridded values of the grid that were selected now have the current pickup value, which is indicated in the color bar.
Note that the Assign Default Pickup operation is also available from the MB3 pop-up menu in the Grid Manager, but as with all MB3 pop-up menus the operation applies only to the grid under the cursor, not to the set of selected grids.

To quickly set the pickup value to a single grid, use this technique:

  1. Position the cursor over the grid block you wish to assign the pickup value to.
  2. MB3 popup over the grid block, and select Assign [x], where x is the pickup value.

Assign Default Value

Occasionally you might find it useful to set the gridded values of a group of grids to a single default value, as if you were starting from scratch. The Assign Default Value function was made for this situation.
  1. Select one or more grids using the MB1 drag operation.
  2. From the main menu select Grids->Assign Default Value.  Note that the menu doesn't actually say "Default Value". The actual default value is displayed instead of the words.
All of the gridded values of the grid that were selected now have the default value, which varies for each Weather Element. Generally, this value is the minimum allowed value for that Weather Element (e.g., Temperature = -60 F).
Note that the Assign Default Value operation is also available from the MB3 pop-up menu in the Grid Manager, but as with all MB3 pop-up menus the operation applies only to the grid under the cursor, not to the set of selected grids.

To quickly set the value of a single grid to the default value, use this technique:

  1. Position the cursor over the grid block you wish to assign the default value to.

    2. MB3 popup over the grid block, and select Assign [x], where x is the default value.

Run Smart Tools

A set of smart tools (specified via gfeConfig) may appear. The default set is "Show_ISC_Area", "Show_ISC_Grid" and "Show_ISC_Highlight". These tools are described in the Intersite Coordination Training Guide.