Set Spatial Domain The domain selection process is one of the most critical steps in creating an OMEGA simulation. If the domain parameters are not set correctly the model will quickly produce errors and may stop altogether. When "Set Spatial Domain" is pressed two dialog boxes, Set Spatial Domain and Map Operations, will pop up and a world map will be displayed in the Drawing Area window. The dialog boxes are used to input spatial domain information which will then be displayed on the map. The Set Spatial Domain dialog box is the main control for the OMEGA domain. You will use it to define the horizontal regions of the domain and to define the vertical spacing of the model levels. The dialog has four sections: Current Region Controls, Region Parameters, Vertical Parameters, Ocean Parameters, and Action Buttons. How to use each section will be described, followed by exact specifications of each control's actions, valid data range, and default value. The data for each region is stored internally as a list of regions. The Current Region's information will be displayed in the Set Spatial Domain dialog. To view data from the other regions you must use the Current Region Controls. Current Region Controls When you use the cursor to enclose a region on the map, the numbers located at the top of the Set Spatial Domain dialog will increment. By clicking on the arrow buttons you may cycle through the regions. On the map the current region will be outlined by a thick rectangle. Any other regions you may have defined will be drawn with thin rectangles. You may delete any region by clicking on "Delete" (Note: there is NO confirmation process). Current Region - A dynamic label showing the current region and the total number of regions. The current region's values appear in the Region Parameters' text entry boxes and radio buttons. Left Arrow - Decrement the Current Region filling the Region Parameters' information and drawing the Current Region with a thick rectangle. Cyclic action going down: 1 <- 2 <- 3 <- 1 <- 2 ... Right Arrow - Increment the Current Region filling the Region Parameters' information and drawing the Current Region with a thick rectangle. Cyclic action going up: 1 -> 2 -> 3 -> 1 -> 2 ... Delete - Remove the Current Region and shift up any subsequent Regions. For example: four regions are defined, the current region is number 3, and Delete is clicked. Region 3 is removed from the list, and Region 4 becomes Region 3. Region Parameters The Region Parameters section displays several geographic values to help you in selecting the extent of your domain: bounding latitude and longitude coordinates, approximate size in kilometers, resolution range in kilometers, approximate number of grid cells, and the data set used for that region. Each region will be displayed on the map by a colored rectangle. The color is determined by the terrain data set chosen. Note that you must be sure the requested data set is available for the part of the world you are simulating. For example, if you want to model the middle of the ocean you may only use the 5 minute data set (white area on the map). If you want to model a continental interior you may use 30 second data (yellow panels on the map). If you want to model a coastal region, you may combine 5 minute and 30 second data. When making an OMEGA domain it is best to choose your outer most region with 5 minute data and then make smaller sub-regions with the 30 second data. These regions should be nested together, and should have resolution ranges that slightly overlap, so that the final grid will have a smooth transition from coarse to fine resolution. Note that no subsequent region may be drawn outside Region 1, so make sure the first region you draw encloses your entire intended domain. As an example, consider modeling the weather for the city of Washington DC. You might have four regions in the domain. The outer most region could be the Central Eastern part of the US using the 5 minute data set with a resolution range of 50-100km. Region 2 could be Maryland and Virginia using the 30 second data set with a resolution range of 35-55km. The next region, Region 3, may be the be the Chesapeake Bay using the 30 second data set with a resolution range of 10-36km. A final region would be the city itself with 30 second data set with a resolution range of 3-11km. The nested effect will give you a smooth grid with proper resolution gradient. The final grid will have about 1300 cells. NOTE: Becasue of United States export restrictions, your OMEGA System installations may not have 30 arcsecond data. Minimum Longitude - Western edge of Current Region. Negative values are west of the Prime Meridian. Valid Range: -180.00 to 180.00 Default Value: 0.00 Maximum Longitude - Eastern edge of Current Region. Negative values are west of the Prime Meridian. Valid Range: -180.00 to 180.00 Default Value: 0.00 East-West Size - Approximate size of the domain in kilometers. Minimum Latitude - Southern edge of Current Region. Negative values are south of the Equator. Valid Range: -90.00 to 90.00 Default Value: 0.00 Maximum Latitude - Northern edge of Current Region. Negative values are south of the Equator. Valid Range: -90.00 to 90.00 Default Value: 0.00 North-South Size - Approximate size of the domain in kilometers. Min. Resolution - Minimum acceptable resolution for Current Region in km. Valid Range: 1 to 200 km Default Value: 30 km Max. Resolution - Maximum acceptable resolution for Current Region in km. Valid Range: 1 to 200 km Default Value: 60 km Approximate Number of Cells - This value is computed based on the size of the largest region and the minimum resolution. The actual number of cells will depend on terrain and shore line details. Terrain Data Resolution - Radio button pair: only one button may be active. This button controls the terrain data source used to build the part of the grid defined by this region. Regions using 5 minute data will be drawn in black. Regions using 30 second data will be drawn in blue. Default Value: 5 minute Shoreline Data Resolution - Radio button pair: only one button may be active. This button controls the shoreline data source used to build the part of the grid defined by this region. Default Value: 5 minute Vertical Parameters The Vertical Parameters section allows you to change how many total levels to use in the model, and the base thickness of Level 1. From these numbers the total height of the domain is calculated and displayed on the dialog in kilometers. For most applications the default values should be used. Total Number of Levels in Domain - This is the total number of levels of the computational domain. Valid Range: 5 to 39 Default Value: 30 Level 1 Thickness - This is the thickness in meters of the first level. Valid Range: 5.0 to 250.0 meters Default Value: 30 Ocean Parameters Generate Ocean Topography - If this toggle is switched to On, then the gridgenerator will generate an ocean topogrpahy file for the omegamodel's built in ocean model. Action Buttons Clear Form - This button will reset the text entries to zeros, un-select terrain and shoreline data sets, and reset the Vertical Parameters to default values. It does not modify the Region Data in any way. The user must modify the values before continuing. Default - This button will reset all text entries and radio buttons to their default values. It does not modify the Region Data in any way. The user must modify the values before continuing. OK - This button will check the Region data, cause XOMEGA to write out a "grid.inp" file in the grid directory and close the dialog box. If any values are in error, a Set Spatial Domain Error dialog box will pop up alerting the user of the specific errors and suggestions on how to correct them. See below for information on the Error dialog box. No "grid.inp" file will be written if there are errors in the data. Cancel - This button will decline the Region data, remove all regions, reset the values to default, and close the dialog box. There is no confirmation process. Help - This button will open the Help dialog and load this section. Set Spatial Domain Error While entering values into the text entries if you make errors a dialog box will pop up alerting you of the errors and suggesting ways to correct them. The top part of the dialog box contains the error message and the suggestions. The bottom part has a row with three action buttons: Delete Current Region - This button will remove the Current Region from the list similar to Delete on the Set Spatial Domain dialog. Be sure that the Current Region is the one containing the error before clicking this button. Use the arrow buttons if needed to change to the Current Region. This button will dismiss the Error dialog. Modify Regions - This button will return control to the Set Spatial Domain dialog box and dismiss the Error dialog box. You may now modify the regions as usual. Set Refinement Dialog XOMEGA allows for an advanced feature call Point Refinement. To activate this feature you must use the Advanced menu and click on Set Refinement Disks, or use the Map Operations dialog and click on Refinement Disk. The cursor will now draw only circles. These circles represent regions of the domain whose resolution will be fixed to the specified value. The Grid Generator will make sure that the cells produced within the disk are of a fixed resolution. Selecting a refinement disk will enable you to have increased resolution about a specific point, without defining another region. This saves on I/O process time and allows you to pin-point a specific resolution instead of a range. The effect of point refinement is Gaussian in nature: cells produced close to the center point of the disk will be as close to the prescribed resolution as possible, while those farther out will vary in resolution to match the bounding region's resolution. The Valid Range for the resolution of a Refinement Disk is determined by the bounding Region. The resolution should be no smaller than 0.5 times the Minimum Resolution of the bounding region, and no greater than the Maximum Resolution of the bounding region. For example if you have defined a region with 10-20km resolution and want to put a refinement disk within this region, make sure the resolution of the disk is between 5-20km. This will ensure a smooth transition from the refinement disk to the bounding region. The Set Refinement Disks dialog has four sections: Current Disk Controls, Disk Parameters, and two rows of Action Buttons. Current Disk - A dynamic label showing the current disk and the total number of disks. The current disk's values appear in the Disk Parameters' text entry boxes. Left Arrow - Decrement the Current Disk filling the Disk Parameters' information and drawing the Current Disk in thick circle. Cyclic action going down: 1 <- 2 <- 3 <- 4 <- 1 ... Right Arrow - Increment the Current Disk filling the Disk Parameters' information and drawing the Current Disk in thick circle. Cyclic action going up: 1 -> 2 -> 3 -> 4 -> 1 ... Delete - Remove the Current Disk and shift up any subsequent Disks. Longitude - Longitude value of the Current Disk's center point. Valid Range: -180.00 to 180.00 Default Value: 0.00 Latitude - Latitude value of the Current Disk's center point. Valid Range: -90.00 to 90.00 Default Value: 0.00 Radius - The radius of the Current Disk in kilometers. Valid Range: 0.5 km to 100 km Default Value: 0.00 Resolution - The desired resolution for the Current Disk. Valid Range: See discussion above Default: 10.00 Clear Form - This button will reset the text entries to zeros. It does not modify the Disk Data in any way. The user must modify the values before continuing. Default - This button will reset all text entries and radio buttons to their default values. It does not modify the Region Data in any way. The user must modify the values before continuing. OK - This button will check the Disk data, cause XOMEGA to write out a "grid.ref" file in the grid directory and close the dialog box. If any values are in error, a Set Refinement Disk Error dialog box will pop up alerting the user of the specific errors and suggestions on how to correct them. No "refine.lst" file will be written if there are errors in the data. Cancel - This button will decline the Disk data, remove all disks, reset the values to default, and close the dialog box. There is no confirmation process. Help - This button will open the Help dialog and load this section. END Set Spatial Domain