Run an OMS Model

In the Create a New Model section, a model with two potential evapotranspiration (PET) components was created. The PET equations used were the Hamon equation and a modified Jensen-Haise equation. These two equations are shown below. Each has a coefficient, the hamon_coef and the jh_coef, that will be used in the Analyze Model Results section to adjust the computed PET for these equations.

The Hamon PET is computed as a function of daily mean air temperature and possible hours of sunshine (Hamon, 1961)using the equation:

   potet_hamon = hamon_coef * radpl_sunhrs2 * vdsat

where:

• hamon_coef is the monthly air temperature coefficient used in Hamon PET computations,

• radpl_sunhrs is the hours of daylight for each day, in units of 12 hours, and

• vdsat is the saturated water-vapor density (absolute humidity) at the daily mean air temperature (deg C) in grams per cubic meter (g/m3).

The modified Jensen-Haise PET is computed as a function of mean daily air temperature and daily solar radiation using the equation:

potet_jh = jh_coef * (tavgf - jh_coef_hru) * rin

where

jh_coef is the monthly air temperature coefficient used in Jensen-Haise PET computations,

jh_coef_hru is the air temperature coefficient used in Jensen-Haise PET computations for each HRU,

rin is the daily solar radiation expressed in inches of evaporation potential, and

tavgf is the average HRU temperature, in deg F.

To begin the model run process, select the model OmsEtCompare.jma in the Projects window and double click with the left mouse button on the model name or icon. This will open an OmsEtCompare.jma window showing the model structure and its components in the center of the OMS interface. Click on the model name, OmsEtCompare in this middle panel with the left mouse button.

In the lower right side of the OMS interface the OmsEtCompare - Properties window is displayed. CCThe Executor option in this window has three possible choices. Open the selection options by clicking on the down arrow on the right side of the selection field. The choices are

• Batch - Run the model in a batch mode.
• Internal -In Run the model within OMS graphical user interface.
• External - Run the model external to the OMS graphical user interface

Select Internal by clicking on it with the left mouse button.

Next, move to the OMS toobar and click on the Run icon (in red) with the left mouse button.

This will open a second tab with the mode name OmsEtCompare. Displayed in this tab are a number of Run features that will be described below

The Data tab in this window is currently selected. This tab provides access to model data and parameter values. To use these tools a parameter file needs to be loaded. On the left side of toolbar in this tab is the load parameter file icon (in red). Moving your cursor over the down arrow selector brings a list of the available parameter files in the project's Data Files directory. There is currently only one parameter file in the Data File directory and its name with its path C:\omswork\OmsEtTutorial\data\efcarson.pps is displayed. Click on the name with the left mouse button to load this file. The parameter file is for the East Fork Carson River watershed in northeastern California. The basin has been delineated into 23 HRUs.

One feature of the Data tab is a search tool to view selected elements of the parameter file. The search tool has several filters that can be used to find variables and parameters of interest. Click on the down arrow to the right of the term Name Filter to see the filter options. They are

• Name Filter - Searches on the variable and parameter names
• Unit Filter - Searches on the unit of measure (ie mm, m, inch, gm, etc) assigned to the variable or parameter
• Type Filter - Searches on the variable or parameter type (ie double, array, integer, etc)
• Dimension Filter - Searches on the dimension used to define array variables and parameters (ie nmonth, nhru, etc)
• Role Filter - Searches on ?
• Component Filter - Searches the variables and parametes by component name
  

The variable or parameter name being searched for is typed into the Name Search field below the Filter options. A complete name or a partial name can be used in the search, depending on the Options selection made. A number of options are available to limit the search algorithm. These are listed under the Options heading and are

• Exact match - Must exactly match the name.
• Matches name at start - Must match one or more characters of the start of the name.
• Matches name at end - Must match one or more characters of th end of the name.
• Is part of name - Must match a character string of one or more characters anywhere in the name
• Is regex to match name - ??

One additional option in the name search is to make the search Case Sensitive so that capitalized and lower case characters must be matched. This is selected by checking the Case sensitive box.

To demonstrate the search function we will search for the Hamon and Jensen-Haise model coefficients (hamon_coef and jh_coef). Select Name Filter from the Filter option list. A common character string in both parameter names is "coef". Type coef in the Name Search field. Because this string occurs at the end of the name, we select Matches name at end or Is part of the name to find these parameters. Select Is part of the name. The list of parameters that was found with this match include the two parameters we are looking for plus on additional parameter jh_coef_hru. From this search we know that there are only three parameters with the string coef in their name. Had we selected Matches name at end we would have found only the two we were looking for. However, for demonstration purposes, we chose this option to show some additional features. To obtain the view below you may have to expand the window by dragging the sides to expand the size of the window.

To the right of the parameter names is a value field for each that shows the values of each. The parameters hamon_coef and jh_coef are parameters that are defined by month and so are an array of 12 values. The parameter jh_coef_hru is a parameter that is defined for each HRU and so it is an array of 23 values for this basin. Viewing these parameters is a bit cumbersome in this form. However, the values can also be viewed in a spreadsheet form. Select the two parameters hamon_coef and jh_coef by holding down the control key on the keyboard and selecting each parameter with the left mouse button. When these are selected, the Toggle View button (in red) will be highlighted. Click on the Toggle View button with the left mouse button.

This changes the view of the parameters to a spreadsheet view. You can see the 12 monthly values of each parameter. To the right of the Toggle View button are a Select Column and a Select Row button that enables you to select all values in a single column or row respectively. To the right of that is an input field that enables you to change selected values in the spreadsheet.

Place your cursor on the May (5) value of the hamon_coef. Hold the left mouse button down and drag down to September (9) value of the parameter. This will highlight the selected values in the spread sheet. Then type .01 in the input field on the toolbar and hit enter on the keyboard.

The selected parameter values in the spreadsheet now have the value of 0.01.

To return to the original search view you can click on the Toggle View button (in red).

Note that when you return to the search view, the Value field has same values as the modified spreadsheet.

Once all parameter values of interest to the user have been modified, you can save this parameter file by selecting the Save Parameters button (in red). A new window will open and you can enter the name of the new parameter file. The file will be saved in the Data Files directory.

When the parameter file is set to the user preferences, the model can be run using this parameter file by clicking on the green Start/Resume Model Execution button (in red). Click on this with the left mouse button.

As the model executes, a progress bar at the bottom of the tab shows the progress of the execution. When the bar is green across its entire length, the model run is complete.

After model execution, one would like to view the model results. The particular model variables available at the end of the model run are currently a function of the output variables defined in the output component of the model. Clicking on the Output tab of the OmsEtCompare window shows the output file name of the current run and also shows the file names of previous runs made with this model. Note that they are number in sequence. The current run, 054, can be expanded to see which variables have been output. Click on the + symbol to the left of efcarson.csv and then click on the + symbol to the left of efcarson to view the names of the variables in this file. These output variables are available for viewing graphically and in spreadsheet form. The methods available to view these variables is subject of the next section of the tutorial.

The Model tab in the OmsEtCompare window provides a breakPoint selection on the components of the model. Selecting a breakpoint for one or more components causes the model to stop after the component has been executed. The model can then be step forward by clicking the Start/Resume Model Execution button. Variables of interest can be selected using the variable and parameter search option described above. The values of the selected variables and parameters will be displayed each time the execution stops at the breakPoint. This is one method available for component and the use of this feature will be described in more detail in another tutorial.