Functions and Summary.
The CRHM program has an extensive capability for examining functions of model input observations and output variables.
Timebases.
Select the operating time period for the function. Note that "Interval" is not applicable to functions.1) Interval - CRHM execution time step determined by the first observation file loaded. Varies from 15 minutes to 24 hours.
2) Daily - the value is calculated for the day.
3) Monthly - the value is calculated for the month.
4) Calendar Year - the value is calculated for the calendar year.
5) Water Year - the output is calculated over the water year defined by the month.
6) All - the value is calculated for the entire run length.
The timebase is set by the user using the "SELECTION BOX and DISPLAY" situated above the "Start Date" label on the main screen by LEFT clicking on the box.
If Water Year is choosen the starting month of the year is selected by RIGHT clicking on the box to cycle through the months of the year.The functions available are;
1) Average - mean value of the interval values over the timebase period.
2) Minimum - minimum value of the interval values over the timebase period.
3) Maximum - maximum value of the interval values over the timebase period.
4) Total - sum of the interval values over the specified timebase period.
5) Positive - sum of positive interval values over the timebase period.
6) First - first interval value of the timebase period.
7) Last - last interval value of the timebase period.
8) Count - the time (days) that the interval values are greater than zero over the specified timebase period.
9) Count0 - the time (days) that the interval values are equal to zero over the specified timebase period.
10) Delta - change over the timebase period. Calculated as (Last interval of the current timebase period - Last interval of the preceding timebase period). For the very first time period of a run, the First value of the first time period is used instead of the Last interval of the preceding timebase period as this value may not always be available.
Use "Close" to return to the main screen when finished.
Miscellaneous Interval Functions;
These interval functions are always available and are independent of the selected timebase period.2) VP_saturated - interval saturated vapour pressure calculated from the interval temperature value.
3) Watts to MJ/Int - unit conversion Watts to MJ/interval.
4) MJ/Int to Watts - unit conversion MJ/interval. to Watts.
Use "Close" to return to the main screen when finished.
Application to Observations.
1) To display an observation, select an observation and RIGHT CLICK on it to bring up the Add/AddArray/Function menu and select Add. The observation will be displayed on the graphic screen using the function displayed under the Observation listbox. By default this is "Observation" initially.
2) To change the function type, select any observation and RIGHT CLICK on it to bring up the Add/AddArray/Function menu and select "Function". Select the desired function from the pop-up menu. Alternatively, CLICK on the current function selected to sequentially step through the functions.
3) If an observation has multiple dimensions they may all be displayed at once by selecting AddArray. N.B. if OBS or LAY display is greater than 1, only the values from that array element to the last available will be displayed.
Application to Variables Selected ListBox.
The functions may also be applied to the CRHM model output Variables. The process is similar to that outlined above.2) Changing the function type is the same as for observations, Select any observation and RIGHT CLICK on it to bring up the Add/AddArray/Function menu and select Function. Select the desired function from the pop-up menu.
Display Mode.
The output displayed on the chart is set as follows,
a) "Display off" is used when the user is sending the output to the "Summary" file at the end of the run and does not wish the function values to be displayed on the screen during the run. This reduces reduces execution time and screen clutter. The tracees can be enabled at the end of the model run. The values will be written to the "Summary" file if selected (parameter "basin RUN_ID" > zero).
b) "Display Final Value" is used to display the end value of a timebase period over the entire timebase period. The values will be written to the "Summary" file if selected (parameter "basin RUN_ID" > zero).
c) "Display "Trend Value" is used to display the function values over a timebase period as they are processed.The values will be written to the "Summary" file if selected (parameter "basin RUN_ID" > zero).
Use "Close" to return to the main screen when finished.
Writing Summary to a file.
Functions derived from variables and observations are written to the summary file. However, basic variables and basic observations can be written to a file using the export capability.
The name of the summary file by default is "CRHM_summary.sum". However, if the project uses the module "basin" and the parameter "RUN_ID" is greater than zero, its value will be appended to the file name, e.g. "CRHM_summary_1.sum".
The summary file is only written at the end of running a project. However, the graphics screen is updated immediately when a function variable is added if the input data used is already available.
Different Displays of Daily Totals.
When displaying daily values they can be displayed on the actual day and some times with a 24 hour delay. This is normal as observation like t, RH, u, and Qsi are applied on that day. However, when CRHM is using daily simulations the variables such as runoff, soil moisture and melt are used as input to the next process on the following day.