The Synthesise Hourly Data... dialog is invoked using the Edit Hourly Data... button in the Hourly Data panel. This dialog allows you to interactively edit individual hourly values for all the different weather parameters as well as synthesise data using either daily or monthly averages.
Editing or Data Synthesis
The operation of this dialog is governed by the button located in the top-right corner. As shown in the animation immediately below, this button allows you to choose between editing the daily data or editing monthly averages from which synthetic weather data will be generated.
Editing Daily Data
This is the default mode and allows you to edit the individual hourly values for the different weather parameters. You can use the slider running along the top of the dialog to select the day of the year to edit. As you drag this slider (or use the mouse wheel when it has the focus), both the graph and the data grid will update. This allows you to visually detect spurious values within the data or recognise the exact conditions you wish to change.
Monthly Averages
When you select this mode, the slider at the top of the dialog is replaced by a series of 12 buttons representing the months of the year. Each month is displayed in the graph and data grid as hourly values averaged over each day in that month. You can then edit these values based on monthly data you obtain from the internet or other climate sources.
Once you have edited the values as you require and clicked the Synthesise Data button, Weather Tool will generate synthetic data for each of the parameters selected in the Affect Only check boxes. This is done by interpolating between each monthly dataset, using the day representing the middle of each month as the reference. This means that days either side of this middle day will gradually transition towards the values set for the adjacent months.
Obtain Data
This group of controls allows you to generate daily values based on the min, max or average of a range of days. You can select the start and end date of the averaging period directly, or use the small menu button to select a standard period. Choosing the Copy to Graph » button will replace values in the graph and data grid with the generated vakues.
Apply Data
This control group determines both the range of days in the year that the synthetically generated values will be applied to and which weather parameters will be affected.
Date Range
You can set the start and end range of period directly using the day and month selectors, or click the small menu button and select from a range of standard periods. For example, you may have 6 weeks of data missing from what is otherwise a good weather file - hence you only want to fill in the missing range with synthetic data. Alternatively, you may want to make only a single much colder to simulate a worst-case design condition.
Interpolate Days
Check this box if you want to smootly interpolate between each monthly values. This creates gradual changes between day of the year with the edited values applied directly to the middle day in each month and all other days interpolated pro-rata between adjacent months. Unchecking this box makes each day in the month exactly the same with large steps between the end of one month and the start of the next.
Affect Only
You can use these items to select only the weather parameters you want the data synthesis to be applied to. For example, you may be missing only relative humidity data and therefore would uncheck all other items.
Synthesis Data
Use this button to actually generate and apply the new synthetic data.
Clear Sky Radiation
Use this button to replace all your current solar radiation values with those for an idealised clear-sky for the current latitude/longitude. This effectively assumes no cloud at all throughout the year, with direct beam and diffuse radiation levels generated accordingly.
Min, Max, Avg - Rescale
These controls are located between the graph and the data grid. They represent the daily minimum, maximum and average values for the currently selected weather parameter calculated over the current day. If you have daily min, max and/or average values from an external source, you can modify the current data set by changing any of these three values and clicking the Rescale button. This will retain the overall shape of the daily data curve, but modify it such that it results in the new extent.