## Automatic Derivative Calculation

The Clidata system introduces user-defined automatic calculation of many derived elements from daily measured values. The derivatives system adopts a simplistic, user-friendly approach, such that the user defines only what he/she wants to calculate and the Clidata system carries out the calculations automatically without interaction. The definition of the formulas used for the calculation is very flexible, and the user is able to define very complex calculations.

**The system is able to calculate:**

- Hourly values – the definition of the general formula related to a time during a day. For example, the calculation of relative humidity from the temperature, wet bulb temperature, pressure and wind speed, or the calculation of the absolute difference between two consecutive observation of the same element.
- Daily aggregated values – the definition of the general formula for daily maximum, minimum, sum or average.
- Monthly/Yearly values – definition of the calculation, not only for the month and year, but also for the 1-3 decade or 1-6 pentade of the month. You can calculate the maximum, minimum, sum or average for these time periods. Alternatively, you can calculate the number of days which satisfy certain conditions over a period (e.g. the number of "summer days", where temperature for a "summer day" is above 25 °C).
- Normals – definition of the long term calculation of the normal values; calculated for each month and for the year.
- Extreme values – user-defined calculation of the long term minima, maxima and averages.
- Value interpolation – for the data measured regularly during a day the system can automatically infill missed values from those neighbouring by the interpolation process.
- Days with phenomenon – the system automatically calculates the number of days in month and year in which the specific phenomenon has been observed. From this, the system also calculates (for long term period) the normal number of days for each of the months and for the year.