The following input data are required:
observations - array of weather observations. An observation consists of:
	timeMeasured - timestamp for observation
	elementMeasurementTypeId - Code for parameter
	logIntervalId: 1 for hour value
	value: the observed value
Four different weather parameters should be provided:
* TM - Mean temperature (Deg. Celcius)
* RR - Aggregated rainfall (Millimeters)
* UM - Relative humidity
* Q0 - Global radiation (Wh/m2)
* BT - Leaf wetness
They should all be hourly values, they should all be complete hourly series in the exact same period. 
Minimum period length is 4 days 
The following input data are optional:
calculationStart - the time when calculation should start
calculationEnd - the time whe calculation should end