Very cold days percent wrt 10th percentile of reference period
ecatx10p.RdLet infile1 be a time series of the daily maximum temperature TX, and infile2 be the 10th percentile TXn10 of daily maximum temperatures for any period used as reference. Then the percentage of time where TX < TXn10. is calculated. TXn10 is calculated as the 10th percentile of daily maximum temperatures of a five day window centred on each calendar day of a given climate reference period. Note that both TX and TXn10 have to be givenin the same units. The date information of a timestep in outfile is the date of the last contributing timestep in infile1.