I have time series data of maximum water level in cm on an hourly basis for a number of years 1961-2016. the data sets are categorized as observed set from water gauges and simulated data from some model. The observed data set has no missing value but there is a long range of data about 10 years having same negative value.(i dont know why? )should i consider it as NaN? I want to calculate the trend of these two uni variate time series? i also need to compare these two series? or one can say how well the simulated time series fit with observed time series?
i have converted my time series into timetable, then i compared them using cross correlation and Nash Sutcliffe coefficient.
tried to plot this data, as well. here is its plot. S1 is observed data plot, and S2 is Simulated data plot.
please guide me how can i find the trend of these series? observed data is attached for your convience. i am badly stuck after reading all helping texts in this regard?