Increase the data variation range

Hi All,

I have time series of water level data. The data is tidal data and it has a variation like a sinusoidal curve. What I want to do is I want to increase the variation of the time series. I want a program or code to find out the maximum of the sinusoidal curve and then increase the values. I want to increase the peak in both negative and positive. I don’t know how to do that in excel . Would somebody give me some tips on how to proceed ?

The attached figure shows the time series of two sets of data. One is current and another is new . I want the increase the variation of new data in both higher and lower direction by 0.2. HOw do I do this ?

Thanks

JD