Dear R experts and statisticians, 
    
I have some time series datasets, they are several years vegetation indices (about 50 data points per year) sampled from different station. These indices have similar dynamics with seasonal change.

My questions are, 
1) How can I compare the difference among the indices, and how can I say there is significant differnce between two time series. They don't have the same values in the same date, but they may have the similar tendency and change curves? 

2) I also want to compare the interannual variation of the vegetation index in the same station. Of course, the index can be separated into several sub-series, i.e., one year one sub-series. Now I have the same question as 1), how can I compare the significant differnce between different year?
    
If there are mature theoretical framework can resolve my questions, is there any package in R can do this? 

Any further advice is highly appreciated. 
    
   
Regards, 
   
Bin Zhao 

2008-11-24 , 10:53:58 

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