Dear users

I am fitting a Generalized Additive Mixed Models (gamm) model to

establish possible relationship between explanatory variables (water

temperature, dissolved oxygen and chlorophyll) and zooplankton data

collected in the inner and outer estuarine waters. I am using monthly

time-series which are auto-correlated.

In the case of the inner waters, I have applied satisfactoryly (by ACF

and PACF) an corAR1() as follows:

gamm.zoo <- gamm(zoo~s(water.temperature) + s(dissolved.oxygen) +

s(chlorophyll), dataÚtos,family=gaussian,corr=corAR1() )

But in the case of the outer estuarine waters, our data has a seasonal

auto-correlation. I have tried to applied corARMA(p,q), but it is not

completely satisfactory because I have an autocorrelation of order 1

and 12 as an seasonal ARIMA=(1,0,0)(1,0,0)

I have tried to model it with

corr=corARMA(p, fixed=c(NA,0,0,0,0,0,0,0,0,0,0,NA,NA)))

However, I am not completely sure I am modelling what I should.

I suspect the autocorrelation structure in the error term has been

taken into account with corAR1/corARMA, but I cannot work it out how

it is the random structure. I do not need to incorporate a random

structure in my model, only need to take into account the

autocorrelation term structure in the error term, but I am not sure

that the model aforementioned is doing what I am trying to do.

Any help would be appreciated.

Thanks in advance

Guille