I proceeded with performing the seasonal adjustments I proposed at the end of my last blog post (see “Temporal Data” post). Briefly, I used the ratios of mean monthly naphthalene concentrations over the annual naphthalene concentrations for all air monitoring data (i.e. both sites combined). These ratios were then used as adjustment factors to simulate monthly observations for the NATA data that I have. The monthly simulated data was then averaged over a year-long period to obtain the “seasonally adjusted” annual estimates.

The graph below displays the seasonally adjusted versus the unadjusted naphthalene annual concentrations. The adjustment factors caused the annual estimates to increase slightly. These seasonal estimates will now be used as my simulated input data for estimation of annual concentrations for my LUR. model.