IMPORTANT: Corrected bug in ana_srflux.h

[arango]

Finally, I have time to browse the literature, Googling, and write a Matlab script to check a bug in ana_srflx.h as discussed in the ​Forum Indeed, the 15.0 factor used to compute the zenith is incorrect. We need to have instead:

        zenith=cff1+cff2*COS(Hangle-lonr(i,j)*deg2rad)

In my Matlab script, I compared against a WRF-ROMS coupled solution for the US West Coast at a particular point in the grid:

Here, the X-axis is the time since initialization and it is in GMT time zone. We need to subtract 8 hours for local Pacific Standard Time (PST) to analyze the results. As you can see, the WRF-ROMS coupled solution values agree well with the red curve that computes zenith with updated above equation. I am now satisfied that I proved to myself that it is a bug.

Many thanks to all that brought this bug to my attention.

[arango]

Forgot to correct how Dangle is computed. We need to have:

      Dangle=23.44_dp*COS((172.0_dp-yday)*2.0_dp*pi/365.2425_dp)

The length of the year is 648 seconds less to a value of 365.2425 days.