Shortwave and longwave radiation parameterizations

[arango]

There has been some inquires in the past about the computation of shortwave and longwave radiation using analytical options. See the following ROMS forum​link.

A bug was corrected in the albedo equation (ana_srflux.h) that computes the optical thickness of the atmosphere under a cloudless skies (Zillman, 1972). The original paper is very difficult to get because is a technical report. This equation can be found in the literature with 0.1 and 0.01 coefficients. There is a lot of literature using this equation and refering it to Zillman (1972). I contacted John Zillman (now retired) and he mentioned that he could not locate a copy of the over 500 page Australian Bureau of Meteorological Study. However, he menstioned that the formula appears in several places in the text and in each case the coefficient is 0.1. Anyway, this is something that we see a lot in the literature. Authors quoting others but not reading the original paper. Then, errors are easily propagated.

I documented well these options in the code and put the units for the saturation of vapor pressure (e_sat) and water vapor pressure (vap_p) which is very important for these parameterizations.