Correction and commentary for "Ocean forecasting in terrain-following coordinates: Formulation and skill assessment of the regional ocean modeling system" by Haidvogel et al., J. Comp. Phys 227, pp 3595-3624

Although our names appear as co-authors in the above article (Haidvogel et al. (2008) [1], hereafter H2008), we were not aware of its existence until after it was published. In reading the article, we discovered that a significant portion of it (~40%, or 10 pages) repeats three large fragments from our own previously published work, Shchepetkin and McWilliams (2005) [2] (hereafter SM2005), but now presented in such a way that the motivation for the specific algorithmic choices made in ROMS and the relations among the different model components are no longer clear. The model equations appearing in H2008, Section 2.1 (taken from an earlier article, Haidvogel et al. (2000) [3]) are not entirely consistent with the actual equations solved in the ROMS code, resulting in contradictions within H2008 itself. In our view the description in H2008 does not constitute a mathematically accurate statement about the hydrodynamic core of ROMS. The purpose of this note is to clarify and correct this, as well as to explain some of the algorithmic differences among ROMS versions now in use.

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