“This book is mainly about derivations. For this reason, it is well suited for self-study and could be used in an advanced graduate course focused on variation methods and fluid mechanics. The material covered in this book should appeal to graduate students, postdocs, professors, and research scientists in physical oceanography, applied mathematics, applied physics, atmospheric dynamics, and ocean engineering.” (Colin R. Meyer, Pure and Applied Geophysics, Vol. 175, 2018)