depth.h

// Copyright 2009-2018 Toby Schneider (http://gobysoft.org/index.wt/people/toby)
//                     GobySoft, LLC (2013-)
//                     Massachusetts Institute of Technology (2007-2014)
//                     Community contributors (see AUTHORS file)
//
//
// This file is part of the Goby Underwater Autonomy Project Libraries
// ("The Goby Libraries").
//
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// modified for C++ by s. petillo spetillo@mit.edu
// ocean engineering graduate student - mit / whoi joint program
// massachusetts institute of technology (mit)
// laboratory for autonomous marine sensing systems (lamss)

#ifndef DEPTHH
#define DEPTHH

#include <cmath>

// Calculates Depth given the Pressure at some Latitude.
// Taken directly from MATLAB OceansToolbox depth.m

inline double pressure2depth(double P, double LAT)
{
    // function DEPTH=depth(P,LAT);
    /*
    DEPTH   Computes depth given the pressure at some latitude
    D=DEPTH(P,LAT) gives the depth D (m) for a pressure P (dbars)
    at some latitude LAT (degrees).
    
    This probably works best in mid-latiude oceans, if anywhere!

    Ref: Saunders, Fofonoff, Deep Sea Res., 23 (1976), 109-111
    

    Notes: RP (WHOI) 2/Dec/91
    I copied this directly from the UNESCO algorithms

    CHECKVALUE: DEPTH = 9712.653 M FOR P=10000 DECIBARS, LATITUDE=30 DEG
    ABOVE FOR STANDARD OCEAN: T=0 DEG. CELSUIS ; S=35 (IPSS-78)
  */

    using namespace std; // for math functions

    double X = sin(LAT / 57.29578);
    X = X * X;
    // GR= GRAVITY VARIATION WITH LATITUDE: ANON (1970) BULLETIN GEODESIQUE
    double GR = 9.780318 * (1.0 + (5.2788E-3 + 2.36E-5 * X) * X) + 1.092E-6 * P;
    double DEPTH = (((-1.82E-15 * P + 2.279E-10) * P - 2.2512E-5) * P + 9.72659) * P;
    DEPTH = DEPTH / GR;

    return DEPTH;
}

#endif