gnss-sdr/src/algorithms/libs/rtklib/rtklib_tides.cc

/*!
 * \file rtklib_tides.cc
 * \brief Tidal displacement corrections
 * \authors <ul>
 *          <li> 2007-2008, T. Takasu
 *          <li> 2017, Javier Arribas
 *          <li> 2017, Carles Fernandez
 *          </ul>
 *
 * This is a derived work from RTKLIB http://www.rtklib.com/
 * The original source code at https://github.com/tomojitakasu/RTKLIB is
 * released under the BSD 2-clause license with an additional exclusive clause
 * that does not apply here. This additional clause is reproduced below:
 *
 * " The software package includes some companion executive binaries or shared
 * libraries necessary to execute APs on Windows. These licenses succeed to the
 * original ones of these software. "
 *
 * Neither the executive binaries nor the shared libraries are required by, used
 * or included in GNSS-SDR.
 *
 * -----------------------------------------------------------------------------
 * Copyright (C) 2007-2008, T. Takasu
 * Copyright (C) 2017, Javier Arribas
 * Copyright (C) 2017, Carles Fernandez
 * All rights reserved.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * -----------------------------------------------------------------------------
 */

#include "rtklib_tides.h"
#include "rtklib_rtkcmn.h"


/* solar/lunar tides (ref [2] 7) ---------------------------------------------*/
// #ifndef IERS_MODEL
void tide_pl(const double *eu, const double *rp, double GMp,
    const double *pos, double *dr)
{
    const double H3 = 0.292;
    const double L3 = 0.015;
    double r;
    double ep[3];
    double latp;
    double lonp;
    double p;
    double K2;
    double K3;
    double a;
    double H2;
    double L2;
    double dp;
    double du;
    double cosp;
    double sinl;
    double cosl;
    int i;

    trace(4, "tide_pl : pos=%.3f %.3f\n", pos[0] * R2D, pos[1] * R2D);

    if ((r = norm_rtk(rp, 3)) <= 0.0)
        {
            return;
        }

    for (i = 0; i < 3; i++)
        {
            ep[i] = rp[i] / r;
        }

    K2 = GMp / GME * std::pow(RE_WGS84, 2.04) * std::pow(RE_WGS84, 2.0) / (r * r * r);
    K3 = K2 * RE_WGS84 / r;
    latp = asin(ep[2]);
    lonp = atan2(ep[1], ep[0]);
    cosp = cos(latp);
    sinl = sin(pos[0]);
    cosl = cos(pos[0]);

    /* step1 in phase (degree 2) */
    p = (3.0 * sinl * sinl - 1.0) / 2.0;
    H2 = 0.6078 - 0.0006 * p;
    L2 = 0.0847 + 0.0002 * p;
    a = dot(ep, eu, 3);
    dp = K2 * 3.0 * L2 * a;
    du = K2 * (H2 * (1.5 * a * a - 0.5) - 3.0 * L2 * a * a);

    /* step1 in phase (degree 3) */
    dp += K3 * L3 * (7.5 * a * a - 1.5);
    du += K3 * (H3 * (2.5 * a * a * a - 1.5 * a) - L3 * (7.5 * a * a - 1.5) * a);

    /* step1 out-of-phase (only radial) */
    du += 3.0 / 4.0 * 0.0025 * K2 * sin(2.0 * latp) * sin(2.0 * pos[0]) * sin(pos[1] - lonp);
    du += 3.0 / 4.0 * 0.0022 * K2 * cosp * cosp * cosl * cosl * sin(2.0 * (pos[1] - lonp));

    dr[0] = dp * ep[0] + du * eu[0];
    dr[1] = dp * ep[1] + du * eu[1];
    dr[2] = dp * ep[2] + du * eu[2];

    trace(5, "tide_pl : dr=%.3f %.3f %.3f\n", dr[0], dr[1], dr[2]);
}


/* displacement by solid earth tide (ref [2] 7) ------------------------------*/
void tide_solid(const double *rsun, const double *rmoon,
    const double *pos, const double *E, double gmst, int opt,
    double *dr)
{
    double dr1[3] = {0.0, 0.0, 0.0};
    double dr2[3] = {0.0, 0.0, 0.0};
    double eu[3];
    double du;
    double dn;
    double sinl;
    double sin2l;

    trace(3, "tide_solid: pos=%.3f %.3f opt=%d\n", pos[0] * R2D, pos[1] * R2D, opt);

    /* step1: time domain */
    eu[0] = E[2];
    eu[1] = E[5];
    eu[2] = E[8];
    tide_pl(eu, rsun, GMS, pos, dr1);
    tide_pl(eu, rmoon, GMM, pos, dr2);

    /* step2: frequency domain, only K1 radial */
    sin2l = sin(2.0 * pos[0]);
    du = -0.012 * sin2l * sin(gmst + pos[1]);

    dr[0] = dr1[0] + dr2[0] + du * E[2];
    dr[1] = dr1[1] + dr2[1] + du * E[5];
    dr[2] = dr1[2] + dr2[2] + du * E[8];

    /* eliminate permanent deformation */
    if (opt & 8)
        {
            sinl = sin(pos[0]);
            du = 0.1196 * (1.5 * sinl * sinl - 0.5);
            dn = 0.0247 * sin2l;
            dr[0] += du * E[2] + dn * E[1];
            dr[1] += du * E[5] + dn * E[4];
            dr[2] += du * E[8] + dn * E[7];
        }
    trace(5, "tide_solid: dr=%.3f %.3f %.3f\n", dr[0], dr[1], dr[2]);
}
// #endif /* !IERS_MODEL */


/* displacement by ocean tide loading (ref [2] 7) ----------------------------*/
void tide_oload(gtime_t tut, const double *odisp, double *denu)
{
    const double args[][5] = {
        {1.40519E-4, 2.0, -2.0, 0.0, 0.00},  /* M2 */
        {1.45444E-4, 0.0, 0.0, 0.0, 0.00},   /* S2 */
        {1.37880E-4, 2.0, -3.0, 1.0, 0.00},  /* N2 */
        {1.45842E-4, 2.0, 0.0, 0.0, 0.00},   /* K2 */
        {0.72921E-4, 1.0, 0.0, 0.0, 0.25},   /* K1 */
        {0.67598E-4, 1.0, -2.0, 0.0, -0.25}, /* O1 */
        {0.72523E-4, -1.0, 0.0, 0.0, -0.25}, /* P1 */
        {0.64959E-4, 1.0, -3.0, 1.0, -0.25}, /* Q1 */
        {0.53234E-5, 0.0, 2.0, 0.0, 0.00},   /* Mf */
        {0.26392E-5, 0.0, 1.0, -1.0, 0.00},  /* Mm */
        {0.03982E-5, 2.0, 0.0, 0.0, 0.00}    /* Ssa */
    };
    const double ep1975[] = {1975, 1, 1, 0, 0, 0};
    double ep[6];
    double fday;
    double days;
    double t;
    double t2;
    double t3;
    double a[5];
    double ang;
    double dp[3] = {0};
    int i;
    int j;

    trace(3, "tide_oload:\n");

    /* angular argument: see subroutine arg.f for reference [1] */
    time2epoch(tut, ep);
    fday = ep[3] * 3600.0 + ep[4] * 60.0 + ep[5];
    ep[3] = ep[4] = ep[5] = 0.0;
    days = timediff(epoch2time(ep), epoch2time(ep1975)) / 86400.0 + 1.0;
    t = (27392.500528 + 1.000000035 * days) / 36525.0;
    t2 = t * t;
    t3 = t2 * t;

    a[0] = fday;
    a[1] = (279.69668 + 36000.768930485 * t + 3.03E-4 * t2) * D2R;                 /* H0 */
    a[2] = (270.434358 + 481267.88314137 * t - 0.001133 * t2 + 1.9E-6 * t3) * D2R; /* S0 */
    a[3] = (334.329653 + 4069.0340329577 * t - 0.010325 * t2 - 1.2E-5 * t3) * D2R; /* P0 */
    a[4] = 2.0 * GNSS_PI;

    /* displacements by 11 constituents */
    for (i = 0; i < 11; i++)
        {
            ang = 0.0;
            for (j = 0; j < 5; j++)
                {
                    ang += a[j] * args[i][j];
                }
            for (j = 0; j < 3; j++)
                {
                    dp[j] += odisp[j + i * 6] * cos(ang - odisp[j + 3 + i * 6] * D2R);
                }
        }
    denu[0] = -dp[1];
    denu[1] = -dp[2];
    denu[2] = dp[0];

    trace(5, "tide_oload: denu=%.3f %.3f %.3f\n", denu[0], denu[1], denu[2]);
}


/* iers mean pole (ref [7] eq.7.25) ------------------------------------------*/
void iers_mean_pole(gtime_t tut, double *xp_bar, double *yp_bar)
{
    const double ep2000[] = {2000, 1, 1, 0, 0, 0};
    double y;
    double y2;
    double y3;

    y = timediff(tut, epoch2time(ep2000)) / 86400.0 / 365.25;

    if (y < 3653.0 / 365.25)
        { /* until 2010.0 */
            y2 = y * y;
            y3 = y2 * y;
            *xp_bar = 55.974 + 1.8243 * y + 0.18413 * y2 + 0.007024 * y3; /* (mas) */
            *yp_bar = 346.346 + 1.7896 * y - 0.10729 * y2 - 0.000908 * y3;
        }
    else
        {                                  /* after 2010.0 */
            *xp_bar = 23.513 + 7.6141 * y; /* (mas) */
            *yp_bar = 358.891 - 0.6287 * y;
        }
}


/* displacement by pole tide (ref [7] eq.7.26) --------------------------------*/
void tide_pole(gtime_t tut, const double *pos, const double *erpv,
    double *denu)
{
    double xp_bar;
    double yp_bar;
    double m1;
    double m2;
    double cosl;
    double sinl;

    trace(3, "tide_pole: pos=%.3f %.3f\n", pos[0] * R2D, pos[1] * R2D);

    /* iers mean pole (mas) */
    iers_mean_pole(tut, &xp_bar, &yp_bar);

    /* ref [7] eq.7.24 */
    m1 = erpv[0] / AS2R - xp_bar * 1E-3; /* (as) */
    m2 = -erpv[1] / AS2R + yp_bar * 1E-3;

    /* sin(2*theta) = sin(2*phi), cos(2*theta)=-cos(2*phi) */
    cosl = cos(pos[1]);
    sinl = sin(pos[1]);
    denu[0] = 9E-3 * sin(pos[0]) * (m1 * sinl - m2 * cosl);         /* de= Slambda (m) */
    denu[1] = -9E-3 * cos(2.0 * pos[0]) * (m1 * cosl + m2 * sinl);  /* dn=-Stheta  (m) */
    denu[2] = -33E-3 * sin(2.0 * pos[0]) * (m1 * cosl + m2 * sinl); /* du= Sr      (m) */

    trace(5, "tide_pole : denu=%.3f %.3f %.3f\n", denu[0], denu[1], denu[2]);
}


/* tidal displacement ----------------------------------------------------------
 * displacements by earth tides
 * args   : gtime_t tutc     I   time in utc
 *          double *rr       I   site position (ecef) (m)
 *          int    opt       I   options (one of the following)
 *                                 1: solid earth tide
 *                                 2: ocean tide loading
 *                                 4: pole tide
 *                                 8: elimate permanent deformation
 *          double *erp      I   earth rotation parameters (NULL: not used)
 *          double *odisp    I   ocean loading parameters  (NULL: not used)
 *                                 odisp[0+i*6]: consituent i amplitude radial(m)
 *                                 odisp[1+i*6]: consituent i amplitude west  (m)
 *                                 odisp[2+i*6]: consituent i amplitude south (m)
 *                                 odisp[3+i*6]: consituent i phase radial  (deg)
 *                                 odisp[4+i*6]: consituent i phase west    (deg)
 *                                 odisp[5+i*6]: consituent i phase south   (deg)
 *                                (i=0:M2,1:S2,2:N2,3:K2,4:K1,5:O1,6:P1,7:Q1,
 *                                   8:Mf,9:Mm,10:Ssa)
 *          double *dr       O   displacement by earth tides (ecef) (m)
 * return : none
 * notes  : see ref [1], [2] chap 7
 *          see ref [4] 5.2.1, 5.2.2, 5.2.3
 *          ver.2.4.0 does not use ocean loading and pole tide corrections
 *-----------------------------------------------------------------------------*/
void tidedisp(gtime_t tutc, const double *rr, int opt, const erp_t *erp,
    const double *odisp, double *dr)
{
    gtime_t tut;
    double pos[2];
    double E[9];
    double drt[3];
    double denu[3];
    double rs[3];
    double rm[3];
    double gmst;
    double erpv[5] = {0};
    int i;
#ifdef IERS_MODEL
    double ep[6], fhr;
    int year, mon, day;
#endif

    trace(3, "tidedisp: tutc=%s\n", time_str(tutc, 0));

    if (erp)
        {
            geterp(erp, tutc, erpv);
        }

    tut = timeadd(tutc, erpv[2]);

    dr[0] = dr[1] = dr[2] = 0.0;

    if (norm_rtk(rr, 3) <= 0.0)
        {
            return;
        }

    pos[0] = asin(rr[2] / norm_rtk(rr, 3));
    pos[1] = atan2(rr[1], rr[0]);
    xyz2enu(pos, E);

    if (opt & 1)
        { /* solid earth tides */
            /* sun and moon position in ecef */
            sunmoonpos(tutc, erpv, rs, rm, &gmst);

#ifdef IERS_MODEL
            time2epoch(tutc, ep);
            year = static_cast<int>(ep[0]);
            mon = static_cast<int>(ep[1]);
            day = static_cast<int>(ep[2]);
            fhr = ep[3] + ep[4] / 60.0 + ep[5] / 3600.0;

            /* call DEHANTTIDEINEL */
            //    dehanttideinel_((double *)rr,&year,&mon,&day,&fhr,rs,rm,drt);
#else
            tide_solid(rs, rm, pos, E, gmst, opt, drt);
#endif
            for (i = 0; i < 3; i++)
                {
                    dr[i] += drt[i];
                }
        }
    if ((opt & 2) && odisp)
        { /* ocean tide loading */
            tide_oload(tut, odisp, denu);
            matmul("TN", 3, 1, 3, 1.0, E, denu, 0.0, drt);
            for (i = 0; i < 3; i++)
                {
                    dr[i] += drt[i];
                }
        }
    if ((opt & 4) && erp)
        { /* pole tide */
            tide_pole(tut, pos, erpv, denu);
            matmul("TN", 3, 1, 3, 1.0, E, denu, 0.0, drt);
            for (i = 0; i < 3; i++)
                {
                    dr[i] += drt[i];
                }
        }
    trace(5, "tidedisp: dr=%.3f %.3f %.3f\n", dr[0], dr[1], dr[2]);
}