tFrontalMeltPhysics.cc - pism - [fork] customized build of PISM, the parallel ice sheet model (tillflux branch)
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tFrontalMeltPhysics.cc (2684B)
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1 /* Copyright (C) 2018, 2019 PISM Authors
2 *
3 * This file is part of PISM.
4 *
5 * PISM is free software; you can redistribute it and/or modify it under the
6 * terms of the GNU General Public License as published by the Free Software
7 * Foundation; either version 3 of the License, or (at your option) any later
8 * version.
9 *
10 * PISM is distributed in the hope that it will be useful, but WITHOUT ANY
11 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
12 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 * details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with PISM; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19 #include <cmath> // pow
20
21 #include "FrontalMeltPhysics.hh"
22
23 #include "pism/util/ConfigInterface.hh"
24
25 namespace pism {
26 namespace frontalmelt {
27
28 FrontalMeltPhysics::FrontalMeltPhysics(const Config &config) {
29 m_alpha = config.get_number("frontal_melt.routing.power_alpha");
30 m_beta = config.get_number("frontal_melt.routing.power_beta");
31 m_A = config.get_number("frontal_melt.routing.parameter_a");
32 m_B = config.get_number("frontal_melt.routing.parameter_b");
33 }
34
35 /*!
36 * Parameterization of the frontal melt rate.
37 *
38 * This function implements equation 1 from [@ref Rignotetal2016].
39 *
40 * q_m = (A * h * Q_sg ^{\alpha} + B) * TF^{\beta}
41 *
42 * where A, B, alpha, beta are tuning parameters. Note that Rignot (2016) is an update on
43 * Xu 2013 with slightly different parameter values.
44 *
45 * @param[in] h water depth, meters
46 * @param[in] q_sg subglacial water flux, m / day
47 * @param[in] TF thermal forcing, Celsius
48 *
49 * @returns frontal melt rate, m / day.
50 */
51 double FrontalMeltPhysics::frontal_melt_from_undercutting(double h, double q_sg, double TF) const {
52 if (h <= 0.0 or q_sg < 0.0 or TF < 0.0) {
53 return 0.0;
54 }
55
56 return (m_A * h * pow(q_sg, m_alpha) + m_B) * pow(TF, m_beta);
57 }
58
59 /*!
60 * Parameterization of the frontal melt rate.
61 *
62 * This function implements the ISMIP6 equation
63 *
64 * q_m = (A * h * Q_sg ^{\alpha} + B) * TF^{\beta}
65 *
66 * where A, B, alpha, beta are tuning parameters. Note that Rignot (2016) is an update on
67 * Xu 2013 with slightly different parameter values.
68 *
69 * @param[in] h water depth, meters
70 * @param[in] q_sg subglacial water flux, m / day
71 * @param[in] TF thermal forcing, Celsius
72 *
73 * @returns frontal melt rate, m / day.
74 */
75 double FrontalMeltPhysics::frontal_melt_from_ismip6(double h, double q_sg, double TF) const {
76 return (m_A * h * pow(q_sg, m_alpha) + m_B) * pow(TF, m_beta);
77 }
78
79 } // end of namespace frontalmeltmodel
80 } // end of namespace pism