ERF_Constants.H

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#ifndef ERF_CONSTANTS_H_
#define ERF_CONSTANTS_H_
 
#include <cmath>
#include <limits>
#include <AMReX_REAL.H>
 
constexpr amrex::Real zero         = amrex::Real(0.0);
constexpr amrex::Real one          = amrex::Real(1.0);
constexpr amrex::Real two          = amrex::Real(2.0);
constexpr amrex::Real three        = amrex::Real(3.0);
constexpr amrex::Real four         = amrex::Real(4.0);
constexpr amrex::Real myhalf       = amrex::Real(0.5);
constexpr amrex::Real fourth       = amrex::Real(0.25);
constexpr amrex::Real third        = amrex::Real(1.0/3.0);
constexpr amrex::Real eightthirds  = amrex::Real(8.0/3.0);
 
// Safe overly large value to fill data so that it is not uninitialized
//      but we can easily identify if the value is used in a computation
// Would like to use the following but std::sqrt will not be allowable
//       in constexpr until C++26
// const amrex::Real bogus_large_value = std::sqrt(std::numeric_limits<amrex::Real>::max());
#ifdef AMREX_USE_FLOAT
constexpr amrex::Real bogus_large_value = amrex::Real(1.e18);
#else
constexpr amrex::Real bogus_large_value = amrex::Real(1.e150);
#endif
 
// lsm_undefined: sentinel written into the LSM MultiFabs for cells
// the land model did NOT process (e.g. sea-ice / open-water points, where Noah-MP returns the
// -9999 fill value instead of a computed flux). The surface layer detects this
// and falls back to the Monin-Obukhov (MOST) flux for those cells -- analogous
// to how WRF computes the atmospheric surface flux from a skin temperature via
// the surface-layer scheme rather than taking an undefined LSM flux.
constexpr amrex::Real lsm_undefined = bogus_large_value;
 
// Physical ceiling [mm] on interval precip handed to Noah-MP over one land call.
// 500 mm is far above any real rate, so a larger value signals noisy IC/BC or a
// corrupt accumulator snapshot; the coupling clamps to this and warns (ERF_NOAHMP.cpp).
constexpr amrex::Real lsm_max_precip_interval = amrex::Real(500.0);
 
constexpr amrex::Real PI           = amrex::Real(3.14159265358979323846264338327950288);
constexpr amrex::Real PIoTwo       = PI/two;
constexpr amrex::Real four_thirds_pi = four/three*PI;
 
// Physical Constants
constexpr amrex::Real R_d          = amrex::Real(287.0);    // dry air constant for dry air [J/(kg-K)]
constexpr amrex::Real R_v          = amrex::Real(461.505);  // water vapor constant for water vapor [J/(kg-K)]
constexpr amrex::Real Cp_d         = amrex::Real(1004.5);   // We have set this so that with qv=0 we get identically gamma = amrex::Real(1.4)
constexpr amrex::Real Cp_v         = amrex::Real(1859.0);
constexpr amrex::Real Cp_l         = amrex::Real(4200.0);
 
constexpr amrex::Real epsv         = R_v / R_d - one;
constexpr amrex::Real RdoCp        = R_d / Cp_d;
constexpr amrex::Real CpoRd        = Cp_d / R_d;
constexpr amrex::Real RvoRd        = R_v / R_d;
constexpr amrex::Real RdoRv        = R_d / R_v;
 
constexpr amrex::Real L_v          = amrex::Real(2.5e6);    // latent heat of vaporization (J / kg)
 
constexpr amrex::Real p_0          = amrex::Real(1.0e5);    // reference surface pressure [Pa]
constexpr amrex::Real Gamma        = amrex::Real(1.4);      // c_p / c_v [-]
constexpr amrex::Real KAPPA        = amrex::Real(0.41);     // von Karman constant
constexpr amrex::Real CONST_GRAV   = amrex::Real(9.81);
 
// Derived Constants
constexpr amrex::Real ip_0         = one/p_0;
constexpr amrex::Real iR_d         = one/R_d;
constexpr amrex::Real iGamma       = one/Gamma;
 
constexpr amrex::Real rhor         = amrex::Real(1000.); // Density of water, kg/m3
constexpr amrex::Real rhos         = amrex::Real(100.);  // Density of snow, kg/m3
constexpr amrex::Real rhog         = amrex::Real(400.);  // Density of graupel, kg/m3
constexpr amrex::Real tbgmin       = amrex::Real(253.16);    // Minimum temperature for cloud water., K
constexpr amrex::Real tbgmax       = amrex::Real(273.16);    // Maximum temperature for cloud ice, K
constexpr amrex::Real tprmin       = amrex::Real(268.16);    // Minimum temperature for rain, K
constexpr amrex::Real tprmax       = amrex::Real(283.16);    // Maximum temperature for snow+graupel, K
constexpr amrex::Real tgrmin       = amrex::Real(223.16);    // Minimum temperature for graupel, K
constexpr amrex::Real tgrmax       = amrex::Real(283.16);    // Maximum temperature for graupel, K
 
constexpr amrex::Real a_rain       = amrex::Real(842.);   // Coeff.for rain term vel
constexpr amrex::Real b_rain       = amrex::Real(0.8);    // Fall speed exponent for rain
constexpr amrex::Real a_snow       = amrex::Real(4.84);   // Coeff.for snow term vel
constexpr amrex::Real b_snow       = fourth;   // Fall speed exponent for snow
constexpr amrex::Real a_grau       = amrex::Real(94.5);   // Lin (1983) (rhog=400)
constexpr amrex::Real b_grau       = amrex::Real(0.5);    // Fall speed exponent for graupel
 
// Autoconversion
constexpr amrex::Real qcw0         = amrex::Real(1.e-3);  // Threshold for water autoconversion, g/g
constexpr amrex::Real qci0         = amrex::Real(1.e-4);  // Threshold for ice autoconversion, g/g
constexpr amrex::Real alphaelq     = amrex::Real(1.e-3);  // autoconversion of cloud water rate coef
constexpr amrex::Real betaelq      = amrex::Real(1.e-3);  // autoconversion of cloud ice rate coef
 
constexpr amrex::Real erccoef      = one;    // Rain/Cloud water collection efficiency
constexpr amrex::Real esccoef      = one;    // Snow/Cloud water collection efficiency
constexpr amrex::Real esicoef      = amrex::Real(0.1);    // Snow/cloud ice collection efficiency
constexpr amrex::Real egccoef      = one;    // Graupel/Cloud water collection efficiency
constexpr amrex::Real egicoef      = amrex::Real(0.1);    // Graupel/Cloud ice collection efficiency
 
constexpr amrex::Real nzeror       = amrex::Real(8.e6);   // Intercept coeff. for rain
constexpr amrex::Real nzeros       = amrex::Real(3.e6);   // Intersept coeff. for snow
constexpr amrex::Real nzerog       = amrex::Real(4.e6);   // Intersept coeff. for graupel
constexpr amrex::Real qp_threshold = amrex::Real(1.e-8);  // minimal rain/snow water content
 
constexpr amrex::Real boltz    = amrex::Real(1.38065e-23);
constexpr amrex::Real avogadro = amrex::Real(6.02214e26);
constexpr amrex::Real mwdair   = amrex::Real(28.966);
constexpr amrex::Real mwwv     = amrex::Real(18.016);
constexpr amrex::Real lcond    = amrex::Real(2.501e6);
constexpr amrex::Real lfus     = amrex::Real(3.337e5);
constexpr amrex::Real lsub     = lcond+lfus;
constexpr amrex::Real rair     = boltz*avogadro/mwdair;
constexpr amrex::Real rh20     = rair/mwwv;
constexpr amrex::Real rga      = one/CONST_GRAV;
 
constexpr amrex::Real diffelq = amrex::Real(2.21e-05);     // Diffusivity of water vapor, m2/s
constexpr amrex::Real therco  = amrex::Real(2.40e-02);     // Thermal conductivity of air, J/m/s/K
constexpr amrex::Real muelq   = amrex::Real(1.717e-05);    // Dynamic viscosity of air
 
constexpr amrex::Real a_bg = one/(tbgmax-tbgmin);
constexpr amrex::Real a_pr = one/(tprmax-tprmin);
constexpr amrex::Real a_gr = one/(tgrmax-tgrmin);
 
constexpr amrex::Real crain = b_rain / amrex::Real(4.0);
constexpr amrex::Real csnow = b_snow / amrex::Real(4.0);
constexpr amrex::Real cgrau = b_grau / amrex::Real(4.0);
 
constexpr amrex::Real lat_vap  = amrex::Real(2.5e6);     // Latent heat of vaporization (J/kg)
constexpr amrex::Real lat_ice  = amrex::Real(3.337e5);   // latent heat of fusion (J/kg)
constexpr amrex::Real tmelt    = amrex::Real(273.15);  // melting temp.
constexpr amrex::Real h2otrip  = amrex::Real(273.15);  // Triple point temperature of water (K)
constexpr amrex::Real tboil    = amrex::Real(373.16);  // Boiling point of water at 1 atm (K)
constexpr amrex::Real ttrice   = amrex::Real(20.00);   // transition range from es over H2O to es over ice
constexpr amrex::Real epsilo   = RdoRv;
constexpr amrex::Real omeps    = one - epsilo;
constexpr amrex::Real rhoh2o   = amrex::Real(1.000e3);  // density of liquid water
 
static constexpr int  ORB_UNDEF_INT  = 2000000000;  // undefined int
#endif