as_consts.jl

# AS_CONSTS: returns values of many constants used in AIR_SEA TOOLBOX
# AS_CONSTS: returns values of many constants used in the AIR_SEA TOOLBOX.  At end of this file are values of constants from COARE to be used when running the test program t_hfbulktc.m 

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# 8/19/98: version 1.1 (contributed by RP)
# 4/7/99: version 1.2 (revised to include COARE test values by AA)
# 8/5/99: version 2.0
# 3/5/23: ported to Julia by Donglai Gong

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# ------- physical constants
const g           = 9.8;       # acceleration due to gravity [m/s^2]
const sigmaSB     = 5.6697e-8; # Stefan-Boltzmann constant [W/m^2/K^4]
const eps_air     = 0.62197;   # molecular weight ratio (water/air)
const gas_const_R = 287.04;    # gas constant for dry air [J/kg/K]
const CtoK        = 273.16;    # conversion factor for [C] to [K]

# ------- meteorological constants
const kappa          = 0.4;    # von Karman's constant
const Charnock_alpha = 0.011;  # Charnock constant (for determining roughness length at sea given friction velocity), used in Smith formulas for drag coefficient and also in Fairall and Edson.  use alpha=0.011 for open-ocean and alpha=0.018 for fetch-limited (coastal) regions. 
const R_roughness   = 0.11;    # limiting roughness Reynolds for aerodynamically smooth flow         

# ------ defaults suitable for boundary-layer studies

const cp            = 1004.7;   # heat capacity of air [J/kg/K]
const rho_air       = 1.22;     # air density (when required as constant) [kg/m^2]
const Ta_default    = 10;       # default air temperature [C]
const P_default     = 1020;     # default air pressure for Kinneret [mbars]
const psych_default = "screen"; # default psychmometer type (see relhumid.m)
const Qsat_coeff    = 0.98;     # satur. specific humidity coefficient reduced by 2% over salt water

# the following are useful in hfbulktc.m 
#     (and are the default values used in Fairall et al, 1996)

const CVB_depth     = 600;    # depth of convective boundary layer in atmosphere [m]
const min_gustiness = 0.5;    # min. "gustiness" (i.e., unresolved fluctuations) [m/s]
                              # should keep this strictly >0, otherwise bad stuff might happen (divide by zero errors)
const beta_conv     = 1.25;   # scaling constant for gustiness

# ------ short-wave flux calculations

const Solar_const = 1368.0; # the solar constant [W/m^2] represents a mean of satellite measurements made over the last sunspot cycle (1979-1995) taken from Coffey et al (1995), Earth System Monitor, 6, 6-10.

# ------ long-wave flux calculations

const emiss_lw = 0.985;     # long-wave emissivity of ocean from Dickey et al. (1994), J. Atmos. Oceanic Tech., 11, 1057-1076.
const bulkf_default = "berliand";  # default bulk formula when downward long-wave measurements are not made.

# ------ constants used for COARE; to use simply delete the %     

# g           = 9.7803;   # acceleration due to gravity [m/s^2]
# sigmaSB     = 5.67e-8;  # Stefan-Boltzmann constant [m^2/K^4] 
# gas_const_R = 287.1;    # gas constant for dry air [J/kg/K]
# cp          = 1004.67;  # heat capacity of air [J/kg/K]
# beta_conv   = 1.20;     # scaling constant for gustiness  
# emiss_lw    = 0.97;     # long-wave emissivity