% 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 



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% 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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



% ------- physical constants



g           = 9.8;       % acceleration due to gravity [m/s^2]

sigmaSB     = 5.6697e-8; % Stefan-Boltzmann constant [W/m^2/K^4]

eps_air     = 0.62197;   % molecular weight ratio (water/air)

gas_const_R = 287.04;    % gas constant for dry air [J/kg/K]

CtoK        = 273.16;    % conversion factor for [C] to [K]





% ------- meteorological constants



kappa          = 0.4;    % von Karman's constant

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. 

R_roughness   = 0.11;    % limiting roughness Reynolds # for aerodynamically 

                         % smooth flow         

                         

                        

% ------ defaults suitable for boundary-layer studies



cp            = 1004.7;   % heat capacity of air [J/kg/K]

rho_air       = 1.22;     % air density (when required as constant) [kg/m^2]

Ta_default    = 10;       % default air temperature [C]

P_default     = 1020;     % default air pressure for Kinneret [mbars]

psych_default = 'screen'; % default psychmometer type (see relhumid.m)

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)



CVB_depth     = 600; % depth of convective boundary layer in atmosphere [m]

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)

beta_conv     = 1.25;% scaling constant for gustiness





% ------ short-wave flux calculations



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



emiss_lw = 0.985;     % long-wave emissivity of ocean from Dickey et al

                      % (1994), J. Atmos. Oceanic Tech., 11, 1057-1076.



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                           

