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cdnlp

PURPOSE ^

CDNLP: computes neutral drag coefficient following Large&Pond (1981).

SYNOPSIS ^

function [cd,u10]=cdnlp(sp,z)

DESCRIPTION ^

 CDNLP: computes neutral drag coefficient following Large&Pond (1981).
 [cd,u10]=CDNLP(sp,z) computes the neutral drag coefficient and wind 
 speed at 10m given the wind speed at height z following Large and 
 Pond (1981), J. Phys. Oceanog., 11, 324-336. 

 INPUT:   sp - wind speed  [m/s]
          z - measurement height [m]

 OUTPUT:  cd - neutral drag coefficient at 10m
          u10 - wind speed at 10m  [m/s]

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [cd,u10]=cdnlp(sp,z)
0002 % CDNLP: computes neutral drag coefficient following Large&Pond (1981).
0003 % [cd,u10]=CDNLP(sp,z) computes the neutral drag coefficient and wind
0004 % speed at 10m given the wind speed at height z following Large and
0005 % Pond (1981), J. Phys. Oceanog., 11, 324-336.
0006 %
0007 % INPUT:   sp - wind speed  [m/s]
0008 %          z - measurement height [m]
0009 %
0010 % OUTPUT:  cd - neutral drag coefficient at 10m
0011 %          u10 - wind speed at 10m  [m/s]
0012 
0013 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0014 % 3/8/97: version 1.0
0015 % 8/26/98: version 1.1 (vectorized by RP)
0016 % 8/5/99: version 2.0
0017 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0018 
0019 as_consts;           % define physical constants
0020 a=log(z./10)/kappa;  % log-layer correction factor
0021 tol=.001;            % tolerance for iteration [m/s]
0022 
0023 u10o=zeros(size(sp));
0024 cd=1.15e-3*ones(size(sp));
0025 u10=sp./(1+a.*sqrt(cd));
0026 
0027 ii=abs(u10-u10o)>tol;
0028 while any(ii(:)),
0029   u10o=u10;
0030   cd=(4.9e-4+6.5e-5*u10o);    % compute cd(u10)
0031   cd(u10o<10.15385)=1.15e-3;
0032   u10=sp./(1+a.*sqrt(cd));   % next iteration
0033   ii=abs(u10-u10o)>tol;      % keep going until iteration converges
0034 end;

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