Home > atmlab > h2o > parametrisations > ice_psd_Heyms_84.m

ice_psd_Heyms_84

PURPOSE ^

ice_psd_Heyms_84 returns the particle size distribution in cirrus clouds.

SYNOPSIS ^

function [y]=ice_psd_Heyms_84(T,D)

DESCRIPTION ^

 ice_psd_Heyms_84 returns the particle size distribution in cirrus clouds.
    
     Returns a vector with the particle size distribution 
     for a given temperature, for a mid-latitude cirrus cloud.
     This parameterisation is based on the temperature averaged 
     distribution of maximum dimension of ice particles, and the
     temperature averaged observed ice water content. The range 
     of the dimension of the particles for this parameterization
     is from 20*10^-6 m to 3*10^-3 m 

     This parameterisation is taken from Heymsfield and Platt,
     "A parameterization of the particle size spectrum of ice clouds
     in terms of the ambient temperature and ice water content"
     J. Atmos. Sci., vol.41, No.5, 846-855, 1984

 FORMAT   [y] = ice_psd_Heyms_84(T,D)     

 OUT      y is a vector with the particle size distribution [#/m^3/m]
  
 IN       T    Temperature [Kelvin]
          D    the vector with the maximum dimension of
               the ice particles [m],
               where the concentration will be calculated

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

DOWNLOAD ^

ice_psd_Heyms_84.m

SOURCE CODE ^

0001 % ice_psd_Heyms_84 returns the particle size distribution in cirrus clouds.
0002 %
0003 %     Returns a vector with the particle size distribution
0004 %     for a given temperature, for a mid-latitude cirrus cloud.
0005 %     This parameterisation is based on the temperature averaged
0006 %     distribution of maximum dimension of ice particles, and the
0007 %     temperature averaged observed ice water content. The range
0008 %     of the dimension of the particles for this parameterization
0009 %     is from 20*10^-6 m to 3*10^-3 m
0010 %
0011 %     This parameterisation is taken from Heymsfield and Platt,
0012 %     "A parameterization of the particle size spectrum of ice clouds
0013 %     in terms of the ambient temperature and ice water content"
0014 %     J. Atmos. Sci., vol.41, No.5, 846-855, 1984
0015 %
0016 % FORMAT   [y] = ice_psd_Heyms_84(T,D)
0017 %
0018 % OUT      y is a vector with the particle size distribution [#/m^3/m]
0019 %
0020 % IN       T    Temperature [Kelvin]
0021 %          D    the vector with the maximum dimension of
0022 %               the ice particles [m],
0023 %               where the concentration will be calculated
0024 
0025 
0026 % History: 2004-07-19  Created by Bengt Rydberg
0027 
0028 
0029 function [y]=ice_psd_Heyms_84(T,D)
0030 
0031 T=T-273.15;
0032 
0033 if T>-20
0034    error('Only temperatures below or equal to -253.15  are allowed')
0035 end
0036 if T<-60
0037    error('Only temperatures larger than or equal to -213.15 K are allowed')
0038 end
0039 if D(1)<20*1e-6
0040    error('Only Dmin larger than 20*1e-6 m is allowed')
0041 end
0042 if D(end)>3*1e-3
0043    error('Only Dmax smaller that 3*1e-3 m is allowed')
0044 end
0045 if T<=-20 & T>-25
0046    IWCmean=0.027;
0047    N100_IWC=5.17*1e3;B1=-2.56;N1000_IWC=12.0;B2=-3.74;
0048    elseif T<=-25 & T>-30
0049       IWCmean=0.025;      
0050       N100_IWC=7.00*1e3;B1=-2.51;N1000_IWC=10.4;B2=-4.49;
0051    elseif T<=-30 & T>-35
0052       IWCmean=0.0175;
0053       N100_IWC=7.43*1e3;B1=-2.21;N1000_IWC=13.7;B2=-3.94;
0054    elseif T<=-35 & T>-40
0055       IWCmean=0.0126;
0056       N100_IWC=1.98*1e4;B1=-2.29;N1000_IWC=10.3;B2=-4.37;
0057    elseif T<=-40 & T>-45
0058       IWCmean=0.0034;
0059       N100_IWC=7.50*1e3;B1=-3.23;N1000_IWC=4.86;B2=-3.23;
0060    elseif T<=-45 & T>-50
0061       IWCmean=0.0025;
0062       N100_IWC=5.60*1e3;B1=-3.15;N1000_IWC=4.00;B2=-3.15;
0063    elseif T<=-50 & T>-55
0064       IWCmean=0.0018;
0065       N100_IWC=3.89*1e3;B1=-3.83;N1000_IWC=0.86;B2=-3.83;
0066    elseif T<=-55 &T>=-60
0067       IWCmean=0.0009;
0068       N100_IWC=5.58*1e3;B1=-3.85;N1000_IWC=8.06;B2=-3.85;
0069 end
0070 
0071 A1=N100_IWC/100^(B1);
0072 A2=N1000_IWC/1000^(B2);
0073 warning off
0074 D0=(A2/A1)^(1/(B1-B2));
0075 warning on
0076 n=length(D);
0077 if D0>20 & D0<3000
0078    A1=N100_IWC*1e6/(1e-4)^(B1);
0079    A2=N1000_IWC*1e6/(1e-3)^(B2);
0080    N2=A2.*D.^(B2)*IWCmean;
0081    N1=A1.*D.^(B1)*IWCmean;
0082    for i=1:1:n
0083        if N1(i)<=N2(i)
0084           N(i)=N1(i);
0085        else
0086           N(i)=N2(i);
0087        end
0088    end
0089  
0090 elseif D0<=20
0091        A2=N1000_IWC*1e6/(1e-3)^(B2);
0092        N2=A2.*D.^(B2)*IWCmean;
0093        N=N2;
0094 
0095 elseif D0>3000
0096        A1=N100_IWC*1e6/(1e-4)^(B1);
0097        N1=A1.*D.^(B1)*IWCmean;
0098        N=N1;
0099 end
0100 
0101 y=N;

Generated on Mon 15-Sep-2014 13:31:28 by m2html © 2005