Refreshing the MATLAB codes

matlab/RunLowtran.m

@@ -1,13 +1,44 @@
+clear;
 
-alt_km = 0;
-zenithangle = [0, 60, 80];
+%% Set parameters
+% Units: distance in km, wavelength in nm, angle in degree
+model = 5;   % selects the geographical - seasonal model atmosphere
+             % 0: If meteorological data are specified (horizontal path only)
+             % 1: Tropical Atmosphere
+             % 2: Midlatitude Summer
+             % 3: Midlatitude Winter
+             % 4: Subarctic Summer
+             % 5: Subarctic Winter
+             % 6: 1976 US Standard
+             % 7: If a new model atmosphere (e.g. radiosonde data) is to be read in
 
-p.model=5;
-p.h1=alt_km;
-p.angle=zenithangle;
-p.wlshort= 200;
-p.wllong=30000;
 
-T = lowtran_transmission(p);
+%% For a horizontal (constant-pressure) path
+[wavelength_x, transmittance_y] = lowtran_horizaltrans(...
+                     'model',model,...
+                     'altitude',0,...
+                     'transmission_distance',10,...
+                     'wavelength_start',200,...
+                     'wavelength_end',2000);
+figure(1);
+plot(wavelength_x, transmittance_y)
+ylim([0,1])
+xlabel('wavelength (nm)')
+ylabel('transmittance')
+title({'Horizontal transmittance at altitude 0 km'; ...
+       'with transmission distance of 10 km at subarctic winter.'})
 
-plot_transmission(T)
+%% For a vertical or slant path from a certain altitude to space
+[wavelength_x, transmittance_y] = lowtran_groud2space(...
+                     'model',model,...
+                     'altitude',0,...
+                     'zenith_angle',45,...      % vector could work
+                     'wavelength_start',200,...
+                     'wavelength_end',2000);
+figure(2);
+plot(wavelength_x, transmittance_y)
+ylim([0,1])
+xlabel('wavelength (nm)')
+ylabel('transmittance')
+title({'Transmittance from altitude 0 km to space'; ...
+       'with zenith angle 45° at subarctic winter.'})

matlab/lowtran_groud2space.m

@@ -0,0 +1,65 @@
+function [wavelength,transmittance] = lowtran_groud2space(varargin)
+% Lowtran model from Matlab. 
+% Senario: a vertical or slant path from a certain altitude to space
+% https://www.scivision.dev/matlab-python-user-module-import/
+assert(~verLessThan('matlab', '9.5'), 'Matlab >= R2018b required')
+
+%% Deal with input values
+% Order of parameters and default values: 
+%     'model', 5;
+%     'altitude', 0;
+%     'zenith_angle', 45;
+%     'wavelength_start', 200;
+%     'wavelength_end', 2000;
+occupy = [0,0,0,0,0];
+for i = 1:length(varargin)
+    switch class(varargin{i})
+        case 'char'
+            if strcmp(varargin{i},'model')
+                model = varargin{i+1};
+                occupy(1) = 1;
+            elseif strcmp(varargin{i},'altitude')
+                altitude = varargin{i+1};
+                occupy(2) = 1;
+            elseif strcmp(varargin{i},'zenith_angle')
+                zenith_angle = varargin{i+1};
+                occupy(3) = 1;
+            elseif strcmp(varargin{i},'wavelength_start')
+                wavelength_start = varargin{i+1};
+                occupy(4) = 1;
+            elseif strcmp(varargin{i},'wavelength_end')
+                wavelength_end = varargin{i+1};
+                occupy(5) = 1;
+            end
+    end
+end
+if occupy(1) == 0
+    model = 0;
+end
+if occupy(2) == 0
+    altitude = 10;
+end
+if occupy(3) == 0
+    zenith_angle = 45;
+end
+if occupy(4) == 0
+    wavelength_start = 1;
+end
+if occupy(5) == 0
+    wavelength_end = 1;
+end
+
+%% Apply lowtran code
+p.model = model;
+p.h1 = altitude;
+p.angle = zenith_angle;
+p.wlshort = wavelength_start;
+p.wllong = wavelength_end;
+
+c1 = py.dict(p);
+T = py.lowtran.transmittance(c1);
+transmittance = squeeze(xarray2mat(T{'transmission'}));
+transmittance = transmittance.';
+wavelength = xarray2mat(T{'wavelength_nm'});
+
+end

matlab/lowtran_horizaltrans.m

@@ -0,0 +1,64 @@
+function [wavelength,transmittance] = lowtran_horizaltrans(varargin)
+% Lowtran model from Matlab.
+% Senario: a horizontal (constant-pressure) path
+% https://www.scivision.dev/matlab-python-user-module-import/
+assert(~verLessThan('matlab', '9.5'), 'Matlab >= R2018b required')
+
+%% Deal with input values
+% Order of parameters and default values: 
+%     'model', 5;
+%     'initial_altitude', 0;
+%     'transmission_distance', 10;
+%     'wavelength_start', 200;
+%     'wavelength_end', 2000;
+occupy = [0,0,0,0,0];
+for i = 1:length(varargin)
+    switch class(varargin{i})
+        case 'char'
+            if strcmp(varargin{i},'model')
+                model = varargin{i+1};
+                occupy(1) = 1;
+            elseif strcmp(varargin{i},'altitude')
+                altitude = varargin{i+1};
+                occupy(2) = 1;
+            elseif strcmp(varargin{i},'transmission_distance')
+                transmission_distance = varargin{i+1};
+                occupy(3) = 1;
+            elseif strcmp(varargin{i},'wavelength_start')
+                wavelength_start = varargin{i+1};
+                occupy(4) = 1;
+            elseif strcmp(varargin{i},'wavelength_end')
+                wavelength_end = varargin{i+1};
+                occupy(5) = 1;
+            end
+    end
+end
+if occupy(1) == 0
+    model = 0;
+end
+if occupy(2) == 0
+    altitude = 10;
+end
+if occupy(3) == 0
+    transmission_distance = 1;
+end
+if occupy(4) == 0
+    wavelength_start = 1;
+end
+if occupy(5) == 0
+    wavelength_end = 1;
+end
+
+%% Apply lowtran code
+p.model = model;
+p.h1 = altitude;
+p.range_km = transmission_distance;
+p.wlshort = wavelength_start;
+p.wllong = wavelength_end;
+
+c1 = py.dict(p);
+T = py.lowtran.horiztrans(c1);
+transmittance = squeeze(xarray2mat(T{'transmission'}));
+wavelength = xarray2mat(T{'wavelength_nm'});
+
+end