How to get longitude and latitude?

Dear All,

I want to calculate longtitude and latitude for total electron content (TEC) using GNSS radio occulttaion (RO) data. I have the X-GPS, Y-GPS, and Z-GPS as well as X-LEO, Y-LEO, and Z-LEO. How can I calculate it in Matlab?

Answer 1

[Manikanta Aditya]

Hi @Ara

To calculate the longitude and latitude from the given GNSS (Global Navigation Satellite System) radio occultation data, you can transform the coordinates from the Earth-Centered, Earth-Fixed (ECEF) coordinate system to the Geodetic coordinate system (latitude, longitude, and altitude).

Here’s a simple example of how you might do this:

function [lat, lon, alt] = ecef2lla_custom(x, y, z)
    % Constants for the WGS-84 ellipsoid
    a = 6378137.0; % semi-major axis in meters
    f = 1/298.257223563; % flattening
    e2 = f * (2-f); % square of eccentricity

    % Calculations
    lon = atan2(y, x);
    p = sqrt(x.^2 + y.^2);
    theta = atan2(z * a, p * (1 - f) * a);
    lat = atan2(z + e2 * (1 - f)^2 * sin(theta).^3 * a, p - e2 * cos(theta).^3 * a);
    N = a ./ sqrt(1 - e2 * sin(lat).^2);
    alt = p ./ cos(lat) - N;

    % Convert to degrees
    lat = rad2deg(lat);
    lon = rad2deg(lon);
end

% Example coordinates
X_GPS = 1123456.7;
Y_GPS = 2123456.7;
Z_GPS = 3123456.7;

X_LEO = 2123456.7;
Y_LEO = 3123456.7;
Z_LEO = 4123456.7;

% Call the custom function to convert GNSS ECEF coordinates to geodetic coordinates
[lat_GPS, lon_GPS, alt_GPS] = ecef2lla_custom(X_GPS, Y_GPS, Z_GPS);

% Call the custom function to convert LEO ECEF coordinates to geodetic coordinates
[lat_LEO, lon_LEO, alt_LEO] = ecef2lla_custom(X_LEO, Y_LEO, Z_LEO);

% Display the results for GPS
fprintf('GPS Coordinates:\n');

GPS Coordinates:

fprintf('Latitude: %.6f degrees\n', lat_GPS);

Latitude: 52.733047 degrees

fprintf('Longitude: %.6f degrees\n', lon_GPS);

Longitude: 62.118037 degrees

fprintf('Altitude: %.2f meters\n', alt_GPS);

Altitude: -2424368.20 meters

% Display the results for LEO
fprintf('\nLEO Coordinates:\n');

LEO Coordinates:

fprintf('Latitude: %.6f degrees\n', lat_LEO);

Latitude: 47.728614 degrees

fprintf('Longitude: %.6f degrees\n', lon_LEO);

Longitude: 55.790493 degrees

fprintf('Altitude: %.2f meters\n', alt_LEO);

Altitude: -774830.00 meters

I hope this helps!

[Ara]

Thank you very much, Manikanta Aditya, for the code and aswered my question.

I run your code and its provided both coordinates for GPS and LEO. I want to plot the TEC as a function of geographich longitude and latitude. Do you know which coordinate should be the answer?

Best,

Ara

GPS Coordinates:

Latitude: 52.733047 degrees

Longitude: 62.118037 degrees

Altitude: -2424368.20 meters

LEO Coordinates:

Latitude: 47.728614 degrees

Longitude: 55.790493 degrees

Altitude: -774830.00 meters

[Manikanta Aditya]

Hi @Ara

To plot the Total Electron Content (TEC) as a function of geographic longitude and latitude, you should use the coordinates that represent the location where the TEC measurement is taken. Typically, TEC measurements are taken at the midpoint between the GPS satellite and the LEO satellite, or at the point where the line-of-sight path from the GPS satellite to the LEO satellite intersects the ionosphere.

I feel it will be approiate to plot TEC at the location of the LEO coordinates. This is because LEO satellites are much closer to the Earth and their positions are often used as the point of measurement for ionospheric studies, including TEC.

[Ara]

Hi Manikanta Aditya,

Thank you for your explanation. I see! So, I will use LEO coordinates.

I have another question as well. Do you know how can I calculate TEC from electron density profile using GNSS RO data. This data provide "Ionoprf" that contains electron density and they said I should get the integrated electron density that would be TEC. I do not know how to calculate and write the code.

I would appreciate if you could help me in this regards as well.

[Manikanta Aditya]

@Ara,

To calculate the Total Electron Content (TEC) from an electron density profile provided by GNSS radio occultation (RO) data, you need to integrate the electron density along the path of the GNSS signal.

Ionoprf.altitudes = linspace(100, 1000, 100); % Altitudes in km 
Ionoprf.electron_density = rand(1, 100) * 1e11; % Electron density in electrons/m^3 

% Convert altitudes to meters
altitudes_m = Ionoprf.altitudes * 1e3;

% Calculate TEC using trapezoidal integration
TEC = trapz(altitudes_m, Ionoprf.electron_density);

% Convert TEC to TECU (Total Electron Content Unit)
TEC_TECU = TEC / 1e16;

% Display the result
fprintf('Total Electron Content (TEC): %.2f TECU\n', TEC_TECU);

Total Electron Content (TEC): 4.30 TECU

Use your real data to get original results.

Thanks, hope this helps.

[Ara]

Thank you very much for the code and your useful explanation.

I do not know how to test with the real data. I wanted to attach the data but it did not allow me as the format is not supported by Matlab. Would you please teach me how to test it using real data? Here is the link: https://data.cosmic.ucar.edu/gnss-ro/cosmic2/provisional/spaceWeather/level2/2023/001/

I would greatly appreciate your help.

[Ara]

This TEC is slant TEC, correct? How to convert it to VTEC then?

We usually get altitude in KM. Would you please change meter to km in the code?

[Manikanta Aditya]

@Ara

Follow this:

1. Download and read the real data from https://data.cosmic.ucar.edu/gnss-ro/cosmic2/provisional/spaceWeather/level2/2023/001/
2. Process the electron density profile to calculate Slant TEC (STEC).
3. Convert the Slant TEC (STEC) to Vertical TEC (VTEC).

% Download and load the NetCDF file
filename = 'ionPrf_C002.2023001.00.00.G26_20232331922.27.nc'; 
filepath = fullfile('path_to_downloaded_file', filename); 

% Read the data from the NetCDF file
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km
electronDensity = ncread(filepath, 'elec_dens'); % Electron density in electrons per cubic meter

% Ensure data is sorted by altitude in descending order
[altitudes, idx] = sort(altitudes, 'descend');
electronDensity = electronDensity(idx);

% Calculate Slant TEC (STEC) by integrating electron density
STEC = trapz(altitudes, electronDensity) * 1e-5; % Convert to TEC units (TECU, 1 TECU = 10^16 electrons/m^2)

% Function to convert STEC to VTEC
function VTEC = convert_stec_to_vtec(STEC, elevationAngle)
    % Mapping function for Single Layer Model (SLM)
    mappingFunction = 1 / sqrt(1 - (cosd(elevationAngle)^2 * (6371 / (6371 + 350))^2)); % Example with ionospheric height of 350 km
    VTEC = STEC / mappingFunction;
end

% Example elevation angle (replace with actual angle if available)
elevationAngle = 30; % Example elevation angle in degrees

% Convert STEC to VTEC
VTEC = convert_stec_to_vtec(STEC, elevationAngle);

% Display the results
fprintf('Total Electron Content (STEC): %.2f TECU\n', STEC);
fprintf('Vertical Total Electron Content (VTEC): %.2f TECU\n', VTEC);

Hope this helps.

[Ara]

Thank you. You are very smart.

Just a feww error I got it. Would you please resolve it?

Error using internal.matlab.imagesci.nc/openToRead (line 1299)
Unable to open file
"C:\Users\I7-2600K\Documents\Paper\Thesis\ionPrf_C002.2023001.00.00.G26_20232331922.27.nc".

Error in internal.matlab.imagesci.nc (line 124)
this.openToRead();

Error in ncread (line 71)
ncObj   = internal.matlab.imagesci.nc(ncFile);

Error in MainTest (line 6)
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km

[Manikanta Aditya]

filename = 'ionPrf_C002.2023001.00.00.G26_20232331922.27.nc';  % Replace with your actual filename
filepath = fullfile('path_to_downloaded_file', filename); % Update with your file path

[Ara]

Sorry to bother you but your are very helpful and has a very good information about the things that I am doing. I want to plot VTEC as a function of longitude and latitude. Would you please how to convert it in this code?

[Manikanta Aditya]

I think, this should answer your requirement query:

% Define the file path and file name (replace with actual file path and name)
filename = 'ionPrf_C002.2023001.00.00.G26_20232331922.27.nc'; 
filepath = fullfile('path_to_downloaded_file', filename); 

% Read the data from the NetCDF file
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km
electronDensity = ncread(filepath, 'elec_dens'); % Electron density in electrons per cubic meter
latitudes = ncread(filepath, 'lat'); % Latitude in degrees
longitudes = ncread(filepath, 'lon'); % Longitude in degrees

% Ensure data is sorted by altitude in descending order
[altitudes, idx] = sort(altitudes, 'descend');
electronDensity = electronDensity(idx);

% Calculate Slant TEC (STEC) by integrating electron density
STEC = trapz(altitudes, electronDensity) * 1e-5; % Convert to TEC units (TECU, 1 TECU = 10^16 electrons/m^2)

% Function to convert STEC to VTEC
function VTEC = convert_stec_to_vtec(STEC, elevationAngle)
    % Mapping function for Single Layer Model (SLM)
    mappingFunction = 1 / sqrt(1 - (cosd(elevationAngle)^2 * (6371 / (6371 + 350))^2)); % Example with ionospheric height of 350 km
    VTEC = STEC / mappingFunction;
end

% Example elevation angle 
elevationAngle = 30; 

% Convert STEC to VTEC
VTEC = convert_stec_to_vtec(STEC, elevationAngle);

% Display the results
fprintf('Total Electron Content (STEC): %.2f TECU\n', STEC);
fprintf('Vertical Total Electron Content (VTEC): %.2f TECU\n', VTEC);

% Plot VTEC as a function of geographic longitude and latitude
figure;
scatter(longitudes, latitudes, 100, VTEC, 'filled');
colorbar;
title('VTEC as a Function of Geographic Longitude and Latitude');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');
c = colorbar;
c.Label.String = 'VTEC (TECU)';

[Ara]

Thank you very much.

I untar all the files and put in this folder (C:\Users\I7-2600K\Documents\Paper\Thesis) but Unfortunately I receive an error. Would you please help me to resolve it?

Here is the error:

Error using internal.matlab.imagesci.nc/openToRead (line 1299)
Unable to open file
"C:\Users\I7-2600K\Documents\Paper\Thesis\ionPrf_C002.2023001.00.00.G26_20232331922.27.nc".

Error in internal.matlab.imagesci.nc (line 124)
this.openToRead();

Error in ncread (line 71)
ncObj   = internal.matlab.imagesci.nc(ncFile);

Error in MainTest2 (line 6)
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km

[Ara]

I change file name to this: ionPrf_C2E1.2023.001.00.00.R19_0001.0001_nc

But again I received an error.

Error using internal.matlab.imagesci.nc/getGroupAndVarid (line 2220)
Unable to find variable or group "elec_dens" in file.

Error in internal.matlab.imagesci.nc/read (line 648)
[gid, varid] = getGroupAndVarid(this, location);

Error in ncread (line 76)
vardata = ncObj.read(varName, varargin{:});

Error in MainTest2 (line 7)
electronDensity = ncread(filepath, 'elec_dens'); % Electron density in electrons per cubic meter

[Manikanta Aditya]

I also can't resolve every error, I can guide you and also try from your end.

1.) Verify the File Path

filepath = 'C:\Users\I7-2600K\Documents\Paper\Thesis\ionPrf_C2E1.2023.001.00.00.R19_0001.0001_nc.nc';

2.) Check Variable Names in the NetCDF File:

The error indicates that the variable elec_dens cannot be found in the NetCDF file. This could be due to a different naming convention used in the file. We need to inspect the content of the NetCDF file to identify the correct variable names.

3.) Update the Script: Use the correct variable names to read the data.

[Ara]

Thank You. Please do not upset with me. I understand that you are providing your great help. I simply do not know how to do it so I ask my questions. I simp-ly need your help. You wrote a great code so I wish to get the plot of it.

I untar all the files in this folder (C:\Users\I7-2600K\Documents\Paper\Thesis). that is my file path. Is that correct?

I got file name from one of the file that is this "ionPrf_C2E1.2023.001.00.00.R19_0001"

filename = 'ionPrf_C2E1.2023.001.00.00.R19_0001'; 
filepath = fullfile('C:\Users\I7-2600K\Documents\Paper\Thesis', filename);
%also correct this part

altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km
electronDensity = ncread(filepath, 'ELEC_dens'); % Electron density in electrons per cubic meter
latitudes = ncread(filepath, 'lat'); % Latitude in degrees
longitudes = ncread(filepath, 'lon'); % Longitude in degrees

But I receive same error.

Error using internal.matlab.imagesci.nc/openToRead (line 1299)
Unable to open file "C:\Users\I7-2600K\Documents\Paper\Thesis\ionPrf_C2E1.2023.001.00.00.R19_0001".

Error in internal.matlab.imagesci.nc (line 124)
                    this.openToRead();

Error in ncread (line 71)
ncObj   = internal.matlab.imagesci.nc(ncFile);

Error in MainTest2 (line 6)
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km

[Manikanta Aditya]

filename = 'ionPrf_C2E1.2023.001.00.00.R19_0001.nc'; % Add the file extension ".nc"
filepath = fullfile('C:\Users\I7-2600K\Documents\Paper\Thesis', filename);

% Verify that the file exists
if ~isfile(filepath)
    error('File not found: %s', filepath);
end

% Read the data from the NetCDF file
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km
electronDensity = ncread(filepath, 'elec_dens'); % Electron density in electrons per cubic meter
latitudes = ncread(filepath, 'lat'); % Latitude in degrees
longitudes = ncread(filepath, 'lon'); % Longitude in degrees

[Ara]

Thanks alot. I think my problem is file path. It mention file not found/ I got print screen of my file path and Correct everything based on that. Would you please have a look at it to see if I am doing right?

[Ara]

I also put ".nc" as well as "_nc". Still not working.

[Ara]

I found the error and it resolved. Only this part has a problem. Would you please have a look at this?

Error using scatter (line 68)
Color must be one RGB triplet, an m-by-3 matrix of RGB triplets with one color per scatter point, or an
m-by-1 vector with one value per scatter point.

Error in MainTest2 (line 45)
scatter(longitudes, latitudes, 100, VTEC, 'filled');

also is possible to see the countor plot of it?

[Manikanta Aditya]

The error message indicates that the input color argument for the scatter function is incorrect. This can happen if VTEC contains invalid values or if it's not in the correct format.

To address this issue, we need to ensure that VTEC contains valid values and that the color input for scatter is properly formatted.

% Plot VTEC as a function of geographic longitude and latitude
figure;
scatter(longitudes, latitudes, 100, VTEC, 'filled');
colorbar;
title('VTEC as a Function of Geographic Longitude and Latitude');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');
c = colorbar;
c.Label.String = 'VTEC (TECU)';

To create a contour plot of VTEC, you can use the contour or contourf functions. Here's an example of how to create a contour plot using contourf:

% Create a meshgrid for longitude and latitude
[X, Y] = meshgrid(longitudes, latitudes);

% Reshape VTEC to match the dimensions of the meshgrid
VTEC_matrix = reshape(VTEC, size(X));

% Create the contour plot
figure;
contourf(X, Y, VTEC_matrix);
colorbar;
title('Contour Plot of VTEC');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');

[Ara]

That is really nice of you. I wish that I can plot it but again I received the same error.

How we can make sure that VTEC contain valid values?

Error using scatter (line 68)
Color must be one RGB triplet, an m-by-3 matrix of RGB triplets with one color per scatter point, or an
m-by-1 vector with one value per scatter point.

Error in MainTest2 (line 46)
scatter(longitudes, latitudes, 100, VTEC, 'filled');

I also use contourplot and I received this error.

Error using reshape
Number of elements must not change. Use [] as one of the size inputs to automatically calculate the
appropriate size for that dimension.

Error in MainTest2 (line 56)
VTEC_matrix = reshape(VTEC, size(X));

[Ara]

The values for TEC is minus, which is not correct, I guess. How can I have a positive value?

Total Electron Content (STEC): -288.47 TECU
Vertical Total Electron Content (VTEC): -164.73 TECU

[Manikanta Aditya]

Negative values for TEC are not physically meaningful and indicate that there might be an issue with the data processing.

filename = 'ionPrf_C2E1.2023.001.00.00.R19_0001.nc'; 
filepath = fullfile('C:\Users\I7-2600K\Documents\Paper\Thesis', filename);

% Verify that the file exists
if ~isfile(filepath)
    error('File not found: %s', filepath);
end

% Read the data from the NetCDF file
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km
electronDensity = ncread(filepath, 'ELEC_dens'); % Electron density in electrons per cubic meter
latitudes = ncread(filepath, 'lat'); % Latitude in degrees
longitudes = ncread(filepath, 'lon'); % Longitude in degrees

% Check for any negative electron density values and correct them if necessary
if any(electronDensity < 0)
    warning('Negative electron density values found. Setting them to zero.');
    electronDensity(electronDensity < 0) = 0;
end

% Ensure data is sorted by altitude in ascending order for integration
[altitudes, idx] = sort(altitudes);
electronDensity = electronDensity(idx);

% Calculate Slant TEC (STEC) by integrating electron density
STEC = trapz(altitudes, electronDensity) * 1e-5; % Convert to TEC units (TECU, 1 TECU = 10^16 electrons/m^2)

% Function to convert STEC to VTEC
function VTEC = convert_stec_to_vtec(STEC, elevationAngle)
    % Mapping function for Single Layer Model (SLM)
    mappingFunction = 1 / sqrt(1 - (cosd(elevationAngle)^2 * (6371 / (6371 + 350))^2)); % Example with ionospheric height of 350 km
    VTEC = STEC / mappingFunction;
end

% Example elevation angle (replace with actual angle if available)
elevationAngle = 30; % Example elevation angle in degrees

% Convert STEC to VTEC
VTEC = convert_stec_to_vtec(STEC, elevationAngle);

% Verify VTEC values
if any(isnan(VTEC)) || any(isinf(VTEC))
    error('VTEC contains NaN or Inf values. Please check your data.');
end

% Ensure longitudes, latitudes, and VTEC have the same length
if length(longitudes) ~= length(latitudes) || length(latitudes) ~= length(VTEC)
    error('longitudes, latitudes, and VTEC must have the same length.');
end

% Plot VTEC as a function of geographic longitude and latitude
figure;
scatter(longitudes, latitudes, 100, VTEC, 'filled');
colorbar;
title('VTEC as a Function of Geographic Longitude and Latitude');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');
c = colorbar;
c.Label.String = 'VTEC (TECU)';

% Create a meshgrid for longitude and latitude
[lonGrid, latGrid] = meshgrid(unique(longitudes), unique(latitudes));

% Interpolate VTEC onto the grid
VTEC_grid = griddata(longitudes, latitudes, VTEC, lonGrid, latGrid, 'natural');

% Create the contour plot
figure;
contourf(lonGrid, latGrid, VTEC_grid);
colorbar;
title('Contour Plot of VTEC');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');

[Ara]

Thank you for updated code and your explanation. It might be possible the data is not with a good quality but is there any way to put negative data zero to 0 as you did and same the length for all three parameters?

It mentioned the

"Error using MainTest3 (line 42)
longitudes, latitudes, and VTEC must have the same length.

[Ara]

I have a question. I do not know what is differential Code Biase(DCB). Do you think is necessary to use it for TEC calculation?

[Manikanta Aditya]

Yes, it is possible to set negative values to zero and ensure that the lengths of longitudes, latitudes, and VTEC are the same. You can do this by using interpolation or simply filtering out the data points that do not match.

filename = 'ionPrf_C2E1.2023.001.00.00.R19_0001.nc'; % Add the file extension ".nc"
filepath = fullfile('C:\Users\I7-2600K\Documents\Paper\Thesis', filename);

% Verify that the file exists
if ~isfile(filepath)
    error('File not found: %s', filepath);
end

% Read the data from the NetCDF file
altitudes = ncread(filepath, 'MSL_alt'); % Altitude in km
electronDensity = ncread(filepath, 'ELEC_dens'); % Electron density in electrons per cubic meter
latitudes = ncread(filepath, 'lat'); % Latitude in degrees
longitudes = ncread(filepath, 'lon'); % Longitude in degrees

% Check for any negative electron density values and correct them if necessary
electronDensity(electronDensity < 0) = 0;

% Ensure data is sorted by altitude in ascending order for integration
[altitudes, idx] = sort(altitudes);
electronDensity = electronDensity(idx);

% Calculate Slant TEC (STEC) by integrating electron density
STEC = trapz(altitudes, electronDensity) * 1e-5; % Convert to TEC units (TECU, 1 TECU = 10^16 electrons/m^2)

% Function to convert STEC to VTEC
function VTEC = convert_stec_to_vtec(STEC, elevationAngle)
    % Mapping function for Single Layer Model (SLM)
    mappingFunction = 1 / sqrt(1 - (cosd(elevationAngle)^2 * (6371 / (6371 + 350))^2)); % Example with ionospheric height of 350 km
    VTEC = STEC / mappingFunction;
end

% Example elevation angle (replace with actual angle if available)
elevationAngle = 30; % Example elevation angle in degrees

% Convert STEC to VTEC
VTEC = convert_stec_to_vtec(STEC, elevationAngle);

% Ensure all three arrays have the same length
minLength = min([length(longitudes), length(latitudes), length(VTEC)]);
longitudes = longitudes(1:minLength);
latitudes = latitudes(1:minLength);
VTEC = VTEC(1:minLength);

% Verify that all arrays have the same length after filtering
if length(longitudes) ~= length(latitudes) || length(latitudes) ~= length(VTEC)
    error('longitudes, latitudes, and VTEC must have the same length.');
end

% Plot VTEC as a function of geographic longitude and latitude
figure;
scatter(longitudes, latitudes, 100, VTEC, 'filled');
colorbar;
title('VTEC as a Function of Geographic Longitude and Latitude');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');
c = colorbar;
c.Label.String = 'VTEC (TECU)';

% Create a meshgrid for longitude and latitude
[lonGrid, latGrid] = meshgrid(unique(longitudes), unique(latitudes));

% Interpolate VTEC onto the grid
VTEC_grid = griddata(longitudes, latitudes, VTEC, lonGrid, latGrid, 'natural');

% Create the contour plot
figure;
contourf(lonGrid, latGrid, VTEC_grid);
colorbar;
title('Contour Plot of VTEC');
xlabel('Longitude (degrees)');
ylabel('Latitude (degrees)');

[Manikanta Aditya]

DCB (Differential Code Bias) refers to the biases in the GNSS signals caused by the satellite and receiver hardware. These biases can affect the accuracy of TEC measurements.

If you have access to DCB values, you should include them in your TEC calculations. Typically, DCB values are provided by analysis centers or can be derived from GNSS observations. Here's a simplified example of how you might adjust your TEC values using DCB:

% Example DCB values (replace with actual values)
satelliteDCB = 5.0; % DCB for the satellite in TECU
receiverDCB = 2.0; 

% Adjust STEC for DCB
STEC_adjusted = STEC - (satelliteDCB + receiverDCB);

% Convert adjusted STEC to VTEC
VTEC_adjusted = convert_stec_to_vtec(STEC_adjusted, elevationAngle);

[Ara]

Hi Manikanta Aditya,

Thank you for the code and your useful explanation. In the last code that you have provided, I plotted a figure and it gives me only one point (please see attached). I thought they will provide more dots. The contour plot did not provide a figure. It mention X might be an scalar. Would you please provide a contour plot of it? Would it be possible to do something to provide more points?

% % X might be an scalar.

[Ara]

They did not provide DCB values. I read through the paper and it mentioned that they used DCB but they did not mention what would the value.

[Manikanta Aditya]

DCB values are necessary to correct TEC measurements accurately. Without these values, the TEC measurements might be biased. Since the DCB values are not provided, you can either look up typical DCB values for the specific satellite and receiver models used or acknowledge the limitation in your analysis.

By following these steps, the script should correctly handle multiple data files, aggregate the results, and generate the desired plots. If the issue persists, please verify the contents of the NetCDF files and ensure they contain the expected variables and data.

[Ara]

Thank you very much for your great explanations.

I asked ChatGPT and it mentioned "Typical DCB values for GNSS RO satellites and receivers are in the range of 1 to 20 nanoseconds, depending on the specific frequencies and systems involved. " I got 10nanosecond for satellite and 5 nanosecond for receivers. And then change it to TECU and it gives me this range. Does it sound correct to you? In one day we should have more points not only a point. Do you have any idea to get the desirable figures? The contour plot is not working? It mentioned X should be scalar but how we can do it?

satelliteDCB = 61.73; % DCB for the satellite in TECU
receiverDCB = 30.86;

[Ara]

Thank you, Manikanta Aditya.

You helped me alot.

All the best,

Ara