Plot a precipitation grid, Matlab

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SuzieChan 2020-4-22

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https://ww2.mathworks.cn/matlabcentral/answers/519895-plot-a-precipitation-grid-matlab

评论： Star Strider 2020-4-22

采纳的回答： Star Strider

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Hi, I want to plot a precipitation grid across the extent of my DEM.

The data I have are for 8 locations and show 2 things: (i) lat/long; (ii) total precip for each location.

Can you help me use the meshgrid and scatteredinterpolant functions to do this?

Here are the data:

%Lat     Long      Total Precip (mm)
2879 -1.57772    1020
406  -1.73752    981
3642 -1.70167    1002
3362 -1.74618    1500
3147 -1.7017     1807
274  -1.69155    1492
2494 -1.61264    1325
227  -1.609      997

% Define the data
lat=precip_data(:,1);
lon=precip_data(:,2);
total_precip=precip_data(:,3);
% Do I need to change the lat/long corrdinates to projected UTM?
% DEM coordinate system is CT_TransverseMercator / OSGB1936 datum.
% How do I create the meshgrid and scatteredInterpolant for each of the 8 data?

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Answer 1

Star Strider 2020-4-22

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https://ww2.mathworks.cn/matlabcentral/answers/519895-plot-a-precipitation-grid-matlab#answer_427629

在 MATLAB Online 中打开

Try this:

D = [53.2879 -1.57772    1020
    53.406  -1.73752    981
    53.3642 -1.70167    1002
    53.3362 -1.74618    1500
    53.3147 -1.7017     1807
    53.274  -1.69155    1492
    53.2494 -1.61264    1325
    53.227  -1.609      997];
N = 20;                                                     % Size Of Interpolation Vectors/Matrices
Ltv = linspace(min(D(:,1)), max(D(:,1)), N);                % Latitude Vector For Interpolation
Lnv = linspace(min(D(:,2)), max(D(:,2)), N);                % Longitude Vector For Interpolation
[Ltm,Lnm] = ndgrid(Ltv, Lnv);                               % Matrices For Interpolation
Pm = griddata(D(:,1), D(:,2), D(:,3), Ltm, Lnm);            % Interpolate
figure
surf(Ltm, Lnm, Pm)
grid on
view(40,40)
xlabel('Latitude')
ylabel('Longitude')
zlabel('Precipitation (Interpolated)')

Change 'N’ to get different results.

.

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SuzieChan 2020-4-22

编辑：SuzieChan 2020-4-22

Hi Star.

How can I plot this surface across the extent of my DEM? Do I need to change the surface coordinate system to UTM first? I want it to look like a 2D precip gradient across the DEM surface.

Star Strider 2020-4-22

I have no idea what you are talking about.

You simply asked for an interpolation approach using the data you posted, and I provided it. If you are using Mapping Toolbox functions (that I do not have access to because I do not have the Mapping Toolbox), then perhaps a similar approach exists in its functions.

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