Plot a precipitation grid, Matlab

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)
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

% 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?

Answer 1

[Star Strider]

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.

.

[SuzieChan]

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]

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.