Plotting filled contours on top of worldmap

Hi all,

I was trying to plot a filled contour on top of a worldmap but for some reason one of the values seem to be drawn all over the map as shown. I used the following code:

lat = 30:5:75;
lon = 5:5:50;
temp = [20, 18, 45, 53, 5, 44, 13, 11, 35, 48];
lat=reshape(lat,2,[]);
lon=reshape(lon,2,[]);
temp=reshape(temp,2,[]);
load coastlines
worldmap('world')
contourfm(lat,lon,temp)
geoshow(coastlat,coastlon,'color','k')
contourcbar
colormap(jet)

However the following block of code with contourm is giving a contour line with all the different colors (values) in temp plotted:

lat = 30:5:75;
lon = 5:5:50;
temp = [20, 18, 45, 53, 5, 44, 13, 11, 35, 48];
lat=reshape(lat,2,[]);
lon=reshape(lon,2,[]);
temp=reshape(temp,2,[]);
load coastlines
worldmap('world')
contourm(lon,lat,temp)
geoshow(coastlat,coastlon,'color','k')
contourcbar
colormap(jet)

Wondering how to get the same while using contourfm and a worldmap, and where I have been doing it wrong.

Thanks

Answer 1

[Voss]

I'm not able to see the problem as described, using the data posted.

However, check the order of the arguments you're using in contourm. You have contourm(lon,lat,temp), but contourfm(lat,lon,temp).

lat should be first in both.

lat = -85:5:85;
lon = -175:5:175;
[lat,lon] = meshgrid(lat,lon);
temp = 5+48*rand(size(lat));

figure()
load coastlines
worldmap('world')
contourfm(lat,lon,temp)
geoshow(coastlat,coastlon,'color','k')
contourcbar
colormap(jet)

figure()
load coastlines
worldmap('world')
% contourm(lon,lat,temp)
contourm(lat,lon,temp)
geoshow(coastlat,coastlon,'color','k')
contourcbar
colormap(jet)

[Mathan]

Thanks. I actually wanted to plot the temperature contours only between the latitude and longitude values given inlat = -85:5:85 and lon = -175:5:175 (just for this particular region), and leave the rest of the entire worldmap just white.

Thanks

[Voss]

Those are the values I'm using. Change them to what you like.

[Mathan]

So I used the values in my original question and the result turned out to be like this:

lat = 30:5:75;
lon = 5:5:50;
temp = [20, 18, 45, 53, 5, 44, 13, 11, 35, 48];
figure()
load coastlines
worldmap('world')
contourfm(lat,lon,temp)
geoshow(coastlat,coastlon,'color','k')
contourcbar
colormap(jet)

[Voss]

It doesn't make sense to try to make a contour from three vectors. That's why I made meshgrid-style lat and lon matrices and a temp matrix.

[Mathan]

Ah ok..I get that now. Thank you so much.

[Voss]

You're welcome!