One thing to be aware of is that colors that are below red correspond to spikes, or focused areas of large changes in Z. These do not always show up well in a contour plot.
load vars
surf(LAT,LON,Z,'FaceColor','interp','EdgeColor','interp')
colormap(CB)
Still, I can see what you mean. When I create a contourm plot, I can see areas where the colors should be but are not.
LatLim=[35,39];
LonLim=[11,17];
CX1=[140,300];
figure
worldmap(LatLim,LonLim)
levels = linspace(CX1(1),CX1(2),size(CB,1));
contourm(LAT,LON,Z,levels)
colormap(CB)
caxis(CX1)
I think the issue is related to your data not being sampled regularly (is scattered rather than gridded). This means the corresponding LAT value changes column to column, and the corresponding LON value changes row to row. Were your LAT and LON data gridded in this fashion, then I don't think you would see this issue.
One approach is to use scatteredInterpolant to create a gridded data set. However, this will change how things appear in the areas you do not have data (the data is not 'square' on a map).
F = scatteredInterpolant(LAT(:),LON(:),Z(:));
Lat = linspace(LatLim(1),LatLim(2),200);
Lon = linspace(LonLim(1),LonLim(2));
[lonq,latq] = meshgrid(Lon,Lat);
zq = F(latq,lonq);
figure
worldmap(LatLim,LonLim)
contourfm(latq,lonq,zq,levels,'LineStyle','none')
colormap(CB);
hc=colorbar;
hc.Ticks=linspace(CX1(1),CX1(2),size(CB,1)+1);
hc.TickLabels=num2str(hc.Ticks','%.1f');
caxis(CX1);
The fix here, then, might be to do something to the gridded results to exclude areas for which you do not have any data. I played around with inpolygon. By getting the boundary values of the original LAT and LON variables, I can then use inpolygon with the new gridded latq and lonq values to set the values where the data is unknown to nan.
% find the boundaries of the orginal LAT/LON data
X = [LON(:,1);LON(end,:)';flipud(LON(:,end));LON(1,:)'];
Y = [LAT(:,1);LAT(end,:)';flipud(LAT(:,end));LAT(1,:)'];
in = inpolygon(lonq,latq,X,Y);
zq(~in)=nan;
figure
ax=worldmap(LatLim,LonLim);
levels = linspace(CX1(1),CX1(2),size(CB,1));
contourfm(latq,lonq,zq,levels,'LineStyle','none');
setm(ax,'FontSize',10);
colormap(CB);
hc=colorbar;
% ylabel(hc,['TB_{',fn{idx}(3:end),'} (K)']);
hc.FontSize=9;
hc.Ticks=linspace(CX1(1),CX1(2),size(CB,1)+1);
hc.TickLabels=num2str(hc.Ticks','%.1f');
caxis(CX1);
This may actually be better, as you are now only showing data where you have data.
