NCEP and MODIS data map scales are not matching

Hi,

I am trying to plot wind vector over modis sateelite data map using pcolor() and quiver(). The script is making a map, however, the scales of both maps are not overlapping. Does anyone have any idea what could be the problem and how to fix it? Thanks in advance!

*note: the script and result image is attched below.

% chlorophyll data
file='modis_mapped_monthly_4km.nc';
ncdisp(file);
var=ncread(file, 'var_name');
lat=ncread(file, 'lat');
lon=ncread(file, 'lon');
[lat1,lon1]=meshgrid(lat,lon);
var_map=pcolor(lon1,lat1,var)
var_map.EdgeAlpha = 0;  
load coastlines
hold on
plot(coastlon,coastlat,'k')
colorbar

% wind vector 
wnd_vec='uvwnd.10m.mon.mean.nc'
ncdisp(wnd_vec)
lat=ncread(wnd_vec, 'lat')
lon=ncread(wnd_vec, 'lon')
[lat1,lon1]=meshgrid(lat,lon)
u=ncread(wnd_vec, 'uwnd')
v=ncread(wnd_vec, 'vwnd')
hold on
quiver(lat1,lon1,u,v,'k')

Answer 1

[Shubham]

Hey @Mansi Gupta,

I understand that you are trying to plot the wind vector over the MODIS satellite data map however the two plots are not completely overlapping.

The arguments passed in the “pcolor()” and “quiver()” are not in the same order. This seems to be the reason which is causing mismatch in the dimensions of the wind vector data and the MODIS satellite data.

Here is a code snippet where wind vectors are plotted over a world map.

% Generate sample data 
lon = -180:5:175; 
lat = -90:5:85; 
[lon1, lat1] = meshgrid(lon, lat); 
u = sind(lon1);  % Sample wind vector component u 
v = cosd(lat1);  % Sample wind vector component v 

% Create figure 
figure 

% Set up world map 
ax = axesm('MapProjection', 'eqdcylin'); 
axis off 

% Plot world map 
load coastlines 
geoshow(coastlat, coastlon, 'Color', 'k', 'LineWidth', 1); 

% Add boundary to the world map 
framem 

% Plot wind vectors 
quiverm(lat1, lon1, u, v, 'k'); 

% Adjust figure 
title('Wind Vectors over World Map') 

It produced the following output figure:

You can also refer to the following:

https://www.mathworks.com/help/matlab/ref/pcolor.html

https://www.mathworks.com/help/releases/R2020b/matlab/ref/quiver.html

Hope this helps!!