How to calculate the area of each grid cell?

I have gridded data of air temperature with the spatial resolution 1.25 x 1.25 degrees (lon-lat). The data covers the Northern Hemisphere, and the first latitude is 90 degrees.

I need to calculate the area of each grid cell, and my approach is to do that from the latitude bands.

An alternative could be to read in the area of each grid cell directly from the netCDF file. Is that possible in MATLAB?

Here is my code I have tried; I am not sure if that is correct.

i=1:72;
j=2:73;
R=6371; % Earth's radius in km^2
deltalon=1.25; 
area=(pi/180)*R^2*((sind(latitude(i)) - sind(latitude(j)))*deltalon); % Area of each grid cell in km^2

Answer 1

[Chad Greene]

The easiest way is to use the cdtarea function in the Climate Data Toolbox for Matlab. For gridded coordinates Lat,Lon, syntax is just

A = cdtarea(Lat,Lon); 

for area in square meters, or

A = cdtarea(Lat,Lon,'km2'); 

for area in square kilometers.

[Lei Liu]

Thank you, Chad! And thanks for CDT!

I met the same problem, and tried this toolbox. I also compared the calculated area with that estimated in ArcGIS, after reprojecting from geographic projection to an equal area projected one. The area calculated in Matlab with this tool was 26239000 km2, while that estimated in ArcGIS was 26567500 km2. It's acceptable. Good!

[Chad Greene]

Fantastic; thanks for the feedback, Lei!

[asutosh acharya]

Can someone help me to calculate area within the countour ? For exaplme the area within 2.5 degree global temparature contour .

Thank you