Mean for 4D

I have a .mat file. The dimensions for u and v are 9 (years) x 7 (months) x 119 x 177

How can i take the mean over each year?? How to handle the 4D data? The result should 9(year)*119*117

load('ice_drift_2006_2015_winter.mat', 'long1', 'lat1', 'u', 'v', 'flag')

Answer 1

[James Tursa]

umean = squeeze(mean(u,2));