The monthly mean data, mesoscale grid boundaries of 20N - 40S,
115W - 60W, are presented in a matrix format consisting of 60 
rows (lattitude) by 55 columns (longitude). The upper left hand
corner,element (1,1), represents the mean data from the 1 degree
box centered at 19.5 N, 114.5 W. The mean data from the the 1
degree box centered at 39.5S, 60.5W is given in element (60,55).