checkMODISA_chlor_a_Latitude.r

## NOTE: as is this code downloads 3 files, 22Mb in total


 ## files to compare
 files <- c("A2015283.L3m_DAY_CHL_chlor_a_4km.nc", "A2015284.L3m_DAY_CHL_chlor_a_4km.nc", "A2015285.L3m_DAY_CHL_chlor_a_4km.nc")
 baseu <- "http://oceandata.sci.gsfc.nasa.gov/cgi/getfile"
 
 ## download the files
 for (i in seq_along(files)) {
   if (!file.exists(files[i])) {
     download.file(file.path(baseu, files[i]), files[i], mode = "wb")
   }
 }
 
library(ncdf4)

## open each file and print "lat" range
for (i in seq_along(files)) {
  nc <- nc_open(files[i])
  lat <- ncvar_get(nc, "lat")
  print(sprintf("%s latitude range: %f,%f", files[i], min(lat), max(lat)))
  nc_close(nc)
}
 
# [1] "A2015283.L3m_DAY_CHL_chlor_a_4km.nc latitude range: -89.979179,89.979164"
# [1] "A2015284.L3m_DAY_CHL_chlor_a_4km.nc latitude range: -269.979187,-90.020836"
# [1] "A2015285.L3m_DAY_CHL_chlor_a_4km.nc latitude range: -89.979179,89.979164"