I am trying to combine two raster layers (one is nighttime satellite data, the other is the GPW population density data). I am using raster calculator to combine the two (the following is for a division operation, but the same problem occurs even for addition or subtraction) but get stripes of values, which tend to be either 0 or nodata. I attach a screenshot to show what this looks like:
Why is this happening? I have made sure the raster layers are georeferenced with the same system (WGS84) and have even tried aligning the rasters, but to no avail. Sorry if this is a rookie question - I'm fairly new to the software.
EDIT: http://beta.sedac.ciesin.columbia.edu/data/set/gpw-v4-population-density gpw is 2015 version of this data
satellite data is here: http://ngdc.noaa.gov/eog/dmsp/downloadV4composites.html particularly the stable lights layer of 2013