I got a little confused while compositing monthly chlorophyll-a images of MODIS-Aqua for the period 2003-2018.
While compositing the data I also was created the counts of valid pixels, that is, the number of pixels that contributed to the composite. So, in a year, I would know which points had valid pixels for the 12 months.
The issue is that when I look at the [img TOP]count image[/img] I see horizontal lines that I do not understand their origin. These lines become even clear with [img MIDDLE]more years[/img] combined. Looking at the monthly chlorophyll images it seems to me the missing values are random and I do not see any tendency for the straight lines that appear on counts.
I computed the counts using different software and this issue is present independent of the software used. However, using [img BOTTOM]Google Earth Engine[/img], the problem is not there and the distribution of the counts looks more natural to me.
So, what might be the issue?
I appreciate your kind help in understanding the reason for this issue.
Thanks in advance for your consideration.