Earthdata Forum

I downloaded a GeoTiff from this website https://neo.gsfc.nasa.gov/view.php?datasetId=MY1DMM_CHLORA&year=2016

On QGIS, the numbers goes from 6-255. The legend on the website goes from 0.01 - 60mg/mg3. Can anyone provide me with guidance on how to display the data using mg/mg3?

Hello,

NEO is an older website. The 0-255 numbers refer to the data scaling, which was 256-bit. This can be converted to the mg/m3 scale (there used to be a scale online) but there is an easier way.

Use the Giovanni system, https://giovanni.gsfc.nasa.gov/. Select MODIS-Aqua chlorophyll monthly data for your month of choice, select a region if you do not want a global image, and plot the data (using the Plot Data button). The output can be downloaded as GeoTIFF. Also note that you can select a better color palette data range (or palette) and plot the data on a log scale, which is usually better for chlorophyll a data.

If you need additional guidance, please reply.

You can also download the MODIS monthly Chla from L3/4 browser, or try the methods described here: https://oceancolor.gsfc.nasa.gov/data/download_methods/

Let us know if you find these helpful.
Guoqing