Earthdata Forum

Hello, I'm currently working with Chlorophyll-a data in R. I obtained the dataset (SNPP_VIIRS.20201231T211200.L2.OC.nc) from NASA's OceanColor website. After loading the data into R and extracting the variables (geophysical_data/chlor_a, navigation_data/latitude, navigation_data/longitude), I subsetted the data to focus on the area where longitude is between -121 and -115, and latitude is between -20.5 and -18. For example, at lon = -117.1744, lat = -18.00001, I got chlor_a = 0.07979830.

When I plotted the data of chlor_a, I noticed that areas which appear blank on the official image from the website show Chlorophyll values in my plot. Does the blank in the image indicate the clounds block but the Chlorophyll-a can still be calculated based on the algorithm? Could I have made an error in my process or they do have the values in the subset area? Thank you!

This algorithm returns the near-surface concentration of chlorophyll-a (chlor_a) in mg m-3, calculated using an empirical relationship derived from in situ ...The Chlorophyll Concentration dataset shows global near-real-time concentrations of chlorophyll-a in the ocean. Concentrations are presented in milligrams per cubic meter (mg/m3). Chloro phylls are pigments found in photosynthetic plants that transform sunlight into energy.