Confusion about "alpha" band for MODIS Aqua

I’m working with modis:09:CREFL data for a harmful algal blooms paper, and I am trying to figure out how to call the chlorophyll-a band, which I believe is the "alpha" band, but I’m not sure because it doesn’t have a clear description. Is it possible I have to derive it myself? I doubt it because NASA’s SeaDAS software has chl-a as a built-in option.