Chlorophyll fluorometers are inexpensive, easy to use, and consume little power. Their deployment in global and regional observation systems forms a basis for understanding primary production and ocean carbon cycles via estimates of chlorophyll concentration from fluorescence as a proxy for phytoplankton biomass. Yet studies have shown large global biases in estimates of chlorophyll concentration based on fluorometry1. What can we learn from our knowledge of spectral absorption of various phytoplankton photosynthetic and photoprotective pigments both common to, and diverse across, various species that can help produce a fluorometer with less global variability? How can we create a calibration standard for fluorometers that leads to open, traceable, and repeatable calibrations that correspond to a global mean? We present some design ideas, calibration experiments, and in situ field results that light the way towards the "better chlorophyll fluorometer".
1. Roesler, C., Uitz, J., Claustre, H., Boss, E., Xing, X., Organelli, E., Briggs, N., Bricaud, A., Schemchtig, C., Poteau, A., D'Ortenzio, F., Ras, F., Drapeau, J., Haëntjens, N., and Barbieux, M. (2017). Recommendations for obtaining unbiased chlorophyll estimates from in situ chlorophyll fluorometers: A global analysis of WET Labs ECO sensors. Limnology and Oceanography: Methods, 15(6), 572-585.