|Chlorophyll-dependent fluorescence over North America. |
Most of the signal is attributed to cornfields.
The strong signals shown in the figure can be attributed to massive photosynthesis in North American cornfields, which exceeds that of the Amazon basin during the North American growing season.
Fluorescence by chlorophyll increases when plants are under stressed, and can be used on a laboratory scale to monitor response to drought or pathogens. Back at the satellite level, this phenomenon is also used to phytoplankton blooms in oceans.