Extreme events driving year-to-year differences in gross primary
productivity across the US
Abstract
Solar-Induced chlorophyll Fluorescence (SIF) has previously been shown
to strongly correlate with gross primary productivity (GPP), however
this relationship has not yet been quantified for the recently launched
TROPOspheric Monitoring Instrument (TROPOMI). Here we use a Gaussian
mixture model to develop a parsimonious relationship between SIF from
TROPOMI and GPP from flux towers across the conterminous United States
(CONUS). The mixture model indicates the SIF-GPP relationship can be
characterized by a linear model with two terms. We then estimate GPP
across CONUS at 500-m spatial resolution over a 16-day moving window. We
find that CONUS GPP varies by less than 4% between 2018 and 2019.
However, we observe four extreme precipitation events that induce
regional GPP anomalies: drought in west Texas, flooding in the
midwestern US, drought in South Dakota, and drought in California. Taken
together, these events account for 28% of the year-to-year GPP
differences across CONUS.