Assessing the viability of measuring the light response of solar-induced chlorophyll fluorescence (SIF) from space

Peter Somkuti,  Colorado State University,  peter.somkuti@colostate.edu (Presenter)
Jennifer Johnson,  Carnegie Institution,  jjohnson@carnegiescience.edu

Throughout the course of a day, terrestrial vegetation undergoes a change in solar illumination as the position of the sun in the sky moves from sunrise to sunset. With this variation of incident irradiance, the solar-induced chlorophyll fluorescence (SIF) emitted by the plants changes as well as a result of two separate components: the total absorbed radiance and the physiological status of the vegetation in question.

This so-called light response can be reliably measured in laboratory conditions as well as ground-based measurement sites. Space-based measurements, however, are inherently more difficult due to limitations from revisit times and spatial sampling. Most SIF-capable space-based instrumentation is further limited due to their polar orbits, which only allow measurements around their equatorial crossing time. For many currently operating instruments this results in almost exclusively mid-day measurements. Since the launch of OCO-3 and its subsequent installation onboard the International Space Station, we now have access to a SIF measurement record with larger variations in terms of measurement time-of-day. Upcoming instruments, such as the geostationary GeoCarb (launch in 2023), have the potential of even further expanding the coverage of SIF measurements.

Using an observing system simulation experiment-type framework, we explore the potential of measuring SIF light response curves using a combination of both existing (e.g., OCO-2, OCO-3) and future (e.g., GeoCarb) instruments. We analyze various spatial and temporal aggregation options to understand in which regions and under which conditions we can expect sufficient coverage of the light response curve to then further infer the photosynthetic capacity of the underlying vegetation.

Poster: Poster_Somkuti__89_25.pdf 

Presentation Type: Poster

Session: 1.2c Results expected from future missions

Session Date: Monday (6/14) 9:45 AM