ChinaSpec: a network for long-term in situ measurements of solar-induced
fluorescence and reflectance in China
Abstract
Remotely sensed solar-induced fluorescence (SIF) has emerged as a novel
approach for terrestrial vegetation monitoring. The in situ continuous
optical remote sensing tool in conjunction with concurrent eddy
covariance (EC) flux measurements provides a new opportunity to advance
terrestrial ecosystem science. Here we introduce a network of
ground-based SIF observations at flux tower sites across the mainland
China referred as ChinaSpec. Until now, it consists of 15 tower sites
including 5 cropland sites, 4 grassland sites, 4 forest sites and 2
wetland sites. At each of these sites, an automated spectroscopy system
was deployed to collect continuous super-high resolution spectra for
high-frequency SIF retrievals in synergy with EC flux measurements. The
goal of ChinaSpec is to provide ground SIF measurements and promote the
collaborations between optical remote sensing and EC flux communities in
China. We present here the details of instrument specifications, data
collection and processing procedures, data sharing and utilization
protocols, and future plans. Furthermore, we show the examples how
ground SIF observations can be used to track vegetation photosynthesis
from diurnal to seasonal scales, to assist in the validation of
fluorescence models and satellite SIF products (e.g., from OCO-2, TanSat
and TROPOMI) with the measurements from these sites since 2016. This
network of SIF observations could improve our understanding of the
controls on the biosphere-atmosphere carbon exchange and enable the
improvement of carbon flux predictions. This SIF network will also help
integrate ground SIF measurements with EC flux networks which will
advance ecosystem and carbon cycle researches globally.