ASICA results have led to a number of major research outputs including two completed PhD theses, four published papers, three submitted manuscripts, and one article in production for Nature. These papers document many of the goals of the Action that have been reached successfully:
An accepted paper in Nature, led by INPE PI Luciana Gatti (ASICA) on the analysis of long-term CO2 records from our flasks: Gatti et al., Amazonia as a carbon source linked to deforestation and climate change, Nature, 2021, in press
- To complete this paper we had to continue the measurements from four air strips for another five years, adding the period 2016-2021 to the existing 2010-2015 record. Analysis was done jointly with the full team
A published paper in Nature Geosciences: Peters, W. et al. Increased water-use efficiency and reduced CO2 uptake by plants during droughts at a continental scale. Nature Geoscience 19, 1 (2018).
- This paper resulted from our investments in δ¹³C inverse modeling, supported by ASICA.
The paper on mechanisms of drought-stress during the ENSO of 2015/2016: Schaik, E. van et al. Changes in surface hydrology, soil moisture and gross primary production in the Amazon during the 2015/2016 El Niño. Philosophical Transactions Of The Royal Society Of London Series B-Biological Sciences 373, 20180084 (2018).
- This paper resulted from our work on biosphere modeling as well as hydrological modeling for the basin, done to better understand isotopic exchange and the carbon balance of the region.
The paper from Dipayan Paul (ASICA) describing the ASICA dryer that we developed under this Action: Paul, D. et al. Evaluation of a field-deployable NafionTM-based air-drying system for collecting whole air samples and its application to stable isotope measurements of CO2. Atmospheric Measurement Techniques 13, 4051–4064 (2020).
- This paper was a major achievement and a milestone in the project, as we indicated already before the action that the capacity to dry very wet tropical air would be key to our success
A publication by Erik van Schaik (ASICA) describing a new retrieval method for sun-induced fluorescence suitable for tropical environments like the Amazon: Schaik, E. van et al. Improved SIFTER v2 algorithm for long-term GOME-2A satellite retrievals of fluorescence with a correction for instrument degradation. Atmospheric Measurement Techniques 13, 4295–4315 (2020).
- The spin-off to look into SIF retrievals came by when we realized this dataset might hold new clues to the photosynthesis response of vegetation during the ENSO drought of 2015/2016. A specific tropical retrieval (accounting for high water vapor) was needed though. The resulting dataset is freely downloadable for everyone.
A paper by Getachew Adnew (ASICA) on plant experiments with the UU-built Δ17O instrument: Adnew, G. A., Pons, T. L., Koren, G., Peters, W. & Röckmann, T. Leaf-scale quantification of the effect of photosynthetic gas exchange on Δ17O of atmospheric CO2. Biogeosciences 17, 3903–3922 (2020).
- This paper could not have been possible without the investments in high-precision measurement techniques that we did in ASICA.
A paper by Koren et al (2018): Widespread reduction in sun-induced fluorescence from the Amazon during the 2015/2016 El Niño. Philosophical Transactions Of The Royal Society Of London Series B-Biological Sciences 373, 20170408 (2018).
- This paper uniquely describes the ENSO impact on Amazon rain forest photosynthesis as documented through SIF and hydrological modeling
A submitted paper by Getachew Adnew (ASICA) on the determination of leaf conductance from Δ17O: Adnew et al., Exploring the use of 17O-excess of CO2 for estimating mesophyll conductance of C3 and C4 plants, submitted to Plant Physiology, (2021)
- This paper tried a breakthrough method to use 17O (instead of 18O or 13C) to measure leaf-conductance in plants. The plan to do this was suggested in our Action, and the covid-19 extension allowed us to complete the manuscript and submit it.
A paper in preparation by Gerbrand Koren (ASICA) on the legacy drought of 2016 detected from ASICA measurements: Koren et al., “Persistent impact of the 2015/16 El Nino drought on the 2016 dry season in the Amazon”, (2021)
- This paper identifies a so-far undetected secondary drought that followed the ENSO of 2015/2016, and in fact constitutes a carry-over from that drought through soil moisture deficits that persist. It resulted from our previous investments in modeling of this region, and in the unique record of CO2 that we now also publsihed in Nature.
