my work at BG | Research Highlights | Publications
My work at BGI
Current work is focused on three main areas:
- Using data driven methods to partition water fluxes into component parts e.g. soil evaporation and plant transpiration.
- Finding signatures of ecosystem plant status from sub-daily patterns in water, carbon and energy fluxes.
- Examining the underlying physical and biochemical processes controlling latent heat fluxes.
EGU 2019: Ecosystem scale estimates of transpiration: an overview of methods for eddy covariance data.
Jacob Nelson (1), Oscar Perez-Priego (1), Rafael Poyatos (2), Sha Zhou (3), Yao Zhang (3), Mirco Migliavacca (1), Nuno Carvalhais (1), Markus Reichstein (1), and Martin Jung (1)
(1) Max Planck Institute for Biogeochemistry, Jena, Germany (email@example.com), (2) CREAF, Cerdanyola del Vallès, Barcelona, Spain, (3) Department of Earth and Environmental Engineering, Columbia University, New York, NY, 10027, USA
''See the presentation here.
Coupling Water and Carbon Fluxes to Constrain Estimates of Transpiration: The TEA Algorithm
While it is widely known that plants need water to survive, exactly how much water plants in an ecosystem use is hard to quantify. However, many places have been measuring how much total water leaves an ecosystem, both the water plants use directly and the water that simply evaporates from the soil or the surfaces of leaves, using eddy covariance towers. These eddy covariance towers also measure the coming and going of carbon, such as the total amount of carbon taken up by photosynthesis. Here we present the idea that by using the signals from both photosynthesis and total water losses together, we can capture the water signal related to plants, namely, transpiration, using an algorithm called Transpiration Estimation Algorithm (TEA). To verify that TEA is working the way we expect, we test it out using artificial ecosystem simulations where transpiration and photosynthesis come from mathematical models. By thoroughly testing TEA, we have a better idea of how it will work in a real world situation, hopefully opening the door for a better understanding on how much water ecosystems are using and how it might affect our changing planet.
Comparison of mean seasonal cycle of T/ET (5‐day aggregation) results from model simulations (JSBACH, CASTANEA, and MuSCIA) and TEA algorithm partitioning of original EC data (ET, GPP, and meteorological variables). Modeled years were 2001–2006 for FI‐Hyy and FR‐Hes, and 1998–2003 for DE‐Tha. Seasonal cycles are an average of 5 days. TEA = Transpiration Estimation Algorithm; EC = eddy covariance; ET = evapotranspiration; GPP = gross primary productivity. FI‐Hyy = Hyytiälä, Finland; FR‐Hes = Hesse beech forest in France; DE‐Tha = Anchor Station Tharandt, Germany.
See the full paper here.
- Stoy, Paul C., Tarek El-Madany, Joshua B. Fisher, Pierre Gentine, Tobias Gerken, Stephen P. Good, Shuguang Liu, Diego G. Miralles, Oscar Perez-Priego, Todd H. Skaggs, Georg Wohlfahrt, Ray G. Anderson, Martin Jung, Wouter H. Maes, Ivan Mammarella, Matthias Mauder, Mirco Migliavacca, Jacob A. Nelson, Rafael Poyatos, Markus Reichstein, Russell L. Scott, and Sebastian Wolf. “Reviews and Syntheses: Turning the Challenges of Partitioning Ecosystem Evaporation and Transpiration into Opportunities.” Biogeosciences Discussions, March 12, 2019, 1–47. https://doi.org/10.5194/bg-2019-85
- Nelson, Jacob A., Nuno Carvalhais, Matthias Cuntz, Nicolas Delpierre, Jurgen Knauer, Jérome Ogée, Mirco Migliavacca, Markus Reichstein, and Martin Jung. Coupling Water and Carbon Fluxes to Constrain Estimates of Transpiration: The TEA Algorithm. Journal of Geophysical Research: Biogeosciences, December 21, 2018. https://doi.org/10.1029/2018JG004727
- Nelson, Jacob A., Nuno Carvalhais, Mirco Migliavacca, Markus Reichstein, and Martin Jung. Water-Stress-Induced Breakdown of Carbon Water Relations: Indicators from Diurnal FLUXNET Patterns. Biogeosciences 15, no. 8 (April 20, 2018): 2433â€“47. https://doi.org/10.5194/bg-15-2433-2018
- Nelson, Jacob A., and Bruce Bugbee. 2015. “Analysis of Environmental Effects on Leaf Temperature under Sunlight, High Pressure Sodium and Light Emitting Diodes.” PloS One 10 (10): e0138930. https://doi.org/10.1371/journal.pone.0138930
- Nelson, Jacob A., and Bruce Bugbee. 2014. “Economic Analysis of Greenhouse Lighting: Light Emitting Diodes vs. High Intensity Discharge Fixtures.” PloS One 9 (6): e99010. https://doi.org/10.1371/journal.pone.0099010
Data and Code
Conferences and Workshops
- Examining Transpiration from Ecosystem to Global Scales, 5-7 September 2018 at the Max Planck Institute for Biogeochemistry in Jena, Germany. http://www.bgc.mpg.de/~jnelson/transpiration2018/
- Nelson, JA, N Carvalhais, M Cuntz, N Delpierre, J Knauer, M Migliavacca, J Ogee, M Reichstein, and M Jung. 2017. “Data Driven Estimation of Transpiration from Net Water Fluxes: The TEA Algorithm.” In AGU Fall Meeting Abstracts.
- Nelson, Jacob, Martin Jung, Nuno Carvalhais, Mirco Migliavacca, and Markus Reichstein. 2016. “Understanding Ecosystems’ Sub-Daily Water and Carbon Flux Changes during Dry-down Events.” In EGU General Assembly Conference Abstracts, 18:17549.