Huntzinger, Deborah (Debbie): Northern Arizona University (Project Lead)
Schwalm, Christopher: Woodwell Climate Research Center (Co-Investigator)
Fisher, Joshua: Chapman University (Institution Lead)
Bachelet, Dominique: Oregon State University (Participant)
Project Funding:
2012 - 2014
NRA: 2011 NASA: Carbon Monitoring System
Funded by NASA
Abstract:
This study will generate improved global estimates of land-atmosphere carbon exchange
by combining and enhancing the technical infrastructure and observational constraints
within the NASA Carbon Monitoring System (CMS) Flux Project with new “bottom-up”
a priori surface flux estimates. These new surface flux products will be derived from a community of models that represent our best process-based understanding of how carbon
is exchanged between the land and the atmosphere. We will leverage and build off of an
existing NASA funded grant: The Multi-Scale Synthesis and Terrestrial Model
Intercomparison Project (MsTMIP). MsTMIP is a coordinated, large-scale
intercomparison effort that combines common forcing data and a detailed simulation
protocol in order to improve the diagnosis and attribution of carbon sources and sinks
across both global and regional scales.
What MsTMIP does that other intercomparisons have failed to do, is create a framework
that isolates, interprets, and helps inform understanding of how differences in process
parameterizations among current “bottom-up” models impact their flux estimations. As a
result, the MsTMIP framework allows for the isolation and quantification of the intermodel variance in estimates of land-atmosphere carbon exchange due to model structure,
or variations in the types of processes consider in the model and how these process are
represented. This inter-model variance provides a robust assessment of uncertainty in
land surface priors due to varying model physics, a component currently missing from the
CMS-Flux system.
CMS-Flux has the ability to produce ensembles of atmospheric CO2 distributions using
perturbations to transport and surface fluxes. These ensembles can help build
understanding of the relationship between surface flux and atmospheric CO2
concentrations, particularly if the consistency (or inconsistency) between surface flux
representations and atmospheric CO2 measurements can be linked back to representation
of processes within the models. However, to do so effectively CMS-Flux needs to include
a priori flux estimates that are more representative of our current understanding of landatmosphere sources and sinks than what is currently in
the system. In other words, the a priori flux estimates need to be informed by the range of
models used by the scientific community given that there is no consensus on the “best”
model overall. CMS-Flux is currently limited with respect to the land surface bottom-up
priors because: 1) it uses only two closely related land surface models, and as a result has
a restricted representation of the “true” uncertainty in the land surface bottom-up fluxes;
2) the uncertainty in the bottom-up fluxes themselves is not quantified in the system; and,
3) the atmospheric inversion system is disconnected from the TBMs in that one unified
system cannot currently be run.
This proposed effort improves the current CMS-Flux product with four key advances.
First, we propose to leverage the existing NASA funded MsTMIP activity to generate
new a priori “bottom-up” land-surface flux products for the CMS-Flux system. Second,
we will quantify uncertainties in a priori flux estimates. Third, we will develop the
technical infrastructure of CMS-Flux to handle multiple land-surface models as priors.
Four, we will combine the new a priori input products with the enhanced CMS
infrastructure to test the influence of prior flux estimates (and their associated
uncertainty) on posterior flux estimations from the inversion. Finally, the new
infrastructure will also be used to compare existing terrestrial biospheric model estimates
to the atmospheric CO2 constraints within CMS-Flux, providing another means of
evaluating understanding of the processes controlling land-atmosphere carbon exchange.
Combined, this proposed activity will expand the operational-use of CMS-Flux and allow
for more robust posterior flux estimates and their associated uncertainties.
Publications:
Jung, M., Reichstein, M., Schwalm, C. R., Huntingford, C., Sitch, S., Ahlstrom, A., Arneth, A., Camps-Valls, G., Ciais, P., Friedlingstein, P., Gans, F., Ichii, K., Jain, A. K., Kato, E., Papale, D., Poulter, B., Raduly, B., Rodenbeck, C., Tramontana, G., Viovy, N., Wang, Y., Weber, U., Zaehle, S., Zeng, N. 2017. Compensatory water effects link yearly global land CO2 sink changes to temperature. Nature. 541(7638), 516-520. DOI: 10.1038/nature20780
Schwalm, C. R., Huntzinger, D. N., Fisher, J. B., Michalak, A. M., Bowman, K., Ciais, P., Cook, R., El-Masri, B., Hayes, D., Huang, M., Ito, A., Jain, A., King, A. W., Lei, H., Liu, J., Lu, C., Mao, J., Peng, S., Poulter, B., Ricciuto, D., Schaefer, K., Shi, X., Tao, B., Tian, H., Wang, W., Wei, Y., Yang, J., Zeng, N. 2015. Toward "optimal" integration of terrestrial biosphere models. Geophysical Research Letters. 42(11), 4418-4428. DOI: 10.1002/2015GL064002
2013 NASA Terrestrial Ecology Science Team Meeting Poster(s)
- Multi-Scale Synthesis and Terrestrial Model Intercomparison Project – A Systematic Approach for Evaluating Land-Atmosphere Flux Estimates
-- (Deborah Nicole Huntzinger, Christopher R Schwalm, Anna M Michalak, Mac Post, Kevin M Schaefer, Andy Jacobson, Yaxing Wei, Robert B. Cook)
[abstract]
More details may be found in the following project profile(s):
