Advanced

Simultaneous assimilation of SMOS soil moisture and atmospheric CO2 in-situ observations to constrain the global terrestrial carbon cycle

Scholze, M. LU ; Kaminski, T.; Knorr, W. LU ; Blessing, S.; Vossbeck, M.; Grant, J. P. LU and Scipal, K. (2015) In Remote Sensing of Environment 180. p.334-345
Abstract

Carbon dioxide (CO 2) is the most important anthropogenic greenhouse gas contributing to about half of the total anthropogenic change in the Earth's radiation budget. And about half of the anthropogenic CO2 emissions stay in the atmosphere, the remainder is taken up by the biosphere. It is of paramount importance to better understand CO2 sources and sinks and their spatio-temporal distribution. In the context of climate change this information is needed to improve the projections of future trends in carbon sinks and sources. Since the terrestrial carbon and water cycles are tightly coupled by biological plant processes, i.e. through the stomatal gas exchange with the atmosphere, it is expected that... (More)

Carbon dioxide (CO 2) is the most important anthropogenic greenhouse gas contributing to about half of the total anthropogenic change in the Earth's radiation budget. And about half of the anthropogenic CO2 emissions stay in the atmosphere, the remainder is taken up by the biosphere. It is of paramount importance to better understand CO2 sources and sinks and their spatio-temporal distribution. In the context of climate change this information is needed to improve the projections of future trends in carbon sinks and sources. Since the terrestrial carbon and water cycles are tightly coupled by biological plant processes, i.e. through the stomatal gas exchange with the atmosphere, it is expected that information on the soil moisture state will help to constrain terrestrial carbon fluxes. In the present feasibility study we employ the Carbon Cycle Data Assimilation System CCDAS to pioneer the assimilation of the SMOS L3 soil moisture product together with another biophysical data set - in this case atmospheric CO2 flask samples. The two data streams are assimilated into a process-based model of the terrestrial carbon cycle over two years. CCDAS aims to optimise model process parameters and subsequently land surface CO2 exchange fluxes. We find that the assimilation of SMOS data improves the agreement with independent soil moisture data from the active ASCAT instrument. In both cases the assimilation also improves the fit of modelled atmospheric CO2 to the observations at flask sampling sites which have not been used in the assimilation. Reduction of uncertainty relative to the prior is generally high for both regional net ecosystem productivity and net primary productivity and considerably higher than for assimilating CO2 only, which quantifies the added value of SMOS observations as a constraint on the terrestrial carbon cycle. The study demonstrates a high potential for a SMOS L4 carbon flux product.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
SMOS soil moisture, Terrestrial carbon cycle, Uncertainty estimation, Variational data assimilation
in
Remote Sensing of Environment
volume
180
pages
334 - 345
publisher
Elsevier
external identifiers
  • scopus:84977943904
ISSN
0034-4257
DOI
10.1016/j.rse.2016.02.058
language
English
LU publication?
yes
id
3893d49d-418b-4e2f-b988-eb2116386c06
date added to LUP
2016-12-22 08:22:07
date last changed
2017-11-05 05:11:29
@article{3893d49d-418b-4e2f-b988-eb2116386c06,
  abstract     = {<p>Carbon dioxide (CO <sub>2</sub>) is the most important anthropogenic greenhouse gas contributing to about half of the total anthropogenic change in the Earth's radiation budget. And about half of the anthropogenic CO<sub>2</sub> emissions stay in the atmosphere, the remainder is taken up by the biosphere. It is of paramount importance to better understand CO<sub>2</sub> sources and sinks and their spatio-temporal distribution. In the context of climate change this information is needed to improve the projections of future trends in carbon sinks and sources. Since the terrestrial carbon and water cycles are tightly coupled by biological plant processes, i.e. through the stomatal gas exchange with the atmosphere, it is expected that information on the soil moisture state will help to constrain terrestrial carbon fluxes. In the present feasibility study we employ the Carbon Cycle Data Assimilation System CCDAS to pioneer the assimilation of the SMOS L3 soil moisture product together with another biophysical data set - in this case atmospheric CO<sub>2</sub> flask samples. The two data streams are assimilated into a process-based model of the terrestrial carbon cycle over two years. CCDAS aims to optimise model process parameters and subsequently land surface CO<sub>2</sub> exchange fluxes. We find that the assimilation of SMOS data improves the agreement with independent soil moisture data from the active ASCAT instrument. In both cases the assimilation also improves the fit of modelled atmospheric CO<sub>2</sub> to the observations at flask sampling sites which have not been used in the assimilation. Reduction of uncertainty relative to the prior is generally high for both regional net ecosystem productivity and net primary productivity and considerably higher than for assimilating CO<sub>2</sub> only, which quantifies the added value of SMOS observations as a constraint on the terrestrial carbon cycle. The study demonstrates a high potential for a SMOS L4 carbon flux product.</p>},
  author       = {Scholze, M. and Kaminski, T. and Knorr, W. and Blessing, S. and Vossbeck, M. and Grant, J. P. and Scipal, K.},
  issn         = {0034-4257},
  keyword      = {SMOS soil moisture,Terrestrial carbon cycle,Uncertainty estimation,Variational data assimilation},
  language     = {eng},
  month        = {06},
  pages        = {334--345},
  publisher    = {Elsevier},
  series       = {Remote Sensing of Environment},
  title        = {Simultaneous assimilation of SMOS soil moisture and atmospheric CO<sub>2</sub> in-situ observations to constrain the global terrestrial carbon cycle},
  url          = {http://dx.doi.org/10.1016/j.rse.2016.02.058},
  volume       = {180},
  year         = {2015},
}