On Estimating Global Monthly Carbon Dioxide Fluxes by Region, utilizing the observational data obtained by “IBUKI”

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On Estimating Global Monthly Carbon Dioxide Fluxes by Region,
utilizing the observational data obtained
by the Greenhouse gases Observing SATellite “IBUKI” (GOSAT)

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1. Summary of the achievement

(1) Improved precision of CO2 source/sink (flux) estimates
Monthly CO2 sources and sinks (net fluxes) in 64 subcontinental-scale
regions over a 12 month period from June 2009 to May 2010 were estimated
using both CO2 concentrations retrieved from the soundings of the
Greenhouse gases Observing SATellite “IBUKI” (GOSAT) and the published
ground-based CO2 values (Note 1). It has been confirmed that uncertainties
in CO2 flux estimates can be reduced significantly (as much as by about 50%)
with the addition of the GOSAT data to the ground-based monitoring data
(refer to the attached document for more detail). This constitutes the first
concrete demonstration of the utility of satellite data in estimating global
CO2 fluxes. This result was published as a scientific paper in the
Scientific Online Letters on the Atmosphere (SOLA) issued by the
Meteorological Society of Japan on October 29, 2011.

(2) Contribution of the CO2 flux estimation with GOSAT data
i) With the addition of the GOSAT observational data to the ground-based
monitoring data, significant uncertainty reduction was achieved in the
monthly regional CO2 flux estimates. It is expected that continuous CO2
monitoring by GOSAT and further refinement of the data processing
methods will lead to effective monitoring of variations in monthly
regional CO2 fluxes.

ii) In particular, uncertainties of CO2 fluxes estimated for South America,
Africa, the Near and Middle East, and Asia have been reduced by as much
as about 50% (annual average) with the addition of the GOSAT data to the
ground-based monitoring data.

iii) The seasonal trends of summertime CO2 uptake associated with plant
photosynthesis and wintertime CO2 emission in high latitudinal regions of
the northern hemisphere are broadly consistent with past findings. It is
expected that the response of terrestrial biosphere to future climate
change, in terms of changes in flux amounts, may be detected in its early
stage with continuing observation by GOSAT and further refinements in the
data processing methods.

iv) The global annual flux for the period of June 2009 to May 2010 was
evaluated at around 4 gigatons of carbon per year, which is almost
equivalent to the values calculated from the growth rates of CO2
concentrations in the atmosphere for this period. The validity of this
annual flux and the contributions of anthropogenic emissions or fluxes of
natural origin will be the subject of further investigations.

v) Monthly fluxes calculated from the GOSAT data and the ground-based
monitoring data in some regions show differences to those calculated from
only the ground-based monitoring data. It is expected that continuous
monitoring by GOSAT and further research undertakings will yield further
understanding of the CO2 flux behavior.

2. Next steps

(1) Evaluation and verification of the results of CO2 flux estimation by
overseas research institutes and researchers in the carbon cycle research
field.
The 64-regional monthly flux estimates will be disseminated to affiliated
researchers selected by means of GOSAT Research Announcements for Principal
Investigators, in order for these estimates to be evaluated and verified.
In addition we will evaluate the accuracy and consistency of the results by
means of comparisons with independent flux estimation results from overseas
research groups. At the same time, suggestions from researchers worldwide
engaged in this field will be collected by means of international workshops
and meetings. On the basis of these results, we intend to make improvements
as they prove necessary, and thereafter the monthly regional CO2 fluxes
will be recalculated (Note 3). With this improved CO2 flux data product, the
product of the three-dimensional distributions of CO2 concentration (Note 4)
will be prepared and released to the general public.

(2) Ongoing development of the GOSAT follow-on
With this first demonstration of the utility of the GOSAT data, we seek to
expand the contribution of GOSAT to carbon cycle research, global
environmental monitoring, and climate change policy making. The MOE, NIES
and JAXA have begun investigations aimed at the development of a GOSAT
follow-on – one with enhanced capacities for efficient measurements. A
launch date has been set for around 2016 at the earliest.
The GOSAT follow-on would carry an advanced Fourier Transform Spectrometer
in order to increase the number of measurements. Furthermore, improvements
will be made in the data processing algorithms and flux estimation models
in order to obtain more precise flux estimates.
With the planned launch of a satellite Orbital Carbon Observatory 2 (OCO-2)
by the United States in the near future, we intend to continue to
collaborate and cooperate internationally with these communities on the
measurement of greenhouse gases from space.

(Note 1)
Published global CO2 data from NOAA/ESRL/GMD as GLOBALVIEW-CO2 2011.
(Ref. http://www.esrl.noaa.gov/gmd/ccgg/globalview/co2/co2_intro.html)
Expressed as “GV data” in the attached document.

(Note 2)
Online journal of Scientific Online Letters on the Atmosphere (SOLA) issued
by the Meteorological Society of Japan
Title of the paper: On the benefit of GOSAT observations to the estimation
of regional CO2 fluxes
Authors: H. Takagi, T. Saeki, T. Oda, M. Saito, V. Valsala, D. Belikov,
R. Saito, Y. Yoshida, I. Morino, O. Uchino, R. J. Andres, T. Yokota,
and S. Maksyutov
Bibliography: SOLA, 2011, Vol. 7, 161-164, doi:10.2151/sola.2011-041

(Note 3)
This will be released as the Level 4A product of the GOSAT standard data
products.

(Note 4)
This will be released as the Level 4B product, 3D distribution of CO2
concentration at intervals of 6 hours in every 2.5 degree mesh, of the GOSAT
standard data products.

Appendix
On the estimation of regional CO2 fluxes from GOSAT observations
http://www.jaxa.jp/press/2011/10/20111028_ibuki_e.html#at

URL:
http://www.jaxa.jp/press/2011/10/20111028_ibuki_e.html

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