Initiating the ALOS Kyoto & Carbon Initiative
Å. Rosenqvist, T. Ogawa, M. Shimada and T. Igarashi
National Space Development Agency of Japan (NASDA)
Earth Observation Research Center (EORC)
Roppongi
1-9-9,
Minato-ku,
Tokyo
106-0032,
Harumi Triton Square,
X-22F,
Harumi1-8-10,Chuo-ku,
TokyoJapan
104-6023, Japan

Abstract - The ALOS Kyoto & Carbon Initiative is aninternational endeavour initialized by NASDA, with the main
objective to support information needs raised by the UNFCCC
Kyoto Protocol and by the international global carbon cycle
science community, by provision of systematic, consistent,
repetitive and regional scale data of the global forest cover. Ofcentral importance for the Initiative is a Dedicated DataAcquisition Strategy for the polarimetric Phased Array L-band
Synthetic Aperture Radar (PALSAR) sensor onboard theAdvanced Land Observation Satellite (ALOS) satellite, which,as a major project output, is foreseen to result in an extensive
data archive with consistent time series of dual-polarization(HH/HV) PALSAR data over any given land area on the Earth.
Tentative plans for derived data products include regional scale
image mosaics, maps of annual forest change, wetland flood
distribution/duration, and rice cultivation.

1. B ACKGROUND
1.1

The UNFCCC and the Kyoto Protocol
Climate change, caused by the rapid and uncontrolled
increase of greenhouse gases in the Earth’s atmosphere during
the past 150 years, is a major public, political and scientificconcern worldwide. Public concern resulted in the 1992
United Nations Framework Convention on Climate Change(UNFCCC), which is an official acknowledgement of theclimate change phenomenon as such, as well as a recognition
by international policy makers that immediate cross-borderactions are required to halt and reverse the current destructivetrend. The UNFCCC was in 1997 strengthened with theKyoto Protocol, which provides legally binding nationalemission reduction commitments, as well as a time table for
implementation. Although politically controversial and hotly
debated in every aspect, it is clear that when – or if –eventually ratified, the Protocol will not only constitute a
landmark agreement for the global environment, but also for
the international scientific community in that it puts
political pressure for quantitative measurements of carbon
sources and sinks with high, verifiable accuracy.
While CO2 released by burning of fossil fuels constitutes
the single most important emission source, the Kyoto
Protocol allows emissions to be balanced by vegetation,
which may sequester or release atmospheric carbon dependingon the land use, and this is where remote sensing potentially
may come into relevance.

1.2 Global carbon cycle science
Viewing the climate change issue in a broader context
than the Kyoto Protocol, the central role of the global carbon
cycle has long been recognized by the international science
community. The major concern here is incomplete
understanding of the processes that govern the global carbon
cycle, and the large uncertainties that are associated withcurrent models and measurements. These uncertainties are
partly results of lack of appropriate data or inadequacy of
existing data sets. This deficiency is being addressed by theIntegrated Global Observing Strategy Partnership (IGOS-P),
which calls for a united multi-diciplinary scientific effort toresolve the present uncertainties, through the establishmentof a dedicated global carbon cycle observation strategy. This
strategy involves characterization of the terrestrial,
atmospheric and oceanic components of the carbon cycle bysynergetic utilization of in situ, modelling and othermeasurement techniques, including remote sensing.
Although carbon cycle science thematically is moreexhaustive than the Kyoto Protocol, we note that both relate
to the same basic information needs - that for accurate
measurements of carbon sources and sinks. Hence, researchand support to one topic will inevitably also benefit theother, and vice versa.
2. T HE ALOS KYOTO & CARBON INITIATIVE
2.1 Science justification
The ALOS Kyoto & Carbon Initiative is based on theconviction that remote sensing data - and here specifically
ALOS PALSAR data - can play a significant role to support,
partly or fully, some of the information needs posed by theKyoto Protocol as well as by the scientific community
dealing with the terrestrial carbon cycle. In a recent report [1]by the Terrestrial Carbon Theme working group of IGOS-P,
the need for such support was voiced: “The challenges [to aterrestrial carbon observation strategy] are to ensure thatimportant existing observations continue and key newobservations are initiated [and] to identify activities andagencies willing to contribute to establishing global carbon
observations…”. The ALOS Kyoto & Carbon Initiative is aresponse to this request.
In the Kyoto context, the concept of remote sensing isless well known, and active effort from the remote sensing

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community to meet the specific Kyoto needs by adapting
mission design and intensifying R/D is required in order toassure that the technology is appropriately considered.
The Kyoto “data requirements” are however not easily
understood and to this end a workshop was organized in 1999
by the ISPRS and the University of Michigan [2], to review
the status and potential of remote sensing and to identify
areas of potential support. The ALOS Kyoto & Carbon
Initiative aims respond to three of the themes identified, as
outlined in §2.2 - §2.4 below:
2.2 Provision of systematic data observations and dataarchives
The fundamental need for systematic data observations
applies both to Kyoto as well as in the carbon cycle context.
Article 10(d) of the Kyoto Protocol states that countries shall“co-operate in scientific and technical research and promote
the maintenance and the development of systematic
observation systems and development of data archives toreduce uncertainties related to the climate system, [and] theadverse impacts of climate change...”. IGOS-P, in turn,states that “it is evident that further progress in our
understanding of the global carbon cycle and its likely future
evolution depends on improved observations of the terrestrial
carbon processes”.
Provision of systematic observations and establishment
of data archives for long-term studies is clearly one of thepotential strengths of remote sensing. However, sporadic
observations with local emphasis, which presently is how(high resolution) remote sensing data most commonly are
acquired, is not adequate as it does not provide a means for
extrapolation of locally developed methods and results to aregional scale context. In order to make remote sensing data
an attractive and useful data source in the context discussed
here, data acquisitions should be planned in a systematicmanner, with regional-continental scale coverage, fixed sensorcharacteristics, and a temporal repetition frequency adapted tothe phenomenon to be monitored. Furthermore, long-term
continuity of comparable sensor systems into, and beyond,the first emission commitment period (2008-2012), as wellas parallel operations of sensors/platforms withcomplementary characteristics are also important points toconsider.
The ALOS Kyoto & Carbon Initiative aims to respond to
this need through the establishment of a Dedicated Data
Acquisition Strategy in which the above points are taken into
account as far as possible. Ultimately a trade-off, where
ALOS technical constraints and other acquisition
requirements also will have to be taken into consideration,
the acquisition plan tentatively comprises PALSAR
acquisitions of:• all land areas at 36 months’ repeat interval during theALOS mission life time;• all forested areas with at least 12 months’ repeat interval
during the ALOS mission life time;• regional “super sites” (Amazon, Congo and Ob riverbasins; S-E Asia paddy areas; + TBD) every 46-day passduring one full year.
The basic PALSAR acquisition mode considered is dual
polarizations (HH/HV) with a fixed (35° - TBD) off-nadir
angle. The 12- and 36-months’ repetition cycles are based on
the concept “same area, same season” in order to minimize
seasonal bias in the time series. Dry season is preferred intropical regions, summer or winter (TBD) in temperate andboreal zones. Data takes with 46-days’ repeat will be timed tocapture a full flooding cycle, or rice cultivation cycle in theparticular region of interest. As far as technically feasible,
full polarization (experimental mode only) and synergy withthe optical AVNIR-2 sensor will also be attempted.
2.3 Detection and quantification of changes in forest cover
A theme of central importance in the Kyoto Protocol,
relating to the concept of afforestation, reforestation anddeforestation (ARD) under Article 3.3: “The net changes ingreenhouse gas emissions by sources and removals by sinks
resulting from direct human-induced land-use change andforestry activities, limited to afforestation, reforestation anddeforestation since 1990, measured as verifiable changes incarbon stocks in each commitment period, shall be used tomeet the commitments under this Article of each Party
included in Annex I”. Since the Protocol exclusively relates
to forest change areas (i.e. through ARD), quantification of
biomass stocks is not a direct Kyoto requirement. However,in order to quantify the biomass loss following e.g. adeforestation event, some sort of a priori knowledge about
the biomass level prior to the event is nevertheless required.
Comprising standing stocks and changes due to bothhuman-induced and natural activities, the same basic datarequirement is raised in the carbon context by IGOS-P:“Estimates of above- and below- ground biomass providefundamental information on the size and changes of theterrestrial carbon pool as land use and associated land
management practices change”. This theme can be divided
into: (i) identification of areas subject to change, (ii)quantification of biomass stocks, and (iii) associated biomasschanges therein.
For the ALOS Kyoto & Carbon Initiative to meet theneed for (i), the 12-month time series of PALSAR dataacquired within the data acquisition plan described above in§2.2 should be utilized. Plain identification of changes inforest cover is a rather straightforward task, which to a large
extent can be performed in an operational manner. Annualforest change “ARD” maps, indicating areas of change
between subsequent years due to e.g. clearfelling or
regeneration, is a product tentatively foreseen.

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Quantification of biomass stocks (ii) may partially beconceived with ALOS PALSAR. While stock inventories inmature forest stands above the L-band sensitivity range mustbe ruled out, retrieval of biomass-related biophysicalparameters in sparse and regenerating areas may well beforeseen. Using SAR time sequences rather than single-date
imagery strengthens accuracy and also provides forquantification of incremental biomass changes in regeneration
or degradation areas (iii). The 12-month time series utilized
under (i) for “ARD” mapping is foreseen to be essential also
for this task.
It is acknowledged that retrieval of biomass-related forest
parameters is still in a research stage and that additional work
is required before robust operational methods will emerge.
Yet, we believe that the systematic PALSAR observations
planned within the ALOS Kyoto & Carbon Initiative will
help to advance this important field of research.
2.4

Mapping and monitoring of certain methane sources
Irrigated rice is a significant anthropogenic source of CH4,
which presumably will have to be accounted for under theKyoto Protocol from the second emission commitment
period and onwards (2013-), when agricultural soils areincluded in addition to ARD. And amongst nonanthropogenic CH4 contributors, floodplains and wetlands
areas are sources of major importance. IGOS-P remark that“satellite observation techniques and modelling tools should
be developed to estimate methane fluxes from wetlands” andwhile CH4 fluxes per se cannot be measured by PALSAR,
key input parameters to emission models in forms of thespatial and temporal variations of inundation can be provided,
as already demonstrated by JERS-1 SAR [3]. The uniquenessand importance of L-band SAR in this context cannot be
overly emphasized, as it is the only space-borne sensor
configuration with the capacity of deriving such information.
Progressing on-going JERS-1 SAR R/D activities within
NASDA with, regional-scale mapping of the spatio-temporal
dynamics of irrigated rice and seasonally inundated wetlands isforeseen to be a major undertaking within the ALOS Kyoto& Carbon Initiative. PALSAR data acquired with 46-days’
repetition during a period of one full year, will be required tocharacterize the rapid variations associated with forest
inundation and rice cultivation, as listed in the tentative dataacquisition plan outlined under §.2.2. Wetland regions
tentatively under consideration include the drainage basins ofthe Amazon and Paraguay rivers in South America, theCongo river in central Africa, and the Ob river on the West
Siberian Plan. As for irrigated rice, PALSAR coverage ofmajor cultivation areas in South and South-East Asia isplanned.
Derived data products will conceivably comprise timesequences of co-registered regional-scale PALSAR mosaics
and derived flood duration and rice cultivation maps.

2.5 Project organization
Given the sheer amount of data foreseen to be acquired andprocessed, and the scientific tasks to be considered, the ALOS
Kyoto & Carbon Initiative will rely on close alliance withnational and international institutions. Building on theexisting network established within the JERS-1 Global
Forest Mapping project [4], a decentralized organization will
be employed, where collaborating parties are responsible for acertain data product and/or region of interest.
2.6 Scientific support and spin-off applications
Successful definition and implementation of the DedicatedData Acquisition Strategy is indeed of paramount importance,
as it constitutes the heart and foundation of the Initiative as
such. In order to assure that the acquisition plan actually
meets the Kyoto and carbon cycle science requirements, a
Scientific Advisory Panel has been established, to which
well-renowned scientists active in the relevant fields,
including representatives from the UNFCCC and IGOS-P,
have been invited. The panel will also be consulted in thedefinition phase of the products to be generated, as discussed
briefly above under §2.2-2.4 above.
Note that not all PALSAR data collected are intended to
be processed within the Initiative. Rather, one of the basic
objectives of the acquisition plan is to provide theinternational science community - as well as policy makers
and commercial users - with a comprehensive data archivefrom which consistent PALSAR time series can be found foran arbitrary location of interest. It is believed that this typeof data archive will prove useful also for applications far
beyond those of Kyoto support and carbon cycle science.
R EFERENCES[1] Cihlar J., et al. (Eds.), 2001. IGOS-P Carbon Cycle
Observation Theme: Terrestrial and atmosphericcomponents. A report to IGOS-P by the TerrestrialCarbon Theme Team.
[2] Rosenqvist, Å., Imhoff, M., Milne T. and Dobson C.
(Eds.), 1999. Remote Sensing and the Kyoto Protocol:
A Review of Available and Future Technology for
Monitoring Treaty Compliance. Report (159 pp.). Ann
Arbor, MI, USA, October 20-22, 1999.
[3] Rosenqvist Å., Forsberg B., Pimentel T., Rauste Y.,
and Richey J., 2001. The use of spaceborne radar data tomodel inundation patterns and trace gas emissions inthe central Amazon floodplain. International Journal ofRemote Sensing [in press].
[4] Rosenqvist Å., Shimada M., Chapman B., Freeman
A., De Grandi G.F., Saatchi S. and Rauste Y., 1999.
The Global Rain Forest Mapping Project - a review.
International Journal of Remote Sensing, 2000, Vol.
21, No. 6&7, pp 1375-1387.

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