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| Titel |
GPP estimates in a biodiesel crop using MERIS products |
| VerfasserIn |
M. L. Sánchez, N. Pardo, I. Pérez, M. A. García, V. Paredes |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250059856
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| Zusammenfassung |
| Greenhouse gas emissions in Spain in 2008–2009 were 34.3 % higher than the
base-year level, significantly above the burden-sharing target of 15 % for the period
2008–2012. Based on this result, our country will need to make a major effort to meet the
committed target on time using domestic measures as well as others foreseen in
the Kyoto Protocol, such as LULUFC activities. In this framework, agrofuels, in
other words biofuels produced by crops that contain high amounts of vegetable oil
such as sorghum, sunflower, rape seed and jatropha, appear to be an interesting
mitigation alternative. Bearing in mind the meteorological conditions in Spain,
sunflower and rape seed in particular are considered the most viable crops. Sunflower
cultivated surface in Spain has remained fairly constant in recent years, in contrast
to rapeseed crop surface which, although still scarce, has followed an increasing
trend.
In order to assess rape seed ability as a CO2 sink as well as to describe GPP
dynamic evolution, we installed an eddy correlation station in an agricultural plot
of the Spanish plateau. Measurements at the plot consisted of 30-min NEE flux
measurements (using a LI-7500 and a METEK USA-1 sonic anemometer) as well as other
common meteorological variables. Measurements were performed from March to
October.
This paper presents the results of the GPP 8-d estimated values using a Light Use
Efficiency Model, LUE. Input data for the LUE model were the FPAR 8-d products supplied
by MERIS, the PAR in situ measurements, and a scalar f varying, between 0 and 1, to take
into account the reduction of the maximum PAR conversion efficiency, É0, under limiting
environmental conditions. The f values were assumed to be dependent on air temperature and
the evaporative fraction, EF, which was considered as a proxy of soil moisture. É0, a key
parameter, which depends on biome types, was derived through the results of a linear
regression fit between the GPP 8-d eddy covariance composites observed and the LUE
concurrent 8-d model estimates. The model fitted observed GPP 8-d satisfactory
(R2=91%). The É0 value obtained, 2.777 g C m-2 MJ-1, was substantially higher than
the typical values reported in the literature for other types of agricultural crops. |
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