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| Titel |
Changes in evapotranspiration in semi-arid and semi-humid regions of China based on upscaling eddy covariance measurements |
| VerfasserIn |
Huimin Lei, Tingting Gong, Dawen Yang |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104818
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| Publikation (Nr.) |
 EGU/EGU2015-4256.pdf |
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| Zusammenfassung |
| The semi-arid and semi-humid region (about 4.98x105 km2) of China is a critical
climate zone, not only because it is in the climate transitional zone with strong
coupling of soil moisture and precipitation, but also because it is an ecologically
vulnerable zone and a main crop-producing region. In addition, human activities in this
region have been largely ongoing such as afforestation, deforestation, farmland
management and intense grazing. Evapotranspiration (ET) is a main component of
the water cycle and plays an important role in such a climate-land system. Thus,
changes in evapotranspiration are fundamental to understand how climate and human
activities affect water cycle and to guide agricultural water management and ecological
restoration.
In this study, data-driven regional ET is upscaled from 12 flux towers using a support
vector regression (SVR) model, by combining satellite remote sensing data and ground-based
meteorological observations. Two ET products will be generated with different spatial
resolution and time span. One is based on the Moderate Resolution Imaging Spectrometer
(MODIS) products with a spatial resolution of 1 km during 2000~2011, and the other
is based on the AVHRR Normalized Difference Vegetation Index (NDVI) with a
spatial resolution of 8 km during 1982~2011. Variables that may have influences on
ET, such as land surface temperature (LST), Enhanced Vegetation Index (EVI),
normalized differential vegetation index (NDVI), short-wave radiation (SWR), water
vapor deficit (VPD), will be selected as explanatory variables. The SVM model will
first be tuned and trained at the site scale, and then applied to estimate regional
ET.
Based on the upscaled regional ET, this study will evaluate how changes in ET respond to
climate change; moreover, the impacts of human activities on ET will be examined, such
as how afforestation and farmland management affect ET. Furthermore, impacts
of changes in ET on other water cycle components will be analyzed, with the aid
of other observations (e.g., GRACE total water storage change, river discharge). |
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