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| Titel |
Using the Synergy Between GERB/SEVIRI and Micrometeorological Data to Study the Relationship Between Surface Net Radiation and Soil Heat Flux at Local and Regional Scales |
| VerfasserIn |
A. G. Ferreira, A. Velazquez Blazquez, E. Soria, E. Lopez-Baeza |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250030750
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| Zusammenfassung |
| The surface energy exchange between the land surface and the atmosphere can be described
by the energy balance equation Rn - H - LE – G = 0, where Rn represents net radiation, H the
sensible heat flux, LE, the latent heat flux and G the soil heat flux. In this work the
relationship between Rn and G is studied over vineyard crops, a relative sparse vegetation
cover crop where, according to the literature, it is expected that G consumes a significant
proportion of Rn. In order to study this relationship at local and regional scales,
micrometeorological observations and METEOSAT Second Generation (MSG) satellite data
have been used. MSG through the GERB (Geostationary Earth Radiation Budget) and the
SEVIRI (Spinning Enhanced Visible and Infrared Imager) sensors can provide estimates
of net radiation and required land surface temperature (LST) information with a
frequency of 15 min intervals. The necessary micrometeorological parameters, to
compare with satellite data, were collected during the full vine growing season of 2007
(May to September) in a field experiment carried out at the Valencia Anchor Station
(VAS) site area. The VAS is a robust reference meteorological station which is
successfully used preferentially for validation of low spatial resolution satellite data
and products. It is located on the natural region of the Utiel-Requena Plateau, at
about 80 km west from the city of Valencia, Spain, and represents a reasonable
homogeneous area of about 50 km x 50 km dedicated primarily to growing vines.
The methodology utilized to study the relationship between Rn and G at local and
regional scales, was that proposed by Santanello and Friedel (2002), where surface
temperature can be obtained from SEVIRI that provides estimates of LST with
unprecedented frequency of 15 min intervals with a spatial resolution of 3.1 km,
thus totally covering its diurnal course. The preliminary results show that: 1- the
correlation between the ground measurements and SEVIRI LST is significantly good,
presenting a Pearson correlation coefficient r of 0.96, with a squared correlation
coefficient R2 of 0.93 and root mean square error, RMSE of 3.51 ºC, and standard
deviation, std, of 3.52. This makes apparent the good representativity of the VAS
temperature measurements at SEVIRI scale and 2- the comparison between simulated
GERB Rn at the surface and the measured one over the VAS field campaigns, at
the spatial resolution of 1 km, and over a vineyard mobile micrometeorological
station, shows good agreement for both periods and stations, winter of 2004 at the
VAS, and summer of 2006 over vineyards, presenting RMSEs of 17 Wm-2 and 42
Wm-2, respectively, as well as high Pearson correlations and low standard deviations
indicating that the methodology applied is able to reproduce net radiation at surface
level.
Besides this and from this preliminary study, we may conclude that it is possible to
anticipate the significance of using the synergy between GERB/SEVIRI and ground
measurements in order to derive Rn, and consequently G over local and regional areas.
Further studies will include the calculation of Rn, and therefore G at GERB pixel spatial
resolution. |
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