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Regional simulation of ecosystem CO2 and water vapor exchange for agricultural land using NOAA AVHRR and Terra MODIS satellite data: Application to Zealand, Denmark / Rasmus M. Houborg in Remote sensing of environment, vol 93 n° 1 (30/10/2004)

Public [article]  inRemote sensing of environment > vol 93 n° 1 (30/10/2004) . - pp 150 - 167 Titre : Regional simulation of ecosystem CO2 and water vapor exchange for agricultural land using NOAA AVHRR and Terra MODIS satellite data: Application to Zealand, Denmark Type de document : Article/Communication Auteurs : Rasmus M. Houborg, Auteur ; H. Soegaard, Auteur Année de publication : 2004 Article en page(s) : pp 150 - 167 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] agriculture [Termes descripteurs IGN] atmosphère terrestre [Termes descripteurs IGN] couvert végétal [Termes descripteurs IGN] covariance [Termes descripteurs IGN] Danemark [Termes descripteurs IGN] dioxyde de carbone [Termes descripteurs IGN] flux [Termes descripteurs IGN] Green Leaf Area Index [Termes descripteurs IGN] image NOAA-AVHRR [Termes descripteurs IGN] image Terra-MODIS [Termes descripteurs IGN] indice de végétation [Termes descripteurs IGN] nuage [Termes descripteurs IGN] turbulence [Termes descripteurs IGN] vapeur d'eau Résumé : (Auteur) While accurate information on ecosystem C02 and water vapor exchange is available at eddy covariance flux tower sites, method, methods to expand predictions of C02 and energy exchange to regional or global scales with high fidelity are lacking. The main objective of this study was to examine the applicability of land surface and atmospheric products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Very High Resolution Radiometer (AVHRR) for assessing the spatial variation in C02 and water vapor fluxes for cloudless agricultural land pixels at the Island of Zealand, Denmark. The spatial distribution of green leaf area index, directbeam ark: diffuse solar radiation and air humidity was inferred on the basis of late morning MODIS data that was combined with afternoon AVHRR data to resolve the diurnal variation in air and surface temperature. These variables were used in a coupled "twoleaf' ecosystem model operating at an hourly time scale. The enhanced vegetation index (EVI) was strongly correlated with field measurements of green leaf area index (r2=0.91) and remained sensitive to variations in green biomass up to green leaf area indices of 45. Evaluation against standard meteorological data showed that instantaneous estimates of air temperature, actual vapor pressure and incoming solar radiation could be retrieved with overall root mean square errors of 2.5°C, 138.3 Pa and 47.7 Wm2, respectively. The combination of late morning and afternoon inferences made it possible to resolve the diurnal course in key model parameters, and predicted rates of ecosystem C02 and water vapor exchange were comparable to eddy covariance measurements at a single flux tower. A large spatial diversity in C02 and water vapor exchange was maintained throughout the study period due to significant regional variations in meteorological input variables and large spatial differences in canopy development. The results of this study stress the necessity of pixel based estimates for an accurate evaluation of regional budgets of C02 and water vapor exchange. Numéro de notice : A2004-426 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26953 [article]

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Combining weather prediction and remote sensing data for the calculation of evapotranspiration rates: application to Denmark / E. Boegh in International Journal of Remote Sensing IJRS, vol 25 n° 13 (July 2004)

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 25 n° 13 (July 2004) . - pp 2553 - 2574 Titre : Combining weather prediction and remote sensing data for the calculation of evapotranspiration rates: application to Denmark Type de document : Article/Communication Auteurs : E. Boegh, Auteur ; H. Soegaard, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 2553 - 2574 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] correction atmosphérique [Termes descripteurs IGN] Danemark [Termes descripteurs IGN] erreur moyenne quadratique [Termes descripteurs IGN] évapotranspiration [Termes descripteurs IGN] humidité de l'air [Termes descripteurs IGN] image NOAA-AVHRR [Termes descripteurs IGN] prévision météorologique [Termes descripteurs IGN] trajectographie Résumé : (Auteur) Evapotranspiration rates in Denmark were estimated using Advanced Very High Resolution Radiometer (AVHRR) satellite data and weather conditions predicted by a high-resolution weather forecast model (HIRLAM). The predictions were used both for atmospheric correction of satellite data and for remote sensing based calculation of net radiation, sensible heat fluxes and evapotranspiration rates. Climate predictions at 12 GMT were used as proxies for the atmospheric conditions at the time of the afternoon satellite passage (12.30-14.30 GMT). The air temperature at the time of the satellite passage was retrieved with a rms error of 1.9ºC, and the rms error of the retrieved air humidity was 204 Pa. The evapotranspiration results were significantly influenced by the spatial distribution of weather conditions. Due to the encirclement of Denmark by sea shorelines, sea breezes extending more than 30 km inland were responsible for the intrusion of cooler air temperatures which increased the sensible heat fluxes and suppressed the evapotranspiration rates. The predictions were linearly related to eddy-covariance flux measurements representing agricultural land, beech forest and conifer forest, but the relationships were also characterized by a large degree of scattering. The results are discussed in relation to inaccuracies and future perspectives. Numéro de notice : A2004-260 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26787 [article]

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