Author
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PELGRUM, HENK - WINAND STARING CENTRE |
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SCHMUGGE, THOMAS |
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Submitted to: IEEE IGARSS Annual Proceedings
Publication Type: Proceedings Publication Acceptance Date: 3/1/1998 Publication Date: N/A Citation: N/A Interpretive Summary: None. Technical Abstract: The JORNada Experiment (JORNEX) on the Jornada Experimental Range in southern New Mexico aims at the description of the surface energy balance of a desert grassland ecosystem using remotely sensed data. One of the objectives of the study is to derive the length scales of the land surface characteristics involved in the calculation of the surface energy balance. For determining the length scales of the land surface characteristics, dat from the airborne sensor DAEDALUS have been analyzed. The data were recorded June 19, 1997. This sensor measures radiances in twelve bands ranging from visible to thermal infrared. The spatial resolution of these data is 4 meters. For this research, data from one thermal and one near-infrared band have been analyzed. Three sub sites with different vegetation characteristics were distinguished: grass, mesquite (shrubs) and a transition site with patches of both grass and mesquite. Length scales for each site were determined on the basis of semi-variograms calculated from the DAEDALUS data. The variogram analysis showed that the grass sites had larger length scales (35-40 m) compared to the mesquite site (10-20 m), whereas the largest length scales were found at the transition site 75-100 m). However, a variogram analysis based on field data showed that the actual length scale of the grass site was smaller than what the remote sensing data showed. For the mesquite site there was agreement between the variograms based on field and remote sensing data. A comparison of the thermal and near infrared band showed that the length scale of the thermal infrared data was always smaller compared to the near infrared data. |
