Proceedings, XXth congress: Proceedings, XXth congress

Altan, M. Orhan

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Persistent identifier:: 1663674213

Title:: Proceedings, XXth congress

Sub title:: Istanbul, 12 - 23 July 2004

Year of publication:: 2004

Place of publication:: Istanbul

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 1663674213

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.; Auch bezeichnet als XXth International Congress for Photogrammetry and Remote Sensing

Editor:: Altan, M. Orhan

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Document type:: Multivolume work

Volume

Persistent identifier:: 166368779X

Title:: Proceedings, XXth congress

Scope:: IV, 226 Seiten

Year of publication:: 2004

Place of publication:: Istanbul

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 166368779X

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(35,B8)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Altan, M. Orhan

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: QUALITY ASSESSMENT OF GLOBAL MODIS LAI PRODUCT FOR THE REGIONAL SCALE APPLICATIONS Sun-Hwa Kim and Kyu-Sung Lee

Document type:: Multivolume work

Structure type:: Chapter

(1 2004 DIS . On 1der- than ence the land y the leto jon of over ation 6 as land body, rtion 1 the ed to s and jatial > Me jah nd were ed on he International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 cloud covers, some pixels certainly has continuing cloud cover during the eight days. Fortunately, such cloud cover information is supplied with the MODIS LAI product. Figure 6 showed the cloud coverage at every pixel location and the LAI estimation algorithm used. As seen in Figure 6, about 30% pixels of the MODIS LAI image were affected by cloud cover. The 5% pixels of this MODIS LAI image were produced by the backup algorithm based on NDVI. In particular, most of the pixels corresponding to the backup algorithm were forest. Although the MODIS LAI product at this study area was mainly estimated by main RT algorithm and not affected by cloud, the effects of the backup algorithm and cloud should be considered at the quality assessment of MODIS LAI over other sites. ey =A, oe I = Figure 6. MODIS LAI QA images of cloud effect (left: white- cloud, black- no cloud) and estimation algorithm (right: white- RT model, black-backup model). As seen in Table 2 and Figure 7, the MODIS LAI values, which were estimated by the backup algorithm and affected by cloud cover, showed large difference as compared to the reference LAI map. In these pixels, the MODIS LAI is lower than the reference LAI value. Since the portion of area of the backup algorithm and the cloud cover was relatively small, they might have not affected the overall statistics of MODIS LAL However, since the more than two third of the study area is occupied by forest, the over-estimation of MODIS LAI in forest shows great influence on the total image (Figure 7). In grass and cropland, although they were small portion, the MODIS LAI values were lower than the reference LAI value. Under-estimatior II Over-estimation E etf mm Total image [- RT model Back-up model | Cloud area 7 Nan-cloud area : Forest Crop&Grass a 0. 10. 20. 30 40.50 60. 70 80 - 90; 100 Coverage(%) Figure 7. Estimation patterns of MODIS LAI for each schemes (Under-estimation means MODIS LAI was lower than reference LAI Over-estimation means MODIS LAI was higher than reference LAI) 4. CONCLUSIONS During the last decades, there was a great amount of time and efforts to develop the global ecological variables by the earth observing system (EOS) program. The MODIS global LAI product is one of such variables that are now being provided. To use such valuable information at regional and local scales, it is crucial to validate the quality of the product. In this study, we made a simple and direct comparison between the MODIS LAI data and the reference LAI surface that was derived by an empirical approach to relate the field-measured LAI to Landsat ETM+ reflectance. Although the validation can be further expanded into larger areas, the preliminary results obtained from this study indicate that the MODIS LAI product is different from the reference data. At the temperate forest, the MODIS LAI estimates were higher than the reference LAI values during the leaf-on season of September. The discrepancy between the MODIS LAI and the reference LAI may be caused by the uncertainties in the input variables of MODIS LAI algorithm, effects of cloud at each pixels, estimation algorithm, and land cover type. In general, MODIS LAI values were higher than the reference LAI in forest and they were lower than in grass and cropland. Additionally, MODIS LAI data affected by backup algorithm and cloud showed higher value as compared RT algorithm and no-cloud condition. The validations of MODIS LAI product are being carried out at the several study sites throughout the world. Due to the km spatial resolution of the data, the validation is often restricted by the size of test area and the collection of accurate ground- truth data. Temperate forest is even more complicated than any other ecosystems, which include a variety of species and stand structure. Further study is planned to assess the quality of the . MODIS LAI estimate for local and regional applications. 5. REFERENCES Bonan, G, 1993. Importance of leaf area index and forest type when estimating photosynthesis in boreal forests. Remote sensing of Environment, 43, pp.303-314. Brown, L., J. M. Chen, S.G Leblanc, and J. Cihlar, 2000. A Shortwave modification to the simple ratio for LAI retrieval in boreal forest: An image and model analysis. Remote sensing of Environment, 71, pp. 16-25. Carlson, T.N. and D.A. Reley, 1997. On the relation between NDVI, Fractional Vegetation Cover, and Leaf Area Index. Remote Sensing of Environment, 62, pp. 241-252. Chen, J.M. and J. Cihlar, 1996. Retrieving leaf area index of Boreal conifer forests using Landsat TM images. Remote Sensing of Environment, 55, pp. 153-162. Chen, J. M., PM. Rich, S.T. Gower, J.M. Norman, and S.Plummer, 1997. Leaf area index of boreal forests: Theory, techniques, and measurements. Journal of Geophysical Research, 102 (D24), pp.29429-29443. Chen, J.M., G Palic, L. Brown, 2002. Derivation and validation of Canada-wide coarse-resolution leaf area index maps using high-resolution satellite imagery and ground measurements. Remote Sensing of Environment, 80, pp.165-184. Cohen, W.B., T.K. Maierpserger, S.T. Gower, and D. P. Turner, 2003. An improved strategy for regression of biophysical variables and Landsat ETM+ data. Remote Sensing of Environment, 84, pp.561-571.

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