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Träfflista för sökning "AMNE:(TECHNOLOGY Other technology Space engineering) ;pers:(Fransson J E S)"

Sökning: AMNE:(TECHNOLOGY Other technology Space engineering) > Fransson J E S

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1.
  • Eriksson, Leif E.B., 1970-, et al. (författare)
  • Stem volume estimation for boreal forest using ALOS PALSAR
  • 2007
  • Ingår i: 5th International Symposium on Retrieval of Bio- and Geophysical Parameters from SAR Data for Land Applications, Bari, Italy, September 25-28, 2007, ESA, Istituto di Studi sui Sistemi Intelligenti per l´Automazione.
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • An evaluation of ALOS PALSAR data for standwise forest stem volume estimation has been performed at a Swedish test site. The site is dominated by coniferous tree species. SAR data from three operational PALSAR modes, including single, dual and quad polarization, have been analyzed. In total, images from 18 different dates were included. Altogether, 56 forest stands with stem volume in the range of 45-650 m3 ha-1 (average 325 m3 ha-1) were analyzed by relating backscatter intensity to field data. The estimation accuracy of stem volume at stand level was calculated in terms of root mean square error (RMSE). For the best case investigated an RMSE of 30% was obtained for one of the single polarization images acquired in the winter season. In this case no saturation was observed for high stem volumes. The corresponding RMSEs for the dual and quad polarization images were between 62%, and 81%. The better results for single polarization might be explained by particularly favourable weather conditions at image acquisition. An extended evaluation will be performed to verify the cause.
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2.
  • Eriksson, Leif E.B., 1970-, et al. (författare)
  • ALOS PALSAR calibration and validation activities in Sweden
  • 2008
  • Ingår i: Proceedings of The First Joint PI Symposium of ALOS Data Nodes for ALOS Science Program in Kyoto, Kyoto, Japan, 19 - 23 November, 2007. - 1349-113X. - 978-4-906653-04-1 ; JAXA-SP-07-012
  • Konferensbidrag (övrigt vetenskapligt)
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3.
  • Eriksson, Leif E.B., 1970-, et al. (författare)
  • ALOS PALSAR Calibration and Validation Results from Sweden
  • 2007
  • Ingår i: IEEE Geoscience and Remote Sensing Symposium (IGARSS 2007), Barcelona, Spain, July 23-27, 2007. ; DOI: 10.1109/IGARSS.2007.4423115, s. 1589-1592
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • In 2006 calibration activities for ALOS PALSAR were conducted in Sweden. Four five-metre trihedral corner reflectors and three smaller dihedral reflectors were deployed and operated during eight months. 23 PALSAR scenes were acquired over the calibration site allowing an evaluation of the quality and temporal stability of the data. Results show that the co-polarized data have been stable during the whole calibration period with variations in the trihedral responses lower than 0.7 dB. The measured resolution in azimuth was 4.4 m and in slant range 4.7 m for single polarization images and 9.5 m for polarimetric data. For the cross-polarized data large variations in the dihedral responses were found. It is assumed that this is caused by a larger sensitivity to pointing errors. For the polarimetric data, estimation of Faraday rotation gave values ranging from 0.1º to 3º.
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6.
  • Pantze, Andreas, et al. (författare)
  • Mapping and monitoring clear-cuts in Swedish forest using ALOS PALSAR satellite images
  • 2009
  • Ingår i: Proceedings of IGARSS 2009 Symposium, Earth Observation – Origins to Applications, Cape Town, South Africa, 13-17 July, 2009. - 978-1-4244-3395-7 ; III, s. 589-592
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • This study presents results for observing forest changes in Sweden using multi-temporal L-band satellite data and is a part of the JAXA's ALOS Kyoto and Carbon Initiative. An extensive dataset of images acquired by the Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) is investigated for clear-cut detection in boreal forests in northern Sweden (Lat. 64 degrees 14' N, Long. 19 degrees 50' E). Strong forest/non-forest contrast and temporal consistency were found for the Fine Beam Dual HV-polarized backscatter during unfrozen conditions. Thus, a simple thresholding algorithm that exploits the temporal consistency of pair-wise HV-backscatter measurements has been developed for clear-cut detection. When applied to an image pair acquired during favorable weather conditions, the detection algorithm identified 76% of the clear-cut pixels within a reference layer, with zero erroneously detected pixels. With further refinement the developed methodology can be an option to present operational alternatives for clear-cut detection.
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7.
  • Sandberg, Gustaf, 1982-, et al. (författare)
  • Comparison of L- and P-band biomass retrievals based on backscatter from the BioSAR campaign
  • 2009
  • Ingår i: Proceedings of IGARSS 2009 Symposium, Earth Observation – Origins to Applications, Cape Town, South Africa, 13-17 July, 2009. - 978-1-4244-3395-7 ; IV, s. 169-172
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • With the continued threat of global warming, the need to obtain consistent and accurate measurements of the carbon stored in forests is strong. L- and P-band SAR backscatter data have shown to be sensitive to forest biomass, which in turn is coupled to the stored carbon. In this paper a biomass retrieval method is developed for L- and P-band using data from the BioSAR campaign conducted in Sweden during thespring 2007 over hemi-boreal forest. The results show that the use of L-band data gives an underestimation of biomass for stands with high biomass; while for P-band no such underestimation is seen. RMSEs are found to be 30-40% of the mean biomass for L-band and about 25% for P-band for stands with biomass ranging from 10 to 290 tons/ha.
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9.
  • Santoro, M, et al. (författare)
  • Signatures of ALOS PALSAR L-Band Backscatter in Swedish Forest
  • 2009
  • Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892. ; 47:12, s. 4001-4019
  • Tidskriftsartikel (refereegranskat)abstract
    • The Phased Array type L-band Synthetic Aperture Radar onboard the Advanced Land Observing Satellite has, since its launch, been acquiring an extensive data set of images over two forest test sites in Sweden. The sites of Remningstorp (Lat. 58 degrees 30' N, Long. 13 degrees 40' E) in the south and Krycklan (Lat. 64 degrees 14' N, Long. 19 degrees 50' E) in the north of Sweden are characterized by hemiboreal and boreal forests, respectively. In this paper, we have investigated the signatures of standwise backscatter measurements from forests with different growth stages in relation to polarization, environmental conditions, image viewing geometry, and spatial resolution. The HV backscatter presented stronger sensitivity to the forest growth stage than the HH and VV backscatter. Under unfrozen conditions, the dynamic range of fine-beam data acquired at 34.3 degrees was 8-9 dB for the HV polarization and 6-7 dB for the HH polarization. At 21.5 degrees, in the polarimetric mode, the dynamic range was 6, 7, and 9 dB at VV, HH, and HV polarizations, respectively. Regardless of the specific polarization, the backscatter was temporally consistent under unfrozen conditions, with a small increase of backscatter in regrowing young forest for wet conditions. Under thawing and frozen conditions, repeated measurements were available only for the HH backscatter at 34.3 degrees. For thawing conditions, the backscatter level was similar to the unfrozen conditions even though the signatures differed depending on temperature dynamics, snow-cover properties, and precipitation. Under frozen conditions, the signatures varied depending on temperature. For images acquired when the temperature was well below the freezing point, the backscatter was low, and the dynamic range was small (2-4 dB); nonetheless, the measurements were consistent. Images acquired when temperature was close to the freezing point presented a behavior similar to unfrozen conditions. The sensitivity of the backscatter to the image viewing geometry for different growth stages was studied for data acquired under dry unfrozen conditions. The backscatter difference increased for increasing look angle because of the increase in volume scattering and the decrease of ground-surface backscatter. The largest difference was observed at 41.5 degrees with 2.5-4-dB difference for the HH and 4-5-dB difference for the HV case. Loss of spatial resolution (20-50 m) did not have any effect on the backscatter signatures in Krycklan, whereas in Remningstorp, the smallest stands were affected.
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