SPOT-4 HRVIR and Vegetation Sensors - Book Report/Review Example

SPOT-4 HRVIR and Vegetation SensorsForests fire is a phenomenon triggered by prolonged dry spells and may end up destroying hectares of vegetation if not checked in time. Indisputably, such fires are one of the main factors that can affect the entire terrestrial ecosystem and significantly contribute to global warming. A case in point is the 1997-1998 dry season in Roraima (Brazil, Amazonia) that saw vegetation of unknown worth being razed down by forest fires. The spread of this fire was monitored in real times by several satellites.

Since then satellites images have been in used in both global and regional scales in monitoring forest fires for climate studies and impact assessment. This research paper analyzes the contribution of SPOT-4’s imagery provided by high resolution HRVIR and coarse resolution VEGETATION sensors. This analysis is done on the basis of understanding the characteristics of these sensors and their potential benefit for forest mapping and detection of forest fires. Research methodologyThis study began by gathering VEGETATION (VGT) data in order to get a synoptic perspective of the extent of fire in Roraima State.

P-products of 21 April 1998 were obtained from VITO (Vegetation Imagery Processing Centre, Belgium) via CNES (Centre National d’Etudes Spatiales, France). Vegetation under study covered an area of 2000km by 2000km. Through application of several satellite programming facilities, it was possible to gather off-nadir SPOT-4 HRVIE data, either during the blaze or after some time. An intensive study site (ISS) was then defined to enable comparison of VGT and HRVIR. The ISS was covered by six contiguous SPOT-4 HRVIR scenes.

Also, HRVIR scene obtained on 16 April along Rio Branco River was used. Finally, one SPOT-3 HRV image obtained in October the same year was used as reference of the initial state at the start of the dry season preceding the fires. Short-wave infrared was used in the discrimination of dry soils and dry burned vegetation. Then NOAA images were used to ascertain if an area has been effectively burnt.The SPOT-4 sensors – that is VGT and HRVIR and field data obtained were used to assess the impact of large scale fires in the State of Roraima (Brazil).

The wall to wall coverage using SPOT VGT instrument was employed to enhance the chances of getting cloud-free VGT images when the risks of forests fires are high. Y Also, after establishing the burnt area from the images, the tentative amount of biomass burnt could also be determined proximate estimations. Critical discussion of the findings The study was successful as for the first time the researchers were able to indicate the spatial distribution of fires in the State of Roraima, the nature of ecosystem that been damaged and the probable impacts in terms of carbon emissions.

VGT and HRVIR sensors onboard SPOT 4 satellites effectively provided these data/images. However, the research had limitation as the remote sensing technology could hardly assess the real environmental impact of, for instance, carbon emission released into the environment. This was worsened by the fact that the technology is not yet able to detect exact composition of the ecosystem. Also, the technology is prone to errors as there is thin line separating burnt vegetation and red soil in the Amazon.

The research also relied on extrapolation of results from other regions to assess the impact of forests fires in Amazonia. This certainly comprises the accuracy of the final impact assessment. ReferencePhulpin, T. et al. (2002) aUsing SPOT-4 HRVIR and vegetation sensors to assess impact of tropical forest fires in Roraima, Brazil,a International Journal of Remote Sensing