An MSG Case Study with Image Fusion over Brazil

Authors:

  • Humberto Barbosa
  • Diego Rocha
  • Ivon Wilson

At the Laboratory for Analyzing and Processing Satellite Images (LAPIS), techniques to retrieve parameters related with atmosphere and land applications are developed by using MSG data. During the second training of the South American network operators group of EUMETCast-GEONETCast participants were introduced to a case of severe convection took place on 4 June 2010 over Brazil showing the use of the image fusion. Effectiveness of this technique was to merge spatial distortion from images with different spatial and spectral characteristics through data fusion of RGB (R: IR 0.16μm; G: 0.08μm; B: 0.06μm) bands with HRV band. This example of application was developed under ILWIS 3.6 and ENVI technique Gram-Schmidt Spectral Sharpening.


Here, we exemplify the application of Gram-Schmidt (G-S) method for merging images with different spectral and spatial characteristics through the MSG-SEVIRI data fusion of RGB (bands 3, 2, 1) (Fig. 3a) with HRV (band 12) on the case of the 4 June 2010 at 18:00 UTC (Fig. 3b). And then compared with the Sandwich technique which is combined HRV with Enhanced IR10.8 images (Fig. 4). While later (Fig. 4) emphasis the absorption of the spatial information, the former (Fig.3b) describes the prevention of the spectral characteristic in the fused result. As a result, a new set of multispectral bands (RGB) is displayed in Figure 3(b), where one of them is replaced by the panchromatic image (HRV). Further studies are needed in this case to better understand these results. In particular, we see that the differences are smaller in the areas where there is a more uniform cloud cover. It is worth noticing that the figures 1-2 show the original MSG images in reflectance values, depicted in bands 1, 2, 3 and 12. The meteorological conditions associated to this event was triggered by synoptic low pressure systems over the Atlantic travelling along a northwest-southeast axis towards East Coast of Northeastern Brazil (NEB) (Fig. 1), and whose interaction with water vapor intrusions from the African intertropical convergence zone induces secondary pressure minima over the coast. The position of the storms varies from strictly parallel to the shore line. During this event, extraordinary rainfall amounts occurred over the region, with a maximum accumulated precipitation over 110 mm at Alagoas state. This case has been used for training session during EUMETCast training event 2010 in Brazil because it displays many classic text book satellites of frontals systems in lower latitudes of both hemispheres over the Atlantic and Tropical Africa.


Figure 1 - (a) Meteosat band 2 and (b) band 1.


Figure 2 – (a) Meteosat band 3 and (b) band 12.


Figure 3 – (a) Meteosat RGB (bands 3, 2, 1) and (b) Fusion of RGB (bands 3, 2, 1) with HRV (band 12).


Figure 4 – The “Sandwich technique” which is combined HRV with Enhanced IR10.8 images.

 
an_msg_case_study_with_image_fusion_over_brazil.txt · Last modified: 2010/10/19 15:10 by diego
 
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