Download - GLIMS: Global Land Ice Measurements from Space

Chapter 4Methods and Algorithms4.1 Algorithms of the GLIMS - ProjectIn chapter 2 the data and algorithms of the GLIMS - project are discussed. In thischapter the methods used to obtain the GLIMS - specic metadata are described.The glacier used as test area for explaining the methods is the Alpeiner Ferner,located in the northern section of Stubaital.As described in chapter 3 (see 3.1), the Landsat 5 TM and the ASTER sensor haveslightly dierent bands. Table 4.1 shows the bands for the Landsat 5 TM and forthe ASTER sensor used in this study.TM Sensor Landsat 5 TM /µm ASTER /µm ASTER Sensor1 (blue) 0.45- 0.52 -2 (green) 0.52 - 0.60 0.52 - 0.60 13 (red) 0.63 - 0.69 0.63 - 0.69 24 (NIR) 0.76 - 0.90 0.78 - 0.86 35 (SWIR) 1.55 - 1.75 1.60 - 1.70 47 (SWIR) 2.08 - 2.35 2.145 - 2.43 1 5 - 9Table 4.1: Spectral bandwidths in µm of the Landsat 5 TM sensor and the ASTER sensor.1 =sum of band 5 to band 9 of the ASTER sensor.Table 4.2 shows the spectral radiance L max,λ /(W/m 2 sr 1 µm 1 ) and the solarexoatmospheric spectral irradiance E sun /(W/m 2 µm 1 ) for the Landsat 5 TM andthe ASTER sensor. The values for the ASTER sensor of the spectral reectanceL max,λ are values for normal gains settings. ASTER data has gain settings fromhigh gain, normal gain, low gain 1 and low gain 2. The values for E sun for theASTER sensor are obtained from Smith, 2005 (Smith, 2005) from the middle col-29