V. B. Sochava Institute of Geography SB RAS, Irkutsk Study area - - PowerPoint PPT Presentation
Modeling of Air Temperature at Tunkinskaya Hollow with The Use of Landsat Space Images N.N.Voropay, E.I.Istomina, O.V.Vasilenko V. B. Sochava Institute of Geography SB RAS, Irkutsk Study area Characteristics of altitudinal zones Tunkinskaya
n
Tv is air temperature recorded by sensor, Ts - temperature calculated from the satelite image, k - coefficient of proportionality associated with the emissivity of the object and the difference in air temperature and surface.
Ts – temperature in Kelvin scale, Qcal – calibrated brightness of pixel in 6th chanel, K1 – constant 1 (equal to 666,09 or 607,76 for ETM+ and TM sensors), K2 – constant 2 (equal to 1282,71 or 1260,56 for ETM+ and TM sensors), Lmaxλ и Lminλ – incoming radiation constant (equal to 12,65 and 3,2 for ETM+ or 15,303 and 1,238 for ТМ sensor), Qcalmin – minimal image digital number (1), Qcalmax – maximal image digital number (255).
λ λ λ λ
min min) Qcal
min Qcal
Qcal min max L L L L + − =
λ
25,5 23,5 22,5 23 22,5 21,5 22 22,5 20 21 24,5 23 25
1) 2)
6-channel of Landsat image
25,2 23,7 26,0 17,0 18,0 18,0 18,6 15,9 15,9 14,8 23,7 23,7 23,2
3) k=Tv/Ts
0,99 1,01 1,16 0,74 0,80 0,84 0,84 0,71 0,80 0,71 0,97 1,03 0,93
3) k=Tv/Ts
0,99 1,01 1,16 0,74 0,80 0,84 0,84 0,71 0,80 0,71 0,97 1,03 0,93
4) k=ax+b, r values Correlation coefficient
NDVI
1 channel 0,37 2 channel 0,63 3 channel 0,71 4 channel
5 channel 0,74
7 channel 0,91
5) Calculation of a, b and Tv Tv = (ax+b)Ts, where Tv is desired value of air temperature х – brightness in the 7-th channel Ts – temperature determined from the 6-th channel
n Tv~kTs
Ts Tv The original image