ALOS Data Users Handbook

ALOS Data Users Handbook1L = ⋅′α NL αR{( O − B − B − C ) − ( B − B′− C )}Equation 7.2-7Where,−2 −1−1L: Incidence radiance [ W ⋅ m ⋅ sr ⋅ μ m ]−2 −1−1R: Equipment sensitivity [ DN / ( W ⋅ m ⋅ sr ⋅ μ m )]−2 −1−1O: Signal output digital value [ DN / ( W ⋅ m ⋅ sr ⋅ μ m )]C: Dummy pixel output mean value at the time when the signal output value O is obtained [ DN ]B α : Offset of the exposure coefficient pulse at the time when the signal output value O is obtained[ DN ]B NL : Non-linear offset of output to the incidence radiance [ DN ]B: Output digital value at the dark [ DN ]C': Dummy pixel output mean value at the time when the output value B at the dark is obtainedDN[ ]B α ': Offset of the exposure coefficient pulse at the time when the output value B at the dark isobtained [ DN ]The detail each parameter expressed in the above expression is described as follows.(3) Radiometrically Corrected ProcessingWhen the radiometric model equation is expressed byx − b − cy = , calculate the correction coefficientacorresponding to ‘a’, ‘b’, ‘c’, and the radiometric correction is carried out. Where, ‘x’ is defined as anuncorrected input value before performing the radiometric correction. ‘y’ is defined as a radiometricallycorrected output value for every band and pixel number.a) Calculation of the correction coefficient ‘a’‘a’ is composed of the reference sensitivity, the pixel-to-pixel sensitivity deviation, the normalized exposurecoefficient, fluctuation of reflection rate of the pointing mirror, and sensitivity correction coefficient. It iscalculated based on the encoder data in the TT&C system telemetry data, the Detector temperature, Detectormodule temperature, and Signal Processor temperature.a = A( j,k,g ) ⋅ D( i, j,k,g ) ⋅ I( a, j,g ) ⋅ P( i, j, θ ) ⋅ K( i, j,k,g,T ,T ,T ) Equation 7.2-8DPRESPWhere, K( i, j,k,g,TD ,TPRE,TSP) is sensitivity correction coefficient.b) Calculation of the correction coefficient ‘b’‘b’ is composed of the offset level and the PD dark current. It is calculated based on the Detector temperaturein the TT&C System telemetry data for every band and pixel number.7-15