Modular Multispectral Radiometer (MMR) Calibration

Markham, B.L., F.M. Wood Jr., and S.P. Ahmad. 1988. Radiometric calibration of 
the reflective bands of NS001-thematic mapper simulator (TMS) and modular 
multispectral radiometers (MMR). In Recent Advances in Sensors Radiometry and 
Data Processing for Remote Sensing Proc., SPIE 24, pp. 96-108. 


1989 Calibration coefficients used for data reduction (Markham 1989) for
 MMR (SN 114):

Waveband Gain 
(Volts Watts-1m-2sr-1um-1)
Offset 
(Volts)
Temperature Sensitivity coefficient (oC)
1 0.00601   -0.0039 625.00
2 0.00689 -0.0039 1112.00
3 0.00712 -0.0042  -1486.00
4 0.01024 -0.0094  286.00
5 0.02048   0.0096 -74.40
6 0.04108  0.0322  -73.12
7 0.12229  0.0076  -70.24
Reference Temperature 28.5 degrees Centigrade. 


WAVEBAND'S 1-7 FORMULAE

Temperature Correction Step
Vc(j) = ((R(j) + Td,0) / (R(j) + Td)) * V(j) 

[1] 


where: 
j = MMR waveband 1-7
Vc(j) = waveband response  corrected to Td,0 (volts)
V(j) = waveband response (volts)
R(j) = specific waveband linear temperature sensitivity coefficient (oC)
Td,0 = reference temperature (oC)
Td = (ln(V10 - 1.9316)) / (-0.04446) from Barnes Engineering
    where: 
    V10 = response of detector thermistor (volts)

Apply Calibration Gain and Offset for Radiances
Ls(j) or Lp(j) = [Vc(j) - O(j)] / G(j) 

[2]

where: 

Ls(j) = waveband spectral radiance for surface (Watts-1m-2sr-1um-1)
Lp(j) = waveband spectral radiance for reference panel ( Watts-1m-2sr-1um-1)
O(j) = waveband offset (volts)
G(j) = waveband gain (Volts Watts-1m-2sr-1um-1)

Linear Interpolation for Estimated Reference Panel Values from Surrounding Measured Values
Lp(t,j) = Lp(t1,j) + {((t - t1)/(t2 - t1)) * (Lp(t2,j) - Lp(t1,j))} 

[3]


where:
Lp(t1,j) and Lp(t2,j) = waveband reference panel radiance bracketing the
      surface radiances at times t1 and t2  (Watts-1m-2sr-1um-1)
Lp(t,j) = waveband radiance of the reference panel at the surface radiance
       time t (Watts-1m-2sr-1um-1

Time correction of Reference Panel Value
Lp(t,j) = Lp(t1,j) * (sin(sea(t1)) / sin(sea(t)))

[4] 


where:
sea(t1) = solar elevation angle at time t1
sea(t) = solar elevation angle at time t

Calculate Reflectance Factor
RF(j) = Ls(j) / (Lp(t,j) / RFp(j))

 [5] 

where: 

Ls(j) = waveband surface radiance (Watts-1m-2sr-1um-1)
RF(j) = waveband surface reflectance factor (%)
RFp(j) = waveband reflectance factor for the reference panel(%) 


WAVEBAND 8 (THERMAL) FORMULAE 

Thermal waveband 8 coefficients 1989 Calibration coefficients used for data reduction (Markham 1989) for MMR (SN 114):
AC = 0.1296
BC = 14.42
AA = -0.75249E-03
AB = -0.43519E-05
KA = 0.39019E-03
KB = 0.19078E-05 

Where AC and BC are calibration coefficients for the equation used to calculate the calibration corrected temperature (Tc), and AA, AB, KA and KB are the calibration coefficients for the equation used to calculate the surface radiance (Ls). All of
these coefficients are unitless. 

Tc = (V9 - AC) * BC 

 [6]

where: 

Tc = chopper temperature (oC)
V9 = response (volts) of the chopper thermistor
AC, BC = calibration coefficients
Lc = 0.11927 / {exp(1278.88 / (Tc + 273.00)) - 1.0} 

[7] 


where: 
Lc = chopper radiance (W m-2)
Ld = 0.11927 / {exp(1278.88 / (Td + 273.00)) - 1.0} 

[8]


where:
Ld = detector radiance (W m-2)
Ls = Lc + (KA + KB * Tc) * V8 + (AA + AB * Tc) 

[9] 


where: 
V8 = waveband 8 response voltage
Ls = surface radiance (W m-2)
KA, KB, AA, AB = calibration coefficients
Ls = Ld + (KA + KB * Td) * V8 + (AA + AB * Td)  

[10]


where:
V8 = waveband 8 response (volt)
Ls = surface radiance (W m-2)
KA, KB, AA, AB = calibration coefficients
Tc = 1278.88 / ln((0.11927 / Ls) + 1.0) - 273.0 

[11] 


where:
Tc = calibration corrected temperature measurement (oC)