MODTRAN TAPE7 Column Descriptions

• MODTRAN TAPE7 Column Descriptions
  • Current Interpretation of MODTRAN tape7 output
  • LOWTRAN7 Description of tape7 output
  • and COMMENTS

Current Interpretation of MODTRAN tape7 output

• tape7.scn: MODTRAN tape7.scn file from which the data was plotted

The same column descriptions also apply to tape7. The difference between the tape7 file and the tape7.scn file is that the former is in [1/cm] which is the native unit of MODTRAN output prior to MODTRAN3. The output wavelength for the tape7.scn file can be user-specified. In this example, the tape7.scn output file has wavelengths specified in [microns] and radiance in [W/sr/cm^2/um].

The following columns are labelled as follows with the definition/description. The plots that correspond to the various spectra was generated using the following tape5 file.

• tape5: MODTRAN tape5 file that created the plots on this page

The conditions are for an 18% reflector being imaged at AVIRIS altitudes for a Mid-latitude Summer atmosphere (MLS). This particular card deck is an MLS version of the card deck with radiosonde profiles for the day of the AvirisRochesterEmbayment19990520 collect.

The resulting tape7.scn file has been converted to the ENVI spectral library files

• tape7.sli: ENVI Spectral Library containing the tape7.scn data and
• tape7.sli.hdr: ENVI Spectral Library header file

FREQ MCRN

The band-center wavelength of the given spectral point entry for the following radiometric parameters.

TRAN

The transmission from the target to the sensor, i.e., tau2 in the Big Equation.

• Plot of TRAN Column [Unitless]:
  

PTH THRML

The thermal emission term of the path radiance (neglible in the reflective region)

• Plot of PTH_THRML Column [W/(sr cm^2 um)]:
  

THRML SCT

The thermal scattering term of the path radiance (negligible in the reflective region)

SURF EMIS

Radiant mission of the target as a function of its temperature and emissivity

• Plot of SURF_EMIS Column [W/(sr cm^2 um)]:
  

SOL SCAT

The solar multiple-scattered radiance term of the path radiance.

• Plot of SOL_SCAT Column [W/(sr cm^2 um)]:
  

SING SCAT

The solar single-scattered radiance term of the path radiance.

• Plot of SING_SCAT Column [W/(sr cm^2 um)]:
  

GRND RFLT

The total ground reflected radiance. For a target of reflectivity 1.0, this term would be (Direct Reflected Radiance) + (Diffuse Reflected Radiance) or %$\frac{E^{'}_{s \lambda}\cos\theta \tau_1(\lambda)\tau_2(\lambda)}{\pi}+L_{d \lambda} \tau_2$% in the Big Equation

• Plot of GRND_RFLT Column [W/(sr cm^2 um)]:
  

DRCT RFLT

This is the direct reflected radiance. For a target of reflectivity 1.0, this term would be (Direct Reflected Radiance) or %$\frac{E^{'}_{s \lambda}\cos\theta \tau_1(\lambda)\tau_2(\lambda)}{\pi}$% in the Big Equation

• Plot of DRCT_RFLT Column [W/(sr cm^2 um)]:
  

TOTAL RAD

This is the total radiance reachin the sensor which should be equivalent to %$\frac{E^{'}_{s \lambda}\cos\theta \tau_1(\lambda)\tau_2(\lambda)r(\lambda)}{\pi} + L_{d \lambda}\tau_2 r(\lambda) + L_{u\lambda}$% in the Big Equation. Because of the simplified form of this equation, adjacency and environmental effects may not represented in the equation resulting in a larger value for TOTAL RAD computed by MODTRAN.

• Plot of TOTAL_RAD Column [W/(sr cm^2 um)]:
  

REF SOL

This is SOL@OBS multiplied by tau1 and tau2. This column is most likely in units of irradiance [W/cm^2], not radiance, since SOL@OBS is in irradiance units and tau1*tau2 is unitless. (N.B. Found some old notes attributed to Lee Sanders that REF_SOL for the version we were using back during his research, was EsTau1Tau2 -- RolandoRaqueno - 08 Mar 2007)

• Plot of REF_SOL Column [W/(cm^2 um)]:
  

SOL@OBS

This is the downwelling solar irradiance at the altitude of the observer. This value should be DRCT RFLT if we move the target to the height of the sensor. N.B. The units should be Irradiance in the plot -- RolandoRaqueno - 06 Nov 2006

• Plot of SOL@OBS Column [W/(cm^2 um)]:
  SOL@OBS Column [W/(cm^2 um)]" width="360" height="255" />

DEPTH

Negative Log of the transmittance column TRAN

• Plot of DEPTH Column [1/m] or [1/km], not sure of this ???:
  

LOWTRAN7 Description of tape7 output

• LOWTRAN7_OUTPUT_DESCRIPTIONS.PDF: LOWTRAN7 Output descriptions taken from "User's Guide to LOWTRAN7" published by AFGL

-- RolandoRaqueno - 18 Nov 2004

Another explanation of the column descriptions, just to add to the confusion.

• ontar_tp7_explanation.rtf: Tape7 column descriptions from ONTAR