Dear All,
I have been using 6S atmospheric correction model for the estimation of surface reflectance for different features. But this time I need surface radiance instead of surface reflectance for further use. Is it possible that the surface reflectance estimated using 6S model can be converted to surface radiance?
Just like we can convert the Top of Atmosphere (TOA) reflectance into TOA radiance (using the following equation) for Landsat sensors (TM/ETM+), is it possible that we can also convert the surface reflectance into surface radiance?
ρλ = π x Lλ x d2 / ESUNλ x cos θs
where
ρλ= Planetary TOA reflectance [unitless]
π= Mathematical constant equal to ~3.14159 [unitless]
Lλ= Spectral radiance at the sensor's aperture [W/(m2 sr μm)]
d= Earth–Sun distance [astronomical units]
ESUNλ= Mean exoatmospheric solar irradiance [W/(m2 μm)]
θs= Solar zenith angle [degrees]
Reference: Chander, G., Markham, B.L., Helder, D.L., 2009. Summary of current radiometric calibration coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI sensors. Remote Sens. Environ. 113, 893–903. http://dx.doi.org/10.1016/j. rse.2009.01.007
Hi Majid,
Have a look to Section 2 from Gilabert et al., "An atmospheric correction method for the automatic retrieval of surface reflectances from TM images", 1994:
https://www.researchgate.net/profile/MA_Gilabert/publication/245309635_An_atmospheric_correction_method_for_the_automatic_retrieval_of_surface_reflectance_from_TM_images/links/546c9f460cf2c4819f22a031.pdf
Regards
Article An atmospheric correction method for the automatic retrieval...
Hi Breton,
Thanks for your answer, but my question is different.
I don't want an atmospheric correction method rather I am looking for a method to convert the surface reflectance into surface radiance.
Did you really have a look to Section 2.1 from https://www.researchgate.net/profile/MA_Gilabert/publication/245309635_An_atmospheric_correction_method_for_the_automatic_retrieval_of_surface_reflectance_from_TM_images/links/546c9f460cf2c4819f22a031.pdf ?
Article An atmospheric correction method for the automatic retrieval...
You want the value of radiancie that a field radiometer should be read in the field at the same time of image adquired. That's right?
That is a challenge.The computer code apply for two paths, sun to surface and surface to sensor, then, the second path you have to dismiss.
If anyone knows in this world, that man is Pzremyslaw Zelazowski, a young brilliant scientist and very friendly.
you can contact him at
http://www.eci.ox.ac.uk/people/pzelazowski.html
Dear Majid,
This is very simple issue you have to go back from surface reflectance to at satellite reflectance according to an equation that relates both. According to Tasumi et al. (2008) the following is the equation:
Reflectance_at_surface = (reflectance_at_satellite - Cb*(1-Tin,b))/((Tin,b)*(Tout,b))
The reflectance_at_satellite is the equation you gave in your question and it includes the variable radiance that you want to compute.
Cb is a constant calibrated value, Tin,b and Tout,b are narrow band
transmittances for incoming solar radiation and for surface reflected shortwave radiation. Narrowband transmittances, Tin,b and Tout,b, must be calculated, and were found by Tasumi et al., (2005b).
Tin,b for example can be computed as folllow
C1*Expontial((C2* Pair/kt*Cos(θh)) - ((C3*W+C4)/cos((θh))+C5
where C1 to C5 are given constants, Kt is a unitless “clearness” coefficient 0 < Kt
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