I will share how i have been doing.I have seven wavelength absorption data for a day on basis of 2 min resolution. I assumed at 880 nm total absorption is due to black carbon. Now i find out the absorption for 370nm by using AAE =1 for pair of waveleth (370 and 880). from here i calculated the attributed absorption for 370nm, which is termed as absorption due to BC alone in 370nm. Then i subtracted this attributed absorption from total absorption at 370nm, which is equivalent to BrC absorption.But I am getting NEGATIVE absorption value at 370nm. Where I am doing wrong.?? kindly help??
Hi Saifi,
What model aethalometer are you using, is your data already compensated for optical saturation?
In general BC absorbs uniformly across all seven wavelengths and aromatic organic compounds (Brown Carbon; BrC) show increased absorption at shorter wavelengths. The difference between compensated 880 nm and 370 nm is referred to Delta-C and is used as an indicator of biomass combustion.
The attached presentation provides additional information.
@Matthew S Landis
Dear Matthew,
Thanks for responding. My query here is how to find the percentage contribution of black and brown carbon separately from the corrected 7 absorption coefficient wavelength reading?
Saifl this might help you
Article Relative importance of black carbon, brown carbon, and absor...
If you are using Aethalometer AE33, did you calculate absorption coefficients babs based on the MAC values given in the manual (see the pic.). AE33 convert babs to eBC (ng/m3) and use eBC as outputs, so in order to get accurate babs, you need to use the specific MAC given, might finally result in negative values.
- Badges
- Science topic