Brewer weighting coefficients | WG2 - Algorithms | Forum

(Testing discusion from Kostas Fragkos)

I have found a paper from Savastiouk and McElroy (V. Savastiouk and C.T. McElroy. Brewer Spectrophotometer Total Ozone Measurements Made During the 1998 Middle Atmosphere Nitrogen Trend Assessment (MANTRA) Campaign. Atmos.-Ocean, 43 (4), 315-324, 2005. http://www.tandfonline.com/doi...../ao.430403) and a powerpoint presentation from John Rimmer (ftp://ftp.nilu.no/pub/NILU/gei.....mmerWF.ppt), so when i apply the described methology there i get as solutions for the weighting coefficients [-1 0.46 2.23 -1.69], which are pretty close to the nominal, but when i check the files from the linefit (dispro) i see there completely different values for the coefficients eg for step 157

157 Wavelength(A) 0.00 3062.86 3100.51 3135.12 3167.99 3200.07 SO2: 1.1494
Resolution(A) 0.00 10.94 10.83 10.94 10.86 10.51
O3 Abs (1/cm) 0.0000 1.7836 1.0049 0.6763 0.3749 0.2939 O3: 0.3415
Ozone weighting: 0.00 0.00 -1.00 0.05 3.05 -2.10 O3: 0.4447
SO2 weighting: 0.00 -1.00 0.00 0.00 4.43 -3.43 SO2: 1.1307
Rayleigh coeff.: 0 5097 4835 4609 4407 4220

Moreover, i have noticed that in the majority of brewers the weighting coefficients, differ significant from the standard. So i am wondering if i haven’t understood something good from the described methodology (which it seems very straight-foward to me, the only you need to know is the exact wavelength and the SO2 cross sections and solving a linear system of 3 equations you get the intrumental dependent O3 weighting coeffiecients) or there is something else i miss in the procedure (???) and i can’t reproduce the same results as from linefit. I would appreciate if you could give me any advice so as to solve this issue.