Oxford MIPAS meeting#15
24 Sep 02

Present

L1/L2 Data Delivery [Prev] [Next]

L1 Calibration [Prev] [Next]
Official status of MIPAS L1 Calibration reported at Envisat Calibration Review on 12 Sep 02.
Newly delivered ESTEC data for 2081-2083 (email from Herb Nett below) uses:
  1. 'old' (pre-flight) non-linearity correction
  2. new MW dictionary for spectral calibration and ILS retrievals
  3. retrieved ILS parameters in PS2 file without spectral correction

    REC Analysis (AD) [Prev] [Next]
    REC analysis performed for old (aug02)/new 2081-2083 ESTEC/ESA retrievals (read down the columns, then left to right, for decreasing confidence in fit)

    Source Old Fit New Fit Source Old Fit New Fit Source Old Fit New Fit
    o3 -0.11 -0.13 h2o_st 0.06 0.00 hocl 1.83 2.01
    no2 0.05 0.06 nh3 -0.59 -0.59 f12 11.99 11.57
    hno3 -0.10 -0.16 hcn 0.11 0.20 ocs 3.11 3.37
    so2 0.05 0.04 n2o5 1.07 1.05 hno4 -5.89 -13.72
    ch4 -0.11 0.00 pre 0.68 0.35 c2h2 10.24 11.77
    n2o 0.04 0.05 clono2 0.50 1.69 f14 24.36 13.24
    co2mix 0.30 0.40 cof2 3.49 3.78 c2h6 36.22 27.05
    h2o_12 0.02 -0.01 co2 -3.39 0.09 clo 18.71 14.14
    nonlte -0.15 0.13 ccl4 6.55 5.47 f11 0.38 0.39

    Noticeable differences are
    • pressure error signature (pre) and co2 reduced, which might indicate improved pressure/pointing retrieval
    • nonlte has inverted sign, now positive as expected but still much smaller than predicted value +1.

    Spectral Shift (AD) [Prev] [Next]
    Spectral shift in residuals not much changed in new L2 data for 2081-2083
    • Herb Nett has also investigated residual spectral shifts in calibration microwindows after fitting Ksc (stretch term on spectral axis) [Plot]
    • Polynomial adjustment has been incorporated into ESA L2 reprocessing of orbit 2081 data (not yet distributed to CalVal groups)
    • REC analysis [Plots] shows some improvement in A band but not much change in C band.
    Note that these modifications will be implemented in ESA L2 processing, so the L1B data spectral calibration will have to be corrected separately by each group.
Extracts from email from Herb Nett (23 Sep 02) 

Following discussion during our meeting on 29 Aug 2002 (CM7) we 
re-processed orbits 2081 - 2083. As for previous delivery data 
can be retrieved from our ftp site ftp.estec.esa.nl. Could you please 
transfer files until end next week & confirm by e-mail?

Changes are:

1. use 'old' non-linearity correction coefficients (from pre-launch char. 
   measurements) for scene and cal data, for band A, AB, B detectors

2. use of new microwindow dictionary for spectral cal. & ILS retrievals.
   The dictionary is the one presented by Alastair Burgess at CM7 and at the cal 
   review, after removing a few 'problematic' MWs (see file 
   MW_dictionary_reduced_020918.txt)
   
3. use of retrieved ILS parameters in PS2 file, no spectral correction.