WP 3: Cross comparison
Leaders: V. Catoire, M. Dorf
Cross-comparison/validation will be addressed on each payload on species relevant for dynamics
(blue colour in the Table below) and chemistry (green).The cross-comparison and cross-validation will
focus on a direct comparison of simultaneously monitored species by different instruments on the same
payload. The goal is to evaluate the absolute accuracy of the measurements by comparing the results
of the different techniques.
All instruments onboard the MIPAS and LPMA gondolas perform remote sensing measurements, whereas
the instruments mounted on the TWIN and SPIRALE payloads perform in-situ observations. This
facilitates cross-comparison especially also for the remote sensing instruments, since most of
them even use the same viewing geometry, i.e. MIPAS/TELIS and LPMA/DOAS.
Nevertheless, there are essential differences in the individual techniques that give rise to
systematic uncertainties and discrepancies: different spectroscopic approaches, which might also
result in different light-paths for the observations, differences in the altitude and time
resolution, instrumental characterisation and calibration issues (e.g. calibration standards),
different retrieval approaches and profile inversion techniques.
A direct comparison of results obtained with different techniques will greatly help to identify
some of the systematic uncertainties and further improve the reliability of balloon-borne
observations. Table 1 summarizes the chemical species included in the cross-comparison/validation.
The CO2 and CH4 measurements from the picoSDLA instrument operated on TWIN,
and the CH4 and CO measurements of OFCEAS on SPIRALE are very recent and a comparison
with measurements of the other instruments onboard the TWIN and SPIRALE payloads will be used for
their validation. Since instruments on both payloads perform in-situ measurements, biases due to
geophysical hypotheses for vertical profile retrievals will be avoided. Table below lists the techniques
used for the cross-comparisons. It can be seen that very various methods and spectroscopic windows
will be employed, which will give confidence in the results obtained.
Payload | MIPAS | TWIN | LPMA | SPIRALE | |
Instruments | MIPAS, TELIS, DOAS, miniDOAS | BONBON, HALOX-B, picoSDLA | LPMA, DOAS, miniDOAS | SPIRALE, OFCEAS | |
Dynamics | N2O | cross comparison | |||
H2O | cross comparison | ||||
CO | cross comparison | cross comparison | |||
CH4 | cross comparison | cross comparison | |||
CO2 | cross comparison | cross comparison | |||
Ozone | O3 | cross comparison | cross comparison | ||
Chemistry | ClO | cross comparison | |||
BrO | cross comparison | ||||
NO2 | cross comparison | ||||
HNO3 | cross comparison | cross comparison | |||
HOCl | cross comparison |
Species | Instrument | Measurement
technics |
Wavelength
or wavenumber range |
N2O | MIPAS | FTIR limb emission | 1100 - 1330 cm-1 |
TELIS | sub-mm/far-IR
limb emission |
16.75 cm-1 | |
CO2 | BONBON | GC-MS | chemical method |
picoSDLA | IR laser absorption | 3729.712 cm-1 | |
CH4 | BONBON | GC-MS | chemical method |
picoSDLA | IR laser absorption | 3085.8 - 3085.9 cm-1 | |
SPIRALE | IR laser absorption | 1260.811 cm-1 | |
OFCEAS | IR laser absorption | 4300.366 cm-1 | |
CO | MIPAS | FTIR limb emission | 2050 - 2210 cm-1 |
TELIS | sub-mm/far-IR
limb emission |
61.42 cm-1 | |
SPIRALE | IR laser absorption | 2123.699 cm-1 | |
OFCEAS | IR laser absorption | 4300.700 cm-1 | |
H2O
& isotopic fractionation |
MIPAS | FTIR limb emission | 800 - 1700 cm-1 |
TELIS | sub-mm/far-IR
limb emission |
16.2 - 16.4 cm-1
60.5 - 60.7 cm-1 61.3 - 61.7 cm-1 |
|
O3 | DOAS | UV/vis | 560 - 615 cm-1 |
LPMA | FTIR | 779 - 781 cm-1
3040 - 3041 cm-1 |
|
O3
& isotopic fractionation |
DOAS | UV/vis | 560 - 615 cm-1 |
MIPAS | FTIR limb emission | 700 - 1150 cm-1 | |
TELIS | sub-mm/far-IR
limb emission |
16 - 22 cm-1
60 cm-1 |
|
NO2 | DOAS | UV/vis | 430 - 485 cm-1 |
MIPAS | FTIR limb emission | 1590 - 1650 cm-1 | |
TELIS | sub-mm/far-IR
limb emission |
17.54 cm-1 | |
DOAS | UV/vis | 430 - 485 cm-1 | |
LPMA | FTIR | 2914 - 2915 cm-1 | |
HNO3 | MIPAS | FTIR limb emission | 860 - 890 cm-1
and other bands |
TELIS | sub-mm/far-IR
limb emission |
16 - 22 cm-1 | |
HOCl | MIPAS | FTIR limb emission | 1210 - 1270 cm-1 |
TELIS | sub-mm/far-IR
limb emission |
20.44 cm-1
60 cm-1 |
|
ClO | MIPAS | FTIR limb emission | 810 - 870 cm-1 |
TELIS | sub-mm/far-IR
limb emission |
16.72 cm-1 | |
BrO | DOAS | UV/vis | 340 - 360 cm-1 |
TELIS | sub-mm/far-IR
limb emission |
17.51 cm-1 |
For spectroscopic measurements, the wavelength range is given.
Link to the description of the other workpackages.
-
WP 1: Chemistry
- Leaders: F. Stroh, C. Camy-Peret
-
WP 2: Dynamics
- Leaders: N. Huret, A. Engel
-
WP 4: Satellite Validation
- Leaders: H. Oelhaf, S. Payan