Level 1b error budget for MIPAS on ENVISAT

Kleinert, Anne; Birk, Manfred; Perron, Gaétan; Wagner, Georg

doi:10.5194/amt-2018-185

Cited by 2 publications

(5 citation statements)

References 21 publications

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“…This correction leads to a further reduction of the drift caused by the progressive ageing of the photoconductive detectors. Now the drift error is estimated to be less than 0.5% across the entire MIPAS mission (Kleinert et al, 2018).…”

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confidence: 99%

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Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

Pettinari

Barbara

Ceccherini

et al. 2021

Preprint

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Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measured the middle-infrared limb emission spectrum of the atmosphere from 2002 to 2012 on board ENVISAT, a polar-orbiting satellite. Recently, the European Space Agency (ESA) completed the ﬁnal reprocessing of MIPAS measurements, using Version 8 of the Level 1 and Level 2 processors, which include more accurate models, processing strategies and auxiliary data. The list of retrieved gases has been extended, it now includes a number of new species with weak emission features in the MIPAS spectral range. The new retrieved trace species include carbonyl chloride (COCl2), also called phosgene. Due to its toxicity, its use has been reduced over the years, however it is still used by chemical industries for sevaeral applications. Besides its direct injection in the troposphere, stratospheric phosgene is mainly produced from the photolysis of CCl4, a molecule present in the atmosphere because of human activity. Since phosgene has a long stratospheric lifetime, it must be carefully monitored as it is involved in the ozone destruction cycles, especially over the winter polar regions. In this paper we exploit the ESA MIPAS Version 8 data in order to discuss the phosgene distribution, variability and trends in the middle and lower stratosphere and in the upper troposphere. The zonal averages show that phosgene volume mixing ratio is larger in the stratosphere, with a peak of 40 pptv between 50 and 30 hPa at equatorial latitudes, while at middle and polar latitudes it varies from 10 to 25 pptv. A moderate seasonal variability is observed in polar regions, mostly between 80 and 50 hPa. The comparison of MIPAS/ENVISAT COCl2 v.8 proﬁles with the ones retrieved from MIPAS/balloon and ACE-FTS measurements highlights a negative bias of about 2 pptv, mainly in polar and mid-latitude regions. Part of this bias is attributed to the fact that the ESA Level 2 v.8 processor uses an updated spectroscopic database. For the trend computation, a ﬁxed pressure grid is used to interpolate the phosgene proﬁles and, for each pressure level, VMR monthly averages are computed in pre-deﬁned 10°-wide latitude bins. Then, for each latitudinal bin and pressure level, a regression model has been ﬁtted to the resulting time-series in order to derive the atmospheric trends. We ﬁnd that the phosgene trends are different in the two hemispheres. The analysis shows that the stratosphere of the Northern Hemisphere is characterised by a negative trend, of about −7 pptv/decade, while in the Southern Hemisphere phosgene mixing ratios increase with a rate of the order of +4 pptv/decade. In the upper troposphere a positive trend is found in both hemispheres.

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confidence: 99%

“…Radiometrically calibrated and geolocated spectra are created by the Level 1b processor (Kleinert et al, 2007) from the MIPAS interferograms. Version 8 of the Level 1b processor includes several improvements as compared to earlier versions (Kleinert et al, 2018). The most relevant for our analysis is the detector non-linearity correction.…”

mentioning

confidence: 99%

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

Pettinari

Barbara

Ceccherini

et al. 2021

Preprint

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“…3), the O 3 noise errors are very similar to those during daytime below around 70 km but significantly smaller above, being 10-20% at 75-95 km, 20-30% at 95-100 km (except near the tropics where the errors are smaller) and larger than 30% above 100 km. The 1σ gain uncertainties were estimated to be 1.1% and 0.8% for the A and AB bands, respectively (see Kleinert et al, 2018). The response of retrieved ozone to the gain calibration is, to first order, multiplicative.…”

Section: Measurement Errorsmentioning

confidence: 98%

“…The uppermost altitude of the continuum retrieval has been extended from 50 to 60 km. The background continuum is strongly constrained to zero above 60 km (we used 50 km in the previous version), and the vertical offset profiles for the microwindows in band A (MWs #1-30) and band AB (MWs #31-38) (see Table A1) are strongly regularised towards the a priori values taken from the empirically determined offset correction profiles by Kleinert et al (2018). See more details in Kiefer et al (2023).…”

Section: Background Continuum Radiance Offset and Water Vapour Interf...mentioning

confidence: 99%

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MIPAS ozone retrieval version 8: middle atmosphere measurements

López‐Puertas

García‐Comas

Funke

et al. 2023

Preprint

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Abstract. We present a new version of O3 data retrieved from the three MIPAS observations modes of the middle atmosphere (MA, UA and NLC). The O3 profiles cover altitudes from 20 up to 100 km altitudes for daytime and up to 105 km at nighttime, for all latitudes, and the period 2005 until 2012. The data has been obtained with the IMK–IAA MIPAS level 2 data processor and are based on ESA version 8 re-calibrated radiance spectra with improved temporal stability. The processing included several improvements with respect to the previous version, such as the consistency of the microwindows and spectroscopic data with those used in the nominal mode V8 data, the O3 a priori profiles, and updates of the non-LTE parameters and of the nighttime atomic oxygen. Random errors are dominated by the measurement noise with 1σ values for single profiles for daytime of <5 % below ~60 km, 5–10 % between 60 and 70 km, 10–20 % at 70–90 km and about 30 % at 95 km. For nighttime, they are very similar below 70 km but smaller above (10–20 % at 75–95 km, 20–30 % at 95–100 km and larger than 30 % above 100 km). The systematic error is ~6 % below ~60 km (dominated by uncertainties in spectroscopic data), and 8–12 % above ~60 km, mainly caused by non-LTE uncertainties. The systematic errors in the 80–100 km range are significantly smaller than in the previous version. The major differences with respect to the previous version are: 1) The new retrievals provide O3 abundances in the 20–50 km altitude range larger by about 2–5 % (0.2–0.5 ppmv); 2) O3 abundances reduced by ~2–4 % between 50 and 60 km in the tropics and mid-latitudes; 3) reduced O3 abundances in the nighttime O3 minimum just below 80 km, leading to a more realistic diurnal variation; 4) larger daytime O3 concentrations in the secondary maximum at the tropical and mid-latitudes (~40 %, 0.2–0.3 ppmv); and 5) nighttime O3 abundances in the secondary maximum reduced by 10–30 %. The O3 profiles retrieved from the nominal mode (NOM) and the middle atmosphere modes are fully consistent in their common altitude range (20–70 km). Only at 60–70 km daytime O3 of NOM seems to be larger than that of MA/UA by 2–10 %. Compared to other satellite instruments, MIPAS seems to have a positive bias of 5–8 % below 70 km. Noticeably, the new version of MIPAS agrees much better than before with all instruments in the upper mesosphere/lower thermosphere, reducing the differences from ~ ±20 % to ~ ±10 %. Further, the diurnal variation of O3 in the upper mesosphere (near 80 km) has been significantly improved.

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Level 1b error budget for MIPAS on ENVISAT

Cited by 2 publications

References 21 publications

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

MIPAS ozone retrieval version 8: middle atmosphere measurements

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