Improved Limb Atmospheric Spectrometer (ILAS) data retrieval algorithm for Version 5.20 gas profile products

Yokota, Tatsuya; Nakajima, H.; Sugita, T.; Tsubaki, Hiroe; Itou, Yasuhiro; Kaji, M.; Kanzawa, Hiroshi; Park, J. H.; Sasano, Yasuhiro

doi:10.1029/2001jd000628

Cited by 67 publications

(148 citation statements)

References 43 publications

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“…In the comparisons we employ results from the latest retrieval version 3. The retrieval is based on an onion peeling method Yokota et al (2002). Multiple parameters for gases and aerosols are derived simultaneously on a 1 km altitude grid using a least-squares fit (Oshchepkov et al, 2006).The CFC results are based on the spectrum obtained by spectrometer 1 that is fitted in its entirety.…”

Section: Scisat/ace-fts Datamentioning

confidence: 99%

MIPAS IMK/IAA CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) measurements: accuracy, precision and long-term stability

et al. 2016

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) and were used to validate MIPAS CFC-11 and CFC-12 products during that time, as well as profiles from the Improved Limb Atmospheric Spectrometer, ILAS-II. In general, we find that MIPAS shows slightly higher values for CFC-11 at the lower end of the profiles (below ∼ 15 km) and in a comparison of HATS ground-based data and MIPAS measurements at 3 km below the tropopause. Differences range from approximately 10 to 50 pptv (∼ 5-20 %) during the RR period. In general, differences are slightly smaller for the FR period. An indication of a slight high bias at the lower end of the profile exists for CFC-12 as well, but this bias is far less pronounced than for CFC-11 and is not as obvious in the relative differences between MIPAS and any of the comparison instruments. Differences at the lower end of the profile (below ∼ 15 km) and in the comparison of HATS and MIPAS measurements taken at 3 km below the tropopause mainly stay within 10-50 pptv (corresponding to ∼ 2-10 % for CFCPublished by Copernicus Publications on behalf of the European Geosciences Union. 3356 E. Eckert et al.: MIPAS IMK/IAA CFC-11 and CFC-12: accuracy, precision and long-term stability 12) for the RR and the FR period. Between ∼ 15 and 30 km, most comparisons agree within 10-20 pptv (10-20 %), apart from ILAS-II, which shows large differences above ∼ 17 km. Overall, relative differences are usually smaller for CFC-12 than for CFC-11. For both species -CFC-11 and CFC-12 -we find that differences at the lower end of the profile tend to be larger at higher latitudes than in tropical and subtropical regions. In addition, MIPAS profiles have a maximum in their mixing ratio around the tropopause, which is most obvious in tropical mean profiles. Comparisons of the standard deviation in a quiescent atmosphere (polar summer) show that only the CFC-12 FR error budget can fully explain the observed variability, while for the other products (CFC-11 FR and RR and CFC-12 RR) only two-thirds to three-quarters can be explained. Investigations regarding the temporal stability show very small negative drifts in MIPAS CFC-11 measurements. These instrument drifts vary between ∼ 1 and 3 % decade −1 . For CFC-12, the drifts are also negative and close to zero up to ∼ 30 km. Above that altitude, larger drifts of up to ∼ 50 % decade −1 appear which are negative up to ∼ 35 km and positive, but of a similar magnitude, above.

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Section: Scisat/ace-fts Datamentioning

confidence: 99%

MIPAS IMK/IAA CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) measurements: accuracy, precision and long-term stability

et al. 2016

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“…PT(NAT) values that considered the 14% positive bias differed from the values without the bias by less than 5%. Yokota et al (2002) and Yokota et al (2006) suggested that the presence of PSCs yields systematic errors in ILAS-II nitric acid and water vapor data by the nongaseous contribution correction in the retrieval scheme. However, the systematic errors had little effect on PT(NAT) values.…”

Section: Psc Distribution In the Sh In 2003mentioning

confidence: 99%

Variation in PSC Occurrence Observed with ILAS-II over the Antarctic in 2003

Saitoh

Hayashida

Sugita

et al. 2006

SOLA

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The Improved Limb Atmospheric Spectrometer (ILAS)-II frequently observed polar stratospheric clouds (PSCs) in the Southern Hemisphere (SH) throughout the winter of 2003. Simultaneous observations of the aerosol extinction coefficient (AEC) at 780 nm, nitric acid, and water vapor data were analyzed to investigate the ambient thermodynamic conditions associated with observed PSCs. PSCs were first observed with ILAS-II at the end of May, and observed most frequently in August/September as temperatures cooled. At approximately 20 km late in the PSC season, however, PSCs were less likely to occur, despite cold temperatures, because of the lower concentration of nitric acid due to denitrification caused by sedimentation of previously occurring PSCs. The probability of PSC occurrence and the probability of ambient temperatures colder than nitric acid trihydrate (NAT) saturation temperature (TNAT ) were well correlated below 20 km throughout the winter. In contrast, PSC frequency at 22 km from late August to early September was low even when temperatures were sufficiently colder than TNAT; this is, at least, partly because of the decrease in background aerosol particles in the atmosphere. IntroductionPolar stratospheric clouds (PSCs) consist mainly of nitric acid and water/ice and form in winter and early spring in the lower stratosphere over both polar regions (e.g., Solomon 1999). PSCs play a crucial role in ozone depletion processes; they provide surfaces for heterogeneous reactions that convert inactive chlorine into active chorine (e.g., Solomon 1999) and cause denitrification (e.g., Fahey et al. 1990) and nitrification (e.g., H ubler et al. 1990). Activated chlorine causes severe ozone depletion, especially in the Southern Hemisphere (SH), which is known as the "ozone hole". The climatology of PSC frequency in the SH was examined using aerosol data from the Stratospheric Aerosol Measurement (SAM) II from 1978to 1989(Poole and Pitts 1994, data from the Polar Ozone and Aerosol Measurement (POAM) II from 1994 to 1996 (Fromm et al. 1997), and data from multiple solar occultation sensors from 1978 to 2000 .Poole and Pitts (1994) examined the relationship between PSC frequency and temperature and showed that PSC formation in the SH is less likely later in PSC season than earlier. Other studies (e.g., Watterson and Tuck 1989;Hervig et al. 1997;Mergenthaler et al. 1997) have suggested that PSC formation late in PSC season in the SH is strongly affected by preceding denitrification and dehydration. However, there have been few studies on the variability of the relationship between PSC frequency and temperature over the course of a PSC season that are based on extensive observations of aerosols, nitric acid, and water vapor in the SH.Against this background, we used data obtained by the PSC identification and TNAT calculationPSCs were identified from ILAS-II AEC data over the SH using methods similar to those for ILAS data in the NH (Hayashida et al. 2000). First, averages and standard deviations for ILAS-II AEC data at te...

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“…The profiles in the altitude range from 18 to 45 km are retrieved with a vertical resolution of 1.5 to 2 km and a 1-σ precision of better than 1.5 ppbv. Detailed information on the data characteristics and analysis of systematic retrieval errors, resulting from spectroscopic and instrumental uncertainties can be found in (Urban et al, 2005) and (Urban et al, 2006 are simultaneously retrieved by the so-called onion-peeling method, primarily using the strong absorption lines around 7.6 and 11.3 µm for the HNO 3 retrieval, with vertical resolutions of 1.3 to 2.9 km at tangent heights of 15 and 55 km (see Yokota et al, 2002, for details of the retrieval algorithm cloud-clearing technique.). For the version 1.4 ILAS-II algorithm, spectroscopic data were adopted from the year 2000 edition of the HITRAN database, including updates through the end of 2001 (Rothman et al, 2003).…”

Section: Balloon-borne Mipas-b and Mkiv Measurementsmentioning

confidence: 99%

Validation of nitric acid retrieved by the IMK-IAA processor from MIPAS/ENVISAT measurements

Wang

Höpfner²,

Mengistu~Tsidu³

et al. 2007

Atmos. Chem. Phys.

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Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVISAT satellite provides profiles of temperature and various trace-gases from limb-viewing mid-infrared emission measurements. The stratospheric nitric acid (HNO 3 ) from September 2002 to March 2004 was retrieved from the MIPAS observations using the science-oriented data processor developed at the Institut für Meteorologie und Klimaforschung (IMK), which is complemented by the component of non-local thermodynamic equilibrium (non-LTE) treatment from the Instituto de Astrofísica de Andalucía (IAA). The IMK-IAA research product, different from the ESA operational product, is validated in this paper by comparison with a number of reference data sets. Individual HNO 3 profiles of the IMK-IAA MI-PAS show good agreement with those of the balloon-borne version of MIPAS (MIPAS-B) and the infrared spectrometer MkIV, with small differences of less than 0.5 ppbv throughout the entire altitude range up to about 38 km, and below 0.2 ppbv above 30 km. However, the degree of consistency is largely affected by their temporal and spatial coincidence, and differences of 1 to 2 ppbv may be observed between 22 and 26 km at high latitudes near the vortex boundary, due to large horizontal inhomogeneity of HNO 3 . Statistical comparisons of MIPAS IMK-IAA HNO 3 VMRs with respectCorrespondence to: D. Y. Wang (dwang@unb.ca) to those of satellite measurements of Odin/SMR, ILAS-II, ACE-FTS, as well as the MIPAS ESA product show good consistency. The mean differences are generally ±0.5 ppbv and standard deviations of the differences are of 0.5 to 1.5 ppbv. The maximum differences are 2.0 ppbv around 20 to 25 km. This gives confidence in the general reliability of MIPAS HNO 3 VMR data and the other three satellite data sets.

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Improved Limb Atmospheric Spectrometer (ILAS) data retrieval algorithm for Version 5.20 gas profile products

Cited by 67 publications

References 43 publications

MIPAS IMK/IAA CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) measurements: accuracy, precision and long-term stability

MIPAS IMK/IAA CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) measurements: accuracy, precision and long-term stability

Variation in PSC Occurrence Observed with ILAS-II over the Antarctic in 2003

Validation of nitric acid retrieved by the IMK-IAA processor from MIPAS/ENVISAT measurements

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Improved Limb Atmospheric Spectrometer (ILAS) data retrieval algorithm for Version 5.20 gas profile products

Cited by 67 publications

References 43 publications

MIPAS IMK/IAA CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements: accuracy, precision and long-term stability

MIPAS IMK/IAA CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements: accuracy, precision and long-term stability

Variation in PSC Occurrence Observed with ILAS-II over the Antarctic in 2003

Validation of nitric acid retrieved by the IMK-IAA processor from MIPAS/ENVISAT measurements

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MIPAS IMK/IAA CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) measurements: accuracy, precision and long-term stability

MIPAS IMK/IAA CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) measurements: accuracy, precision and long-term stability