Simultaneous stratospheric gas and aerosol retrievals from broadband infrared occultation measurements

Oshchepkov, Sergey; Sasano, Yasuhiro; Yokota, Tatsuya; Uemura, Nobuyuki; Matsuda, Hisashi; Itou, Yasuhiro; Nakajima, H.

doi:10.1364/ao.44.004775

Cited by 8 publications

(24 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Improved Limb Atmospheric Spectrometers ILAS and ILAS-II used the solar occultation technique which measures the absorption of stratospheric species in the infrared region of solar radiation Oshchepkov et al, 2005 (Nakajima et al, 2006b).…”

Section: Ilas/ilas-iimentioning

confidence: 99%

Evaluation of CLaMS, KASIMA and ECHAM5/MESSy1 simulations in the lower stratosphere using observations of Odin/SMR and ILAS/ILAS-II

Khosrawi¹,

Müller²,

Proffitt³

et al. 2009

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. 1-year data sets of monthly averaged nitrous oxide (N 2 O) and ozone (O 3 ) derived from satellite measurements were used as a tool for the evaluation of atmospheric photochemical models. Two 1-year data sets, one solar occultation data set derived from the Improved Limb Atmospheric Spectrometer (ILAS and ILAS-II) and one limb sounding data set derived from the Odin Sub-Millimetre Radiometer (Odin/SMR) were employed. Here, these data sets are used for the evaluation of two Chemical Transport Models (CTMs), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA) and the Chemical Lagrangian Model of the Stratosphere (CLaMS) as well as for one ChemistryClimate Model (CCM), the atmospheric chemistry general circulation model ECHAM5/MESSy1 (E5M1) in the lower stratosphere with focus on the Northern Hemisphere. Since the Odin/SMR measurements cover the entire hemisphere, the evaluation is performed for the entire hemisphere as well as for the low latitudes, midlatitudes and high latitudes using the Odin/SMR 1-year data set as reference. To assess the impact of using different data sets for such an evaluation study we repeat the evaluation for the polar lower stratosphere using the ILAS/ILAS-II data set. Only small differences were found using ILAS/ILAS-II instead of Odin/SMR as a reference, thus, showing that the results are not influenced by the particular satellite data set used for the evaluation. The evaluCorrespondence to: F. Khosrawi (farah@misu.su.se) ation of CLaMS, KASIMA and E5M1 shows that all models are in agreement with Odin/SMR and ILAS/ILAS-II. Differences are generally in the range of ±20%. Larger differences (up to −40%) are found in all models at 500±25 K for N 2 O mixing ratios greater than 200 ppbv, thus in air masses of tropical character. Generally, the largest differences were found for the tropics and the lowest for the polar regions. However, an underestimation of polar winter ozone loss was found both in KASIMA and E5M1 both in the Northern and Southern Hemisphere.

show abstract

Section: Ilas/ilas-iimentioning

confidence: 99%

Evaluation of CLaMS, KASIMA and ECHAM5/MESSy1 simulations in the lower stratosphere using observations of Odin/SMR and ILAS/ILAS-II

Khosrawi¹,

Müller²,

Proffitt³

et al. 2009

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…The inversion procedure yielding simultaneous gas and aerosol retrievals from occultation measurements using aerosol physical modeling has been described elsewhere [ Oshchepkov et al , 2005]. The main features of the retrieval scheme and the assumptions in routine ILAS data processing are given below.…”

Section: Methodsmentioning

confidence: 99%

“…However, real AEC spectra could not always be represented as broken straight lines derived from linear interpolation. This problem was more likely with high aerosol amounts, such as those common in PSC observations [ Yokota et al , 2002; Oshchepkov et al , 2002, 2005]. Simultaneous retrievals of gas mixing ratios and aerosol spectra [ Oshchepkov et al , 2002] was shown to alleviate this problem and allow the extraction of useful aerosol information in all ILAS channels.…”

Section: Introductionmentioning

confidence: 99%

ILAS data processing for stratospheric gas and aerosol retrievals with aerosol physical modeling: Methodology and validation of gas retrievals

Oshchepkov¹,

Sasano²,

Yokota³

et al. 2006

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

[1] This paper presents initial results of simultaneous gas and aerosol retrievals from Improved Limb Atmospheric Spectrometer (ILAS) observations taken between November 1996 and June 1997. The solar occultation measurements were processed by an inversion method that included aerosol physical modeling and permitted simultaneous retrieval of O 3 , HNO 3 , CH 4 , H 2 O, NO 2 , N 2 O, N 2 O 5 , ClONO 2 , CFC-11, and CFC-12 trace species and particle volume size distributions for key aerosol/polar stratospheric cloud (PSC) components such as liquid ternary solution, nitric acid trihydrate, nitric acid dihydrate, and water ice. The retrieval method was designed for the version 7.0 ILAS data processing algorithm. Gas retrieval results for the entire ILAS data set were compared to results from the earlier version 6.0 retrieval algorithm that was based on aerosol/PSC contribution estimates in the gas window channel. Gas data from nearby balloon-borne validation measurements and new data on the aerosol retrievals helped explain discrepancies between the two algorithms. The new version 7.0 methodology proved effective for simultaneous retrievals of all trace gases and showed a significant advantage when retrieving CH 4 , H 2 O, NO 2 , N 2 O, and CFC-12 from PSC observations.

show abstract

“…The locations of the maxima of the retrieved particle size distribution are shown to be in a good agreement with those for the original size distributions. The fact that the half width of the retrieved particle size distribution is subject to overestimation, as well as the magnitude of the particle size distribution at the position of its maximum experiencing underestimation as the particle sizes decrease, is explained by the limited sensitivity of the infrared data with respect to size composition of small particles [ Oshchepkov et al , 2005]. Indeed, the highest biases hold for very small binary H 2 SO 4 /H 2 O droplets.…”

Section: Retrievalsmentioning

confidence: 99%

“…In addition, the processing of each LTS spectrum demands consideration of different chemical compositions, even for reliable retrievals of the particle size distribution. It is therefore not probable that such an approach is optimal for the processing of spaceborne occultation measurements when, along with LTS, we need to allow for other PSC and gas components simultaneously [ Oshchepkov et al , 2005].…”

Section: Bicomponent Approximationmentioning

confidence: 99%

Characterization of stratospheric liquid ternary solution aerosol from broadband infrared extinction measurements

et al. 2005

Self Cite

View full text Add to dashboard Cite

[1] Characterization of stratospheric liquid ternary solution (LTS) aerosol is studied as an inverse problem in retrieving particle volume size distribution and chemical composition of ternary droplets using the extinction coefficient over wavelengths of 3 to 12 mm. The retrieval method comprises a constrained, weighted least squares minimization procedure between measured and modeled spectra. The constraints restrict the first derivative of the particle size distribution with respect to particle size and restrict the relationship between weight percents of discrete partials (H 2 SO 4 /H 2 O/HNO 3 ) in the ternary droplets using the Carslaw equilibrium model. In the inverse modeling, emphasis is given to minimize the number of reference spectra up to consideration of two mostly binary components composed of H 2 SO 4 /H 2 O and HNO 3 /H 2 O solutions. This permits the retrieval of particle volume size distribution independently of particle chemical composition and therefore simply adopts the inversion method for the processing of spaceborne occultation measurements when other aerosol/cloud components along with trace gases are subject to identification. We initially carry out numerical tests by applying the inversion method to synthetic extinction measurements in order to study the limitations of the retrievals over wide ranges of microphysical parameters. A case study in processing actual space-borne data obtained by the Improved Limb Atmospheric Spectrometer (ILAS) demonstrates the efficiency of the retrievals.Citation: Sasano, Y., S. Oshchepkov, T. Yokota, and H. Nakajima (2005), Characterization of stratospheric liquid ternary solution aerosol from broadband infrared extinction measurements,

show abstract

Simultaneous stratospheric gas and aerosol retrievals from broadband infrared occultation measurements

Cited by 8 publications

References 27 publications

Evaluation of CLaMS, KASIMA and ECHAM5/MESSy1 simulations in the lower stratosphere using observations of Odin/SMR and ILAS/ILAS-II

Evaluation of CLaMS, KASIMA and ECHAM5/MESSy1 simulations in the lower stratosphere using observations of Odin/SMR and ILAS/ILAS-II

ILAS data processing for stratospheric gas and aerosol retrievals with aerosol physical modeling: Methodology and validation of gas retrievals

Characterization of stratospheric liquid ternary solution aerosol from broadband infrared extinction measurements

Contact Info

Product

Resources

About