Water vapour profiles by ground-based FTIR spectroscopy: study for an optimised retrieval and its validation

Schneider, Mat­thias; Hase, Frank; Blumenstock, T.

doi:10.5194/acp-6-811-2006

Cited by 94 publications

(84 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is much larger than the scatter in the difference with the FTIR profiles meaning that the FTIR well follows the ISOWAT reference, which confirms previous empirical validation exercises made for H 2 O (e.g. Schneider et al, 2006a;Schneider and Hase, 2009;Schneider et al, 2010a). Please note that the depicted red dashed line represents the combined uncertainty of the convolved ISOWAT data and the FTIR data.…”

Section: Ndacc/ftirsupporting

confidence: 68%

See 1 more Smart Citation

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

et al. 2015

Self Cite

View full text Add to dashboard Cite

Abstract. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) integrates tropospheric water vapour isotopologue remote sensing and in situ observations. This paper presents a first empirical validation of MUSICA's H 2 O and δD remote sensing products, generated from groundbased FTIR (Fourier transform infrared), spectrometer and space-based IASI (infrared atmospheric sounding interferometer) observation. The study is made in the area of the Canary Islands in the subtropical northern Atlantic. As reference we use well calibrated in situ measurements made aboard an aircraft (between 200 and 6800 m a.s.l.) by the dedicated ISOWAT instrument and on the island of Tenerife at two different altitudes (at Izaña, 2370 m a.s.l., and at Teide, 3550 m a.s.l.) by two commercial Picarro L2120-i water isotopologue analysers.The comparison to the ISOWAT profile measurements shows that the remote sensors can well capture the variations in the water vapour isotopologues, and the scatter with respect to the in situ references suggests a δD random uncertainty for the FTIR product of much better than 45 ‰ in the lower troposphere and of about 15 ‰ for the middle troposphere. For the middle tropospheric IASI δD product the study suggests a respective uncertainty of about 15 ‰. In both remote sensing data sets we find a positive δD bias of 30-70 ‰.Complementing H 2 O observations with δD data allows moisture transport studies that are not possible with H 2 O observations alone. We are able to qualitatively demonstrate the added value of the MUSICA δD remote sensing data. We document that the δD-H 2 O curves obtained from the different in situ and remote sensing data sets (ISOWAT, Picarro at Izaña and Teide, FTIR, and IASI) consistently identify two different moisture transport pathways to the subtropical north eastern Atlantic free troposphere.

show abstract

Section: Ndacc/ftirsupporting

confidence: 68%

“…It describes the response of the retrieval on actual Schneider et al, 2012), which have been empirically validated in a variety of previous studies (e.g. Schneider et al, 2006a;Schneider and Hase, 2009;Schneider et al, 2010a). A further validation of product type 1 is not the subject of this paper.…”

Section: Ground-based Ndacc/ftirmentioning

confidence: 99%

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…www.atmos-meas-tech.net/5/3007/2012/ the regularisation term of the cost function (2) only works adequately on a log scale (Schneider et al, 2006a). The log-scale retrieval is also required for constraining ratios of absorbing species.…”

Section: The Measurement and Retrieval Principlementioning

confidence: 99%

Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

et al. 2012

Self Cite

View full text Add to dashboard Cite

Abstract. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10 %. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30 ‰ for the ratio between the two isotopologues HD 16 O and H 16 2 O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO 2 retrievals and use them for demonstrating the MUSICA network-wide data consistency.In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multiyear mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

show abstract

“…We apply a constrained profile retrieval similar to the retrieval strategy described by Sussmann et al (2011) for CH 4 . We use a firstorder Tikonhov-Phillips regularization (L 1 ) on a logarithmic scale (Hase et al, 2004;Schneider et al, 2006). The signalto-noise ratio is empirically obtained from the fit residual and the regularization strength is tuned such that approximately 3 degrees of freedom are reached.…”

Section: Ndacc Retrieval Strategy For Comentioning

confidence: 99%

Comparison of XCO abundances from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change measured in Karlsruhe

et al. 2016

View full text Add to dashboard Cite

Abstract. We present a comparison of Karlsruhe XCO records (April 2010-December 2014) from the Total Carbon Column Observing Network (TCCON) and from the spectral region covered by the Network for the Detection of Atmospheric Composition Change (NDACC). The Karlsruhe TCCON Fourier transform infrared (FTIR) spectrometer allows us to record spectra in the mid-infrared (MIR) and nearinfrared (NIR) spectral region simultaneously, which makes Karlsruhe a favourable FTIR site to directly compare measurements from both spectral regions. We compare XCO retrieved from the fundamental absorption band at 4.7 µm (as used by NDACC) and first overtone absorption band at 2.3 µm (TCCON-style measurements). We observe a bias of (4.47 ± 0.17) ppb between both data sets with a standard deviation of 2.39 ppb in seasonal variation. This corresponds to a relative bias of (4.76 ± 0.18) % and a standard deviation of 2.28 %. We identify different sources which contribute to the observed bias (air-mass-independent correction factor, airmass-dependent correction factor, isotopic identities, differing a priori volume mixing ratio profiles) and quantify their contributions. We show that the seasonality in the residual of NDACC and TCCON XCO can be largely explained by the smoothing effect caused by differing averaging kernel sensitivities between the MIR and NIR spectral region. This study aims to improve the comparability of NDACC and TCCON XCO validation data sets as desired for potential future satellite missions and model studies.

show abstract

Water vapour profiles by ground-based FTIR spectroscopy: study for an optimised retrieval and its validation

Cited by 94 publications

References 16 publications

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

Comparison of XCO abundances from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change measured in Karlsruhe

Contact Info

Product

Resources

About