Water vapour and methane coupling in the stratosphere observed using SCIAMACHY solar occultation measurements

Noël, Stefan; Weigel, Katja; Bramstedt, K.; Rozanov, A.; Weber, Mark; Bovensmann, Heinrich; Burrows, J. P.

doi:10.5194/acp-18-4463-2018

Cited by 26 publications

(32 citation statements)

References 59 publications

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“…Reasonable results for greenhouse gases are achieved for altitudes between about 17 and 45 km; see, e.g. Noël et al (2018). At the wavelengths considered in the present study and with the improved calibration performed here, we expect that this validity range can be extended even to somewhat lower altitudes; see also below.…”

Section: Description Of Methodssupporting

confidence: 54%

“…The onion-peeling DOAS (ONPD) retrieval method has been originally developed to derive stratospheric profiles of greenhouse gases. So far, it has been applied to the retrieval of water vapour, CO 2 and methane (Noël et al, 2010(Noël et al, , 2011(Noël et al, , 2016(Noël et al, , 2018. The retrieval method is described in detail in these publications; we therefore give here only a basic summary and the specific settings used in the context of this study.…”

Section: Onion-peeling Doas Approachmentioning

confidence: 99%

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Stratospheric aerosol extinction profiles from SCIAMACHY solar occultation

et al. 2020

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Abstract. The Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument on Envisat provided, between August 2002 and April 2012, measurements of solar and Earthshine spectra from the UV to the shortwave infrared spectral region in multiple viewing geometries. We present a new approach to derive stratospheric aerosol extinction profiles from SCIAMACHY solar occultation measurements based on an onion-peeling method similar to the onion-peeling differential optical absorption spectroscopy (DOAS) retrieval, which has already been successfully used for the derivation of greenhouse gas profiles. Since the retrieval of aerosol extinction requires as input measured transmissions in absolute units, an improved radiometric calibration of the SCIAMACHY solar occultation measurements has been developed, which considers various instrumental and atmospheric effects specific to solar occultation. The aerosol extinction retrieval can in principle be applied to all wavelengths measured by SCIAMACHY. As a first application, we show results for 452, 525 and 750 nm. The SCIAMACHY solar occultation time series has been processed, covering a latitudinal range of about 50–70∘ N. Reasonable aerosol extinctions are derived between about 15 and 30 km with typically larger uncertainties at higher altitudes due to decreasing aerosol extinction. Comparisons with collocated Stratospheric Aerosol and Gas Experiment II (SAGE-II) and SCIAMACHY limb aerosol data products revealed good agreement with essentially no mean bias. However, dependent on altitude, differences of up to ±20 %–30% to SAGE-II at 452 and 525 nm are observed. Similar results are obtained from comparisons with SAGE-III. SCIAMACHY solar occultation data at 750 nm have been compared with corresponding SAGE-III, Optical Spectrograph and InfraRed Imager System (OSIRIS) and SCIAMACHY limb results. The agreement with SCIAMACHY limb data at 750 nm is within 5 %–20 % between 17 and 27 km. SAGE-III and OSIRIS show at this wavelength and altitude range on average about 40 % and 25 % smaller values, with some additional 10 %–20 % modulation with altitude. The altitude variations in the differences are mainly caused by systematic vertical oscillations in the SCIAMACHY occultation data of up to 30 % below about 25 km. These oscillations decrease to amplitudes below 10 % with increasing number of collocations and are no longer visible in monthly anomalies. Major volcanic eruptions as well as occurrences of polar stratospheric clouds (PSCs) can be identified in the time series of aerosol extinction data and related anomalies. The influence of the quasi-biennial oscillation (QBO) is visible above 25 km.

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Section: Description Of Methodssupporting

confidence: 54%

Section: Onion-peeling Doas Approachmentioning

confidence: 99%

Stratospheric aerosol extinction profiles from SCIAMACHY solar occultation

et al. 2020

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“…Some troposphere-stratosphere exchange also happens across the extratropical tropopause due to mixing (e.g., Holton et al, 1986;(Hoor et al, 2004). Reeburgh (2007) estimated that approximately 60 Tg CH4 enters the stratosphere per year, which is likely subject to inter annual variability (e.g., Noël et al, 2018). In the stratosphere, CH4 is lost through reactions with excited atomic oxygen O( 1 D), atomic chlorine (Cl), atomic fluorine (F), and OH (le Texier et al, 1988;Brasseur and Salomon, 2006).…”

Section: Stratospheric Lossmentioning

confidence: 99%

The Global Methane Budget 2000–2017

Saunois¹,

Stavert²,

Poulter³

et al. 2019

Preprint

123

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Abstract. Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Atmospheric emissions and concentrations of CH4 are continuing to increase, making CH4 the second most important human-influenced greenhouse gas in terms of climate forcing, after carbon dioxide (CO2). Assessing the relative importance of CH4 in comparison to CO2 is complicated by its shorter atmospheric lifetime, stronger warming potential, and atmospheric growth rate variations over the past decade, the causes of which are still debated. Two major difficulties in reducing uncertainties arise from the variety of geographically overlapping CH4 sources and from the destruction of CH4 by short-lived hydroxyl radicals (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate new research aimed at improving and regularly updating the global methane budget. Following Saunois et al. (2016), we present here the second version of the living review paper dedicated to the decadal methane budget, integrating results of top-down studies (atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up estimates (including process-based models for estimating land surface emissions and atmospheric chemistry, inventories of anthropogenic emissions, and data-driven extrapolations). For the 2008–2017 decade, global methane emissions are estimated by atmospheric inversions (top-down approach) to be 572 Tg CH4 yr−1 (range 538–593, corresponding to the minimum and maximum estimates of the ensemble), of which 357 Tg CH4 yr−1 or ~ 60 % are attributed to anthropogenic sources (range 50–65 %). This total emission is 27 Tg CH4 yr−1 larger than the value estimated for the period 2000–2009 and 24 Tg CH4 yr−1 larger than the one reported in the previous budget for the period 2003–2012 (Saunois et al. 2016). Since 2012, global CH4 emissions have been tracking the carbon intensive scenarios developed by the Intergovernmental Panel on Climate Change (Gidden et al., 2019). Bottom-up methods suggest larger global emissions (737 Tg CH4 yr−1, range 583–880) than top-down inversion methods, mostly because of larger estimated natural emissions from sources such as natural wetlands, other inland water systems, and geological sources. However the strength of the atmospheric constraints on the top-down budget, suggest that these bottom-up emissions are overestimated. The latitudinal distribution of atmospheric-based emissions indicates a predominance of tropical emissions (~ 65 % of the global budget,

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“…In the early era of limb sounding and solar occultation measurements, onion peeling was the work-horse data analysis algorithm and was used, among others, in the following missions: LIMS (Bailey and Gille, 1986), ATMOS (Norton and 15 Rinsland, 1991), HALOE (Russell III et al, 1993), CRISTA (Offermann et al, 1999). More recently, onion-peeling related algorithms have been used, e.g., for, TIMED-SABER (Russell III et al, 1994), AIM-SOFIE (Gordley et al, 2009a), and SCIAMACHY (Noël et al, 2018). When more computer power along with quasi-analytical algorithms to calculate larger Jacobians became available, onion peeling was often superseded by global-fit-like algorithms (Carlotti, 1988) which solve the inverse problem for the entire limb sequence in one leap.…”

Section: Onion Peelingmentioning

confidence: 99%

Estimating and Reporting Uncertainties in Remotely Sensed Atmospheric Composition and Temperature

Clarmann¹,

Degenstein²,

Livesey³

et al. 2019

Preprint

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Abstract. Remote sensing of atmospheric state variables typically relies on the inverse solution of the radiative transfer equation. An adequately characterized retrieval provides information on the uncertainties of the estimated state variables as well as on how any constraint or a priori assumption affects the estimate. Reported characterization data should be intercomparable between different instruments, empirically validatable, grid-independent, usable without detailed knowledge of the instrument or retrieval technique, traceable, and still have reasonable data volume. The latter condition of adequacy may force one to work with representative rather than individual characterization data. The main sources of uncertainty are measurement noise, calibration errors, simplifications and idealizations in the radiative transfer model and retrieval scheme, auxiliary data errors, and uncertainties in atmospheric or instrumental parameters. Some of these errors affect the result in a random way, while others chiefly cause a bias or are of mixed character. Beyond this, it is of utmost importance to know the influence of any constraint and prior information on the solution. While different instruments or retrieval schemes may require different error estimation schemes, we provide a list of recommendations which shall help to unify retrieval error reporting.

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Water vapour and methane coupling in the stratosphere observed using SCIAMACHY solar occultation measurements

Cited by 26 publications

References 59 publications

Stratospheric aerosol extinction profiles from SCIAMACHY solar occultation

Stratospheric aerosol extinction profiles from SCIAMACHY solar occultation

The Global Methane Budget 2000–2017

Estimating and Reporting Uncertainties in Remotely Sensed Atmospheric Composition and Temperature

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