Atmospheric composition and thermodynamic retrievals from the ARIES airborne FTS system – Part 1: Technical aspects and simulated capability

Illingworth, Sam; Allen, Grant; Newman, Stuart M.; Vance, A.; Marenco, Franco; Harlow, Chawn; Taylor, Jonathan P.; Moore, D. P.; Remedios, J. J.

doi:10.5194/amt-7-1133-2014

Cited by 9 publications

(9 citation statements)

References 55 publications

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“…We have tested a cloud-detection scheme based on the brightness temperature difference in an atmospheric window and non-window spectral region (described further by Illingworth et al, 2014). This method screens ARIES data for otherwise cloudy spectra and therefore false or poor retrievals.…”

Section: Cloud Detection and Screening Performancementioning

confidence: 99%

“…The ARIES is an analogue of the Infrared Atmospheric Sounding Interferometer (IASI) flown on the MetOp-A and B satellites, both having an apodized spectral resolution of ∼ 0.5 cm −1 between 4 and 16 µm. No further description of the ARIES and retrieval formalism will be given here, and readers are referred to Illingworth et al (2014) and references therein for details.…”

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confidence: 99%

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Atmospheric composition and thermodynamic retrievals from the ARIES airborne TIR-FTS system – Part 2: Validation and results from aircraft campaigns

et al. 2014

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Abstract. This study validates trace gas and thermodynamic retrievals from nadir infrared spectroscopic measurements recorded by the UK Met Office Airborne Research Interferometer Evaluation System (ARIES) -a thermal infrared, Fourier transform spectrometer (TIR-FTS) on the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft.Trace-gas-concentration and thermodynamic profiles have been retrieved and validated for this study throughout the troposphere and planetary boundary layer (PBL) over a range of environmental variability using data from aircraft campaigns over and around London, the US Gulf Coast, and the Arctic Circle during the Clear air for London (ClearfLo), Joint Airborne IASI (Infrared Atmospheric Sounding Interferometer) Validation Experiment (JAIVEx), and Measurements, process studies, and Modelling (MAMM) aircraft campaigns, respectively. Vertically resolved retrievals of temperature and water vapour (H 2 O), and partial-column retrievals of methane (CH 4 ), carbon monoxide (CO), and ozone (O 3 ) (over both land and sea) were compared to corresponding measurements from high-precision in situ analysers and dropsondes operated on the FAAM aircraft. Average degrees of freedom for signal (DOFS) over a 0-9 km column range were found to be 4.97, 3.11, 0.91, 1.10, and 1.62 for temperature, H 2 O, CH 4 , CO, and O 3 , respectively, when retrieved on 10 vertical levels. Partial-column mean biases (and bias standard error) between the surface and ∼ 9 km, when averaged across all flight campaigns, were found to be −0.7(±0.3) K, −479(±56) ppm, −11(±2) ppb, −3.3(±1.0) ppb, and +3.5(±1.0) ppb, respectively, whilst the typical a posteriori (total) uncertainties for individually retrieved profiles were 0.4, 9.5, 5.0, 21.2, and 15.0 %, respectively.Averaging kernels (AKs) derived for progressively lower altitudes show improving sensitivity to lower atmospheric layers when flying at lower altitudes. Temperature and H 2 O display significant vertically resolved sensitivity throughout the column, whilst trace gases are usefully retrieved only as partial-column quantities, with maximal sensitivity for trace gases other than H 2 O within a layer 1 and 2 km below the aircraft. This study demonstrates the valuable atmospheric composition information content that can be obtained by ARIES nadir TIR remote sensing for atmospheric process studies.

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Section: Cloud Detection and Screening Performancementioning

confidence: 99%

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confidence: 99%

Atmospheric composition and thermodynamic retrievals from the ARIES airborne TIR-FTS system – Part 2: Validation and results from aircraft campaigns

et al. 2014

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“…Aircraft measurements from NOAA/ESRL/GMD (Tans, 2009) and ARIES operated on UK FAAM aircraft (Illingworth et al, 2014), as well as some research campaigns, provide sparse, intermittent measurements of CH 4 vertical profiles. Because of a limited number of in situ measurements in time and space domain, the quantification of CH 4 emissions from different sources and in different regions still remains largely uncertain.…”

Section: Introductionmentioning

confidence: 99%

Satellite observation of atmospheric methane: intercomparison between AIRS and GOSAT TANSO-FTS retrievals

et al. 2016

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Abstract. Space-borne observations of atmospheric methane (CH 4 ) have been made using the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua satellite since August 2002 and the Thermal and Near-infrared Sensor for Carbon Observation Fourier Transform Spectrometer (TANSO-FTS) on the Greenhouse Gases Observing Satellite (GOSAT) since April 2009. This study compared the GOSAT TANSO-FTS thermal infrared (TIR) version 1.0 CH 4 product with the collocated AIRS version 6 CH 4 product using data from 1 August 2010 to 30 June 2012, including the CH 4 mixing ratios and the total column amounts. The results show that at 300-600 hPa, where both AIRS and GOSAT-TIR CH 4 have peak sensitivities, they agree very well, but GOSAT-TIR retrievals tend to be higher than AIRS in layer 200-300 hPa. At 300 hPa the CH 4 mixing ratio from GOSAT-TIR is, on average, 10.3 ± 31.8 ppbv higher than that from AIRS, and at 600 hPa GOSAT-TIR retrieved CH 4 is −16.2 ± 25.7 ppbv lower than AIRS CH 4 . Comparison of the total column amount of CH 4 shows that GOSAT-TIR agrees with AIRS to within 1 % in the mid-latitude regions of the Southern Hemisphere and in the tropics. In the mid to high latitudes in the Northern Hemisphere, comparison shows that GOSAT-TIR is ∼ 1-2 % lower than AIRS, and in the high-latitude regions of the Southern Hemisphere the difference of GOSAT from AIRS varies from −3 % in October to +2 % in July. The difference between AIRS and GOSAT TANSO-FTS retrievals is mainly due to the difference in retrieval algorithms and instruments themselves, and the larger difference in the highlatitude regions is associated with the low information content and small degrees of freedom of the retrieval. The degrees of freedom of GOSAT-TIR retrievals are lower than that of AIRS, which also indicates that the constraint in GOSAT-TIR retrievals may be too strong. From the good correlation between AIRS and GOSAT-TIR retrievals and the seasonal variation they observed, we are confident that the thermal infrared measurements from AIRS and GOSAT-TIR can provide valuable information to capture the spatial and temporal variation of CH 4 , especially in the mid-upper troposphere, in most periods and regions.

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“…Outputs from the ORFM include transmission, absorption, radiance, optical depth and brightness temperature, making the ORFM a highly versatile tool. The ORFM is a popular RTM used within the National Centre for Earth Observation (NCEO) 30 community in the United Kingdom (UK) and has trace gas retrieval heritage (Illingworth et al, 2014 currently include an illumination source such as a 'sun', so cannot generate SWIR radiance spectra 'out of the box'. Instead, we generate SWIR radiance spectra by multiplying transmission spectra generated in the ORFM with a reference solar irradiance spectrum, namely the Committee on Earth Observation Satellites -Working Group on Calibration and Validation (CEOS-WGCV) recommended SOLar SPECtrum (SOLSPEC) (Thuillier et al, 2003).…”

Section: The Oxford Reference Forward Model (Orfm)mentioning

confidence: 99%

Information Content Analysis: The Potential for Methane Isotopologue Retrieval from GOSAT-2

Malina¹,

Yoshida²,

Matsunaga³

et al. 2017

Preprint

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Abstract. Atmospheric methane is comprised of multiple isotopic molecules, with the most abundant being 12 CH 4 and 13 CH 4 10 making up 98% and 1.1% of atmospheric methane respectively. It has been shown that is it possible to distinguish between sources of methane (biogenic methane, e.g. marshland or abiogenic methane, e.g. fracking) via a ratio of these main methane isotopologues, otherwise known as the δ 13 C value. δ 13 C values typically range between -10 and -80 per mil, with abiogenic sources closer to zero, and biogenic sources showing more negative values. Initially, we suggest that a δ 13 C difference of 10 per mil is sufficient, in order to differentiate between methane source types, based on this we derive that a precision of 15 0.25ppbv on 13 CH 4 retrievals may achieve the target δ 13 C variance. Using an application of the well established Information Content Analysis (ICA) technique for assumed clear sky conditions, this manuscript shows that using a combination of the Shortwave Infrared (SWIR) bands on the planned Greenhouse gases Observing SATellite (GOSAT)-2 mission, 13 CH 4 can be measured with sufficient Information Content (IC) to a precision of between 0.7 and 1.2ppbv from a single sounding (assuming a total column average value of 19.14ppbv), which can then be reduced to the target precision through spatial and 20 temporal averaging techniques. We, therefore, suggest that GOSAT-2 can be used to differentiate between methane source types. Large unconstrained 'a priori' covariance matrices are required in order to achieve sufficient information content and that varying the solar inclination angle has limited impact on information content or retrieval errors.

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Atmospheric composition and thermodynamic retrievals from the ARIES airborne FTS system – Part 1: Technical aspects and simulated capability

Cited by 9 publications

References 55 publications

Atmospheric composition and thermodynamic retrievals from the ARIES airborne TIR-FTS system – Part 2: Validation and results from aircraft campaigns

Atmospheric composition and thermodynamic retrievals from the ARIES airborne TIR-FTS system – Part 2: Validation and results from aircraft campaigns

Satellite observation of atmospheric methane: intercomparison between AIRS and GOSAT TANSO-FTS retrievals

Information Content Analysis: The Potential for Methane Isotopologue Retrieval from GOSAT-2

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