Intercomparison of integrated IASI and AATSR calibrated radiances at 11 and 12 μm

Illingworth, Sam; Remedios, J. J.; Parker, Robert J.

doi:10.5194/acp-9-6677-2009

Cited by 24 publications

(24 citation statements)

References 14 publications

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“…GSICS aims to ensure the comparability of satellite measurements performed from different instruments (sounders/imagers, infrared/microwave) and platforms, to interpret the differences, and to link the measurements to absolute references and standards. Intercomparisons have been performed with HIRS, AIRS, the Spinning Enhanced Visible and Infrared Imager (SEVIRI), and the Advanced Along-Track Scanning Radiometer (AATSR) using simultaneous nadir overpass (SNO) methods or double-difference (DD) methods (e.g., Cao et al 2009;Illingworth et al 2009;Hewison 2008a,b;Tobin 2008;Wang and Cao 2008). Biases are also characterized via the study of residuals between IASI observations and simulations based on radiative transfer code and collocated radiosoundings (Blumstein et al 2010).…”

Section: Independent Radiance Calibration and Validation Studiesmentioning

confidence: 99%

Hyperspectral Earth Observation from IASI: Five Years of Accomplishments

Hilton

Armante

August

et al. 2012

Bulletin of the American Meteorological Society

405

313

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The Infrared Atmospheric Sounding Interferometer (IASI) forms the main infrared sounding component of the European Organisation for the Exploitation of Meteorological Satellites's (EUMETSAT's) Meteorological Operation (MetOp)-A satellite (Klaes et al. 2007), which was launched in October 2006. This article presents the results of the first 4 yr of the operational IASI mission. The performance of the instrument is shown to be exceptional in terms of calibration and stability. The quality of the data has allowed the rapid use of the observations in operational numerical weather prediction (NWP) and the development of new products for atmospheric chemistry and climate studies, some of which were unexpected before launch. The assimilation of IASI observations in NWP models provides a significant forecast impact; in most cases the impact has been shown to be at least as large as for any previous instrument. In atmospheric chemistry, global distributions of gases, such as ozone and carbon monoxide, can be produced in near–real time, and short-lived species, such as ammonia or methanol, can be mapped, allowing the identification of new sources. The data have also shown the ability to track the location and chemistry of gaseous plumes and particles associated with volcanic eruptions and fires, providing valuable data for air quality monitoring and aircraft safety. IASI also contributes to the establishment of robust long-term data records of several essential climate variables. The suite of products being developed from IASI continues to expand as the data are investigated, and further impacts are expected from increased use of the data in NWP and climate studies in the coming years. The instrument has set a high standard for future operational hyperspectral infrared sounders and has demonstrated that such instruments have a vital role in the global observing system.

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Section: Independent Radiance Calibration and Validation Studiesmentioning

confidence: 99%

Hyperspectral Earth Observation from IASI: Five Years of Accomplishments

Hilton

Armante

August

et al. 2012

Bulletin of the American Meteorological Society

405

313

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“…The high spectral stability and the absolute radiometric accuracy of the IASI instrument (e.g. see Strow et al (2008) and Illingworth et al (2009)) rules out the possibility that the large residuals discussed above are attributable to the instrument itself. In fact, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

2011

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Abstract. Since data from the Infrared Atmospheric Sounding Interferometer (IASI) became available in 2007, a number of papers have appeared in the literature which have reported relatively large discrepancies between IASI spectra and forward calculations in the centre of the CO 2 Q-branch at 667 cm −1 . In this paper we show that these discrepancies are primarily due to errors in the temperature profiles used in the forward calculations. In particular, we have used forecasts of temperature profiles from the European Centre for MediumRange Weather Forecasts (ECMWF) to demonstrate that, for the case study considered in this paper, these profiles are affected by systematic errors of the order of ≈10 K at the level of the stratopause. To derive the magnitude and the spatial location of the systematic errors in the temperature profile, we have carried out forward/inverse calculations for a number of clear-sky, daytime, IASI tropical soundings over the sea. The forward calculations have been performed using atmospheric state vectors which have been obtained either from the direct inversion of the IASI radiances or from space-time co-located profiles derived from radiosonde observations and from the ECMWF model. To rule out any effect due to the accuracy of the forward model, we have performed the forward calculations using two independent models. The sensitivity of the temperature biases to the variability of the CO 2 profile and to spectroscopy errors has also been studied.

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“…Illingworth et al (2009) have demonstrated that the likely accuracy in band 1 of the IASI instrument is <0.1 K at 11 µm. By considering work done by Larar et al (2010), and also the internal radiometric accuracy of the IASI instrument, as reported by Blumstein et al (2004), the IASI instrument is likely radiometrically accurate to <0.3 K in the 4.7 µm spectral region.…”

Section: Iasimentioning

confidence: 99%

A comparison of OEM CO retrievals from the IASI and MOPITT instruments

et al. 2011

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Abstract.Observations of atmospheric carbon monoxide (CO) can only be made on continental and global scales by remote sensing instruments situated in space. One such instrument is the Infrared Atmospheric Sounding Interferometer (IASI), producing spectrally resolved, top-of-atmosphere radiance measurements from which CO vertical layers and total columns can be retrieved. This paper presents a technique for intercomparisons of satellite data with low vertical resolution. The example in the paper also generates the first intercomparison between an IASI CO data set, in this case that produced by the University of Leicester IASI Retrieval Scheme (ULIRS), and the V3 and V4 operationally retrieved CO products from the Measurements Of Pollution In The Troposphere (MOPITT) instrument. The comparison is performed for a localised region of Africa, primarily for an ocean day-time configuration, in order to develop the technique for instrument intercomparison in a region with well defined a priori.By comparing both the standard data and a special version of MOPITT data retrieved using the ULIRS a priori for CO, it is shown that standard intercomparisons of CO are strongly affected by the differing a priori data of the retrievals, and by the differing sensitivities of the two instruments. In particular, the differing a priori profiles for MOPITT V3 and V4 data result in systematic retrieved profile changes as expected. An application of averaging kernels is used to derive a difference quantity which is much less affected by smoothing error, and hence more sensitive to systematic error. These conclusions are confirmed by simulations with model profiles for the same region. This technique is used to show Correspondence to: S. Illingworth (smi3@le.ac.uk) that for the data that has been processed the systematic bias between MOPITT V4 and ULIRS IASI data, at MOPITT vertical resolution, is less than 7 % for the comparison data set, and on average appears to be less than 4 %. The results of this study indicate that intercomparisons of satellite data sets with low vertical resolution should ideally be performed with: retrievals using a common a priori appropriate to the geographic region studied; the application of averaging kernels to compute difference quantities with reduced a priori influence; and a comparison with simulated differences using model profiles for the target gas in the region.

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Intercomparison of integrated IASI and AATSR calibrated radiances at 11 and 12 μm

Cited by 24 publications

References 14 publications

Hyperspectral Earth Observation from IASI: Five Years of Accomplishments

Hyperspectral Earth Observation from IASI: Five Years of Accomplishments

The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

A comparison of OEM CO retrievals from the IASI and MOPITT instruments

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