Infrared Continental Surface Emissivity Spectra and Skin Temperature Retrieved from IASI Observations over the Tropics

Capelle, V.; Chédin, A.; Péquignot, Eric; Schlüssel, Peter; Newman, Stuart M.; Scott, N. A.

doi:10.1175/jamc-d-11-0145.1

Cited by 41 publications

(31 citation statements)

References 47 publications

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“…Developed by CNES (Centre National d'Etudes Spatiales) in collaboration with EUMETSAT (European Organization for the Exploitation of Meteorological Satellites), the IASI instrument (Chalon et al, 2001; http://smsc.cnes.fr/IASI), onboard the Metop-A polar platform, is a Fourier transform spectrometer that measures Earth-emitted infrared radiation. Launched in October 2006 and operational since July 2007, it provides 8461 spectral channels, between 15.5 µm (645 cm −1 ) and 3.63 µm (2755 cm −1 ), with a spectral resolution of 0.50 cm −1 after apodization, and a regular spectral sampling interval of 0.25 cm −1 .…”

Section: Iasimentioning

confidence: 99%

“…Entries to the model include AOD, altitude, surface pressure, surface temperature and emissivity, viewing angle, and a set of about 600 atmospheric situations representative of the tropical band (30 • S-30 • N). Over land, surface spectral emissivity is taken from Capelle et al (2012). IASI observations are processed spot by spot (daily), averaged monthly, and gridded 1 • by 1 • .…”

Section: Iasimentioning

confidence: 99%

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Evaluation of IASI-derived dust aerosol characteristics over the tropical belt

Capelle

Chédin²,

Siméon

et al. 2014

Atmos. Chem. Phys.

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Abstract.IASI (Infrared Atmospheric Sounder Interferometer)-derived monthly mean infrared (10 µm) dust aerosol optical depth (AOD) and altitude are evaluated against ground-based Aerosol RObotic NETwork of sun photometers (AERONET) measurements of the 500 nm coarse-mode AOD and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) measurements of altitude at 38 AERONET sites (sea and land) within the tropical belt (30 • N-30 • S). The period covered extends from July 2007 to June 2013. The evaluation goes through the analysis of Taylor diagrams and box-and-whiskers plots, separating situations over oceanic regions and over land. For the AOD, such an evaluation raises the problem of the difference between the two spectral domains used: infrared for IASI and visible for AERONET. Consequently, the two measurements do not share the same metrics. For that reason, AERONET coarse-mode AOD is first "translated" into IASI-equivalent infrared AOD. This is done by the determination, site by site, of an infrared to visible AOD ratio. Because translating visible coarse-mode AOD into infrared AOD requires accurate knowledge of variables, such as the infrared refractive index or the particle size distribution, quantifying the bias between these two sources of AOD is not straightforward. This problem is detailed in this paper, in particular in Appendix A. For the sites over oceanic regions, the overall AOD temporal correlation comes to 0.86 for 786 items (IASI and AERONET monthly mean bins). The overall normalized standard deviation (i.e. ratio of the standard deviation of the test data (IASI) to that of the reference data (AERONET)) is 0.93, close to the desired value of 1. Over land, essentially desert, correlation is 0.74 for 619 items and the normalized standard deviation is 0.86. This slight but significant degradation over land most probably results from the greater complexity of the surface (heterogeneity, elevation) and, to a lesser extent, to the episodic presence of dust within the boundary layer (particularly for sites close to active sources) to which IASI, as any thermal infrared sounder, is poorly sensitive, unlike AERONET. Site by site, disparities appear that are principally due to either the insufficient number of AERONET observations throughout the period considered, to the complexity of the location leading to the mixing of several aerosol types (in the case of the Persian Gulf, for example), to surface heterogeneities (elevation, emissivity, etc.), or to the use of a single aerosol model (called "MITR"). Results using another aerosol model, with a different refractive index, are presented and discussed. Concerning altitude over oceanic regions, correlation is 0.70 for 853 items and the normalized standard deviation is 0.92. A systematic bias of −0.4 km (IASI-CALIOP) is observed, with a standard deviation of 0.48 km. This result is satisfactory, considering the important differences between the two instruments (space-time coverage, definition of the altitude). Altitude results over land, essentially over ...

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Section: Iasimentioning

confidence: 99%

Section: Iasimentioning

confidence: 99%

Evaluation of IASI-derived dust aerosol characteristics over the tropical belt

Capelle

Chédin²,

Siméon

et al. 2014

Atmos. Chem. Phys.

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“…Recently, some researchers have produced a few narrowband emissivity products from which the BBE could be obtained by converting it to BBE via a linear regression function [17,18], including the North American ASTER Land Surface Emissivity Database (NAALSED) composited from the ASTER narrowband emissivity product [19], the University of Wisconsin Global Infrared Land Surface Emissivity Database (UWIREMIS) retrieved by adjusting MODIS narrowband emissivity product (MOD11) with the proposed baseline fit method [20], and those derived from hyperspectral resolution thermal infrared (TIR) data [2,[21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Three Land Surface Broadband Emissivity Datasets from Satellite Data

et al. 2013

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Abstract:This study compared three broadband emissivity (BBE) datasets from satellite observations. The first is a new global land surface BBE dataset known as the Global Land Surface Satellite (GLASS) BBE. The other two are the North American ASTER Land Surface Emissivity Database (NAALSED) BBE and University of Wisconsin Global Infrared Land Surface Emissivity Database (UWIREMIS) BBE, which were derived from two independent narrowband emissivity products. Firstly, NAALSED BBE was taken as the reference to evaluate the GLASS BBE and UWIREMIS BBE. The GLASS BBE was more close to NAALSED BBE with a bias and root mean square error (RMSE) of −0.001 and 0.007 for the summer season, −0.001 and 0.008 for the winter season, respectively. Then, the spatial distribution and seasonal pattern of global GLASS BBE and UWIREMIS BBE for six dominant land cover types were compared. The BBE difference between vegetated areas and non-vegetated areas can be easily seen from two BBEs. The seasonal variation of GLASS BBE was more reasonable than that of UWIREMIS BBE. Finally, the time series were calculated from GLASS BBE and UWIREMIS BBE using the data from 2003 through 2010. The periodic variations of GLASS BBE were stronger than those of UWIREMIS BBE. The long time series high quality GLASS BBE can be incorporated in land surface models for improving their simulation results.

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“…Several centers are now working on the creation of high spectral resolution emissivity atlases from IASI (e.g., Zhou et al 2011;Capelle et al 2012; see also http://ara.lmd.polytechnique.fr), providing monthly or weekly products that capture the natural variability of the Earth's surface and show clear evidence of seasonal variability associated with changes in surface weather and vegetation properties. Figure 13h shows a weekly emissivity map from the atlas of Capelle et al 2012. These atlases may be used directly, or in NWP they may provide a "first guess" emissivity, which can be modified during assimilation to match the properties of each observation.…”

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confidence: 99%

Hyperspectral Earth Observation from IASI: Five Years of Accomplishments

Hilton

Armante

August

et al. 2012

Bulletin of the American Meteorological Society

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411

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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Infrared Continental Surface Emissivity Spectra and Skin Temperature Retrieved from IASI Observations over the Tropics

Cited by 41 publications

References 47 publications

Evaluation of IASI-derived dust aerosol characteristics over the tropical belt

Evaluation of IASI-derived dust aerosol characteristics over the tropical belt

A Comparative Study of Three Land Surface Broadband Emissivity Datasets from Satellite Data

Hyperspectral Earth Observation from IASI: Five Years of Accomplishments

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