402 research outputs found
Water vapour line assignments in the 9250-26 000 cm-1 frequency range
No full textLine parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm-1 region [M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm-1 region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Mérienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radiat. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of H2 16O. Twelve new vibrational band origins are determined and estimates for a further 16 are presented
Water vapour line assignments in the 9250-26 000 cm-1 frequency range
No full textLine parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm-1 region [M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm-1 region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Mérienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radiat. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of H216O. Twelve new vibrational band origins are determined and estimates for a further 16 are presented. © 2005 Elsevier Inc. All rights reserved.info:eu-repo/semantics/publishe
Water vapour line assignments in the 9250-26 000 cm (-1) frequency range
No full textLine parameters for water vapour in natural abundance have recently been determined for the 9250-13 000 cm(-1) region [M.-F. Wrienne, A. Jenouvrier, C. Hermans, A.C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bach, J. Quant. Spectrosc. Radiat. Transfer 82 (2003) 99] and the 13 000-26 000 cm(-1) region [P.-F. Coheur, S. Fally, M. Carleer, C. Clerbaux, R. Colin, A. Jenouvrier, M.-F. Wrienne, C. Hermans, A.C. Vandaele, J. Quant. Spectrosc. Radial. Transfer 74 (2002) 493] using a high-resolution Fourier-transform spectrometer with a long-path absorption cell. These spectra are analysed using several techniques including variational line lists and assignments made. In total, over 15 000 lines were assigned to transitions involving more than 150 exited vibrational states of (H2O)-O-16. Twelve new vibrational band origins are determined and estimates for a further 16 are presented. (c) 2005 Elsevier Inc. All rights reserved
The IASI/Metop-B HCOOH ANNI v4 product
No full text<p>This dataset comprises the version 4 of the HCOOH product retrieved from IASI/Metop-B between July 2022 and June 2023, using the Artificial Neural Network for IASI (ANNI) version 4 retrieval scheme. Each day is represented by a .nc file. For detailed information on the HCOOH product, please refer to Franco et al. (2018) <em>"A General Framework for Global Retrievals of Trace Gases From IASI: Application to Methanol, Formic Acid, and PAN"</em> (JGR, https://doi.org/10.1029/2018JD029633) and for a description of the ANNI v4 retrievals, please consult Clarisse et al. (2023) <em>"The IASI NH3 version 4 product: averaging kernels and improved consistency"</em> (AMT, <a href="https://doi.org/10.5194/amt-16-5009-2023">https://doi.org/10.5194/amt-16-5009-2023</a>). Prior to using this dataset, we recommend reaching out to the main developers Bruno Franco (<a href="mailto:[email protected]">[email protected]</a>) and Lieven Clarisse (<a href="mailto:[email protected]">[email protected]</a>) for guidance and information on more recent product versions.</p>
The IASI/Metop pyrogenic HONO product v2
No full text<p>This dataset comprises the version 2 of the pyrogenic HONO product retrieved from IASI/Metop-A (Oct 2007 - Sept 2021), IASI/Metop-B (March 2013 - Sept 2023), and IASI/Metop-C (Sept 2019 - Sept 2023) using the Artificial Neural Network for IASI (ANNI) version 4 retrieval scheme. Each day with successful pyrogenic HONO detections is represented by a .nc file per instrument. For detailed information on the HONO product, please refer to Franco et al. (2023) <em>"Pyrogenic HONO seen from space: insights from global IASI observations"</em> (ACP, submitted), and for a description of the ANNI v4 retrievals, please consult Clarisse et al. (2023) <em>"The IASI NH3 version 4 product: averaging kernels and improved consistency"</em> (AMT, <a href="https://doi.org/10.5194/amt-16-5009-2023">https://doi.org/10.5194/amt-16-5009-2023</a>). Prior to using this dataset, we recommend reaching out to the main developers Bruno Franco (<a href="mailto:[email protected]">[email protected]</a>) and Lieven Clarisse (<a href="mailto:[email protected]">[email protected]</a>) for guidance and information on more recent product versions.</p>
<p>Compared to v1, IASI HONO product v2 contains more realistic error estimates related to the uncertainties on the fire plume altitude.</p>
Seasonal and spatial variability of carbon monoxide (CO) in the Martian atmosphere from PFS/MEX observations
No full textA subset of more than 100,000 nadir measurements covering more than 7 Martian years (MY 26–MY 33) recorded in the thermal part of the Short Wavelength Channel (SWC) from the Planetary Fourier Spectrometer (PFS) on board Mars Express is exploited to investigate the global distribution and the seasonal cycle of carbon monoxide (CO) on Mars. The retrieval of CO vertical profiles is successfully achieved using a methodology based on the optimal estimation but the low information content is such that we mainly discuss the variability in CO in terms of integrated columns (from the surface to 24 km) or the associated column-averaged mixing ratio. We find a strong seasonality in CO, especially at mid and high-latitudes, which confirms earlier work and the current knowledge of the CO2 condensation/sublimation cycles, as implemented for instance in the Global Environmental Multiscale (GEM) general circulation model for Mars, that we use as a basis for comparison. We report a general consistency between model and observation, with a tendency of the latter to provide lower CO volume mixing ratios (VMRs), except at low latitudes. The spatial distribution of the CO column-averaged VMR is obtained on a seasonal basis and investigated in terms of large-scale patterns but also local peculiarities. Finally, we show that the retrieved profiles systematically present strong CO vertical gradients close to the surface in mid- and equatorial latitudes, likely related to the vertical sensitivity of PFS rather than real near-surface CO enrichment
Spectrum of hot water in the 2000-4750 cm-1 frequency range
No full textAn emission spectrum recorded in an oxyacetylene torch [P.-F. Coheur, P.F. Bernath, M. Carleer, R. Colin, O.L. Polyansky, N.F. Zobov, S.V. Shirin, R.J. Barber, J. Tennyson, J. Chem. Phys. 122 (2005) 074307] is analyzed for the region covering stretching fundamentals and associated hot bands of water. Many lines could be assigned on the basis of previously determined energy levels. New assignments made with a new variational linelist allow a further 800 energy levels covering 15 vibrational states and rotations up to J = 32 to be assigned. A simultaneous re-analysis of previously reported sunspot absorption spectra leads to the assignment of 581 further lines in the L-band spectrum and 67 in the N-band spectrum. © 2006 Elsevier Inc. All rights reserved.info:eu-repo/semantics/publishe
Exploiting night-time averaged spectra from PFS/MEX shortwave channel. Part 2: Near-surface CO retrievals
No full textBecause of its important role in the Martian carbon cycle, carbon monoxide (CO) has been the subject of many measurements from ground and from space. Daytime measurements have been mostly exploited to measure the CO abundance because of their good signal-to-noise ratio, but night-time observations have not been documented yet. We demonstrate here the possibility of using PFS (Planetary Fourier Spectrometer) night-time observations to measure the Martian CO abundance. More particularly in this paper, we show that measuring CO during night with PFS can be achieved by averaging a large number of spectra to reach sufficient signal-to-noise. Furthermore, we show that the number of averaged spectra is not the only driving parameter for the detection of CO. High surface temperatures and high thermal contrast (negative in our case) are the two other conditions required for the measurement of the night-time CO abundance. Because of this, the retrievals are especially successful in the Southern Hemisphere during spring and summer when and where these two conditions are met. For night-time spectra with a positive detection, CO vertical profiles are successfully retrieved using the Optimal Estimation method and are characterized in terms of vertical sensitivity. Successful retrievals imply the use of accurate temperature profiles, and in particular an appropriate representation of the thermal inversion in the lower atmosphere. The temperature was obtained by using the relevant information from the CO2 ν3 band (Bauduin et al., 2020, this issue). A complete error budget of the retrieved CO profiles is also performed and includes different sources of uncertainty. Although the retrieved profiles are not resolved vertically, we show in particular that night-time PFS observations carry information mostly on the CO abundance for the 0–10 km altitude region, and thus provide a stronger constraint on the near-surface CO abundance compared to daytime observations
Exploiting night-time averaged spectra from PFS/MEX shortwave channel. Part 1: Temperature retrieval from the CO2 ν3 band
No full textNadir remote sensing of the night side of Mars is challenging, mainly due to the low signal-to-noise ratio of such observations. We show in a companion paper that the abundance of carbon monoxide (CO) during night can be retrieved from the observations of the Planetary Fourier Spectrometer (PFS). This requires, however, an accurate knowledge of the temperature profile, and especially of the night-time thermal inversions, to properly model the atmospheric emission. While the temperature profile is usually retrieved from the ν2 band of CO2 (centered at 667 cm−1), this work shows that, for averaged night-time PFS observations built from a large ensemble of spectra, the temperature profile can be retrieved from the more saturated ν3 band of CO2 (centered at 2349 cm−1). We show especially that, due to IFOV (instantaneous field-of-view) size differences and boresight offset between the longwave and shortwave channels of PFS, the temperature profile retrieved from the ν3 band is more consistent with the emission observed in the 1-0 band of CO (centered at 2143 cm−1), which is used in the second part paper. We provide a complete characterization of the retrieved temperature profiles in terms of error and vertical sensitivity. Using this, we show that using the ν3 CO2 band allows to properly constrain and characterize the thermal inversions encountered near the surface for most night-time observations. The resulting set of temperature profiles is essential for the retrieval of the night-time CO abundance that is presented in the companion paper. Beyond their usefulness for the night-time CO retrieval, we suggest with a last example that temperature profiles retrieved from the ν3 band of CO2 could be use more generally to study surface thermal inversions encountered at night
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