New assignments, line intensities, and HITRAN database for CH3OH at 10μm

Xu, Li‐Hong; Lees, R. M.; Wang, Peng; Brown, Linda R.; Kleiner, Isabelle; Johns, J. W. C.

doi:10.1016/j.jms.2004.05.017

Cited by 50 publications

(44 citation statements)

References 37 publications

(81 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These two levels are well above the top of the barrier at V 3 = 374 cm À1 , but they are still well below the lowest small-amplitude vibration m 8 near 1034 cm À1 (with A and E components near 1162 and 1171 cm À1 , respectively, when measured from the bottom of the torsional well [25]). Thus, it should in principle be possible to fit torsion-rotation states of the first three torsional levels using the same torsion-rotation Hamiltonian as was used previously [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 87%

Torsion–rotation global analysis of the first three torsional states (νt=0, 1, 2) and terahertz database for methanol

Fisher

Lees

et al. 2008

Journal of Molecular Spectroscopy

Self Cite

178

150

View full text Add to dashboard Cite

a b s t r a c tStimulated by recent THz measurements of the methanol spectrum in one of our laboratories, undertaken in support of NASA programs related to the Herschel Space Observatory (HSO) and the Atacama Large Millimeter Array (ALMA), we have carried out a global analysis of available microwave and high-resolution infrared data for the first three torsional states (m t = 0, 1, 2), and for J values up to 30. This global fit of approximately 5600 frequency measurements and 19 000 Fourier transform far infrared (FTFIR) wavenumber measurements to 119 parameters reaches the estimated experimental measurement accuracy for the FTFIR transitions, and about twice the estimated experimental measurement accuracy for the microwave, submillimeter-wave, and terahertz transitions. The present fit is essentially a continuation of our earlier work, but we have greatly expanded our previous data set and have added a large number of new torsion-rotation interaction terms to the Hamiltonian in our previously used computer program. The results, together with a number of calculated (but unmeasured) transitions, including their line strength, estimated uncertainty, and lower state energy, are made available in the supplementary material as a database formatted to be useful for astronomical searches. Some discussion of several open spectroscopic problems, e.g., (i) an improved notation for the numerous parameters in the torsion-rotation Hamiltonian, (ii) possible causes of the failure to fit frequency measurements to the estimated measurement uncertainty, and (iii) pitfalls to be avoided when intercomparing apparently identical parameters from the internal axis method and the rho axis method are also given.

show abstract

Section: Introductionmentioning

confidence: 87%

Torsion–rotation global analysis of the first three torsional states (νt=0, 1, 2) and terahertz database for methanol

Fisher

Lees

et al. 2008

Journal of Molecular Spectroscopy

Self Cite

178

150

View full text Add to dashboard Cite

show abstract

“…Methanol lines were added to the HITRAN compilation for the first time in 2004 (Rothman et al, 2005). The parameters for the 10 µm region are described in the paper by Xu et al (2004) and were derived from measurements with two high-spectral resolution FTS instruments.…”

Section: Retrieval Strategymentioning

confidence: 99%

“…For the spectroscopic line parameters, we included in our error budget the uncertainty on line intensities provided by the HITRAN database. As methanol line intensities matter, a rough idea of the accuracy of the intensities can be obtained from Table 8 of the Xu et al (2004) study, as it reports an RMS deviation of 7 %. It should be noted that the uncertainty on ozone and its isotopologues lines, according to HITRAN-08 parameters, amounts to between 5 and 10 % (Rothman et al, 2009).…”

Section: Data Characterisation and Error Budgetmentioning

confidence: 99%

Long-term evolution and seasonal modulation of methanol above Jungfraujoch (46.5° N, 8.0° E): optimisation of the retrieval strategy, comparison with model simulations and independent observations

Bader¹,

Stavrakou

Müller

et al. 2014

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. Methanol (CH 3 OH) is the second most abundant organic compound in the Earth's atmosphere after methane. In this study, we present the first long-term time series of methanol total, lower tropospheric and upper tropospheric-lower stratospheric partial columns derived from the analysis of high resolution Fourier transform infrared solar spectra recorded at the Jungfraujoch station (46.5 • N, 3580 m a.s.l.). The retrieval of methanol is very challenging due to strong absorptions of ozone in the region of the selected υ 8 band of CH 3 OH. Two wide spectral intervals have been defined and adjusted in order to maximise the information content. Methanol does not exhibit a significant trend over the 1995-2012 time period, but a strong seasonal modulation characterised by maximum values and variability in June-July, minimum columns in winter and a peak-topeak amplitude of 130 %. Analysis and comparisons with in situ measurements carried out at the Jungfraujoch and ACE-FTS (Atmospheric Chemistry Experiment-Fourier transform spectrometer) occultations have been performed. The total and lower tropospheric columns are also compared with IMAGESv2 model simulations. There is no systematic bias between the observations and IMAGESv2 but the model underestimates the peak-to-peak amplitude of the seasonal modulations.

show abstract

“…We have used line parameters of Xu et al (2004), implemented in the HITRAN database for which a precision of 6% for line intensities is quoted.…”

Section: Methanolmentioning

confidence: 99%

Global distributions of methanol and formic acid retrieved for the first time from the IASI/MetOp thermal infrared sounder

et al. 2011

View full text Add to dashboard Cite

Abstract. Methanol (CH 3 OH) and formic acid (HCOOH) are among the most abundant volatile organic compounds present in the atmosphere. In this work, we derive the global distributions of these two organic species using for the first time the Infrared Atmospheric Sounding Interferometer (IASI) launched onboard the MetOp-A satellite in 2006. This paper describes the method used and provides a first critical analysis of the retrieved products. The retrieval process follows a two-step approach in which global distributions are first obtained on the basis of a simple radiance indexing (transformed into brightness temperatures), and then mapped onto column abundances using suitable conversion factors. For methanol, the factors were calculated using a complete retrieval approach in selected regions. In the case of formic acid, a different approach, which uses a set of forward simulations for representative atmospheres, has been used. In both cases, the main error sources are carefully determined: the average relative error on the column for both species is estimated to be about 50%, increasing to about 100% for the least favorable conditions. The distributions for the year 2009 are discussed in terms of seasonality and source identification. Time series comparing methanol, formic acid and carbon monoxide in different regions are also presented.

show abstract

New assignments, line intensities, and HITRAN database for CH3OH at 10μm

Cited by 50 publications

References 37 publications

Torsion–rotation global analysis of the first three torsional states (νt=0, 1, 2) and terahertz database for methanol

Torsion–rotation global analysis of the first three torsional states (νt=0, 1, 2) and terahertz database for methanol

Long-term evolution and seasonal modulation of methanol above Jungfraujoch (46.5° N, 8.0° E): optimisation of the retrieval strategy, comparison with model simulations and independent observations

Global distributions of methanol and formic acid retrieved for the first time from the IASI/MetOp thermal infrared sounder

Contact Info

Product

Resources

About