dorsal/arxiv
View SchemaAbsorption of infra-red radiation by atmospheric molecular cluster-ions
| Authors | K. L. Aplin, R. A. McPheat |
|---|---|
| Categories | |
| ArXiv ID | physics/0502041 |
| URL | https://arxiv.org/abs/physics/0502041 |
| DOI | 10.1016/j.jastp.2005.01.007 |
| Journal | J. Atmos Sol-Terr Phys, 67, 8-9 pp 775-783, 2005 |
Abstract
Protonated water clusters are a common species of atmospheric molecular cluster-ion, produced by cosmic rays throughout the troposphere and stratosphere. Under clear-sky conditions or periods of increased atmospheric ionisation, such as solar proton events, the IR absorption by atmospheric ions may affect climate through the radiative balance. Fourier Transform Infrared Spectrometry in a long path cell, of path length 545m, has been used to detect IR absorption by corona-generated positive molecular cluster-ions. The column concentration of ions in the laboratory spectroscopy experiment was estimated to be ~10^13 m-2; the column concentration of protonated atmospheric ions estimated using a simple model is ~10^14 m-2. Two regions of absorption, at 12.3 and 9.1 um are associated with enhanced ion concentrations. After filtering of the measured spectra to compensate for spurious signals from neutral water vapour and residual carbon dioxide, the strongest absorption region is at 9.5 to 8.8 um (1050 to 1140 cm-1) with a fractional change in transmissivity of 0.03 plus/minus 0.015, and the absorption at 12.5 to 12.1 um (800 to 825 cm-1) is 0.015 plus/minus 0.008.
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"abstract": "Protonated water clusters are a common species of atmospheric molecular\ncluster-ion, produced by cosmic rays throughout the troposphere and\nstratosphere. Under clear-sky conditions or periods of increased atmospheric\nionisation, such as solar proton events, the IR absorption by atmospheric ions\nmay affect climate through the radiative balance. Fourier Transform Infrared\nSpectrometry in a long path cell, of path length 545m, has been used to detect\nIR absorption by corona-generated positive molecular cluster-ions. The column\nconcentration of ions in the laboratory spectroscopy experiment was estimated\nto be ~10^13 m-2; the column concentration of protonated atmospheric ions\nestimated using a simple model is ~10^14 m-2. Two regions of absorption, at\n12.3 and 9.1 um are associated with enhanced ion concentrations. After\nfiltering of the measured spectra to compensate for spurious signals from\nneutral water vapour and residual carbon dioxide, the strongest absorption\nregion is at 9.5 to 8.8 um (1050 to 1140 cm-1) with a fractional change in\ntransmissivity of 0.03 plus/minus 0.015, and the absorption at 12.5 to 12.1 um\n(800 to 825 cm-1) is 0.015 plus/minus 0.008.",
"arxiv_id": "physics/0502041",
"authors": [
"K. L. Aplin",
"R. A. McPheat"
],
"categories": [
"physics.ao-ph",
"physics.atm-clus",
"physics.geo-ph"
],
"doi": "10.1016/j.jastp.2005.01.007",
"journal_ref": "J. Atmos Sol-Terr Phys, 67, 8-9 pp 775-783, 2005",
"title": "Absorption of infra-red radiation by atmospheric molecular cluster-ions",
"url": "https://arxiv.org/abs/physics/0502041"
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