The MLS HCN Product
Basic Information
HCN is a minor constituent of the atmosphere, whose sources are thought to be at the Earth's surface.
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The HCN Molecule
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How it is part of MLS Science Objectives
HCN is a "secondary" MLS data product, that can provide new information on the extent to which this tropospheric source molecule reaches the stratosphere and may (or may not) be involved with stratospheric chemistry.
How EOS MLS measures HCN
HCN is produced by the 190 GHz (Core+R2B) retrieval. The signal from the HCN molecule is not strong, and as a result the HCN product is noisy and will require some form of averaging for most purposes. The spectral line of HCN lies in the lower sideband of the radiometer, at 177 GHz. This spectral region is relatively free of interfering lines, but the double sideband nature of the measurement mixes the HCN signal with much stronger signals from O3 and HNO3 in the upper sideband. This interference makes the retrieval of HCN problematic in the lower stratosphere. Inspection of HCN retrieved from the measured radiances suggests that it is worse than in the simulation.
(map from 2005d264)
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HCN Information from the Spectroscopy Database
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Quick Product Information for data version v2.2
- Swath Name: HCN
- Vertical Resolution:8 km at 10 hPa
12km at 0.1 hPa
- Useful Range: 10 - 1.0 hPa
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- DAAC Short Name: ML2HCN
- Precision: 50 pptv at 100 - 10 hPa and 1 - 0.1 hPa
30 ppt at 10 - 1.0 hPa
- Accuracy: TBD
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v2.2 HCN Averaging Kernel
colored lines are individual kernels; thick dashed line is full width at half maximum, thick solid is integrated kernel value
Publications related to the MLS HCN data product
2008
- Pumphrey, H.C., C. Boone, K.A. Walker, P. Bernath, N.J. Livesey, "The tropical tape recorder observed in HCN", vol 35, pgs. L05801, 2008. Reprint
2006
- Cofield, R.E., P.C. Stek, "Design and field-of-view calibration of 114-660 GHz optics of the Earth Observing System Microwave Limb Sounder", vol 44, num no. 5, pgs. 1166-1181, 2006. Reprint
- Pumphrey, H.C., C.J. Jimenez, J.W. Waters, "Measurement of HCN in the middle atmosphere by EOS MLS", vol 33, pgs. L08804, 2006. Reprint
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