Aura MLS


Contact: Hugh Pumphrey

HCN is a minor constituent of the atmosphere, whose sources are thought to be at the Earth's surface.

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 retrieved from bands encompassing, in the lower sideband, the 177.26GHz spectral line of HCN. Although the target line is in an uncluttered part of the spectrum, the upper sideband containsmany interfering lines of O3 and HNO3. As a result, the v5.0x HCN product is not recommended for general use at altitudes below 21 hPa. In the recommended range it is usable, but has rather poor precision (necessitating averaging such as weekly zonal means) and resolution.

HCN Information from the Spectroscopy Database

Quick Product Information for data version v5

  • Swath Name: HCN
  • Status Flag: Only use profiles for which the Status field is an even number.
  • Useful Range: 21 - 0.1 hPa
  • DAAC Short Name: ML2HCN
  • Precision: Only use values for which the estimated precision is a positive number.
  • Quality Threshold: >0.2
  • Convergence Threshold: <2.0

Download Aura MLS HCN v5 data

Latest Publications (HCN)

  1. Kloss, C., P. Sellitto, M. von Hobe, G. Berthet, D. Smale, G. Krysztofiak, C. Xue, C. Qiu, F. Jégou, I. Ouerghemmi and B. Legras
    Australian Fires 2019–2020: Tropospheric and Stratospheric Pollution Throughout the Whole Fire Season
    Front. Environ. Sci doi:10.3389/fenvs.2021.652024, 2021
  2. Livesey, N., W. Read, L. Froidevaux, A. Lambert, M. Santee, M. Schwartz, L. Millán, R. Jarnot, P. Wagner, D. Hurst, K. Walker, P. Sheese and G. Nedoluha
    Investigation and amelioration of long-term instrumental drifts in water vapor and nitrous oxide measurements from the Aura Microwave Limb Sounder MLS and their implications for studies of variability and trends
    Atmos. Chem. Phys. doi:10.5194/acp-21-15409-2021, 2021
  3. Pumphrey, H., M. Schwartz, M. Santee, G. Kablick III, M. Fromm and N. Livesey
    Microwave Limb Sounder MLS observations of biomass burning products in the stratosphere from Canadian forest fires in August 2017
    Atmos. Chem. Phys. doi:10.5194/acp-21-16645-2021, 2021
  4. Schwartz, M., M. Santee, H. Pumphrey, G. Manney, A. Lambert, N. Livesey, L. Millán, J. Neu, W. Read and F. Werner
    Australian New Year's PyroCb Impact on Stratospheric Composition
    Geophys. Res. Lett. doi:10.1029/2020gl090831, 2020
  5. Pumphrey, H., N. Glatthor, P. Bernath, C. Boone, J. Hannigan, I. Ortega, N. Livesey and W. Read
    MLS measurements of stratospheric hydrogen cyanide during the 2015–2016 El Niño event
    Atmos. Chem. Phys. doi:10.5194/acp-18-691-2018, 2018
  6. Santee, M.L., G.L. Manney, N.J. Livesey, M.J. Schwartz, J.L. Neu and W.G. Read
    A comprehensive overview of the climatological composition of the Asian summer monsoon anticyclone based on 10 years of Aura Microwave Limb Sounder measurements
    Journal of Geophysical Research: Atmospheres doi:10.1002/2016jd026408, 2017
  7. Allen, D.R., K.W. Hoppel and D.D. Kuhl
    Wind extraction potential from 4D-Var assimilation of stratospheric O3, N2O, and H2O using a global shallow water model
    Atmos. Chem. Phys. doi:10.5194/acp-14-3347-2014, 2014
  8. Schoeberl, M.R., A.E. Dessler, T. Wang, M.A. Avery and E.J. Jensen
    Cloud formation, convection, and stratospheric dehydration
    Earth and Space Science doi:10.1002/2014EA000014, 2014
  9. Pumphrey, H.C., M.L. Santee, N.J. Livesey, M.J. Schwartz and W.G. Read
    Microwave Limb Sounder observations of biomass-burning products from the Australian bush fires of February 2009
    Atmos. Chem. Phys. doi:10.5194/acp-11-6285-2011, 2011
  10. Pommrich, R., R. Mueller, J.U. Grooss, G. Gunther, P. Konopka, M. Riese, A. Heil, M. Schultz, H.C. Pumphrey and K.A. Walker
    What causes the irregular cycle of the atmospheric tape recorder signal in HCN?
    Geophys. Res. Lett. doi:10.1029/2010GL044056, 2010
  11. Li, Q., P.I. Palmer, H.C. Pumphrey, P. Bernath and E. Mahieu
    What drives the observed variability of HCN in the troposphere and lower stratosphere?
    Atmos. Chem. Phys. doi:10.5194/acp-9-8531-2009, 2009
  12. Pumphrey, H.C., C. Boone, K.A. Walker, P. Bernath and N.J. Livesey
    The tropical tape recorder observed in HCN
    Geophys. Res. Lett. doi:10.1029/2007GL032137, 2008
  13. Cofield, R.E. and P.C. Stek
    Design and field-of-view calibration of 114-660 GHz optics of the Earth Observing System Microwave Limb Sounder
    IEEE Trans. Geosci. Remote Sensing doi:10.1109/TGRS.2006.873234, 2006
  14. Pumphrey, H.C., C.J. Jimenez and J.W. Waters
    Measurement of HCN in the middle atmosphere by EOS MLS
    Geophys. Res. Lett. doi:10.1029/2005GL025656, 2006