Comparison of nitric oxide measurements in the mesosphere and lower thermosphere from ACE-FTS, MIPAS, SCIAMACHY, and SMR

[摘要] We compare the nitric oxide measurements in the mesosphere andlower thermosphere (60to 150 km) from four instruments:the Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE-FTS),the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), theSCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY),and the Sub-Millimetre Radiometer (SMR).We use the daily zonal mean data in that altitude range for theyears 2004–2010 (ACE-FTS), 2005–2012 (MIPAS),2008–2012 (SCIAMACHY), and 2003–2012 (SMR).

We first compare the data qualitatively with respect to themorphology, focussing on the major features, and thencompare the time series directly and quantitatively.In three geographical regions, we compare the vertical density profiles oncoincident measurement days. Since none of the instruments delivers continuous daily measurements in thisaltitude region, we carried out a multi-linear regression analysis.This regression analysis considers annual and semi-annualvariability in the form of harmonic terms and inter-annual variability by respondinglinearly to the solar Lyman-α radiation index and thegeomagnetic Kp index.This analysis helps to find similarities and differencesin the individual data sets with respect to the inter-annualvariations caused by geomagnetic and solar variability.

We find that the data sets are consistent and that they onlydisagree on minor aspects. SMR and ACE-FTS deliver thelongest time series in the mesosphere, and they agree with each other remarkably well.The shorter time series from MIPAS and SCIAMACHY also agree withthem where they overlap.The data agree within 30 % when the number densities are large,but they can differ by 50 to 100 % in some cases.

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