Subsidence of high atmospheric air above the Arctic derived from CO time series measured by ground-based microwave radiometers.
Final Report Abstract
In the project a data analysis chain for millimeterwave spectra measured using the KIMRA instrument in Kiruna (68 degrees North) was successfully set up. They found, that the results obtained from the measurements of the KIMRA instrument are in good agreement to existing satellite measurements, namely from the MLS instrument on the AURA satellite and the MIPAS instrument on Envisat. The results were used to validate the newly developed SD-WACCM model. The major findings were that the SD-WACCM model were able to model the CO content of the mesosphere to surprisingly good degree. Surprisingly good, because 1) the model is a global circulation model nudged to a meteorological analysis up to 50 km, 2) the comparison took place at a particular place on earth and 3) the comparison took place at 60 to 70 km, well above the altitude where the nudging has a direct effect. One of the conclusion is accordingly, that dynamics of the mesosphere are determined mainly from below. Inconsistencies in the dynamics could be explained by the fact, that the wave propagation, which provides the link between the stratosphere and the parts of the atmosphere above the stratosphere is only modeled in a statistical sense. The results and experience of Dr. Hoffmann could be used to devise a new instrument to measure the CO content of the mesosphere and to continue this research.
Publications
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Ground-based Observations of the Tracer CO above the Arctic and the Comparison to SD-WACCM model data, 3rd HEPPA Workshop, Granada, Spain, 9.-11. May 2011
Christoph G. Hoffmann, Uwe Raffalski, Mathias Palm, Douglas E. Kinnison, Rolando R. Garcia, Sven H. W. Golchert, Gerd Hochschild, and Justus Notholt
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Observation of strato-mesospheric CO above Kiruna with ground-based microwave radiometry – retrieval and satellite comparison. Atmos. Meas. Tech., 4:2389 – 2408, 2011
C. G. Hoffmann, U. Raffalski, M. Palm, B. Funke, S. H. W. Golchert, G. Hochschild, and J. Notholt
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Application of CO as a tracer for dynamics in the polar winter middle atmosphere – A study based on ground–based microwave observations in Kiruna. PhD thesis, Universität Bremen, 2012
Christoph Gregor Hoffmann
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CO at 40 – 80 km above Kiruna observed by the ground-based microwave radiometer KIMRA and simulated by the Whole Atmosphere Community Climate Model. Atmos. Chem. Phys., 12:3261 – 3271, 2012
C. G. Hoffmann, D. E. Kinnison, R. R. Garcia, M. Palm, J. Notholt, U. Raffalski, and G. Hochschild
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A brief example on the application of remotely sensed tracer observations in atmospheric science – studying the impact of stratosphere – mesosphere coupling on polar ozone variability. In Gerrit Lohmann et al. editors, Earth System Science: Bridging the Gaps between Disciplines, chapter 2.1, pages 15 – 19. Springer, 2013
Christoph G. Hoffmann, Mathias Palm, Justus Notholt, Uwe Raffalski, and Gerd Hochschild
