The mesospheric metal layer topside: Examples of simultaneous metal observations |
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| Institution: | 1. Leibniz-Institute of Atmospheric Physics, Kühlungsborn, Germany;2. National Astronomy and Ionosphere Center, Arecibo Observatory, Arecibo, Puerto Rico;1. NAIC Arecibo Observatory, HC-03 Box 53995, Arecibo, PR 00612, USA;2. CoRA Division/NWRA, 3380 Mitchell Lane, Boulder, CO 80301, USA;1. Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Piazza del Viminale 1, 00184 Roma, Italy;2. Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971 87 Luleå, Sweden;3. CSMFO Lab., Istituto di Fotonica e Nanotecnologie CNR, Via alla Cascata 56/C, 38123 Povo-Trento, Italy;4. Laboratoire des Technologies Innovantes, LTI, Université Abdelmalek Essâadi, Tanger, Morocco;5. School of Physics, CoE-SM and MERG, University of the Witwatersrand, Johannesburg, South Africa;6. MipLAB, Nello Carrara Institute of Applied Physics, CNR-IFAC, Sesto Fiorentino 50019, Italy;1. Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia;2. IFN-CNR CSMFO Lab. and FBK Photonics Unit, Via alla Cascata 56/C, 38123 Povo-Trento, Italy;3. Department of Civil, Environmental and Mechanical Engineering, Trento University, Via Mesiano, 77, 38123 Trento, Italy;4. Ho Chi Minh City University of Technical Education, 1 Vo Van Ngan Street, Thu Duc District, Ho Chi Minh City, Viet Nam;5. Enrico Fermi Center, Piazza del Viminale 1, 00184 Roma, Italy;6. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 2 Okolna St., 50-422 Wroclaw, Poland;7. Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, Riga, LV-1063, Latvia;1. Institute of Atmospheric Physics, German Aerospace Center, Oberpfaffenhofen, Germany;2. Finnish Meteorological Institute, Sodankylä, Finland;3. Sodankylä Geophysical Observatory, Finland;4. University Leicester, United Kingdom;5. National Institute of Water and Atmospheric Research, Lauder, New Zealand;1. IBF-CNR, Via alla Cascata 56/C, 38123 Trento, Italy;2. IFN - CNR CSMFO Lab. & FBK CMM, Via alla Cascata 56/C Povo, 38123 Trento, Italy;3. Department of Industrial Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy;4. FBK CMM-ARES Unit, Via Sommarive 18, Povo, 38123 Trento, Italy;5. Centro di Studi e Ricerche “Enrico Fermi”, Piazza del Viminale 1, 00184 Roma, Italy;6. Institute of Low Temperature and Structure Research PAS, 50-422 Wroclaw, Poland;7. FBK CMM FMPS Unit, Via Sommarive 18, Povo, 38123 Trento, Italy;1. ESA/ESTEC, Noordwijk, The Netherlands;2. Chair of Astronautics, TU Munich, Munich, Germany;3. University of Oldenburg, Germany |
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| Abstract: | We show examples of common volume observations of three metals by lidar focusing on the altitude of the topside of the meteoric metal layer as described by Höffner and Friedman (H&F) The mesospheric metal layer topside: a possible connection to meteoroids, Atmos. Chem. Phys. 4 (2004) 801–808]. In contrast to H&F, we will focus on time scales of a few hours and less whereas the previous study examined the seasonally averaged climatological state on time scales of several days or weeks, and we examine the entire topside, whereas H&F focused on data at 113 km. The examples, taken under different observation conditions in 1997 and 1998 at Kühlungsborn, Germany (54°N, 15°E), show that the metal layers can often be observed at altitudes as high as 130 km if the signal is integrated over a period of several hours. Under such conditions it is possible to derive reasonably good metal abundance ratios from nocturnally averaged data, which, in turn, allow the discussion of metal abundance ratios to broaden from a single altitude as discussed in H&F to an altitude range extending as high as 130 km. The examples herein show, for the first time, that it is possible to track the transition in the metal abundance ratios from the main layer to an altitude region that has not been studied in the past by lidar. On shorter time scales, small structures are detectable and observable, sometimes above 120 km, resulting in, on average, a broad but weak topside layer above 105 km. In particular, the example of 26–27 October 1997, obtained during enhanced meteor activity, is an indication that this broad layer may result from meteor ablation occurring in this altitude range during the observation. Ratios of metal densities for Ca, Fe, K, and Na are remarkably consistent above about 110 km and in close agreement with the results of H&F. They are less consistent with ratios measured in individual meteor trails and appear to have little relation to the ratios measured in CI meteorites. Finally, it is the temporal smoothing of descending sporadic metal atom layers on top of an undisturbed background metal layer that is the basis of the summer topside extension as described by H&F. |
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