Observations at different locations are important for a better understanding of the spatial and temporal behaviour of the thermal structure of the atmosphere temperature. Such measurements can be performed with good temporal and spatial resolution between 80 and 105 km altitude with the worldwide unique mobile Doppler lidar for the mesosphere/lower thermosphere, the containerised potassium resonance lidar (figure 1). First successful measurements have been demonstrated in 1995 at Juliusruh (54°38 ’N, 13°24 ’E) [Höffner and von Zahn, 1995].
Afterwards in 1996 measurements on board the research vessel “Polarstern” have shown for the first time the latitudinal dependency of the mesopause from 71°S to 45°N (figure 2). With these measurements the bimodal behaviour of the mesopause, the so-called “two level mesopause”, was discovered [von Zahn et al., 1996]. Simultaneously the potassium layer was measured and a model of the potassium layer was developed (Eska et al., 1999]. Between June 1996 and February 1999 the mobile lidar was operated routinely at the IAP Kühlungsborn (54◦07 ′N, 11◦46 ′E). With continues measurements about several years at a single location the existence of the two level mesopause was approved [She und von Zahn, 1998] and new findings about the seasonal behaviour of the potassium layer have been obtained [Eska et al., 1998]. These measurements also show the existence of free metal atoms above 110 km altitude [Höffner and Friedman, 2004]. For the first time the metal ratio of ablating meteoroids entering the atmosphere have been obtained by combining the measurements of the K-lidar with the nearby metal lidar [von Zahn et al, 1999]. Since 2001 temperature measurements are performed with a second new stationary K-lidar in conjunction with a RMR lidar. This combination allows simultaneous measurements of temperatures from the troposphere to the lower thermosphere.
The mobile K-lidar was operated between March 1999 and December 2000 at the canaries island Tenerife (28◦18 ′N, 17◦31 ′W) at 2390 m for the examination of the two level mesopause at low latitudes. At Tenerife first measurements with a newly developed daylight filter have been performed [Fricke-Begemann et al.,2002]. At the end of 2000 a continuous measurements about seven days have been achieved [Fricke-Begemann und Höffner, 2005]. Between May 2001 and August 2003 the lidar was located at 450 m altitude on the island of Spitsbergen (78◦14 ′N, 15◦23 ′E) (figure 3). Beside the study of NLC and their seasonal behaviour [Höffner et al., 2003] the main aim was the determination of the thermal structure of the mesopause. Starting in 2004 the K-lidar was reconstructed for improved measurements at daylight [Lautenbach and Höffner, 2004], being the worldwide first iron Dopplerlidar. The new iron lidar was used for a one year campaign at ALOMAR before it was shipped to Antarctica. There at the Australian research station Davis (69°S) the lidar was deployed for more than two years between end of 2010 and beginning of 2013. In Summer 2014 the Fe lidar was again installed at the ALOMAR observatory (69°N).
- J. Höffner und U. von Zahn, Mesopause temperature profiling by potassium lidar: Recent progress and outlook for ALOMAR, ESA SP-370, 403-407, in Lillehammer95, B. Kaldeich-Schürmann, 1995.
- U. von Zahn und J. Höffner, Mesopause temperature profiling by potassium lidar, Geophys. Res. Lett., 23, 141-144, 1996.
- V. Eska, J. Höffner und U. von Zahn, Upper atmosphere potassium layer and its seasonal variations at 54°N, J. Geophys. Res., 103, 29207-29214, 1998.
- C. Y. She und U. von Zahn, Concept of a two-level mesopause: Support through new Lidar observations, J. Geophys. Res., 103, 5855-5863, 1998.
- V. Eska, U. von Zahn und J. M. C. Plane, The terrestrial potassium layer (75-110 km) between 71°S and 54°N: Observations and modelling, J. Geophys. Res., 104, 17173-17186, 1999.
- U. von Zahn, M. Gerding, J. Höffner, W. J. McNeil und E. Murad, Iron, calcium, and potassium atom densities in the trails of Leonids and other meteors: Strong evidence for differential ablation, Meteorit. & Planet. Sci., 34, 1017-1027, 1999.
- C. Fricke-Begemann, M. Alpers und J. Höffner, Daylight rejection with a new receiver for potassium resonance temperature lidars, Opt. Lett., 27(21), 1932-1934, 2002.
- J. Höffner, C. Fricke-Begemann und F.-J. Lübken, First observations of noctilucent clouds by lidar at Svalbard, 78°N, Atmos. Chem. Phys., 3, 1101-1111, 2003.
- J. Höffner und J. S. Friedman, The mesospheric metal layer topside: A possible connection to meteoroids, Atmos. Chem. Phys., 4, 801-808, 2004.
- C. Fricke-Begemann und J. Höffner, Temperature tides and waves near the mesopause from lidar observations at two latitudes, J. Geophys. Res., 110, D19103, doi:10.1029/2005JD005770, 2005.
- J. Höffner und J. S. Friedman, The mesospheric metal layer topside: Examples of simultaneous metal observation, J. Atmos. Solar-Terr. Phys., doi:10.1016/j.jastp.2005.06.101, 2005.
- J. Höffner und C. Fricke-Begemann, Accurate lidar temperatures with narrowband filters, Opt. Lett., 30(8), 890-892, 2005.
- J. Lautenbach und J. Höffner, Scanning iron temperature lidar for mesopause temperature observation, Appl. Optics, 43(23), 4559-4563, 2004.
- J. Lautenbach, J. Höffner, F.-J. Lübken und M. Zecha, The thermal structure at the topside and above of polar mesosphere summer echoes over Spitsbergen 78°N, Ann. Geophys., 26, 1083-1088, 2008.
- J. Höffner und F.-J. Lübken, Potassium lidar temperatures and densities in the mesopause region at Spitsbergen (78°N), J. Geophys. Res., D20114, doi:10.1029/2007JD008612, 2007.