Quicklooks of the „range corrected signal“ at 1064 nm measured by blueYALIS (CHM15kx, Lufft) and at 903 nm from redYALIS (CHM8k, Lufft), both operated by the Meteorological Institute (MIM) of the Ludwig-Maximilians-Universität (48.148 N, 11.573 E, altitude 539 m). From 11 September 2019 redYALIS is located in Garching (48.2611 N, 11.6638 E, altitude 477 m), 12.3 km north of MIM. The signals are not overlap-corrected if not otherwise stated. We are grateful that we are allowed to process the corresponding data (since 1. June 2010) of the CHM15k ceilometer located at the UFS (altitute 2712 m, 93 km south of Munich), owned by the UFS and operated by the German Weather Service for comparison. The temporal resolution is 15 s, the vertical resolution is 15 m (raw data). The quicklooks are smoothed over 5 range bins for blueYALIS and the UFS ceilometer until 12.11.2018. All other signals are not smoothed.

The range corrected signal is proportional to the attenuated backscatter, and in first approximation proportional to the backscatter coefficient of particles. The backscatter coefficient is an indication for the „amount of aerosols“. The signals at 903 nm (redYALIS) are also influenced by water vapor absorption. The images show clouds in white (very strong backscatter signal) and aerosols in green and yellow (medium strong signal). Extended white and red areas down to the ground indicate rain. Note, that „steps“ in the colored areas (visible until 27. October 2014 for the blueYALIS measurements) are due to automatically changed settings of the ceilometer's detection unit.

• 12.06.2009 - 27.10.2014: CHM15kx „1. generation“
• 10.11.2014 - 08.01.2015: CHM15k „Nimbus“ (with overlap-correction provided by the manufacturer)
• 02.02.2015 - 26.05.2015: CHM15kx „Nimbus“
• 27.06.2015 - 14.09.2015: CHM15kx „Nimbus“ (after re-adjustment), CeiLinEx2015-campaign in Lindenberg
• 21.09.2015 - 12.11.2018: CHM15kx „Nimbus“
• 13.11.2018 - 03.06.2019: CHM15kx „Nimbus“ (with overlap-correction provided by the manufacturer)
• since 01.08.2019: CHM15kx „Nimbus“ (new detector, with overlap-correction provided by the manufacturer

• since 25.02.2019: operational (range extended to 15 km)
• since 11.09.2019: located in Garching

Examples with explanations are shown here

• 6. May 2011 (dominant aerosol layer, cirrus clouds)
• 1. August 2011 (low level clouds, mixing layer aerosol)

• On the calibration of ceilometer signals: Wiegner, M. and Geiß, A. (2012): Aerosol profiling with the Jenoptik ceilometer CHM15kx, Atmos. Meas. Tech., 5, 1953-1964, https://doi.org/10.5194/amt-5-1953-2012.
• On the evaluation of ceilometer data: Wiegner, M., Madonna, F., Binietoglou, I., Forkel, R., Gasteiger, J., Geiß, A., Pappalardo, G., Schäfer, K., and Thomas, W. (2014): What is the benefit of ceilometers for aerosol remote sensing? An answer from EARLINET, Atmos. Meas. Tech., 7, 1979-1997, https://doi.org/10.5194/amt-7-1979-2014.
• On water vapor absorption affecting ceilometer measurements at 905-910 nm: Wiegner, M. and Gasteiger, J. (2015): Correction of water vapor absorption for aerosol remote sensing with ceilometers, Atmos. Meas. Tech., 8, 3971–3984, https://doi.org/10.5194/amt-8-3971-2015.
• On the determination of the mixing layer height: Geiß, A., Wiegner, M., Bonn, B., Schäfer, K., Forkel, R., von Schneidemesser, E., Münkel, C., Chan, K. L., and Nothard, R. (2017): Mixing layer height as an indicator for urban air quality?, Atmos. Meas. Tech., 10, 2969-2988, https://doi.org/10.5194/amt-10-2969-2017.
• On the validation of the water vapor correction: Wiegner, M., Mattis, I., Pattantyús-Ábrahám, M., Bravo-Aranda, J. A., Poltera, Y., Haefele, A., Hervo, M., Görsdorf, U., Leinweber, R., Gasteiger, J., Haeffelin, M., Wagner, F., Cermak, J., Komínková, K., Brettle, M., Münkel, C., and Pönitz, K. (2019): Aerosol backscatter profiles from ceilometers: validation of water vapor correction in the framework of CeiLinEx2015, Atmos. Meas. Tech., 12, 471–490, https://doi.org/10.5194/amt-12-471-2019.

If yes, please contact Matthias Wiegner