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Evaluation of the interpretation of ceilometer data with RASS and radiosonde data

Evaluation of the interpretation of ceilometer data with RASS and radiosonde data. Stefan Emeis (KIT), Klaus Schäfer (KIT), Christoph Münkel ( Vaisala ) stefan.emeis@kit.edu. Ceilometers deliver optical backscatter intensities Optical backscatter intensities are:

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Evaluation of the interpretation of ceilometer data with RASS and radiosonde data

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  1. Evaluation of the interpretation of ceilometer data with RASS and radiosonde data Stefan Emeis (KIT), Klaus Schäfer (KIT), Christoph Münkel (Vaisala) stefan.emeis@kit.edu

  2. Ceilometers deliver optical backscatter intensities • Optical backscatter intensities are: • primarily determined by • size and density of aerosol particles • affected by advection • formation and dissolution • secondarily determined by • atmospheric humidity •  evaluation from independent information desirable Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  3. ceilometer Emeis, S., 2010: Measurement Methods in Atmospheric Sciences - In situ and remote. Borntraeger, Stuttgart, 272 pp., 103 figs, 28 tables, ISBN 978-3-443-01066-9. Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  4. Wanted: independent temperature, wind, andhumidityinformation temperature  RASS, radiometer, Raman lidar, interferometer, radiosonde wind  SODAR, windprofiler, RASS, wind lidar, radiosonde humidity  radiometer, Raman lidar, interferometer, DIAL, radiosonde Available: temperature, wind  RASS, atthe same siteasthe ceilometer (upto 540 m) humidity, temperature,  radiosonde, about 60 km away wind (higherlayers) Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  5. CL 31 ceilometer (Vaisala) LD 40 CL 31 Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  6. SODAR-RASS (Doppler-RASS) (METEK) acousticfrequ.: 1500 – 2200 Hz radiofrequ.: 474 MHz resolution: 20 m lowest rangegate: ca. 40 m verticalrange: 540 m Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  7. comparisonto temperature information ceilometer optical backscatter intensity radiosonde profiles RASS potential temperature SODAR (RASS) acoustic backscatter intensity (temp. fluct./vert. temp. grad.) RL fog CBL SL Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  8. ceilometer (top), pot. temp. RASS (middle), acoust. backsc. SODAR (bottom) Feb. 3 Feb. 4 Feb. 5 Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  9. RASS data Augsburg February 2009 potential temperature (top), MLH RASS (middle), MLH SODAR/Ceilo (bottom) Feb. 3 Feb. 4 Feb. 5 Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  10. comparisonto wind information ceilometer optical backscatter intensity SODAR (RASS) horizontal wind speed LLJ > 19 m/s RASS potential temperature Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  11. comparisontomoistureinformation ceilometer optical backscatter intensity radiosonde profiles firstclouds nearsaturation RASS potential temperature RL CBL SL Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  12. influence due to advected particles Eyjafjallajökull ash cloud over Southern Germany ash cloud ash cloud waterclouds CBL SL Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  13. Conclusions • Ceilometers have become a frequent (and rather cheap) tool to monitor • cloud heights, mixing-layer heights and boundary-layer structure • if aerosol particle distribution adapts rapidly to the thermal structure of the • PBL, ceilometers are a good tool to observe this structure • advection of aerosols may play a decisive role, it is dangerous to interpret • ceilometer measurements just locally • particle size spectrum influences ceilometer data in a non-quantifiable way • atmospheric humidity influences ceilometer data in a non-quantifiable way • automated evaluation algorithms for ceilometer data have to be developed • with great care • the combined operation of a ceilometer with a RASS is an option for PBL • research Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  14. Thank you very much for your attention www.imk-ifu.kit.edu Emeis/Schäfer/Münkel - Evaluation of ceilometer data

  15. Emeis/Schäfer/Münkel - Evaluation of ceilometer data

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