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Class presentation 16.2.2007

Applications of the Helsinki Test Bed CL31 Ceilometer data. Anu-Maija Sundström University of Helsinki Division of Atmospheric Sciences. Class presentation 16.2.2007. Background. ”Lidar in Aerosol Research” FMI, Vaisala, University of Helsinki

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Class presentation 16.2.2007

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  1. Applications of the Helsinki Test Bed CL31 Ceilometer data Anu-Maija Sundström University of Helsinki Division of Atmospheric Sciences Class presentation 16.2.2007

  2. Background • ”Lidar in Aerosol Research” • FMI, Vaisala, University of Helsinki • Funded by TEKES (the Finnish Funding Agency for Technology) Jan 2005- Dec 2005 • Vaisala CL31 ceilometer at Kumpula Campus • Two main topics • Particles physical modeling • ”Ceilometer climatology” and relation to particle concentrations

  3. Lidar measurements • CL31 vertically pointing elastic backscatter lidar, operates at 910 nm wavelenght • Lidar ”sees” everything within the measurement volume, i.e. air molecules, aerosols, and hydrometeors • limitations to see very small particles • To study only the aerosol contribution of the backscattered signal we need to exclude • Rain data (also ice) • The molecular scattering A reliable rain data filtering method is needed

  4. Objectives • To test and improve the rain data filtering method • threshold value in relative humidity • present weather sensor • threshold value in a vertical average of lidar backscattering • threshold value in temporal variation of lidar backscattering • To study the relation between PM10 concentrations and lidar backscattering at different locations • E.g. how much the local effects affect results

  5. Data • From Test Bed: • CL31 backscattering profiles from various stations and • Meteorological data (rain, wind) • PM10 concentration • Possibly also other profilers • Important issues: • CL31 device settings • The metadata from the TB-stations

  6. An Example Vallila Test Bed Station 20.8.2005, 1 h averages of PM10 concentrations Temporal variation of modeled and measured backscattering coefficient at Kumpula 20.8.2005 • Vertical mixing ? • What is the signal from Vallila CL31? • ...

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