• Andrejczuk, M., , Grabowski W. W. , , Malinowski S. P. , , and Smolarkiewicz P. K. , 2004: Numerical simulation of cloud-clear air interfacial mixing. J. Atmos. Sci., 61 , 17261739.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bohl, W., 1998: Technische Strömungslehre. (in German). Vogel Buchverlag, 504 pp.

  • Bruun, H. H., 1995: Hot-Wire Anemometry. Oxford University Press, 507 pp.

  • Cruette, D., , Marillier A. , , Dufresne J. L. , , Grandpeix J. Y. , , Nacass P. , , and Bellec H. , 2000: Fast temperature and true air speed measurements with the airborne ultrasonic anemometer-thermometer (AUSAT). J. Atmos. Oceanic Technol., 17 , 10201039.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Elghobashi, S., , and Truesdell C. , 1993: On the two-way interaction between homogeneous turbulence and dispersed solid particles. I: Turbulence modification. Phys. Fluids, 5 , 17901801.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ferrante, A., , and Elghobashi S. , 2003: On the physical mechanisms of two-way coupling in particle laden isotropic turbulence. Phys. Fluids, 15 , 315329.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Frehlich, R., , Meillier Y. , , Jensen M. L. , , and Balsley B. , 2004: A statistical description of small-scale turbulence in the low-level nocturnal jet. J. Atmos. Sci., 61 , 10791085.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Frisch, U., 1995: Turbulence: The Legacy of A. N. Kolmogorov. Cambridge University Press, 296 pp.

  • Gerber, H., , Arends B. G. , , and Ackerman A. S. , 1994: New microphysics sensor for aircraft use. Atmos. Res., 31 , 235252.

  • Goldstein, R. J., 1996: Fluid Mechanics Measurements. Taylor & Francis, 712 pp.

  • Henze, C. M., , and Bragg M. B. , 1999: A turbulence intensity measurement technique for use in icing wind tunnels. J. Aircr., 36 , 577583.

  • Kaimal, J. C., , and Finnigan J. J. , 1994: Atmospheric Boundary Layer Flows. Oxford University Press, 289 pp.

  • Kaimal, J. C., , Wyngaard J. C. , , and Haugen D. A. , 1968: Deriving power spectra from a three-component sonic anemometer. J. Appl. Meteor., 7 , 827837.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Korczyk, P., , Malinowski S. P. , , and Kowalewski T. A. , 2006: Mixing of cloud and clear air in centimeter scales observed in laboratory by means of Particle Image Velocimetry. Atmos. Res., 82 , 173182.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lenschow, D. H., , Friehe C. A. , , and Larue J. C. , 1978: The development of an airborne hot-wire anemometer system. Preprints, Fourth Symp. on Meteorological Observations and Instrumentation, Denver, CO, Amer. Meteor. Soc., 463–466.

  • Merceret, F. J., 1970: On the use of hot-film anemometry to measure turbulence in the presence of heavy rain. J. Appl. Meteor., 9 , 191193.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Merceret, F. J., 1976: Measuring atmospheric turbulence with airborne hot-film anemometers. J. Appl. Meteor., 15 , 482490.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Muschinski, A., , Frehlich R. G. , , Jensen M. L. , , Hugo R. , , Hoff A. M. , , Eaton F. , , and Balsley B. B. , 2001: Fine-scale measurements of turbulence in the lower troposphere: An intercomparison between a kite- and balloon-borne and a helicopter-borne measurement system. Bound.-Layer Meteor., 98 , 219250.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pruppacher, H. R., , and Klett J. D. , 1997: Microphysics of Clouds and Precipitation. Kluwer Academic Publishers, 953 pp.

  • Schmidt, S., , Lehmann K. , , and Wendisch M. , 2004: Minimizing instrumental broadening of the drop size distribution with the M-Fast-FSSP. J. Atmos. Oceanic Technol., 21 , 18551867.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shaw, R. A., , and Oncley S. P. , 2001: Acceleration intermittency and enhanced collision kernels in turbulent clouds. Atmos. Res., 59–60 , 7787.

    • Search Google Scholar
    • Export Citation
  • Siebert, H., , and Muschinski A. , 2001: Relevance of a tuning-fork effect for temperature measurements with the Gill Solent HS ultrasonic anemometer-thermometer. J. Atmos. Oceanic Technol., 18 , 13671376.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Siebert, H., , Wendisch M. , , Conrath T. , , Teichmann U. , , and Heintzenberg J. , 2003: A new tethered balloon-borne payload for fine-scale observations in the cloudy boundary layer. Bound.-Layer Meteor., 106 , 461482.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Siebert, H., , Franke H. , , Lehmann K. , , Maser R. , , Saw E. W. , , Shaw R. A. , , Schell D. , , and Wendisch M. , 2006a: Probing finescale dynamics and microphysics of clouds with helicopter-borne measurements. Bull. Amer. Meteor. Soc., 87 , 17271738.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Siebert, H., , Lehmann K. , , and Wendisch M. , 2006b: Observations of small scale turbulence and energy dissipation rates in the cloudy boundary layer. J. Atmos. Sci., 63 , 14511466.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wyngaard, J. C., 1992: Atmospheric turbulence. Annu. Rev. Fluid Mech., 24 , 205233.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 195 195 37
PDF Downloads 170 170 38

On the Use of Hot-Wire Anemometers for Turbulence Measurements in Clouds

View More View Less
  • 1 Leibniz Institute for Tropospheric Research, Leipzig, Germany
  • | 2 Department of Physics, Michigan Technological University, Houghton, Michigan
© Get Permissions
Restricted access

Abstract

The use of a hot-wire anemometer for high-resolution turbulence measurements in a two-phase flow (e.g., atmospheric clouds) is discussed. Experiments in a small wind tunnel (diameter of 0.2 and 2 m in length) with a mean flow velocity in the range between 5 and 16 m s−1 are performed. In the wind tunnel a spray with a liquid water content of 0.5 and 2.5 g m−3 is generated. After applying a simple despiking algorithm, power spectral analysis shows the same results as spectra observed without spray under similar flow conditions. The flattening of the spectrum at higher frequencies due to impacting droplets could be reduced significantly. The time of the signal response of the hot wire to impacting droplets is theoretically estimated and compared with observations. Estimating the fraction of time during which the velocity signal is influenced by droplet spikes, it turns out that the product of liquid water content and mean flow velocity should be minimized. This implies that for turbulence measurements in atmospheric clouds, a slowly flying platform such as a balloon or helicopter is the appropriate instrumental carrier. Examples of hot-wire anemometer measurements with the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) are presented.

Corresponding author address: Holger Siebert, Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany. Email: siebert@tropos.de

Abstract

The use of a hot-wire anemometer for high-resolution turbulence measurements in a two-phase flow (e.g., atmospheric clouds) is discussed. Experiments in a small wind tunnel (diameter of 0.2 and 2 m in length) with a mean flow velocity in the range between 5 and 16 m s−1 are performed. In the wind tunnel a spray with a liquid water content of 0.5 and 2.5 g m−3 is generated. After applying a simple despiking algorithm, power spectral analysis shows the same results as spectra observed without spray under similar flow conditions. The flattening of the spectrum at higher frequencies due to impacting droplets could be reduced significantly. The time of the signal response of the hot wire to impacting droplets is theoretically estimated and compared with observations. Estimating the fraction of time during which the velocity signal is influenced by droplet spikes, it turns out that the product of liquid water content and mean flow velocity should be minimized. This implies that for turbulence measurements in atmospheric clouds, a slowly flying platform such as a balloon or helicopter is the appropriate instrumental carrier. Examples of hot-wire anemometer measurements with the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) are presented.

Corresponding author address: Holger Siebert, Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany. Email: siebert@tropos.de

Save