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IEEE Transactions on Antennas and Propagation
Volume 48 Number 2, February 2000

Table of Contents for this issue

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Radar Reflection from Clouds: Gigahertz Backscatter Cross Sections and Doppler Spectra

David A. de Wolf, Herman W. J. Russchenberg and Leo P. Ligthart

Page 254.

Abstract:

This work deals with reflections of gigahertz-frequency radar signals from typical clouds over The Netherlands. Four principal mechanisms of reflection are identified. While the backscatter cross sections for these are mostly well known, there is a need to identify which, if any, are dominant in each frequency range. Numerical studies of superpositions of the main backscatter mechanisms are presented for a range of parameter values thought to occur commonly. These studies confirm previous results, but are generalized to incorporate gamma-function particle drop-size distributions. The results are relatively insensitive to the power of the diameter in the distribution function. The Doppler spectra of the reflected signals sometimes exhibit a bimodal form. One possible mechanism investigated here is the observation of reflections that occur simultaneously from turbulently moving globules of particles and from incoherent reflections from particles with diameter-dependent spreads in velocities.

References

  1. H. C. van de Hulst, Light Scattering By Small Particles, New York: Wiley, 1957.
  2. C. F. Bohren and D. R. Huffman, Absorption And Scattering Of Light By Small Particles, New York: Wiley, 1983.
  3. L. Tsang, J. A. Kong and R. T. Shin, Theory of Microwave Remote Sensing, New York: Wiley, 1985.
  4. V. I. Tatarskii, 22151 "The effects of the turbulent atmosphere on wave propagation", Nat. Tech. Inform. Service, U.S. Dept. Commerce, Springfield, VA, Document TT 68-50464, 1971.
  5. A. Ishimaru, Wave Propagation And Scattering In Random Media-Vol. I, II, New York: Academic, 1978.
  6. R. J. Doviak and D. S. Zrnić, Doppler Radar and Weather Observations , 2nd ed.   San Diego: Academic, 1993.
  7. H. R. Pruppacher and J. D. Klett, Microphysics of Clouds and Precipitation, Dordrecht: The Netherlands: D. Reidel, 1978 .
  8. L. P. Ligthart and L. R. Nieuwkerk, "Studies of precipitation processes in the troposphere using an FM-CW radar", J. Atmosph. Ocean. Technol., vol. 6, pp.  798-808, 1989.
  9. D. A. de Wolf and C. Kontogeorgakis, "Reflectivity and attenuation at millimeter to infrared wavelengths for advection fogs at four locations", J. Appl. Meteorol., vol. 38, pp.  126-131, Jan.  1999.
  10. J. Allen Zak, "Drop size distributions and related properties of fog for five locations measured from aircraft", NASA Contractor Rep. 4585 (DOT/FAA/CT-94/02), April 1994.
  11. S. A. Smith and P. R. Jonas, "Observations of turbulence in cirrus clouds ", Atmospheric Research, vol. 43, pp.  1-29, Nov.  1996.
  12. I. Gultepe and D. O. Starr, "Dynamical structure and turbulence in cirrus clouds: Aircraft observations during FIRE", J. Atmos. Sci., vol. 52, pp.  4159-4418, Dec.  1995.
  13. H. G. Booker and W. E. Gordon, "A theory of radio scattering in the troposphere", Proc. IRE, vol. 38, pp.  401-412, 1950.
  14. F. Villars and V. F. Weisskopf, "On the scattering of radio waves by turbulent fluctuations in the atmosphere", Proc. IEEE, vol. 43, pp.  1232-1239,  1955.
  15. C. C. Lin, Statistical Theories of Turbulence, Princeton, NJ: Princeton Univ. Press, 1961.
  16. E. E. Gossard and R. G. Strauch, "The refractive index spectra within clouds from forward-scatter radar observations", J. Appl. Meteor., vol. 20, pp.  170-183, 1981.
  17. E. E. Gossard, "A fresh look at the radar reflectivity of clouds", Radio Sci., vol. 14, pp.  1089-1097, 1979.
  18. U. Merlo, E. Fionda and J. Wang, "Ground level refractivity and scintillation in space-earth links", Appl. Opt., vol. 27, pp.  2247 -2252, 1988.
  19. N. I. Fox and A. J. Illingworth, "The retrieval of stratocumulus cloud properties by ground based cloud radar", J. Appl. Meteorol., vol. 36, pp.  485-492,  May  1997.
  20. V. C. Chen, "Applications of the time frequency processing to radar imaging", Opt. Eng., vol. 36, pp.  1152-1161, Apr.  1997 .
  21. E. E. Gossard, J. B. Snider, E. E. Clothiaux, B. Martner, J. S. Gibson, R. A. Kropfli and A. S. Frisch, "The potential of 8 mm radars for remotely sensing cloud drop size distributions", J. Atmosph. Ocean. Technol., vol. 14, pp.  76-87, Feb.  1997.
  22. F. M. Ralph, P. J. Neiman, D. W. VandeKamp and D. C. Law, "Using spectral moment data from NOAA 404 MHz radar wind profilers to observe precipitation", Bull. Amer. Meteorolog. Soc., vol. 76, pp.  1717-1739, Oct.  1995.
  23. A. S. Frisch, C. W. Fairall and J. B. Snider, "Measurement of stratus cloud and drizzle parameters in ASTER with a K Alpha band Doppler radio and a microwave radiometer", J. Atmosph. Sci., vol. 52, pp.  2788-2799, Aug.  1995 .
  24. G. M. Barnes, "Updraft evolution: A perspective from cloud base", Monthly Weather Rev., vol. 123, pp.  2693-2715, Sep.  1995 .
  25. F. M. Ralph, "Using radar measured radial vertical velocities to distinguish precipitation scattering from clear air scattering", J. Atmosph. Ocean. Technol., vol. 12, pp.  257-267, Apr.  1995 .
  26. A. M. Yaglom, An Introduction to the Theory of Stationary Random Functions, New York: Dover, 1962.
  27. A. Deepak, Ed., Atmospheric Aerosols: Their Formation, Optical Properties, and Effects, Hampton, VA: Spectrum, 1982.