Advances in Radio Science www.adv-radio-sci.net 1684-9965 1684-9973 7 Kleinheubacher Berichte 2008 2009 10.5194/ars-7-279-2009 http://www.adv-radio-sci.net/7/279/2009/ http://www.adv-radio-sci.net/7/279/2009/ars-7-279-2009.html http://www.adv-radio-sci.net/7/279/2009/ars-7-279-2009.pdf 279 284 2009-05-19 Polarisation basis transformation of weather radar measurements in the power domain T. Otto t.otto@tudelft.nl J. Lu M. Chandra Atmospheric Remote Sensing, IRCTR, Delft University of Technology, The Netherlands Former student at the Chair of Microwave Engineering and Photonics, Chemnitz University of Technology, Germany Chair of Microwave Engineering and Photonics, Chemnitz University of Technology, Germany Polarisation diversity in radar remote sensing proved to be very successful in a variety of applications. Hydrometeors as raindrops or ice crystals are anisotropic radar targets giving rise to the use of polarisation diversity in weather radars. One advanced polarimetric weather radar is DLR's POLDIRAD in Oberpfaffenhofen. The huge data archive of this radar consists mainly of power measurements at diverse polarisation bases. <br><br> This study investigates the possibility to apply the polarisation basis transformation directly on power measurements. As a result, empirical transfer functions for the change of the polarisation basis of radar reflectivities are derived. To check their validity they are applied to appropriate polarimetric radar data from the POLDIRAD. Andsager, K., Beard, K V., and Laird, N F.: Laboratory Measurements of Axis Ratios for Large Raindrops, J. Atmos. Sci., 56, 2673–2683, 1999. Beard, K V. and Chuang, C.: A New Model for the Equilibrium Shape of Raindrops, J. Atmos. Sci., 44, 1509 – 1524, 1987. Beard, K V. and Jameson, A R.: Raindrop Canting, J. Atmos. Sci., 40, 448–454, 1983. Bringi, V N. and Chandrasekar, V.: Polarimetric Doppler Weather Radar, Cambridge University Press, 1st edn., p. 410, 2001. % Chandra, M., Schroth, A., and % Lüneburg, E.: Prospective Investigations with % DFVLR-Radar of Possible Relevance in the Assessment of Radio Interference due % to Scattering from Precipitation, DFVLR Forschungsbericht, DFVLR-FB 84-42, \blackbox\bf page range, % 1984. Chandra, M., Wood, S J., Lux, S., Holt, A R., and Schroth, A.: The PADRE Project, European Commission COST 75 Weather Radar Systems, edited by: Collier, C. G., in: Report EUR 16013 EN, ISSN 1018-5593, 507–518, Brussels, Belgium, 1994. Hagen, M.: On the variation of the parametrization of rainfall rate estimation by dual polarization techniques, in: 30th Conference on Radar Meteorology, Preprints, 11B.3, Munich, Germany, 2001. Holt, A R.: Some factors affecting the remote sensing of rain by polarization diversity radar in the 3- to 35-GHz frequency range, Radio Sci., 19, 1399–1412, 1984. Holt, A R., Uzunoglu, N K., and Evans, B G.: An Integral Equation Solution to the Scattering of Electromagnetic Radiation by Dielectric Spheroids and Ellipsoids, IEEE T. Antennas Propag., AP-26, 706–712, 1978. Keenan, T D., Carey, L D., Zrnic, D S., and May, P T.: Sensitivity of 5-cm Wavelength Polarimetric Radar Variables to Raindrop Axial Ratio and Drop Size Distribution, J. Appl. Meteor., 40, 526–545, 2001. Marshall, J S. and Palmer, W M.: The Distribution of Raindrops with Size, J. Meteorol., 5, 165–166, 1948. McCormick, G C. and Hendry, A.: Principles for the radar determination of the polarization properties of precipitation, Radio Sci., 10, 421–434, 1975. Mott, H.: Remote Sensing with Polarimetric Radar, John Wiley & Sons, 1st edn., 68–70, 2007. Pruppacher, H R. and Beard, K V.: A wind tunnel investigation of the internal circulation and shape of water drops falling at terminal velocity in air, Q. J. Roy. Meteor. Soc., 96, 247–256, 1970. Pruppacher, H R. and Pitter, R L.: A Semi-Empirical Determination of the Shape of Cloud and Rain Drops, J. Atmos. Sci., 28, 86–94, 1971. Ray, P S.: Broadband Complex Refractive Indices of Ice and Water, Appl. Optics, 11, 1836–1844, 1972. Schroth, A C., Chandra, M S., and Meischner, P F.: A C-Band coherent polarimetric radar for propagation and cloud physics research, J. Atmos. Oceanic Technol., 5, 803–822, 1988. Tracksdorf, P., Ghorbani, A., Chandra, M., Hagen, M., and Bebbington, D.: Comparison of linear and logarithmic receiver signals from polarimetric weather radar echoes and their temporal decorrelation properties, Adv. Radio Sci., 3, 401–411, 2005.