Time-varying ice crystal orientation in thunderstorms observed with multiparameter radar

Repeated changes associated with lightning have been observed with multiparameter radar in the echoes from the tops of Florida thunderstorms. These lightning-related radar signatures are interpreted as changes in the orientation of ice crystals being preferentially aligned parallel to the in-cloud electric field. The changes occur at intervals on the order of 10 s and are easily observed in the signatures of the differential propagation phase shift and the linear depolarization ratio which are sensitive to propagation effects caused by the oriented ice crystals. The orientation of ice crystals aloft has been previously observed using circularly polarized radar while the simultaneous differential phase shift and linear depolarization measurements reported were obtained with a dual-linear polarized radar. The observations indicate crystal orientation angles greater than 450 and occasionally near vertical. In one case, the crystals were found to be oriented in a layer near radar cloud top spanning a 20-km range and 3 km in depth.

[1]  Martin Hagen,et al.  Polarimetric radar studies of atmospheric ice particles , 1994, IEEE Trans. Geosci. Remote. Sens..

[2]  J. Metcalf.  Radar observations of changing orientations of hydrometeors in thunderstorms , 1995 .

[3]  N. McEwan,et al.  Attenuation and cross-polarization measurements at 20 GHz using the ATS-6 satellite with simultaneous radar observations , 1979 .

[4]  J. V. Iribarne,et al.  On the Orientation of Ice Crystals in a Cumulonimbus Cloud , 1981 .

[5]  John M. Livingston,et al.  Electric fields produced by Florida thunderstorms , 1978 .

[6]  G. Mccormick,et al.  Radar observations of the alignment of precipitation particles by electrostatic fields in thunderstorms , 1976 .

[7]  V. N. Bringi,et al.  Potential Use of Radar Differential Reflectivity Measurements at Orthogonal Polarizations for Measuring Precipitation , 1976 .

[8]  J. Metcalf.  Radar Observations of the Effects of Changing Electric Fields on the Orientations of Hydrometeors , 1992 .

[9]  P. Krehbiel,et al.  The use of dual channel circular-polarization radar observations for remotely sensing storm electrification , 1996 .

[10]  Earle R. Williams,et al.  Large-scale charge separation in thunderclouds , 1985 .

[11]  A. Weinheimer,et al.  The electric field alignment of ice particles in thunderstorms , 1987 .

[12]  D. Cox,et al.  Observations of rapid changes in the orientation and degree of alignment of ice particles along an Earth‐space radio propagation path , 1979 .

[13]  A. R. Jameson.  Relations Among Linear and Circulur Polarization Parameters Measured in Canted Hydrometeors , 1987 .

[14]  C. Saunders,et al.  A Review of Thunderstorm Electrification Processes , 1993 .

[15]  M. Sachidananda,et al.  ZDR measurement considerations for a fast scan capability radar , 1985 .

[16]  N. McEwan,et al.  OTS propagation measurements during thunderstorms , 1981 .

[17]  M. Uman,et al.  The Lightning Discharge , 1987 .

[18]  A. R. Jameson.  The Interpretation and Meteorological Application of Radar Backscatter Amplitude Ratios at Linear Polarizations , 1989 .

[19]  Relationship between atmospheric electricity and microwave radio propagation , 1977, Nature.

[20]  J. W. F. Goddard,et al.  Identification of hydrometeors and other targets by dual‐polarization radar , 1984 .

[21]  V. Chandrasekar,et al.  Auxiliary Signal Processing System for a Multiparameter Radar , 1993 .

[22]  Jothiram Vivekanandan,et al.  Polarimetric radar modeling of mixtures of precipitation particles , 1993, IEEE Trans. Geosci. Remote. Sens..

[23]  G. Mccormick,et al.  Radar Measurement of Precipitation-Related Depolarization in Thunderstorms , 1979, IEEE Transactions on Geoscience Electronics.

[24]  J. Mon.  Backward and forward scattering of microwaves by ice particles: A review , 1982 .

[25]  V. Chandrasekar,et al.  Polarimetric radar signatures of precipitation at S- and C-bands , 1991 .

[26]  Y. M. M. Antar,et al.  Radar observations of polarization characteristics and lightning‐induced realignment of atmospheric ice crystals , 1982 .

[27]  V. N. Bringi,et al.  Technology of Polarization Diversity Radars for Meteorology , 1990 .