Editorial Type:
Article
Article Type:
Research Article

Dual-Polarized Radar and Surface Observations of a Winter Graupel Shower with Negative Zdr Column

V. N. Bringi Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

Search for other papers by V. N. Bringi in
Current site
Google Scholar
PubMed Close
,
P. C. Kennedy Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by P. C. Kennedy in
Current site
Google Scholar
PubMed Close
,
G.-J. Huang Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

Search for other papers by G.-J. Huang in
Current site
Google Scholar
PubMed Close
,
C. Kleinkort Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

Search for other papers by C. Kleinkort in
Current site
Google Scholar
PubMed Close
,
M. Thurai Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

Search for other papers by M. Thurai in
Current site
Google Scholar
PubMed Close
, and
B. M. Notaroš Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado

Search for other papers by B. M. Notaroš in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Feb 2017
DOI:
https://doi.org/10.1175/JAMC-D-16-0197.1
Page(s):
455–470
Restricted access

Abstract

Comprehensive analysis of an unusual graupel-shower event recorded by an S-band polarimetric radar and two optical-imaging surface instruments is presented. The primary radar characteristic was negative differential reflectivity Zdr values along a vertical column. During the afternoon hours of 16 February 2015, a sequence of three showers that were composed primarily of small (8–15-mm diameter) graupel affected the ground instrumentation site that was established for the Multi-Angle Snowflake Camera and Radar (MASCRAD) experiment in the high plains of Colorado. While these showers passed the instrumentation site, the CSU–CHILL radar conducted high-time-resolution (~2.5-min cycle time) range–height indicator (RHI) scans from a range of 13 km. The RHI data show that the negative Zdr values extended vertically through much of the reflectivity cores, implying that the reflectivity-weighted mean axis ratios of the graupel particles in this event remained somewhat prolate throughout their lifetime. To be specific, the cores of the convective showers only extended to heights of ~3.5 km AGL and had fractionally negative (from ~−0.3 to −0.7 dB) Zdr levels in those cores. Particle-image data obtained by the MASC system and by a collocated 2D video disdrometer measured the diameters, shapes, and fall speeds of the graupel particles as they reached the surface. The graupel particles were found to be primarily of the lump type with a slightly prolate mean shape (especially for the larger-diameter particles). Microwave backscatter calculations confirm that the graupel-particle shape and orientation characteristics are consistent with the observed slightly, but consistently, negative Zdr values.

Corresponding author e-mail: Patrick C. Kennedy, patrick.kennedy@colostate.edu

Abstract

Comprehensive analysis of an unusual graupel-shower event recorded by an S-band polarimetric radar and two optical-imaging surface instruments is presented. The primary radar characteristic was negative differential reflectivity Zdr values along a vertical column. During the afternoon hours of 16 February 2015, a sequence of three showers that were composed primarily of small (8–15-mm diameter) graupel affected the ground instrumentation site that was established for the Multi-Angle Snowflake Camera and Radar (MASCRAD) experiment in the high plains of Colorado. While these showers passed the instrumentation site, the CSU–CHILL radar conducted high-time-resolution (~2.5-min cycle time) range–height indicator (RHI) scans from a range of 13 km. The RHI data show that the negative Zdr values extended vertically through much of the reflectivity cores, implying that the reflectivity-weighted mean axis ratios of the graupel particles in this event remained somewhat prolate throughout their lifetime. To be specific, the cores of the convective showers only extended to heights of ~3.5 km AGL and had fractionally negative (from ~−0.3 to −0.7 dB) Zdr levels in those cores. Particle-image data obtained by the MASC system and by a collocated 2D video disdrometer measured the diameters, shapes, and fall speeds of the graupel particles as they reached the surface. The graupel particles were found to be primarily of the lump type with a slightly prolate mean shape (especially for the larger-diameter particles). Microwave backscatter calculations confirm that the graupel-particle shape and orientation characteristics are consistent with the observed slightly, but consistently, negative Zdr values.

Corresponding author e-mail: Patrick C. Kennedy, patrick.kennedy@colostate.edu
Save
Cover Journal of Applied Meteorology and Climatology
Journal of Applied Meteorology and Climatology

  • Aydin, K., and T. A. Seliga, 1984: Radar polarimetric backscattering properties of conical graupel. J. Atmos. Sci., 41, 1887–1892, doi:10.1175/1520-0469(1984)041<1887:RPBPOC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Böhm, H. P., 1989: A general equation for the terminal fall speed of solid hydrometeors. J. Atmos. Sci., 46, 2419–2427, doi:10.1175/1520-0469(1989)046<2419:AGEFTT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Brandes, E. A., K. Ikeda, G. Thompson, and M. Schönhuber, 2008: Aggregate terminal velocity/temperature relations. J. Appl. Meteor. Climatol., 47, 2729–2736, doi:10.1175/2008JAMC1869.1.

    • Search Google Scholar
    • Export Citation

  • Bringi, V. N., and V. Chandrasekar, 2001: Polarimetric Doppler Weather Radar: Principles and Applications. Cambridge University Press, 636 pp.

  • Bringi, V. N., R. Hoferer, D. A. Brunkow, R. Schwerdtfeger, V. Chandrasekar, S. A. Rutledge, J. George, and P. C. Kennedy, 2011: Design and performance characteristics of the new 8.5-m dual-offset Gregorian antenna for the CSU–CHILL radar. J. Atmos. Oceanic Technol., 28, 907–920, doi:10.1175/2011JTECHA1493.1.

    • Search Google Scholar
    • Export Citation

  • Bringi, V. N., B. Notaroš, C. Kleinkort, G.-J. Huang, M. Thurai, and P. Kennedy, 2015: Comprehensive analysis of an unusual winter graupel shower event recorded by an S-band polarimetric radar and two optical imaging surface instruments. 37th Conf. on Radar Meteorology, Norman, OK, Amer. Meteor. Soc., 1A.4. [Available online at https://ams.confex.com/ams/37RADAR/webprogram/Paper276208.html.]

  • Brunkow, D., V. N. Bringi, P. C. Kennedy, S. A. Rutledge, V. Chandrasekar, E. A. Mueller, and R. K. Bowie, 2000: A description of the CSU–CHILL National Radar Facility. J. Atmos. Oceanic Technol., 17, 1596–1608, doi:10.1175/1520-0426(2000)017<1596:ADOTCC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Cober, S. G., and R. List, 1993: Measurements of the heat and mass transfer parameters characterizing conical graupel growth. J. Atmos. Sci., 50, 1591–1609, doi:10.1175/1520-0469(1993)050<1591:MOTHAM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Evaristo, R., T. Bals-Elsholz, E. Williams, A. J. Fenn, M. Donovan, and D. Smalley, 2013: Relationship of graupel shape to differential reflectivity: Theory and observations. 29th Conf. on Environmental Information Processing Technologies, Austin, TX, Amer. Meteor. Soc., 14. [Available online at https://ams.confex.com/ams/93Annual/webprogram/Paper214462.html.]

  • Garrett, T. J., C. Fallgatter, K. Shkurko, and D. Howlett, 2012: Fall speed measurement and high-resolution multi-angle photography of hydrometeors in free fall. Atmos. Meas. Tech., 5, 2625–2633, doi:10.5194/amt-5-2625-2012.

    • Search Google Scholar
    • Export Citation

  • Huang, G.-J., V. N. Bringi, D. Moisseev, W. A. Petersen, L. Bliven, D. Hudak, 2015: Use of 2D-video disdrometer to derive mean density–size and Ze–SR relations: Four snow cases from the Light Precipitation Validation Experiment. Atmos. Res., 153, 34–48, doi:10.1016/j.atmosres.2014.07.013.

    • Search Google Scholar
    • Export Citation

  • Hubbert, J. C., S. M. Ellis, W.-Y. Chang, S. Rutledge, and M. Dixon, 2014: Modeling and interpretation of S-band ice crystal depolarization signatures from data obtained by simultaneously transmitted horizontally and vertically polarized fields. J. Appl. Meteor. Climatol., 53, 1659–1677, doi:10.1175/JAMC-D-13-0158.1.

    • Search Google Scholar
    • Export Citation

  • Kennedy, P. C., and Coauthors, 2015: Preliminary results from the Multi-Angle Snowflake Camera and Radar (MASCRAD) project. 37th Conf. on Radar Meteorology, Norman, OK, Amer. Meteor. Soc., 1A.1. [Available online at https://ams.confex.com/ams/37RADAR/webprogram/Paper275327.html.]

  • Kleinkort, C., G.-J. Huang, E. Chobanyan, A. Manic, M. Ilic, A. Pezeshki, V. N. Bringi, and B. Notaros, 2015: Visual hull method based shape reconstruction of snowflakes from MASC photographs. Proc. 2015 IEEE Int. Symp. on Antennas and Propagation and North American Radio Science Meeting, Vancouver, BC, Canada, Institute of Electrical and Electronics Engineers, 1122–1123, doi:10.1109/APS.2015.7304949.

  • Knight, C. A., and N. C. Knight, 1973: Conical graupel. J. Atmos. Sci., 30, 118–124, doi:10.1175/1520-0469(1973)030<0118:CG>2.0.CO;2.

  • List, R., and R. S. Schemenauer, 1971: Free-fall behavior of planar snow crystals, conical graupel and small hail. J. Atmos. Sci., 28, 110–115, doi:10.1175/1520-0469(1971)028<0110:FFBOPS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Liu, H., and V. Chandrasekar, 2000: Classification of hydrometeors based on polarimetric radar measurements: Development of fuzzy logic and neuro-fuzzy systems and in situ verification. J. Atmos. Oceanic Technol., 17, 140–164, doi:10.1175/1520-0426(2000)017<0140:COHBOP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Locatelli, J. D., and P. V. Hobbs, 1974: Fall speeds and masses of solid precipitation particles. J. Geophys. Res., 79, 2185–2197, doi:10.1029/JC079i015p02185.

    • Search Google Scholar
    • Export Citation

  • Magono, C., and C. W. Lee, 1966: Meteorological classification of natural snow crystals. J. Fac. Sci. Hokkaido Univ., 2, 321–335. [Available online at http://eprints.lib.hokudai.ac.jp/dspace/handle/2115/8672.]

    • Search Google Scholar
    • Export Citation

  • Mishchenko, M. I., 2014: Electromagnetic Scattering by Particles and Particle Groups: An Introduction. Cambridge University Press, 450 pp.

  • Notaros, B., and Coauthors, 2015: Measurement and characterization of winter precipitation at MASCRAD snow field site. Proc. 2015 IEEE Int. Symp. on Antennas and Propagation and North American Radio Science Meeting, Vancouver, BC, Canada, Institute of Electrical and Electronics Engineers, 979–980, doi:10.1109/APS.2015.7304877.

  • Oue, M., M. R. Kumjian, Y. Lu, Z. Jiang, E. E. Clothiaux, J. Verlinde, and K. Aydin, 2015: X-band polarimetric and Ka-band Doppler spectral radar observations of a graupel-producing Arctic mixed-phase cloud. J. Appl. Meteor. Climatol., 54, 1335–1351, doi:10.1175/JAMC-D-14-0315.1.

    • Search Google Scholar
    • Export Citation

  • Pflaum, J. C., J. J. Martin, and H. R. Pruppacher, 1978: A wind tunnel investigation of the hydrodynamic behaviour of growing, freely falling graupel. Quart. J. Roy. Meteor. Soc., 104, 179–187, doi:10.1002/qj.49710443913.

    • Search Google Scholar
    • Export Citation

  • Pruppacher, H. R., and J. D. Klett, 2010: Microphysics of Clouds and Precipitation. Springer, 954 pp.

  • Schönhuber, M., G. Lammer, and W. L. Randeu, 2008: The 2D-video-distrometer. Precipitation: Advances in Measurement, Estimation and Prediction, S. C. Michaelides, Ed., Springer, 3–31, doi:10.1007/978-3-540-77655-0_1.

  • Straka, J. M., D. S. Zrnić, and A. V. Ryzhkov, 2000: Bulk hydrometeor classification and quantification using polarimetric radar data: Synthesis of relations. J. Appl. Meteor., 39, 1341–1372, doi:10.1175/1520-0450(2000)039<1341:BHCAQU>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Szyrmer, W., and I. Zawadzki, 2010: Snow studies. Part II: Average relationship between mass of snowflakes and their terminal fall fall velocity. J. Atmos. Sci., 67, 3319–3335, doi:10.1175/2010JAS3390.1.

    • Search Google Scholar
    • Export Citation

  • Thomas, R. J., P. R. Krehbiel, W. Rison, S. J. Hunyady, W. P. Winn, T. Hamlin, and J. Harlin, 2004: Accuracy of the lightning mapping array. J. Geophys. Res., 109, D14207, doi:10.1029/2004JD004549.

    • Search Google Scholar
    • Export Citation

  • Thurai, M., V. N. Bringi, and W. A. Petersen, 2009: Rain microstructure retrievals using 2-D video disdrometer and C-band polarimetric radar. Adv. Geosci., 20, 13–18, doi:10.5194/adgeo-20-13-2009.

    • Search Google Scholar
    • Export Citation

  • Zikmunda, J., and G. Vali, 1972: Fall patterns and fall velocities of rimed ice crystals. J. Atmos. Sci., 29, 1334–1347, doi:10.1175/1520-0469(1972)029<1334:FPAFVO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 1597 1167 54
PDF Downloads 418 119 12