1 / 11

COPS workshop – October 28th

Evaluation of particle shape and orientation within ice clouds using the S-band Doppler Polarimetric radar Tara – supersite H. Y.Dufournet, H. Russchenberg. COPS workshop – October 28th. Radar Tara : characteristics. FMCW S-band radar (3.3 GHz)

austin-wilcox
Download Presentation

COPS workshop – October 28th

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Evaluation of particle shape and orientation within ice clouds using the S-band Doppler Polarimetric radar Tara – supersite H. Y.Dufournet, H. Russchenberg COPS workshop – October 28th

  2. Radar Tara : characteristics • FMCW S-band radar (3.3 GHz) • Doppler and Polarimetric capabilities : vertical and horizontal reception and transmission performed in sequences transmitter receiver Ice and mixed-phase cloud measurement + precipitation measurement V H V H • Wind mode • antennas: 75 degrees • Polarimetry: VV VH HH OB1 OB2 (3 beams) • time res.: ~ 3 s • min range res.: 15 m • max altitude: ~13 km • microphysical mode • antennas: 45 degrees • Polarimetry: VV VH HH (1 beam) • time res.: ~ 3 s • min range res.: 15 m • max altitude: ~ 7 km

  3. Tara within COPS airport • Period: July and August • Placed in Hornisgrinde • 264 measurements (310 hours of raw data) • Orientation: 116° N (towards ARM site) • measurements mode : mainly wind mode + 8 days in microphysical mode Radar direction ( www.cops2007.de )

  4. Microphysic and radar measurements ? Spectral polarimetric measurements Spectral reflectivity Microphysical characteristics of ice particles: velocity 0 • particle orientation • particle shape • PSD (obtain from a microphysical model, not discussed in this presentation)

  5. 16 15 14 13 12 11 10        sZdr categorization  Built using large data set category num > 10 Horizontal alignment Mono-modal 0 Bi-modal 0 0 Category numb < 9 Vertical alignment 0 0 Mono-modal 0 0 0 0 Bi-modal Category numb = 0  Not classified Category numb = -2  Not good enough sLDR < - 15 dB sρ > 0.97 sZvv > -20 dBZ

  6. sZdr simplified categorization Horizontal alignment Vertical alignment Not classified 1st case: 21/07/07 (SOP 2 – EUFAR related) Frontal activities and mesoscale convective system development Ice and mixed-phase cloud Melting layer Boundary layer echo drizzle rainfall

  7. 21/07 – statistical interpretation (whole box) Category number Plates and dentrites formation region Not classified (aggregates) Mostly horizontally aligned particles Hypothesis: presence of aggregates and plates or dentrites with preferred horizontal alignment

  8. sZdr monomodal plates bimodal plates aggregates alone velocity 21/07 : vertical cloud structure From 2D-C probe (ATR42) From the radar (sZdr) Riming and diffusional growth aggregation www.safire.fr and www.eufar.net

  9. Mean particle velocity (m.s-1) Doppler width (m.s-1) 2nd case: 11/07/07  Showers events A lot of turbulence  processing not optimum yet

  10. 11/07 – statistical interpretation (whole box) Category number Columns formation region Mostly vertically aligned particles Hypothesis: presence of aggregates and columns with preferred vertical alignment Not classified (aggregates)

  11. Conclusion • This new retrieval of particle shape and orientation seems feasible within ice and mixed-phase clouds but more study has to be carry out • 8 days will be processed within COPS using such technique: • 27/06 - 11/07 • 21/07 - 09/08 • 17/08 - 21/08 & 22/08 • 28/08

More Related