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Dual Doppler lidar observations during T-REX Martin Weissmann, Andreas Dörnbrack

Dual Doppler lidar observations during T-REX Martin Weissmann, Andreas Dörnbrack Institut für Physik der Atmosphäre, DLR Oberpfaffenhofen, Germany Ron Calhoun Department of Mechanical and Aerospace Engineering, Arizona State University, USA Andreas Wieser

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Dual Doppler lidar observations during T-REX Martin Weissmann, Andreas Dörnbrack

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  1. Dual Doppler lidar observations during T-REX Martin Weissmann, Andreas Dörnbrack Institut für Physik der Atmosphäre, DLR Oberpfaffenhofen, Germany Ron Calhoun Department of Mechanical and Aerospace Engineering, Arizona State University, USA Andreas Wieser Institut für Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe, Germany

  2. 80° distance ~3 km 260° Owens Valley ASU lidar DLR lidar Independence

  3. instrument: coherent 2-µm Doppler wind lidar (rented from Lockheed Martin Coherent Technologies) deployment: 14 March - 24 April 2006 (6 weeks) nearly continuous measurements emitted pulses: 2 µm, 500Hz, 450 ns measured signal: backscatter from atmospheric aerosols Doppler shift --> radial velocity hemispherical scanner range up to 11 km 180° vertical slice scan (RHI): 30 - 90 s 360° conical scan (PPI): 60 - 120 s up to ~3000 scans per day ASU lidar: older version of the same system

  4. IOP 13, 16 March 2130 UTC West East Sketch from T-REX Scientific Overview Document wave - not stationary small, rapidly evolving vortices along-valley flow pushing beneath westerly downslope flow thermally driven turbulence --> complex and unsteady 3D flow

  5. West East Sketch from T-REX Science Overview Document IOP 13, 16 April 2134 UTC

  6. West East Sketch from T-REX Science Overview Document IOP 13, 16 April 2143 UTC

  7. IOP 13, 16 April 2108 - 2343 UTC animation: http://www.pa.op.dlr.de/trex/filme/2006_04_16_utc2030.AVI similar unsteady flow during all strong mountain wave events

  8. IOP 6, 25 March 2006 "Components" of a rotor, but no full circulation: - with in-situ observations this could look like a rotor - rotor/roll clouds

  9. x x x x Dual Doppler analysis 25 March 1807-1808 UTC x x similar observations several times during IOP6, and around 1300 UTC 17 April (shortly after end of IOP 13)

  10. IOP 6, 25 March 2006, 1802 - 1825 UTC animation: http://www.pa.op.dlr.de/trex/filme/2006_03_25_utc1805.AVI

  11. 1700 UTC 1730 UTC 1830 UTC 1900 UTC 1930 UTC 1800 UTC Conical (PPI) lidar scans at 5° elevation 25 March 2006

  12. Conclusions successful dual Doppler lidar analysis, improvement of algorithms and noise filters planend classical rotor concept does not seem appropriate to explain lidar observations during T-REX observations show: waves/hydraulic jumps stationary for 5-20 min rapidly evolving vortices develop out of hydraulic jump/shear instabilities/wave breaking significant along-valley flow interacts with the downslope flow strong turbulence and 3D-variability due to heating and complex terrain future suggestions: 3D simulations that include an along-valley flow reconsider classic rotor concepts - no clear observational evidence in literature in-situ observations spread over hours cannot be used for a composite during these events Are rotors described in the literature really (all) rotors, or the consequence of misleading 2D-simulations and sparse observations spread over longer time periods in a highly unsteady/turbulent flow system?

  13. THANKS TO Mark Vercauteren and Keith Barr Lockheed Martin Coherent Technologies Susanne Drechsel, University Innsbruck Alexander Klee, University Innsbruck and DLR DLR T-REX Homepage www.pa.op.dlr.de/trex/

  14. IOP 13, 15 April, 1107 - 1440 UTC animation of aereosol backscatter intensity animation: http://www.pa.op.dlr.de/trex/filme/2006_04_15_utc1100_bs.AVI

  15. 1407 UTC Dual Doppler analysis on 15 April 1142 UTC

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