Dual Doppler lidar observations during TREX Martin Weissmann

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 AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Owens Valley 80° distance ~3 km 260° DLR lidar ASU lidar Independence AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

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, 500 Hz, 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 AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Sketch from T-REX Scientific Overview Document wave - not stationary small, rapidly evolving vortices along-valley flow IOP 13, 16 pushing March beneath westerly downslope flow 2130 UTC thermally driven turbulence --> complex and unsteady 3 D flow West East AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Sketch from T-REX Science Overview Document IOP 13, 16 April 2134 UTC West East AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Sketch from T-REX Science Overview Document IOP 13, 16 April 2143 UTC West East AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

IOP 13, 16 April 2108 - 2343 UTC animation: http: //www. pa. op. dlr. de/trex/filme/2006_04_16_utc 2030. AVI similar unsteady flow during all strong mountain wave events AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

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 AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Dual Doppler analysis 25 March 1807 -1808 UTC x x similar observations several times during IOP 6, and around 1300 UTC 17 April (shortly after end of IOP 13) AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

IOP 6, 25 March 2006, 1802 - 1825 UTC animation: http: //www. pa. op. dlr. de/trex/filme/2006_03_25_utc 1805. AVI AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Conical (PPI) lidar scans at 5° elevation 25 March 2006 1930 1700 1730 1830 1900 1800 UTC AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

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 3 D-variability due to heating and complex terrain future suggestions: 3 D 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 2 D-simulations and sparse observations spread over longer time periods in a highly unsteady/turbulent flow system? AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

THANKS TO Mark Vercauteren and Keith Barr Lockheed Martin Coherent Technologies Susanne Drechsel, University Innsbruck Alexander Klee, University Innsbruck and DLR T-REX Homepage www. pa. op. dlr. de/trex/ AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

IOP 13, 15 April, 1107 - 1440 UTC animation of aereosol backscatter intensity animation: http: //www. pa. op. dlr. de/trex/filme/2006_04_15_utc 1100_bs. AVI AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006

Dual Doppler analysis on 15 April 1407 UTC 1142 AMS Mountain Meteorology Conference, Santa Fe, 30 August 2006