Image structures: rain shafts, cold pools, gusts Separate rain fall velocity from air velocity...

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Transcript of Image structures: rain shafts, cold pools, gusts Separate rain fall velocity from air velocity...

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image structures: rain shafts, cold pools, gustsSeparate rain fall velocity from air velocityturbulence retrieval microphysical retrievalDiurnal and MJO composite statisticsrainfrequency and typecloud and subcloud turbulenceshallow cumulus cloud top heights

3-mm W-band Doppler radarmotion-stabilized 0.5 degreesO2 deck view2-m HRDL High-resolution Doppler lidarRevelle cloud and boundary layerDoppler remote sensing

Simon de Szoeke, Alan Brewer, Chris Fairall 01020Shallow PPIHigh PPIShallow RHIZenithminutesHRDL lidar scanningBoth instruments sample features in the atmosphere as they pass over.Mean winds, turbulence, and spatially/temporally evolving wind fieldMotion stabilized Doppler radial/vertical velocities.

6 kmrangeW-band cloud radarContinuously points at zenith2

Revelle cloud and boundary layerDoppler remote sensing

Simon de Szoeke, Alan Brewer, Chris Fairall HRDL and W-band cloud radar measure rain and clear air velocities:coherent fronts and flowsturbulenceSeparate rain fall velocity from air velocityPinsky et al. (2010) air velocity retrievalcloud and subcloud turbulenceCombine with areal precipitation statistics from TOGA C-band radar.composite over MJO convective & suppressed events

NOAA W-band cloud radarOctober 19 hour (UTC)

Kelvin-HelmholtzbillowsDoppler width (m/s)Doppler velocity anomaly (m/s)Stratiform precipitationhas steady fall velocity.makes air velocity visible to radar.DYNAMO has ~100 hours of stratiform rain.Example of generation of turbulence by short-lived shear-driven Kelvin-Helmholtz instability. Billows show alternating billow vertical velocities around 3 km.(Not shown, shear and velocity variance is observed by the ISS wind profiler at this level and time.)4imaging fronts with radar and lidar

radar vertical velocity Processing shows Nyquist-unwrapping and subtracting stratiform rain fall speed.lidar horizontal velocitiesSpatial sampling by lidar RHI and PPI scans show the front passing over the ship in radial Doppler velocity and backscatter retrievals.lidar RHIlidar PPIradar verticalABBBAAsee Alan Brewers talk and poster3D structure of fronts and cold pools links mesoscale convection to boundary layer structures and surface in situ observations.5

Doppler velocity anomaly (m/s) use to diagnose turbulence

f5/3vertical velocity turbulence spectraheight (km)S2 (m2 s1)and we can diagnose turbulence from the vertical velocity spectrum of remotely sensed velocities at many levels of the atmosphere.(Bump of spectral energy at 5-10s period is primarily at higher levels; so Simon suspects it may be due to wave/ship motion affecting the pointing angle of the radar beam. Yet wave frequencies are observed in the true air motion sometimes.)6