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NCAR Enhanced Boundary Layer Integrated Sounding System (EBLISS) Observations for VTMX

NCAR Enhanced Boundary Layer Integrated Sounding System (EBLISS) Observations for VTMX. William Brown, Stephen Cohn , James Pinto, & David Parsons. National Center for Atmospheric Research (NCAR) Atmospheric Technology Division (ATD).

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NCAR Enhanced Boundary Layer Integrated Sounding System (EBLISS) Observations for VTMX

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  1. NCAR Enhanced Boundary Layer Integrated Sounding System (EBLISS) Observations for VTMX William Brown, Stephen Cohn, James Pinto, & David Parsons National Center for Atmospheric Research (NCAR) Atmospheric Technology Division (ATD) 6th Symposium on Integrated Observing Systems, Orlando, FL, January 2002

  2. The Salt Lake ValleyComplex Flows in Complex Terrain • Lake breezes • Blocking by Wasatch • Canyon drainage flows • Upstream orography • Terrain induced eddies and convergence zones Great Salt Lake Wasatch Range * NCAR site Utah lake

  3. VTMX Vertical Transport and MiXing Program • DOE Funded (Lead: Chris Doran PNNL) • Study stable stratified conditions in urban basins • Development of stable layers, intermittent turb., morning/evening bdy layer transitions • Also goal of advancing measurement systems • 14 Groups including DOE, NOAA, NCAR, Univs. • Nine field sites throughout the Salt Lake City Valley • 6 Wind Profilers, 3 lidars, 200 soundings, aircraft, 6 tether-sondes, sodars, sfc met, and tracer releases

  4. ISS Instruments • Southern Valley Site • MAPR – wind profiler • Surface stations • Rawinsondes (GPS)

  5. ISS Enhancements: TAOS, SABL, SODAR TAOS Up to 8 levels wind, P, T, RH Metek SODAR winds to ~350 m SABL backscatter lidar

  6. Oct. 3: Weak Northerly Disturbance SABL:Scanning Aerosol Backscatter Lidar Useful for observing stable layer behavior Could see sudden disturbances on clear nights Rapid increase in aerosol height

  7. Oct. 3: Weak Northerly Disturbance Sounding Oct 3, 7:02 UT Sounding shows cool northerly below 500 m Other observations indicate effect is enhanced by narrowing of valley.

  8. Oct. 3: Weak Northerly Disturbance TAOS Tethered Atmospheric Observing System 5 Sensor packages Initially, Low levels from S, Upper levels N Shallow northerly surge at 05:37 as disturbance arrives. See 200 m (black) winds.

  9. Oct. 3: Weak Northerly Disturbance SODAR Metek DSDPA.90-24 mini-sodar Winds similar to TAOS Vertical motion assoc with disturbance. Increased reflectivity with disturbed flow mixing.

  10. Oct. 8: Wave activity SODAR Oscillations in SODAR reflectivity & vertical velocity We often saw waves as the lake breeze (northerly) flow developed. (Soundings and other observations verify lake breeze)

  11. Oct. 8: Wave activity SABL The lidar also sees waves in aerosol layers. Some mixing(not dramatic).

  12. Oct. 7: Gap Flow The SODAR often shows shallow southerly surges overnight. Note the stronger winds (purple) beginning at 7 Z.

  13. Oct. 7: Gap Flow Sequence of temperature profiles shows cold air and mixing to 300 m. 0900 0700 0500 UTC

  14. Oct. 7: Gap Flow MM5:Model Analysis NCAR *

  15. Oct. 7: Gap Flow MM5 Simulated Low Level Winds Valid 0300 UTC Valid 0900 UTC * * (MM5 simulates northerly surge but overestimates its duration and depthand does not capture intermittency)

  16. Conclusions At VTMX we integrated multiple new sensors into the ISS TAOS and hilltop sfc sensors for low altitudes SODAR (Metek) for low level winds SABL to observe aerosol mixing We are using a mesoscale model for spatial coverage This suite was much more capable than a standard ISS alone. Examples of Observations Include: Stable layer disruption and mixing by weak disturbance Weak mixing induced by wave activity Frequent gap flow from a basin to the south Lake breeze effects from the north

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