NCAR Enhanced Boundary Layer NCAR Enhanced Boundary Layer Integrated Sounding System Integrated Sounding System (EBLISS) Observations for VTMX(EBLISS) Observations for VTMX
William Brown, Stephen Cohn, James Pinto, & David Parsons
6th Symposium on Integrated Observing Systems, Orlando, FL, January 2002
National Center for Atmospheric Research (NCAR) Atmospheric Technology Division (ATD)
• Lake breezes
• Blocking by Wasatch
• Canyon drainage flows
• Upstream orography
• Terrain induced eddies and convergence zones
Great Salt Lake
Utah lake
Wasatch Range
The Salt Lake ValleyThe Salt Lake ValleyComplex Flows in Complex TerrainComplex Flows in Complex Terrain
* NCAR site
VTMX VTMX
• 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
Vertical Transport and MiXing Program
• 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
ISS InstrumentsISS Instruments
Southern Valley Site
• MAPR – wind profiler• Surface stations• Rawinsondes (GPS)
ISS Enhancements:ISS Enhancements: TAOS, SABL, SODAR TAOS, SABL, SODAR
SABLbackscatter lidar
TAOSUp to 8 levelswind, P, T, RH
Metek SODARwinds to ~350 m
Oct. 3: Weak Northerly DisturbanceOct. 3: Weak Northerly Disturbance
Useful for observing stable layer behavior
Could see sudden disturbances on clear nights
Rapid increase in aerosol height
SABL:Scanning Aerosol Backscatter Lidar
Oct. 3: Weak Northerly DisturbanceOct. 3: Weak Northerly DisturbanceSoundingSounding Oct 3, 7:02 UT
Sounding shows cool northerly below 500 mOther observations indicate effect isenhanced by narrowing of valley.
Oct. 3: Weak Northerly DisturbanceOct. 3: Weak Northerly DisturbanceTAOSTAOS 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.
Oct. 3: Weak Northerly DisturbanceOct. 3: Weak Northerly DisturbanceSODARSODAR Metek DSDPA.90-24 mini-sodar
Winds similar to TAOS
Vertical motion assoc with disturbance.
Increased reflectivity with disturbed flow mixing.
Oct. 8: Wave activityOct. 8: Wave activitySODAR
Oscillations in SODAR reflectivity & vertical velocity
We often saw waves as the lake breeze (northerly) flow developed.
(Soundings and other observations verify lake breeze)
Oct. 8: Wave activityOct. 8: Wave activitySABL
The lidar also sees waves in aerosol layers.
Some mixing(not dramatic).
Oct. 7: Gap FlowOct. 7: Gap Flow
The SODAR often shows shallow southerly surges overnight.
Note the stronger winds (purple) beginning at 7 Z.
Oct. 7: Gap FlowOct. 7: Gap Flow
Sequence of temperature profiles shows cold air and mixing to 300 m.
0700
0900
0500 UTC
Oct. 7: Gap FlowOct. 7: Gap Flow
MM5:Model Analysis
*NCAR
Oct. 7: Gap FlowOct. 7: Gap FlowMM5 Simulated Low Level Winds
Valid 0300 UTC Valid 0900 UTC
* *
(MM5 simulates northerly surge but overestimates its duration and depthand does not capture intermittency)
Conclusions Conclusions
At VTMX we integrated multiple new sensors into the ISS TAOS and hilltop sfc sensors for low altitudes
SODAR (Metek) for low level windsSABL to observe aerosol mixingWe 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 disturbanceWeak mixing induced by wave activityFrequent gap flow from a basin to the southLake breeze effects from the north