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