Doppler Lidar Studies of ComplexTerrain and StableBoundaryLayer Flows

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Doppler Lidar Studies of Complex-Terrain and
Stable-Boundary-Layer Flows Robert M. Banta1,
Lisa S. Darby1, and Yelena L. Pichugina ,
1Environmental Technology Lab/NOAA, Boulder,
Colorado
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Spatial Variability and Time Dependence of the
Wipptal Shallow Foehn Event On 30 Oct.
99 Robert M. Banta1, Louisa B. Nance2 , Lisa S.
Darby1 , 1 Environmental Technology Lab/NOAA,
Boulder, Colorado 2 Cooperative Institute for
Research in the Environmental
Science, Boulder, Colorado, USA
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Types of analysis

• Vertical slice
• Vertical structure
• Dimensions, wavelength, depths peak speed (/-)
• Analysis profiles of mean wind, fluctuations
• Azimuth scans
• Horizontal structure, dimensions, variability
  (assess representativeness of vertical slises)
• VAD analysis (mean, turbulence quantities)
• 3-D volumes (stepped el or az scans)
• Animation of repeated scans-dramatically enhance
  interpretation capability

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Innsbruck
Brenner Pass
Foehn Flow
Cloud
Clean region
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Innsbruck
Brenner Pass
Foehn Flow
Cloud
Clean region
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Concluding Remarks How much complexity can you
handle?
losing essence
appropriate simplification
ltunderstandinggt ltimportantgt
analytical? H yes v Pb no x

• We found
• wavelike structure upstream of lidar layers
  evolve in time
• a symmetric momentum structure downstream
• Usual Suspects
• changing upstream profiles (some what) finescale
• 3-D topography
• history of evolution
• interactions with (changing) ambient winds
• Typically ignore!
• Detail compeleteness of MAP dataset-relax some
  simplifications

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SALT LAKE CITY
SALT LAKE VALLEY
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THERMALLY FORCED BASIN SCALE FLOWS IN SALT LAKE
VALLEY
Daytime - flow up basin
Nighttime - flow down basin
Nocturnal canyon outflows, slope flows penetrate
into basin
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Along-Basin Flow Component in Salt Lake Basin
(VTMX)
Nighttime down basin
On nights with small large-scale pressure diff,
flow reverses from daytime up basin to nighttime
down basin
diff between IOP7 and IOP10 no transition on
IOP10 no period of light flow
Daytime up basin
large-scale ? pressure
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Tracer Distribution during VTMX/Urban2000 (Times
MST)
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Doppler lidar (TEA CO2)
High-resolution RAMS simulation (J. Fast) PNNL
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Salt Lake City VTMX, Urban 2000 Results

• Down-basin jet, local slope/valley flows
• Behavior of tracer distribution depends on
  evolution of flow in whole basin, history
• Model (RAMS) runs under ideal circumstances
  amazingly detailed results
• Timing, layering, some details in horizontal
  still not accurately represented
• Thanks to Dr. Jerry Allwine (tracer) Dr. Jerome
  Fast
• (RAMS results)

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SBL Turbulence and Transport

• Why SBL? review
• Daytime vs. Nighttime
• At night poor mixing
• Sfc meas. not representative of structure aloft
• Layering in vert. patches, streams, blobs in
  horiz.
• Accommodating enemy? (active when models work ok)
  probably not
• So problem
• SBL poorly understood ( not well repr. by sfc
  meas)
• SBL poorly represented in phys. of NWP models
  resolution myth

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SBL Turbulence and Transport

• Overall Objectives
• Understand processes controlling turbc,
• fluxes in SBL
• Begin to develop parameterizations for NWP
• Study processes affecting dispersion in
• urban setting VTMX example
• Develop 4DDA adjoint retrieval
• techniques for HRDL important tool

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• Objectives and Approach
• Approach
• Use analyses of CASES-99 High-Resolution Doppler
  Lidar (HRDL) and 60-m tower data
• SBL Objectives
• to determine LLJ properties
• relationship of turbc, fluxes to LLJ
  properties
• to use HRDL data to show periods of high ur2
  on
• case-study nights
• relationship of tower TKE, fluxes to HRDL ur'2
• case studies plus general results using entire
  data set

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200 m
0
0
1
2
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• Role of LLJ in controlling fluxes
• nocturnal LLJ after sunset
• LLJ accel. Shear Turbc
• Hi turbc Hi turb fluxes
• Turb fluxes of momentum, heat, moisture
  critical for
• NWP associated fluxes of airborne
  contaminants
• important for applications
• Upside-down BL (L. Mahrt) not well
  represented in NWP models

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Key LLJ Measurements - characteristics of
jet max
Z

• peak speed
• height
• direction, any directional shear
• structure of waves / turbc below max
• - is effective mixing taking place?
• (DD? cf. chem)
• - over how deep a layer?
• stability (d?/dz)

Zmax

?U/?Z
Umax
U
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Richardson Numbers

• Gradient Ri
• Ri (g/?)(d?/dz) / (du/dz)2
• Jet or Bulk RiJ
• RiJ (g/?)(d?/dz) / (UX/ZX)2

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• Findings
• (HRDL measurements have shown...)
• Stronger LLJ's tend to be higher
• but some LLJ's lower than 100 m
• Turbc assoc with shear zone below LLJ related
  to
• LLJ properties (speed, height, ... RiJ)
• Periods when tower TKE, fluxes high -
  correlated with high horizontal velocity
  variance measured by HRDL
• ? Study published in journal (Bound-Layer
  Meteor., 105, 221-252, 2002.)
• ? Several case studies also published

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SBL Turbulence and Transport

• Principal Results, Deliverables, and DoD
  Contacts
• Progress in understanding relationship between
  LLJ and subjet turbulence
• Progress in understanding roles of features
  (density currents, K-H packets, topog. flows) in
  vertical fluxes
• Journal articles, Conf. papers see list
• Reported at Wkshp on Army-Scale Meteor. (Jon
  Mercurio, Dennis Garvey, Bob Dumais, et al.),
  Walter Bach

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SBL Turbulence and Transport

• Future Plans and Deliverables
• Develop more robust relationships between LLJ
  props and turb fluxes recommend
  parameterizations
• Quantify HRDL u2 relat. to tower TKE, variances
• Publish VTMX tracer results
• Reports, journal articles, conf. papers