Dr' Christa D' PetersLidard

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GLASS LOcal-COupled ProjectLOCO

• Christa D. Peters-Lidard
• NASAs Goddard Space Flight Center (GSFC)
• Hydrological Sciences Branch
• Greenbelt, MD USA

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Outline

• Motivation
• Strawman Proposal
• Case Study Sites

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Motivation

• Quantify surface/boundary layer feedbacks on
  surface fluxes and states (Strength of the
  coupling)
• Assess need for surface/boundary layer feedbacks
  in land surface data assimilation
• Examine propagation of sub-grid land surface
  heterogeneity

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BL Feedbacks Change Fluxes
Uncoupled
600
Coupled 1-D PBL
Sensible Heat Flux (Wm-2) From MOSAIC Model
0
1-3 AUG 1998, (58N,130W)
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LSMs Operate on Patches

• Type A (Shuttleworth, 1988) patches generate
  Internal Boundary Layers which Blend above a
  certain height (e.g., Blyth et al., 1993)
• Blending height a function of patch size L

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History

• Workshop in De Bilt, Apr 2002.
• Summary by Bart van den Hurk et al.

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Strawman Proposal LOCO

• Phase 1 Synthetic column extract column
  boundary conditions from model
• Phase 2 Past Field Campaigns
• PILPS sites Cabauw, FIFE, Boreas, others?
• GABLS sites which?
• Others SGP/ARM/IHOP, LBA, Wangara, others?
• Phase 3 Future Field Campaigns
• Upcoming Sites HEAT (Houston, TX)-Urban
  others?
• New Site(s) Design local coupled testbed(s)

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Case Study 1 Southern Great Plains 97
Experiment (SGP97)
N
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SGP 97 Tethersonde OpsPeters-Lidard and Davis,
JHM, 2000
0700-1100 lt 1 hr 1230-1700 1.5
hrs 6/18,19,22,25-29 7/2-6,14-16 2-5 m 10
s No wind gt10m/s
Launch Frequency Dates Vertical
Spatial Resolution Sampling Interval Notes
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Morning Transition6/22/97 (Day 173)
Potential Temperature (q)
Specific Humidity (q)
Tethersonde_at_1207
Tethersonde_at_1207
Tethersonde_at_1235
Radiosonde_at_1126
Radiosonde_at_1126
Tethersonde_at_1235
Moisture advection due to GP LLJ
Stable surface layer profile
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Mixed Layer AnalysisIdentifies Non-Local
Effects
Entrainment Parameter, A
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July 5 H Predictions A0.2
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SGP 97 H Predictions A0.2
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SGP 97 Flux Prediction Statistics
RMS (W/m2) 52 321
Bias (W/m2) -15 -150
H LE Advection of moisture (presumably by
LLJ)
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Case Study 2 Washita 941-D Boundary Layer
Model MM5/GSPBL/KF/TOPLATS
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8/18 Wet Day, Strongly Forced
SLAB
TOPLATS
OBS
N
17
8/23 Dry Day Weakly Forced
SLAB
TOPLATS
OBS
N
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IBL Can Affect Entire PBL
TOPLATS
MM5-SLAB
350
Sensible Heat Flux (Wm-2)
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Case Study 3 Ozone Exceedance
Houston/Galveston, Texas, USA
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Case Study August, 1998
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Case Study August, 1998
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Case Study August, 1998
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Case Study August, 1998
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Cloud InitiationSea-breeze Front
MM5/TOPLATS
MM5/SLAB
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Conclusions

• Non-local effects such as LLJ, clouds and
  sea-breeze fronts violate local assumptions,
  esp. humidity profiles
• Disaggregation of fluxes/states to patch level
  requires parameterization of IBL/PBL
• Coupled BL-LS feedbacks important