GLASS “LOcal-COupled” Project:“LOCO”

Christa D. Peters-LidardNASA’s Goddard Space Flight Center (GSFC)

Hydrological Sciences Branch

Greenbelt, MD USA

Outline

• Motivation• Strawman Proposal• Case Study Sites

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

BL Feedbacks Change FluxesS

ens

ible

Hea

t Flu

x (W

m-2)

Fro

m M

OS

AIC

Mo

de

l

0

600 UncoupledCoupled 1-D PBL

1-3 AUG 1998, (58N,130W)

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

History

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

et al.

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)”

N

Case Study 1: Southern Great Plains ’97 Experiment (SGP97)

SGP ’97 Tethersonde OpsPeters-Lidard and Davis, JHM, 2000

0700-1100: < 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 >10m/s

Launch

Frequency

Dates

Vertical Spatial

Resolution

Sampling Interval

Notes

Sample Data for 6/22/97 (Julian Day 173)

0

50

100

150

200

250

300

350

400

8 9 10 11 12 13 14

Specific Humidity (g/kg)

Heigh

t AGL

(m)

Tethersonde@1207 Radiosonde@1126 Tethersonde@1235

Sample Data for 6/22/97 (Julian Day 173)

0

50

100

150

200

250

300

350

400

292 294 296 298 300 302 304

Potential Temperature (K)

Heigh

t AGL

(m)

Tethersonde@1207 Radiosonde@1126 Tethersonde@1235

Potential Temperature () Specific Humidity (q)Tethersonde@1207 Tethersonde@1207Tethersonde@1235 Tethersonde@1235Radiosonde@1126Radiosonde@1126

Morning Transition6/22/97 (Day 173)

Stable surface layer profile

Moisture advection due

to GP LLJ

Mixed Layer Analysis:Identifies “Non-Local” Effects

)1(''

A

z

xu

tw

Entrainment Parameter, A

July 5 H Predictions; A=0.2

-200

-100

0

100

200

300

400

500

600

700

0000 0600 1200 1800 2400

Time (GM T)

Sen

sibl

e H

eat

Flu

x, H

(W

/m2 )

Average Surface ECOR

GSFC/U ofA Surface ECOR

ARM/CA RT Surface ECOR

Twin Otter Aircraft

Long EZ Aircraft

Conservation A verage; Ar=0.2

SGP ’97 H Predictions; A=0.2

-200

-100

0

100

200

300

400

500

600

700

-200 -100 0 100 200 300 400 500 600 700

Measured Sensible Heat Flux, H (W/m2)

Pre

dict

ed S

ensi

ble

Hea

t F

lux,

H (

W/m

2 )

H (Direct-TR)

H (Direct-RR)

H (Swiatek)

H (None)

1:1

(a)

RMS (W/m2)

52

321

Bias (W/m2)

-15

-150

H

LE*

*Advection of moisture (presumably by LLJ)

SGP ’97 Flux Prediction Statistics

Case Study 2: Washita ’941-D Boundary Layer Model

MM5/GSPBL/KF/TOPLATS

N

8/18: Wet Day, Strongly Forced

SLAB TOPLATSOBS

N

SLAB

8/23: Dry Day: Weakly Forced

TOPLATSOBS

IBL Can Affect Entire PBLS

ens

ible

Hea

t Flu

x (W

m-2)

TOPLATSMM5-SLAB

0

500

1000

1500

2000

2500

3000

0 5 10 15

Hour in Simulation (from 1200 Z, Aug 23, 1994)

PB

L H

eig

ht

(m A

GL

)

Zpbl-TOPLATSZpbl-SLABObserved

350

Case Study 3: Ozone Exceedance Houston/Galveston, Texas, USA

Case Study: August, 1998

Case Study: August, 1998

Case Study: August, 1998

Case Study: August, 1998

Cloud Initiation:Sea-breeze FrontMM5/TOPLATS MM5/SLAB

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