© Crown copyright Met Office DIurnal cycle Coupling Experiment (DICE) GLASS / GASS joint project Martin Best and Adrian Lock presented by Ayrton Zadra.

© Crown copyright Met Office

DIurnal cycle Coupling Experiment(DICE)

GLASS / GASS joint project

Martin Best and Adrian Lock presented by Ayrton Zadra

© Crown copyright Met Office Courtesy of Mike Ek


GLACE “hotspot” regions

Koster et al (2006)

• areas with significant coupling between precip and evaporation• derived from 12 GCM model which showed various coupling

strengths (bar graphs)• differences in coupling strength are not well known

GLACE = Global Land-Atmosphere Coupling Experiment


Outline of the 3 stages of DICE

LSM and SCM stand-alone performance against observations

What is the impact of coupling?

How sensitive are different LSM and SCM to variations in forcing?

SCM = Single Column ModelLSM = Land Surface Model


• A challenging surface?

• October grass was largely dead

• Rain in September left soil moist

• Excessive evaporation a feature of the first round of DICE (later on)

Google streetview

Courtesy of Joan Cuxart

CASES-99CASES-99 case studycase study

23-26 October 199923-26 October 1999

• Field experiment in Kansas, USA

• We follow Steeneveld et al. (2006)

• 3 day simulation from 2pm local time on 23rd October 1999

• Recall GABLS II ran for from 2pm on 22nd for 2.5 days

• Clear skies throughout

• Gives 3 nights of varying character

• intermittent turbulence

• continuous turbulence

• very stable, almost no turbulent fluxes


Experimental protocol

LSM •Soil spin-up:

• 9 years from saturated using WATCH forcing data

• 10th year forcing data from local site

•Two stage 1a experiments with forcing (obs) from 2m and 55m

•Stage 3a LSM experiments forced with stage 1b SCM data interpolated to 20

SCM

•Large-scale forcing:

• Time-varying geostrophic wind (uniform with height)

• Large-scale horizontal advective tendencies for T, q, u, v estimated from a simple budget analysis of the sondes

• Subsidence for T, q

• No relaxation

• Radiation switched on in all simulations

•SCM in stage 1b use observed sensible and latent heat fluxes and u* (either directly or via cD)

•Stage 3b SCM experiments forced with stage 1a LSM surface fluxes


15 Participating Models

Model Contact Institute Levels Sensitivity tests

Arome & Arpege (NWP)

Eric Bazile Meteo France 60/70 Resolution, soil

Arpege (CMIP5) Isabelle Beau Meteo France

ECEARTH Reinder Ronda, Bert Holtslag Wageningen

University91

GDPS3.0 Ayrton Zadra CMC 79 Surface properties

GFDL Sergey Malyshev, Kirsten Findell Princeton/GFDL 24

GISS_E2 Ann Fridlind, Andy Ackerman GISS 40

WRF (IAP) Bingcheng Wan IAP 119

IFS/HTESSEL Irina Sandu, Gianpaolo Balsamo ECMWF 137 LAI

LMDZ, ORCHIDEE

Sonia Ait-Mesbah, Marie-Pierre Lefebvre, Frederique Cheruy

LMD 70

MESO_NH Maria Jimenez, Patrick LeMoigne, Joan Cuxart IMEDEA, Meteo

France, UIB85 Bare soil

UM/JULES Adrian Lock, Martin Best Met Office 70 Vegetation

NCEP Weizhong Zheng,

Mike Ek

NOAA 65 z0

WRF-NOAH Wenyan Huang, Xinyong Shen, Weiguo Wang

NUIST 60 Many

WRF Wayne Angevine NOAA 119 PBL scheme

CAM5, CLM4 David Lawrence, Ben Sanderson NCAR 26

SCM grids• Solid lines = control model

• Dotted/dashed lines = experiment

• Lowest grid-levels range from 1.5m to 85m

Grid thickness ΔZ (m)

Hei

gh

t Z

(m

)


Highlights fromstages 1 and 2


Stage 1aSurface fluxes from 55m-forced LSMs

Round 1 data

Round 2 data

Remember these will be the SCM surface fluxes in Stage 3b

Not all LSM provided u*(not compulsory under ALMA convention)

SHF

LHF

U*

Obs


Stage 1b near-surface evolution SCM driven by observed surface fluxes

20m 55m

θ55mθ20m

q55m

RH55m

q20m

RH20m

x = obs


Stage 1b vs 2Bulk PBL sensitivity (variables at 55m)

• More spread between coupled models in stage 2 than stand-alone SCM in stage 1b

• More degrees of freedom• Moisture more sensitive than temperature?

θ55m

q55m

Stage 2

θ55m

q55m

Stage 1bx = obs


Stage 1b vs 2Bulk PBL depth (H) sensitivity• Some suggestion that PBL depth is less sensitive

when coupled (especially in the evening)

Stage 1b

Stage 2

PBL depth calculated as whereRiB=0.25

x = obs

H

H


Stage 1a vs 2Surface fluxes

• Similar surface fluxes from LSMs when coupled to their SCM, despite differences in atmospheric moisture

• to be confirmed from stage 3a

Selected stage 1a

wθ

wq

Stage 2

wθ

wq

--- obs


Stage 1a (55m)

Coupling and winds

x --- obs

u*

U @ 200m

U @ 200m

u* U @ 10m

Stage 1b

Stage 2

Stage 2

Stage 2


Stage 3aSurface flux sensitivities


Stage 3a – Qe (latent heat flux)

0 – CMC

1 – GFDL

2 – GISS

3 – IAP

4 – LMD

5 – NCEP

6 – NUIST

7 – SURFEX (default)

8 – SURFEX (root)

9 – WRF

10 – ECMWF (leaf)

11 – ECMWF (default)

12 – MetO

23rd 24th 25th

24th 25th

Nig

htD

ay


Stage 3a – Ustar (friction velocity)

0 – CMC

1 – GFDL

2 – GISS

3 – IAP

4 – LMD

5 – NCEP

6 – NUIST


8 – SURFEX (root)

9 – WRF

10 – ECMWF (leaf)


12 – MetO

23rd 24th 25th

24th 25th

Nig

htD

ay


Stage 3bDaytime sensitivities


Stage 3b daytime sensitivities

• All models have more variability in the PBL moisture than temperature

24th and 25th 24th and 25thθ300m q300m

SCM # SCM #


Stage 3b temperature sensitivity to SHF

Typically weak correlation between daytime PBL temperature and surface sensible heat flux

SHF

θ300m

24th

25th


Stage 3b moisture sensitivity to LHF

Much stronger correlation between daytime PBL moisture and surface latent heat flux

LHF

q300m

24th

25th


Stage 3b sensitivities: PBL depth

• Some models have much greater sensitivity in PBL depth than others

24th and 25th

SCM #

PBL depth


Does PBL depth depend on surface buoyancy flux?

In most models, yes

H24th

25th

θv flux


Stage 3bNighttime sensitivities


Stable boundary layer

• As in daytime, more spread in moisture than temperature

23rd, 24th and 25th 23rd, 24th and 25th



• More negative SHF generally implies colder 50m temperature

• Heat lost to surface



• Larger u* implies warmer 50m temperature on 24th

• More turbulent SBL with more mixing of heat downwards


DICE: summary so far

• Simple case (clear skies, no precipitation, homogeneous surface) but still a challenge for models

• Climatalogical vegetation in LSMs can lead to large errors in evaporation

• This dominated any signal of the impact of coupling in first round

• Second round those LSMs that needed to constrained evaporation (adjusting LAI, root depth, bare soil behaviour)

• Further discussion/developments are required to establish the best way to improve models

• Early results indicate interesting differences in different models’ sensitivity to changes in forcing that are likely to be important in GCMs and need to be understood

• Recent DICE discussions took place at the GEWEX conference, July 2014:

• Planned reruns: additional data from stage 1a, revised stage 3b forcing data

• Papers:

• Martin Best and Adrian Lock to write up intercomparison (overview paper plus two separate papers on LSM and SCM analyses, respectively)

• Special issue (eg BLM): to include participants' own analyses, model sensitivities, etc

More details at http://appconv.metoffice.com/dice/dice.html


Merci !


Stage 3a – LWnet (net longwave radiation)

0 – CMC

1 – GFDL

2 – GISS

3 – IAP

4 – LMD

5 – NCEP

6 – NUIST


8 – SURFEX (root)

9 – WRF

10 – ECMWF (leaf)


12 – MetO

23rd 24th 25th

24th 25th

Nig

htD

ay


Stage 3a – Qh (sensible heat flux)

0 – CMC

1 – GFDL

2 – GISS

3 – IAP

4 – LMD

5 – NCEP

6 – NUIST


8 – SURFEX (root)

9 – WRF

10 – ECMWF (leaf)


12 – MetO

23rd 24th 25th

24th 25th

Nig

htD

ay


Stage 3a – Qg (ground heat flux)

0 – CMC

1 – GFDL

2 – GISS

3 – IAP

4 – LMD

5 – NCEP

6 – NUIST


8 – SURFEX (root)

9 – WRF

10 – ECMWF (leaf)


12 – MetO

23rd 24th 25th

24th 25th

Nig

htD

ay


Daytime sensitivity: θ profiles

θ25th Oct 14:00 CDT14 SCMs


Daytime sensitivity: q profiles

q25th Oct 14:00 CDT14 SCMs


Variability in entrainment buoyancy flux

• Why the discrepancy?

• Aent<0 implies BL warming less than expected from surface heating

• Need to look more into these budgets!

Expected value ~ 0.2

sfv

zv

entw

wA i

''

''


Not really!

Does PBL depth depend on Evaporation Fraction?

H

EF

24th25th


Entrainment sensitivity

• Estimate entrainment fluxes from PBL θv budget

Average over the boundary layer:

Rearranging gives:v

i Sz

ww

t i

surfv

zv

v

''''

vS

z

w

tvv

''

1''''

''

v

i Stw

z

w

wA v

surfv

i

sfv

zv

ent

Horizontal advection and radiation (~small)• I’m ignoring vertical advection


Stage 1b vs 2Entrainment (Aent) sensitivity to coupling

• Wide range of entrainment fluxes, Aent~0 to 0.5

Stage 1b

Stage 2

sfv

zv

entw

wA i

''

''

Calculated from PBL budget



• More negative SHF generally implies colder 50m temperature

• Heat lost to surface



• Larger u* implies warmer 50m temperature on 24th

• More turbulent SBL with more mixing of heat downwards

© Crown copyright Met Office DIurnal cycle Coupling Experiment (DICE) GLASS / GASS joint project Martin Best and Adrian Lock presented by Ayrton Zadra.

Documents

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land surface model slide

simulations scm

lsm experiments

lsm surface fluxes