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PILPS Update & Proposal

Ann Henderson-SellersANSTO Environmentand Andy PitmanMacquarie UniversitySydney, Australia

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PILPS Update August 2003• Arctic basin: ACSYS/PILPS

– completed with 17 papers in Special Issue of Global & Planetary Change (August 2003)

• Tropical forests: PILPS1(c) – still contributing to publs. (e.g. H-S & Pitman, 2002, BAMS)

• Frozen soil and snow: PILPS 2(d)– generating publications & prompting questions

• Luo et al. 2003, J Hydromet. (Valdai analysis)

• Coupled PILPS/AMIP II DSP12– LSS clusters and importance of LSSs in coupled

models now demonstrated

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PILPS - still learning from off-line

• Carbon fluxes: PILPS C1– going very well; possible introduction to carbon

isotopes

• Arid environments: PILPS San Pedro– workshop this week (Bastidas & Gupta)

• Isotopes in GLASS: IPILPS– proposal to be tabled today focuses on:

• Stable water isotopes• Carbon isotopes

• When do these updates go on the GLASS web page?

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PILPS Update - Highlights

• Chronological sequence in LSSs– ‘simple’ schemes; SiBlings; current generation

• Classes of carbon parameterisation– Rapid equilibrium of NPP & early CO2 sinks

– Gradual NPP increase & net CO2 sink zero early

• LSSs behave differently with different GCMs– Choice of LSS matters to climate prediction

• VIC is a better surrogate for ‘truth’ than re-analyses for evaporation at least

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• Chronological sequence in LSSs– ‘simple’ schemes; SiBlings; current generation

Which group is ‘best’????

PILPS - still learning from off-line

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Land-surface Energy Partition

• Energy budgets of 20 models (A-T) & 3 reanalyses

Latent Heat Flux W m-2

Scatter along diagonal shows differences in partitioning surface available energy

Scatter around diagonal due to predictions of different values of surface available energy

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LSS Clusters in All Climates

Buckets; SiBlings; latest LSSScaled latent heat W m-2

Sca

led

sens

ible

hea

t W

m-2

SEBs normalised by ensemble of 3 re-analyses –

SiBlings

Buckets

3 clustersSiBlings

Buckets

SiBlings

Buckets

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• Chronological sequence in LSSs– ‘simple’ schemes; SiBlings; current generation

• LSSs behave differently with different GCMs– Choice of LSS matters to climate prediction

Coupling does not eliminate characteristics or impacts of LSSs

PILPS - Off-line Links to GLACE

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Spatio-temporal Correlation

• Climate trajectories differ for SiBlings & buckets

• LH improves from Arid (worst) to E. Humid (best)

Bucket

SiBling

• SH flows the other way

• Bucket (O) SH v. small & low variability

Bucket

SiBling

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Atm

osp

her

ic fo

rcin

g fr

om

AM

IP A

GC

Ms

Pseudo Land-surface Schemes• Derived a PLSS for every

AMIP II model (A-T): columns

LH

Amazon

Mississippi

Mackenzie

• Apply in 3 basins: Amazon, Mississippi, Mackenzie

• Forced by all AGCMs: rows • Find:

– Agreement on main diagonal• PLSSs do a good job

– Range for different forcings• LSSs respond to different AGCMs

– ‘avg’ forcing is close to reported values

• mean = good estmt.

}}

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Pseudo Land-surface Schemes

• Ranking predicted LHs

Atm

osp

her

ic fo

rcin

g fr

om

AM

IP A

GC

Ms

RankIrannejad et al., GRL 2003

• Stripes show LSSs often dominate over atmospheric forcing– in three diverse

regimes: Amazon, Mississippi, Mackenzie

– for 20 different AMIP II models and land-surface schemes

Amazon

Mississippi

Mackenzie

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PILPS Update - Highlights

• Chronological sequence in LSSs– ‘simple’ schemes; SiBlings; current generation

• LSSs behave differently with different GCMs– Choice of LSS matters to climate prediction

• VIC is a better surrogate for ‘truth’ than re-analyses

Generally, all known data have been (over) used for parameterisation – need new!

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VIC Best “Truth” for E/P Ratios

Mississippi

BALTEX

Murray Darling

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VIC

VICObs

Obs

AMIP modelsmajor basins

VIC closeswater budgets& best at E/P

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Evaluating LSS Performance

SiBlings best cf. VIC

VIC

Intermediateclimates -reanalyses and current LSSs closely grouped

Irannejad et al. 2003 find VIC is best surrogate for truth

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Isotopes in PILPS : IPILPS

• Stable and radioactive isotopes are valuable for both tracing and dating

• Stable water isotope measurements – Demonstrated that the Amazon recycles its

water (3 or 4 times)– Prompted early GCM deforestation experiments

(e.g. Henderson-Sellers & Gornitz, 1984)

• Carbon isotopes differentiate C3 and C4 photosynthesis

• Off-line (PILPS) inter-comparison is timely e.g.– “Heavy” water (HD16O & H2

18O) at the land surface– River routing schemes tested against GNIR – the Global

Network for Isotopes in Rivers

Gibson et al., EOS December 2002

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Recycling Small 18O Gradient

Gradient ~ 1.5‰ per 103 km cf. 2.0‰ for Europe

BelemManaus

Porto Velo

Sao Gabriel

Izobamba

1980s

1960s GNIP

H-S, McGuffie & Zhang, J. Clim., 2002, 15, 2664

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Basin Isotope Modelling

• Isotopes provide an independent climate and water resource validation tool

H-S, Stone, McGuffie etc GRL, 2003,

Manaus

Enhanced D/H ratio

Darling

• Weakened signal in central Amazon (Manaus) indicates increased water recycling

• Logarithmic enhancement in Darling reveals irrigation impacts

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Darling River 2002-3 Drought

Burtundy

WilcanniaWilcannia

MenindieMenindie

BourkeBourke

GunnedahGunnedah

CollarenabriCollarenabri

WalgettWalgett

0

10

20

30

40

50

60

1 3 5 7 9 11 13

delta O-18

del

ta D

Jan 2002Jan 2002

Jul 2002Jul 2002

Jan 2003Jan 2003

18O and Dmeasured in 2002-3 drought

Tracing a non-linear relation

Sydney

Melbourne

Brisbane

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IPILPS: New Data & Results

Belem

Belem, Amazon

Precip

Vapour

D

18O

New isotopic data from Belem

Simulations with ISOLSM

Sim

ula

ted

18

O

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Precip

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IPILPS Science & Timeline • QUESTION: Are the stores and fluxes of two different

“heavy” water isotopes (HD16O & H218O) correctly

characterised at the land surface?• TIMELINE:

– August 2003: Approval by GLASS Panel– September/October 2003:

• Quality control of the available isotopic & met./hydro. data

– November/December 2003: • Experimental framework described and agreed

• Water isotopes only or plus carbon isotopes?

– January/February 2004: Call for participation to all current & past PILPS & AMIP II DSP 12

– April/May 2004: First workshop (possibly in Vienna)– December 2004: Publication of results