The THORPEX Interactive Grand Global Ensemble (TIGGE)

Richard Swinbank, Zoltan Toth and Philippe Bougeault,

with thanks to the GIFS-TIGGE working group and other colleagues

TIGGE overview

Introduction to TIGGE Objectives The TIGGE archive TIGGE-LAM

Early results based on TIGGE data Intercomparison of ensemble forecasts Use of multi-model ensembles

Towards the Global Interactive Forecast System Implementing THORPEX science

The TIGGE User Workshop What users can learn about TIGGE this week

TIGGEA key component of THORPEX: a World Weather Research Programme to accelerate the improvements in the accuracy of 1-day to 2-week high-impact weather forecasts for the benefit of

humanity

The TIGGE project has developed a database of global ensemble forecasts collected in near real-time.

Objectives: Enhance collaboration on ensemble prediction, both

internationally and between operational centres & universities.

Facilitate research on ensemble prediction methods, especially methods to combine ensembles and to correct systematic errors

Enable evolution towards a prototype operational system, the “Global Interactive Forecast System”

For more about TIGGE, see http://tigge.ecmwf.int

TIGGE infrastructure Data collected in near-

real time (via internet) at central TIGGE data archives

Could be implemented at relatively little cost

Can handle current data volumes (approaching 300 GB/day) within available network and storage capabilities

More information in Baudouin Raoult’s presentation tomorrow

NCAR

EPS 1 EPS 2 EPS n

academic NHMS users

Predictability science

Applications

ECMWF CMA

Summary of TIGGE database

CentreEnsemblemembers

Output dataresolution

Forecastlength

Forecasts per day

Fields (out of 73)

Start date

BOM 33 1.50º x 1.50º 10 day 2 55 3 Sep 07

CMA 15 0.56º x 0.56º 10 day 2 60 15 May 07

CMC 21 1.00º x 1.00º 16 day 2 56 3 Oct 07

CPTEC 15 1.00º x 1.00º 15 day 2 55 1 Feb 08

ECMWF 51N200 (Reduced

Gaussian)N128 after day 10

15 day 2 70 1 Oct 06

JMA 51 1.25º x 1.25º 9 day 1 61 1 Oct 06

KMA 17 1.00º x 1.00º 10 day 2 46 28 Dec 07

Météo-France 11 1.50º x 1.50º 2.5 day 1 62 25 Oct 07

NCEP 21 1.00º x 1.00º 16 day 4 69 5 Mar 07

UKMO 24 1.25º x 0.83º 15 day 2 70 1 Oct 06

TIGGE-LAM: TIGGE for limited-area models

The TIGGE-LAM panel, chaired by Tiziana Paccagnella (ARPA-SIM), supports the development of the Limited Area Model Ensemble Prediction System component of TIGGE. This Panel works in close coordination with the GIFS-TIGGE WG, in liaison with pre-existing LAM EPS initiatives and in coordination with the THORPEX regional committees.Aims:

encourage a coordinated approach to LAM EPS for the mutual benefit of WMO members;

facilitate the interoperability of the different modelling systems contributing to TIGGE;

coordinate the archiving of limited-area ensemble forecasts – the three TIGGE archive centres have agreed to host a sub-set of high priority data;

contribute to the definition of scientific issues related to LAM EPS and particularly to TIGGE-LAM and propose specific initiatives to address these issues to advance LAM EPS.

Early Results from TIGGE

Ensemble forecasts Z500 Spaghetti Diagram

Courtesy Mio Matsueda

Comparison of RPSS N. hem Z500

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ecmwf ukmo jma10 categories, cases 20061201-20070228_N90, area n.hemz at 500hPa (cf_as_an)

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ecmwf ukmo ncep jma10 categories, cases 20070328-20070528_N62, area n.hemz at 500hPa (cf_as_an)

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ecmwf ukmo jma cma bmrc10 categories, cases 20070607-20070831_N84, area n.hemz at 500hPa (cf_as_an)0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

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ecmwf ukmo ncep msc jma cma bmrc kma10 categories, cases 20071002-20071115_N45, area n.hemz at 500hPa (cf_as_an)

DJF07 (90c)

JJA07(84c)

ECMWFUKMONCEPMSCJMA

CMABMRC

KMA

ON07(45c)

AM07(62c)

from Park et al, 2008

Comparison of extra-tropical cyclone tracks

Courtesy Lizzie Froude

Ensemble mean error: Position(verified against ECMWF analyses)

Ensemble mean error – Propagation speed

Propagation speed bias

Comparison of multi-model ensemble with ECMWF

Courtesy

Mio Matsueda

MGCE5110 members from each of 5 centres

MCGE168All 12Z forecasts

MCGE327All forecasts for each day

Multi-model combination: MSLP & T2m

Brier skill-scores of multi-model combination of bias-corrected ECMWF, Met Office and NCEP forecasts.Mean Sea Level Pressure and 500 hPa (not shown) show only small benefits from combining different models2m temperature shows more benefit (1-5 days improvement in lead time)More sophisticated weighting led to only small additional skill

Courtesy Christine Johnson

T2m > mean

MSLP > mean

T2m > 90 %

Similarity of ensembles

betweenS

between MSE

D has small values (high similarity, blue) if the between model variance is small compared to the mean-square-error of the multi-model mean.

mslp temp

D+2

D+10

D+2

D+10

MSEbetween

betweenD

Applications: flood prediction

Predictions with a 5-day lead-time for a flood event on River Jiu in Romania

from Pappenberger et al, 2008

Towards the Global Interactive Forecast System (GIFS)

The objective of the GIFS is to realise the benefits of THORPEX research by improving the delivery of improved forecasts of high-impact weather.

As a first step, the GIFS-TIGGE working group set up a pilot project for the exchange of real-time tropical cyclone predictions using “Cyclone XML” format.

Further plans for the development of GIFS will be presented by Zoltan Toth, and discussed later in the workshop.

The TIGGE User Workshop

Overview of the TIGGE project The TIGGE archive and how to access it:

Presentation during TIGGE-B session, Tuesday afternoon Hands-on user demonstrations in coffee/poster breaks Opportunity for you to tell us what you need

Presentations of early results from TIGGE In TIGGE-A/B/C/D sessions and throughout the symposium.

Plans for GIFS Presentation during TIGGE-C, Thursday afternoon Opportunity to get involved in developing improvements to

operational forecasting of high-impact weather: focus group discussion during Thursday coffee/poster break.

Conclusions Since October 2006, the TIGGE archive has been

accumulating regular ensemble forecasts from leading global NWP centres.

The archive is a tremendous resource for the research community at large, and in particular the science working groups of THORPEX.

TIGGE provides the basis for research and development projects targeted at specific applications of severe weather forecasts (health, energy, flood warning, wind storms, fire weather, etc…).

Products to enhance the prediction of high-impact weather will form the basis of the development of the Global Interactive Forecast System.

TIGGE website: http://tigge.ecmwf.int