The THORPEX Interactive Global Ensemble (TIGGE)

and development of a futureGlobal Interactive Forecast System (GIFS)

GIFS-TIGGE WG report for WWRP JSC4

Richard Swinbank, with thanks to Zoltan Toth,

the GIFS-TIGGE working group, THORPEX IPO and other colleagues

TIGGE and GIFS

TIGGE Objectives TIGGE archive status TIGGE-LAM

Research using TIGGE data Publications Calibration & combination of ensemble forecasts Predictability & dynamical processes

GIFS developments Developing links with CBS/SWFDP Examples of tropical cyclone forecast products

TIGGE THORPEX Interactive Grand Global Ensemble

A major 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

GEO task WE-06-03 – “TIGGE and the Development of a Global Interactive Forecast System for Weather”

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”

TIGGE data Ten of the leading global forecast centres are providing regular

ensemble predictions to support research on predictability, dynamical processes and development of probabilistic forecasting methods.

TIGGE data is made available for research after a 48-hour delay. Near real-time access may be granted for specific projects through the THORPEX International Project Office.

Summary of TIGGE database (late 2010)

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

MSC 21 0.9º x 0.9º 16 day 2 56 3 Oct 07

CPTEC 15 0.94º x 0.94º 15 day 2 55 1 Feb 08

ECMWF 51N200 (Reduced

Gaussian)N128 after day 10

15 day 2 70 1 Oct 06

JMA 51 0.56º x 0.56º 9 day 1 61 1 Oct 06

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

Météo-France 35 1.50º x 1.50º 4.5 day 2 62 25 Oct 07

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

UKMO 24 0.83º x 0.55º 15 day 2 72 1 Oct 06

* Delivery of KMA & BoM data currently suspended

TIGGE Archive Usage2010 TIGGE Archive Usage (All Portals)

1

10

100

1000

10000

100000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Volu

me

(GB)

0

30

60

90

120

150

Num

ber o

f Use

rs (C

ount

)

Vol Accessed (GB)

Vol Delivered (GB)

# Active Users

(NCAR + ECMWF)

TIGGE-LAM: TIGGE for limited-area models

The TIGGE-LAM panel, chaired by Tiziana Paccagnella (ARPA-SIM), supports the coordinated 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.The panel facilitates the interoperability of the different modelling systems contributing to TIGGE and coordinates the archiving of limited-area ensemble forecasts – the three TIGGE archive centres have agreed to host a sub-set of high priority dataHighlights:

The TIGGE LAM Panel is being restructured in Regional sub-groups to give more emphasis to the regional component of TIGGE LAM and to facilitate the focus on regional activities. European, North America and Asia sub-groups have already been formed.

The TIGGE-LAM plan is close to being finalised, and the draft version is available from the TIGGE-LAM website http://www.smr.arpa.emr.it/tiggelam/.

See Tiziana’s talk for more details

Publicising TIGGE

Major Article in BAMS

New leaflet to publicise TIGGE to researchers

Contribution to GEO book “Crafting Geoinformation”

Tropical cyclone case study in WMO Bulletin

Update of TIGGE website

TIGGE Research

Following the successful establishment of the TIGGE dataset, the main focus of the GIFS-TIGGE working group has shifted towards research on ensemble forecasting. Particular topics of interest include:

a posteriori calibration of ensemble forecasts (bias correction, downscaling, etc.);

combination of ensembles produced by multiple models; research on and development of probabilistic forecast

products.

TIGGE data is also invaluable as a resource for a wide range of research projects, for example on dynamical processes and predictability. Up to the end of 2010, 43 articles related to TIGGE have been published in the scientific literature

Multi-model ensemble forecasts of T850

Demonstrates benefit of multi-model ensemble, provided that the most skilful models are used.

Renate Hagedorn, ECMWF

Multi-model ensemble compared with reforecast calibration

Reforecast calibration gives comparable benefit to multi-model ensemble

Choice of verification data set (in this case, ERA-Interim) could have subtle but significant effect on relative benefits

Calibration could further enhance benefit of multi-model ensemble

Renate Hagedorn

Uncalibrated precipitation forecasts Probabilistic verification

Based on ECMWF, UKMO, NCEP, 12 hour accumulations, 2 years data (autumn 2007 - autumn 2009) for UK region.

Verified against UKPP composite data; thresholds taken from one-month 5x5 gridpoint ukpp climatologies

Multimodel (pfconcat) has consistent slight advantage over single model ensembles in resolution (solid) and reliability penalty (dotted)

The overall Brier Skill Score (resolution-reliability) is negative for long lead times and high thresholds

Single model ensembles Multimodel ensemble

Jonathan Flowerdew, Met Office

Probability verification- idealised calibration

Use model climatology for forecast thresholds Provides upper bound on benefit from calibration Increases BSS resolution and reduces reliability penalty Multi-model ensemble remains superior

Single model ensembles Multimodel ensemble

Jonathan Flowerdew, Met Office

Precipitation forecasts over USA

24 hour accumulations, data from 1 July 2010 to 31 October 2010.

20 members each from ECMWF, NCEP, UK Met Office, Canadian Meteorological Centre.

80-member, equally weighted, multi-model ensemble verified as well.

Verification follows Hamill and Juras (QJ, Oct 2006) to avoid over-estimating skill due to variations in climatology.

Conclusions:

ECMWF generally most skillful.

Multi-model beats all.

Tom Hamill

Forecasts of cyclone tracks

Jana Čampa, Heini Wernli

North Atlantic eddy-driven jet “regimes”

North Atlantic eddy-driven jet profile is taken as vertically/zonally averaged low-level zonal wind in North Atlantic sector (15-75N, 300-360E)

Split into three clusters S, M, N using K-means clustering

Transition probability defined:

, ,

arg min it ti S M N

X U U

( )A B t tP P X B X A

Tom Frame, John Methven, U. Reading

Brier Skill Score: regime transition probabilities

3 years of TIGGE data for ONDJF (2007-2010), ECMWF, UKMO, MSC

Matsueda (2009)

The state-of-the-art NWP models simulate the blocking frequency well.But models still underestimate the (extreme) blocking frequency.

+5 days

+9 days

+15 days

Blocking frequency comparison (DJF)

Matsueda and Endo (2011, in prep.)

- ECMWF and UKMO have a superior performance in simulating MJO.

- Predicted phase speed tends to be slower than observed one.

- Predicted amplitude tends to be larger than observed one.

MJO Forecast comparison

ECMWF (50 members)

Sin

laku

in

itia

ted

at 1

2UT

C 1

0 Se

p. 2

008

Dol

phin

init

iate

d at

00U

TC

13

Dec

. 20

08

Japan

Philippines

Taiwan

NCEP (20 members)

Black line: Best track

Grey lines: Ensemble member

Munehiko Yamaguchi

Tropical cyclone forecasts – ensemble spread contradictions

ECMWF NCEP

T+

0hT

+48

h

Sp

read

gro

ws

wit

h ti

me

Doe

s n

ot s

pre

ad w

ith

tim

e

SV-based perturbations better capture:• Baroclinic energy conversion within a vortex• Baroclinic energy conversion associated with mid-latitude

waves• Barotropic energy conversion within a vortex

Munehiko Yamaguchi

Steering vector

Asymmetric propagation

vector

23

Comparisons of TC track forecasts NOAA developing EnKF for eventual operational use in hybrid EnKF/variational

data assimilation system. Early June 2010 through end of October 2010; verification against “best track”

information. Out-performs NCEP operational - differences are statistically significant. Also compares well with ECMWF (not shown)

Tom Hamill

Towards the Global Interactive Forecast System (GIFS)

Many weather forecast situations are low probability but high risk – unlikely but potentially catastrophic. Probabilistic forecasting is a powerful tool to improve early warning of high-impact events.

The objective of the GIFS is to realise the benefits of THORPEX research by developing and evaluating probabilistic products to deliver 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.

GIFS concept

EPS1 EPS2 EPS3

Generate Products

Regional Centre

users

National Centre

National Centre

National Centre

users usersusers

In-SituObservations

AirborneObservations

Satellite Observations

GIFS will use global-regional-national cascade pioneered by the WMO Severe Weather Forecast Demonstration Project (SWFDP). No single “GIFS centre”.

Further development and evaluation of products will be done in conjunction with SWFDP and other regional pilot projects.

Use of web-enabled technology for generation and distribution of products.

GIFS development

GIFS-TIGGE WG has initiated a GIFS development project

Develop products, based on TIGGE ensembles, focused on forecasts of Tropical cyclones Heavy precipitation Strong winds

Collaborate with WMO Severe Weather Forecast Demonstration Project (SWFDP) and other FDPs and RDPs to provide an environment for the evaluation of prototype products, and to ensure that products address needs of operational forecasters and end users.

GIFS development project interactionsGIFS development project interactions

GIFS-DP

SWFDP

Southern Africa

SW Pacific

Future subprojectsNW Pacific TCProject

Other pilot projects

Joint Working Groupon Verification

GIFS-TIGGEWorking group

THORPEX Regional

committees

Research community

Operational forecast

community

Other THORPEX and WWRP

WGs

SERA group

Tropical cyclone products from MRI/JMA http://tparc.mri-jma.go.jp/cyclone/

New tropical cyclone product:Strike probability time-series at a city

Tetsuo Nakazawa

Summary 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.

Both multi-model combination of ensemble forecasts and calibration techniques can be used to enhance probabilistic forecast skill.

As the basis of the development of the future Global Interactive Forecast System, products are being developed to enhance the prediction of high-impact weather, starting with tropical cyclones.

GIFS products will be developed & evaluated in conjunction with SWFDP and other regional projects.

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