Transcript The THORPEX Interactive Global Ensemble (TIGGE) and development of a future Global Interactive Forecast System (GIFS) GIFS-TIGGE WG report for WWRP JSC4 Richard Swinbank, with thanks.

The THORPEX Interactive Global Ensemble
(TIGGE)
and development of a future
Global 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)
Centre
Ensemble
members
Output data
resolution
Forecast
length
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
51
N200 (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 Usage
150
10000
120
1000
90
Volume (GB)
100000
100
60
10
30
1
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Month
Aug
Sep
Oct
Nov
Dec
Number of Users (Count)
(NCAR
+ ECMWF)
2010 TIGGE Archive Usage (All
Portals)
Vol Accessed (GB)
Vol Delivered (GB)
# Active Users
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 data
Highlights:
 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
Single model ensembles
Multimodel ensemble
 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
Jonathan Flowerdew, Met Office
Probability verification
- idealised calibration
Single model ensembles




Multimodel ensemble
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
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, 300360E)
 Split into three clusters S, M,
N using K-means clustering

X t  arg min Ut  U i
i S ,M , N

 Transition probability defined:
PA B ( )  P  X t   B X t  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
Blocking frequency comparison (DJF)
+5 days
+9 days
+15 days
Matsueda
(2009)
The state-of-the-art NWP models simulate the blocking frequency well.
But models still underestimate the (extreme) blocking frequency.
MJO Forecast comparison
- 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.
Matsueda and Endo (2011, in prep.)
Tropical cyclone forecasts –
ensemble spread contradictions
ECMWF
NCEP
initiated at 12UTC 10
Sep. 2008
Sinlaku
(50 members)
Japan
Black line: Best track
at 00UTC 13 Dec.
2008
Grey lines: Ensemble
member
Dolphin initiated
(20 members)
Munehiko Yamaguchi
Philippines
Taiwan
Asymmetric
propagation
vector
Does not spread with time
Steering
vector
NCEP
Spread grows with time
T+48h
T+0h
ECMWF
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
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)
23
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
 GIFS will use globalregional-national cascade
pioneered by the WMO
Severe Weather Forecast
Demonstration Project
(SWFDP). No single
“GIFS centre”.
In-Situ
Observations
EPS1
EPS2
Satellite
Observations
EPS3
Generate
Products
 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.
Airborne
Observations
Regional
Centre
National
Centre
users
National
Centre
users
users
National
Centre
users
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 interactions
GIFS development project interactions
SERA group
Joint Working Group
on Verification
GIFS-TIGGE
Working group
SWFDP
Southern Africa
Other THORPEX
and WWRP
WGs
GIFS-DP
THORPEX
Regional
committees
NW Pacific TC
Project
Future subprojects
Other pilot projects
Operational
forecast
community
Research
community
SW Pacific
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