Proposed Predictability, Dynamics & Ensemble Forecasting Expert Team
Richard Swinbank, with Heini Wernli, Masayuki Kyouda and Istvan
Szunyogh,and thanks to other WG members
Joint THORPEX-ICSC & WWRP-JSC meetings, Geneva, July 2013
Contents
Current scope of GIFS-TIGGE and PDP working groups
Proposed new expert team / working group
Scientific linkages between dynamical processes, predictability and ensemble forecasting.
The group’s role within new WWRP structure
TIGGE – Research focus
The TIGGE project (& GIFS-TIGGE working group) was originally focused on the technical work enabling the establishment of the TIGGE archive dataset. The main scientific aspects of THORPEX were covered by Predictability & Dynamical Processes WG, and also Data Assimilation & Observing Systems WG(s).Following the successful establishment of the TIGGE dataset, the 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; combination of ensembles produced by multiple models; research on and development of probabilistic forecast products.
More recently, we have broadened our range of interest to cover improvement of EPSs, including:
representing uncertainties in initial conditions stochastic physics & other techniques to account for model error
PDP group - scope
Since its inception, the PDP working group has covered many aspects of predictability and dynamical processes,
… including the theoretical basis of ensemble forecasting.
The group brings together experts from both academia and operational NWP centres, to accelerate the transfer of cutting-edge science to operational weather forecasting.
It encourages the research community to carry out studies to improve the understanding of the relationship between particular dynamical processes and weather forecast accuracy.
Looking forward -A proposed new working group
The logical evolution of the THORPEX working groups would be the creation of a Predictability Dynamics & Ensemble Forecasting working group, combining elements of the current GIFS-TIGGE and PDP groups.
This new group would provide a centre of scientific expertise on dynamics, predictability and ensemble forecasting that is currently lacking in the core WWRP programme.
Triangular relationship
There are strong links between the three elements of the proposed group
Typhoon Malakas case study
The connections between predictability, dynamics and ensemble forecasting is illustrated by “Predictability of the Tropical Cyclone–Extratropical Flow Interaction Associated with Typhoon Malakas (2010) and Resulting High-Impact Weather Downstream” by Archambault et al (DACA-13)
Typhoon outflow
ET transition at0 UTC 25th Sept
GFS ensemble forecast of Rossby wave train
Ensemble membersEnsemble meanAnalysis
0000 UTC 20 Sep initialization
340-K isentrope on the dynamic tropopause (2-PVU surface)
Verifying 0000 UTC 25 Sep
120-h forecast T+0 h
With thanks to Heather Archambault
GFS ensemble forecast of Rossby wave train
Ensemble membersEnsemble meanAnalysis
0000 UTC 20 Sep initialization
340-K isentrope on the dynamic tropopause (2-PVU surface)
Verifying 0000 UTC 27 Sep
168-h forecast T+48 h
With thanks to Heather Archambault
GFS ensemble forecast of TC–extratropical flow interaction (T+0 h)
Ensemble membersEnsemble meanAnalysis
MSLP of 945 hPa
0000 UTC 20 Sep initialization Verifying 0000 UTC 25 Sep340-K isentrope on the dynamic tropopause (2-PVU surface)
With thanks to Heather Archambault
GFS ensemble forecast of TC–extratropical flow interaction (T+0 h)
Ensemble membersEnsemble meanAnalysis
1000-hPa MSLP contoursTC is too weak and too far
east in forecasts
0000 UTC 20 Sep initialization Verifying 0000 UTC 25 Sep340-K isentrope on the dynamic tropopause (2-PVU surface)
MSLP of 945 hPa
With thanks to Heather Archambault
Ensemble membersEnsemble meanAnalysis
0000 UTC 20 Sep initialization
340-K isentrope on the dynamic tropopause (2-PVU surface)
Verifying 0000 UTC 25 Sep
ECMWF ensemble forecast of Rossby wave train
120-h forecast T+0 h
With thanks to Heather Archambault
Ensemble membersEnsemble meanAnalysis
0000 UTC 20 Sep initialization
340-K isentrope on the dynamic tropopause (2-PVU surface)
Verifying 0000 UTC 27 Sep
ECMWF ensemble forecast of Rossby wave train
168-h forecast T+48 h
With thanks to Heather Archambault
15
WWRP structure and links to WCRP
15
Scope of new Projectsfocused on key “hot spots”
Time scale
S2S
HIW
PPP
WWRP domain
…while expert teams shouldcover the entire domain
Role
Foster scientific research on dynamics, predictability and ensemble forecasting
Support for WWRP projects PPP, S2S, HIW, FDPs, RDPs
Bridge between academic & operational communities Steering development of ensemble prediction
databases (TIGGE and TIGGE-LAM) to support scientific research
Promote use of EPS datasets by the research community
Scientific Scope
Centre of expertise on dynamical processes, predictability and ensemble forecasting.
Understanding & improving probabilistic predictive skill, and its links with dynamical phenomena
Scientific issues include Growth & evolution of errors Stochastic representation of unresolved processes
Covering short- to medium-range forecast timescales (potentially longer)
Relationship with other teams / groups
There are clear linkages with WGNE and other WWRP expert teams. Numerical modelling, Ensembles, Data assimilation, Stochastic parameterization and Evaluation
…are all closely linked on both weather and climate timescales.
Too big for a single expert team or working group – we need a set of more specialised teams…
providing expert support to WWRP projects (S2S, PPP, HIW, RDPs & FDPs)
Other issues
Current GIFS-TIGGE rolesDevelopment of severe weather products
Would fit well into scope of proposed HIW project.Technical management of data archives:
On-going maintenance should be continued through liaison between archive centres & data providers via email;
Management should be overseen by PDEF team. Representative of archive centre on ET.
Current PDP rolesTreatment of systematic model errors
Would be subsumed in WGNE.
Next Steps
Provided that this meeting agrees that the proposed expert team (/working group) is the best way forward…
Approval will be required by CAS (Nov 2013) & WMO-EC (Spring 2014).
Transition arrangements Arrange joint PDP/GIFS-TIGGE meeting in early 2014, to
agree detailed scope & responsibilities of the expert team. Work towards merger of GIFS-TIGGE and PDP groups at end
of 2014 New members of both groups chosen for role in new team.