1. The Sub-seasonal to Seasonal (S2S) Prediction Project
“Bridging the gap between weather and climate”
Co-chairs:
Frédéric Vitart (ECMWF)
Andrew Robertson (IRI) 1

2. Mission Statement
“To improve forecast skill and understanding on the sub-seasonal to seasonal timescale with special emphasis on high-impact weather events”
“To promote the initiative’s uptake by operational centres and exploitation by the applications community”
“To capitalize on the expertise of the weather and climate research communities to address issues of importance to the Global Framework for Climate Services”

3. Sub-Projects S2S Database
Sub-seasonal to Seasonal (S2S) Prediction Project
Interactions and teleconnections between midlatitudes and tropics
Madden-Julian Oscillation
Monsoons
Sub-Projects
Africa
Extremes
Verification
Research Issues
Predictability
Teleconnection
O-A Coupling
Scale interactions
Physical processes
Modelling Issues
Initialisation
Ensemble generation
Resolution
O-A Coupling
Systematic errors
Multi-model combination
Needs & Applications
Liaison with SERA
(Working Group on Societal and Economic Research Applications)
S2S Database

4. Conferences/Education outreach
June 2015: 3-day workshop on Sub-seasonal to seasonal predictability of monsoons (Jeju, Republic of Korea)
April 2016: 3-day workshop co-organized with MJO-TF on intra-seasonal processes and prediction in the Maritime Continent. Singapore
Nov, 2015: 2 week training course at ICTP (Trieste, Italy) for young scientists from developing countries

5. S2S Database

6. S2S Database Daily real-time forecasts + re-forecasts
3 weeks behind real-time
Common grid (1.5x1.5 degree)
Variables archived: about 80 variables including ocean variables, stratospheric levels and soil moisture and temperature

7. Contributing Centres to S2S database
Data provider (11)
Archiving centre (2)
ECMWF EC
UKMO
HMCR
KMA
NCEP
Météo
France
JMA
ISAC
CMA
BoM

8. S2S partners Time-range Resol. Ens. Size Freq. Hcsts Hcst length
Hcst Freq
Hcst Size
ECMWF
D 0-46
T639/319L91 51
2/week
On the fly
Past 20y
2/weekly 11
UKMO
D 0-60
N216L85 4
daily
4/month 3
NCEP
D 0-44
N126L64
4/daily
Fix 1 EC
D 0-32
0.6x0.6L40 21
weekly
CAWCR
T47L17 33
6/month
JMA
D 0-34
T319L60 25
3/month 5
KMA
CMA
D 0-45
T106L40
CNRM
T255L91
Weekly
2/monthly 15
CNR-ISAC
0.75x0.56 L54 40
HMCR
D 0-63
1.1x1.4 L28 20 10

10. S2S Database current status
Open access to researchers from ECMWF (since May 2015) and CMA (since Nov 2015). Subset of data also available from IRI. Data from nine data providers:
ECMWF, NCEP, JMA, BoM, CMA, Météo-France, HMCR, ISAC and UKMO
Total size of the database: 37.7 Tbytes:
real-time: 5 Tbytes
re-forecast: 32.6 TBytes
Plans
End of 2016: all 11 Data Providers
Add new ocean sub-surface and sea-ice variables
Compute and archive indices such as MJO RMMS, SSW index, Weather regimes, Tropical storm tracks, Monsoon indices to be available for the research community from ECMWF and IRI servers.

11. Use of the S2S database Since May 2015
454 registered users from 65 countries at ECMWF
139 register users mostly from China at CMA
ECMWF Server

12. ECMWF S2S server statistics

13. Linkage with CBS S2S database WMO users
A major goal of S2S is to support CBS operational sub-seasonal activities
Research into sub-seasonal predictability under S2S will be conducted in close liaison with developing infrastructure and procedure for operational sub-seasonal prediction as they develop under CBS.]
It has been proposed to use the S2S database to exchange real-time data for CBS activities.
S2S database
Near rt data
+ rfcsts
lead centre
WMO users
Subset
in near real-time
S2S data portal (3-weeks behind RT)
S2S producing
centres
Research and application community

14. S2S sub-projects

15. MJO Subproject MJO and Maritime Continent (MC) Interactions:
Evaluating State of the Art & Characterizing Shortcomings
In collaboration with the WGNE MJO Task Force
Major Objectives:
Assess current model simulation fidelity and prediction forecast skill over the MC across time scales, with emphasis on the MJO, and identify and rectify model biases.
What roles do: 1) multi-scale interactions, 2) topography and land-sea contrast, and 3) ocean/land-atmosphere coupling play in the MC-MJO interaction and how do they influence predictability over the MC.
Modeling Resources to Exploit
1) S2S Database, 2) MJOTF-GASS Multi-Model Exp and 3) ISVHE
Future Field Campaign
Year of Maritime Continent (YMC) is a multi-nation effort to carry out a field campaign in investigating multi-scale weather/climate processes over the MC.
Workshop
Spring 2016 MC Workshop, Singapore – sponsored by S2S and MJOTF.
Nexus of 1) land, atmosphere & ocean interactions and 2) multi-scale interactions: diurnal, mesoscale, synoptic, subseasonal, seasonal & interannual.

16. Scientific Organization
Workshop on Intraseasonal Processes and Prediction in the Maritime Continent
11-13 April 2016 in Singapore
Local Sponsor & Host
Scientific Organization
Invitation Only Workshop : Over 50 Participants
Assess and advance understanding of MJO-MC interactions with the intention of improving subseasonal prediction in the MC and globally.
Session 1: Interactions of the MJO in the MC Region with the Diurnal Cycle
Session 2: Interactions of the MJO in the MC Region with Synoptic Variability, the Monsoons, and Interannual Variability
Session 3: Interactions of the MJO in the MC Region with the Ocean
Session 4: Interactions of the MJO in the MC Region with the Land
Sessions 5 & 6: Model Simulations of Subseasonal Variability in the MC Region
Summary for S2S Newsletter In Preparation

17. Workshop on Intraseasonal Processes and Prediction in the Maritime Continent
Local Sponsors: Meteorological Service Singapore and National Environment Agency: Ms. Chin Ling Wong (Director-General), Chris Gordon (CCRS Director), Chloe Lim, Krysania Tan
Local Organizing Committee: Chris Gordon (CCRS), Teo Chee Kiat (Nanyang Technological U), Tieh- Yong Koh (SIM University), Krysania Tan (CCRS)
International Organizing Committee: Tieh-Yong Koh (Nanyang Technological Univ), Eric Maloney (Colorado State Univ), Tetsuo Nakazawa (S2S ICO), Andrew Robertson (IRI), Frederic Vitart (ECMWF), Duane Waliser (NASA JPL), Steve Woolnough (U. Reading), Chidong Zhang (U of Miami)

18. Africa sub-project Main Goal
To develop skilful forecasts on the S2S time scale over Africa and to encourage their uptake by national meteorological services and other stakeholder groups.
Objectives:
Assess the performance of forecasts for 5-40 days ahead using the S2S forecast archive, with focus on rain-day frequency, heavy rainfall events, dry spells and monsoon onset/cessation dates, with relevance to agriculture, water resources and public health.
Develop metrics for measuring the success of forecasts in ways that are useful for farmers and other stakeholder communities.
Improve understanding of the climate modes that drive sub-seasonal variability in Africa and their representations in models.
The Africa sub-project will work with post-Africa Climate Conference 2013 framework (recently named “Climate Research for Development CR4D)” to connect international with African climate communities. An S2S activity is envisaged to be one of the first CR4D pilot activities, through a joint CR4D-S2S proposal to Future Earth program funding.

19. Monsoon sub-project Major Objectives: Updates: .
Development of a set of scientifically and societally relevant intra-seasonal forecast products and metrics that are applicable to all the major monsoon systems which can be monitored with operational real-time forecast systems.
Case studies of predictability of monsoon onsets
Updates:
Sponsored workshop on S2S Predictability of Monsoons in Jeju Korea June 2015
Demonstration project for prediction of active/break episodes of Australian summer monsoon published (Marshall and Hendon 2015), which can be applied to other monsoons: developed simple rainfall and circulation indices that can be monitored with observations (served on S2S-subproject web page) and verified with forecasts, quantified observed and simulated role for MJO, assessed depiction of active/break cycles and verified forecast skill from one model in S2S archive, estimated potential forecast improvement due to improved prediction of the MJO
Initiated contact with the new Asian-Australian Monsoon and American Monsoon Task Teams (under WCRP-Monsoon Panel) to lead similar study for other monsoons .

20. Monsoon sub-project

21. Extreme weather sub-project
Major Objectives:
Evaluate the predictive skill and predictability of weather regimes and extreme events (droughts, floodings, heat and cold waves)
Assess the benefit of multi-model forecasting for extreme events
Improve understanding of the modulation of extreme weather events by climate modes.
Sub-seasonal prediction of tropical storms
Case studies selected for the strong societal impact
A case study already completed: March 2013 cold wave over Europe. Next cases will includes will include intense tropical cyclone Pam and intra-seasonal variability of precipitation over the US west coast during the 2015 El-Niño event.

22. Tropical Cyclone Pam case study
Multi-model prediction of TC strike probability anomalies March 2015
(NCEP/ECMWF/BoM/JMA/CMA)
2015/02/19 day 19-25
2015/02/26 day 12-18
PAM case study: Tropical cyclone strike (within 300 km) probability anomaly (relative to model climatology) for the forecasts starting on 19 February 2015 (left panel) and 26 February 2016 (right panel) and verifying on 9-15 March During the 9-15 March 2015, Pam, the strongest tropical cyclone of the season, hit Vanuatu (black dot on the map) with devastating consequences.
The multi-model forecasts (combination of NCEP/ECMWF/BoM/JMA and CMA) shows an increased risk of tropical storm strike in the area of Vanuatu at both time ranges.
In fact the anomaly map is consistent with the impact of an MJO event (in this case it was the strongest MJO event on record) on TC density. During the week the MJO active phase was over the west Pacific, which is consistent with less TC activity over the Indian ocean and more TC activity over the western pacific, and the possibility of twin TC genesis (over the northern and Southern hemisphere). The model seems able to predict the increased risk of a twin TC.

23. Modulation of tropical cyclone density anomaly by MJO
MJO Phase 2-3
MJO Phase 4-5
MJO Phase 6-7
MJO Phase 8-1
OBS
ECMWF
NCEP
JMA
BoM
Modulation of TC activity by the MJO. The plots show the anomaly of TC density as a function of MJO phase for 5 different S2S models and the multi-model combination for the time range day The figure shows a remarkable agreement with observations and suggest that all the model simulate very well the modulation of TCs by the MJO. This is an encouraging result for TC prediction
Multi

24. Regimes based on clustering of daily anomalies for 29 cold seasons (1980-2008)
500 hPa geopotential
Obtain well-known Euro-Atlantic regime patterns
The low frequency variability in European temperatures have been often associated with the frequency of occurrence of these well-known Euro-Atlantic flow regimes.
The positive and negative phase of the North Atlantic oscillation the Scandinavian blocking and the Atlantic ridge.
The large spatial scale and the low-frequency nature of such flow patterns are the key attributes for successful predictions at the sub-seasonal time-scale. In fact, circulation patterns like the NAO are often associated with global teleconnections through propagation of Rossby wave trains.
‘k means’ clustering applied to EOF pre-filtered data (retaining 80% of variance)
m2s2

25. Predicting skill associated with the Euro-Atlantic Regimes:
NAO -
NAO +
Bom
Bom
Blocking
Atlantic Ridge
Bom
Bom
Ens. Meand anomaly correlation as a function of forecast lead time for the prediction of the 4 EA regimes.
The scores are computed for the common period of reforecast covering 12 years ( ) we have applied a 5 days running mean prior the Acc computation.
The ACC for NAO- drops below 0.5 between days while for the BL ACC drops about 2-3 days earlier (9-12 days for BL) this results is consistent with other studies.
From L. Ferranti

26. S2S sub-project on verification (and products)
Objectives:
Recommend verification metrics and datasets for assessing forecast quality of S2S forecasts
Provide guidance for a potential centralized effort for comparing forecast quality of different S2S forecast systems, including the comparison of multi-model and individual forecast systems and consider linkages with users and applications
Issues to be addressed:
Identification of current practises in sub-seasonal to seasonal forecasts
Identification of user-relevant variables and quantities to be verified
Provision of guidance on minimum hindcast standards (hindcast length and ensemble size)
Promotion of subseasonal forecasting intercomparison efforts and evaluation of benefit of multi-model approach
Links with WMO Joint Working Group on Forecast Verification Research (JWGFVR), WMO CBS/CCl ET-OPSLS, WMO LC-LRFMME and other S2S sub-projects

27. S2S sub-project on verification (and products)
Website:
Science plan developed with inputs from JWGFVR, SERA and S2S: projects/Verification.pdf
Current activities and plans:
Questionnaire on subseasonal verification practices in operational centers prepared and sent to Global Operational Centers, with the purpose sharing current practices used to verify subseasonal forecasts (both for operations and research) and also help identify gaps and guide novel developments. Results discussed with WMO CBS/CCl ET-OPSLS
Literature survey on S2S verification posted on the sub-project webpage
S2S is now included in the JWGFVR user-oriented verification challenge
Plans for establishing verification of sub-seasonal and longer range forecasts as a theme for the 7th International Verification Methods Workshop (IVMW) organized by the JWGFVR, Berlin in May 2017, and promote a S2S verification and climate metrics session in this workshop
Science plan: Guidance document to stimulate scientific community to address S2S verification problems

28. Teleconnections (Cristiana Stan and Hai Lin)
Better understand and predict sub-seasonal tropical-extratropical interaction pathways
Year of Tropics-Midlatitude
Interactions and Teleconnections
YTMIT
mid 2017-mid 2019
Virtual
Field
Campaign
Description
Intense coordinated effort involving existing observational data, forecasts and applications, diagnostics, theory and modeling experiments
Mission
Foster relationships between research, forecasting, and stakeholder communities, and facilitate the sharing of common interests to explore the links between the tropics and midlatitudes for a better prediction skill at intraseasonal time scales
Research Questions
Are mid-latitude teleconnections from the fluctuating tropical heating fundamentally just time-lagged stationary wave responses to heating, or does time-dependent wave interference play a role?
Why are the North Atlantic weather regimes so influenced by MJO-related heating in the distant Indian and Pacific Oceans?
What is the role of synoptic-scale transients?
Is the impact of extra-tropical forcing associated primarily with the initiation of tropical convection, or can it organize tropical convection of intraseasonal time scale?
What is the role of PV streamers?
Subseasonal-to-Seasonal
Prediction Project

29. Year of Tropics-Midlatitude Interactions and Teleconnections
Mechanistic Experiments
Mechanisms
Better understand and predict sub-seasonal tropical-extratropical interaction pathways
Year of Tropics-Midlatitude
Interactions and Teleconnections
Prediction Centers
YTMIT
mid 2017-mid 2019
Virtual
Field
Campaign
Tropical-Midlatitude Interactions
processes
Satellite Products
Diagnostics
case studies
theory
&
Reanalysis Products
S2S DB & NMME
analysis
calibration
(re)forecast
new variables
Subseasonal-to-Seasonal
Prediction Project
teleconnections

30. The virtual field campaign
YTMIT
Ongoing Activities
Review paper to be submitted to Review of Geophysics
Workshops:
Title: Large-Scale Intra-Seasonal Diabatic Heating Variability in the Tropics and Monsoon Regions: Multi-Scale Interactions and Teleconnections
Date: June, 6-7, 2016
Venue: George Mason University
Sponsor: ONR
Title: Systematic Error
Date: June 19-23, 2017
Venue: Montreal, Canada
Sponsor: WGNE
AGU Fall Meeting 2016 Session (proposed)
ICTP School (proposed)
Date: 2017
Sponsors: ICTP, WWRP/WCRP/S2S
Overview
The virtual field campaign
Ongoing activities

31. Linkage with WGNE
A strong link is already established with the WGNE MJO task Force.
Other joint project discussed at previous WGNE meetings:
Representation of teleconnections in dynamical models
Joint session on teleconnections at the next Systematic Errors Workshop (2017)?

32. MJO Teleconnections (S2S re-forecasts)
Z500 anomalies 10 days after an MJO in Phase 3
Analysis
ECMWF
JMA
NCEP
CAWCR
CNRM EC

33. MJO Diagnostics

34. Bivariate Correlation with ERA Interim – Ensemble Mean
re-forecasts - ALL YEAR

36. Amplitude error relative to ERA Interim

37. Spread/RMS error relationship - 2015
ECMWF
BoM
NCEP

38. Spread/RMS Error relationship – PC1 and PC2 - RT
ECMWF 51 members
WEEK1
WEEK2
WEEK3
WEEK4
BoM 33 members

39. MJO impacts
MJO-NAO teleconnection: modulates significant wave height in NE Atlantic
Marshall et al. 2015