Sub-seasonal to seasonal Prediction Project

Index  Background  S2S Planning group  Implementation plan: - Applications - Research and modelling issues - S2S database - Demonstration projects  Possible links with WWRP PPP

Background There is a need to fill the gap between medium-range and seasonal forecasting and link the activities of WCRP and WWRP The WMO Commission of Atmospheric Sciences (CAS) requested at its 15 th session (Nov. 2009) that WCRP, WWRP and THORPEX set up an appropriate collaborative structure for sub-seasonal prediction. WCRP/WWRP/THORPEX workshop at Exeter (1-3 December 2010). A planning group has been formed in 2011 and kick-off meeting in Geneva 2-3 December 2011 An implementation plan has been written to give priority to: - The establishment of collaboration between operational centres undertaking sub- seasonal prediction for consistency and enable the production of databases of sub- seasonal predictions for standard verification procedures and research. -Facilitate the widespread research use of the data collected for CHFP, TIGGE and YOTC for research. - Sponsorship of a few international research activities - Establishment of a series of regular workshops

Sub-seasonal to Seasonal Prediction Planning group Co-Chairs: Frederic Vitart (ECMWF) Andrew Robertson (IRI) Members: Arun Kumar (NCEP) Harry Hendon (CAWCR) Yuhei Takaya (JMA) Hai Lin (EC) Alberto Arribas (UKMO) June-Yi Lee (U. Hawaii) Duane Waliser (JPL NASA) Ben Kirtman (UM RSMAS) Hyun-Kyung Kim (KMA) Liaison group: Carolina Vera (WCRP JSC Liaison) Richard Graham (UKMO, CBS) Jean-Pierre Ceron ( M é t é o-France, CCL) Barbara Brown (JWVGR) Steve Woolnough (GEWEX/GASS) David Anderson (WMO consultant)

Use of sub-seasonal forecasts in applications Growing, and urgent, requirement for the employment of sub-seasonal predictions for a wide range of societal and economic applications which include: Warnings of the likelihood of severe high impact weather (droughts, flooding, wind storms etc.) to help protect life and property Humanitarian Planning and Response to disasters Agriculture particularly in developing countries — e.g. wheat and rice production Disease planning/control — e.g. malaria, dengue and meningitis River-flow — for flood prediction, hydroelectric power generation and reservoir management for example

Opportunity to use information on multiple time scales Red Cross - IRI example

A particularly difficult time range: Is it an atmospheric initial condition problem as medium-range forecasting or is it a boundary condition problem as seasonal forecasting? Some sources of predictability :  Sea surface temperatures  Land surface conditions: snow-soil moisture  The Madden Julian Oscillation  Stratospheric variability  Atmospheric dynamical processes (Rossby wave propagations, weather regimes…)  Sea ice cover –thickness ? Bridging the gap between Climate and weather prediction

Simulation of the impact of the MJO on the NAO Lin et al, 2010

9 Koster et al, GRL 2010 Impact of soil moisture

Impact of snow initial conditions Jeong et al, Jclim 2012

Baldwin and Dunkerton, 2001 Stratospheric influence on the troposphere?

Stratospheric Warming From Harry Hendon

Stratospheric Warming Source: NOAA

Scientific issues Identify sources of predictability at the sub-seasonal to seasonal time-range Prediction of the MJO and its impacts in numerical models Teleconnections - forecasts of opportunity Monsoon prediction Rainfall predictability and extreme events Polar prediction and sea-ice Stratospheric processes

Modelling issues Role of resolution Role of Ocean-atmosphere coupling Systematic errors Initialisation strategies for sub-seasonal prediction Ensemble generation Spread/skill relationship Design of forecast systems Verification

Research priorities The project will involve: evaluating the potential predictability of sub-seasonal events, including identifying windows of opportunity for increased forecast skill. Specific attention will be paid to the risk of extreme weather, including tropical cyclones, droughts, floods, heat waves and the waxing and waning of monsoon precipitation. understanding systematic errors and biases in the sub-seasonal to seasonal forecast range comparing, verifying and testing multi-model combinations from these forecasts and quantifying their uncertainty focussing on some specific extreme event case studies, such as the Russian heat wave of 2010, the Pakistan floods in 2010, Australian floods of 2011, European cold spell in 2012, as demonstration projects

A main recommendations from the Exeter meeting in 2010 was the establishment of a data bases of operational sub- seasonal predictions. 10 years ago, only a couple of operational centres were producing sub-seasonal forecasts. Over the past years, a few GPCs have set sub-seasonal forecasting systems. Numerical models have shown significant improvements in sub-seasonal prediction over the past years (e.g. MJO). Sub-seasonal forecast database

Examples of improvements in MJO prediction

Sub-seasonal real-time Operational Forecasts Time- range Resol.Ens. SizeFreq.HcstsHcst length Hcst FreqHcst Size ECMWFD 0-32T639/319L62512/weekOn the flyPast 18yweekly5 UKMOD 0-60N96L854dailyOn the fly /month3 NCEPD 0-60N126L6416dailyFix daily4 ECD x0.6L4021weeklyOn the flyPast 15yweekly4 CAWCRD 0-120T47L1733weeklyFix /month33 JMAD 0-34T159L6050weeklyFix /month5 KMAD 0-30T106L21203/monthFix /month10 CMAD 0-45T63L16406/monthFix1982-nowmonthly48 CPTECD 0-30T126L281dailyNo--- Meteo- France D 0-60T63L9141monthlyFix monthly11 SAWSD 0-60T42L196monthlyFix monthly6 HMCRD x1.4 L2810monthlyFix monthly10

Proposal for a sub-seasonal database Use TIGGE protocol (GRIB2) for archiving the data. The data should also be available in NETCDF for the WCRP community. Archive daily means of real-time forecasts + reforecasts. Real-time forecasts 3 or 4 weeks behind real-time Variables archived: most of TIGGE variables + ocean variables and stratospheric levels 1.5x1.5 degree grid or lower once a week. Use of the first 2 months of the CHFP seasonal and climate forecasting systems to compare with the archive (above). Need for daily or weekly/pentads archive.

Demonstration projects A few case studies to demonstrate that using sub-seasonal to seasonal predictions could be of benefit to society. Cases studies could include: Pakistan floods (2010) concurrent with the Russian heat wave Australian floods (2009 or 2011) European Cold spell (2011) At least one of the demonstration projects should be in real-time, which is often the best way to foster collaborations between the research and application communities. The models could be archived near real-time during a limited period of time with additional fields being archived. The period chosen could coincide with test bed studies from other projects (e.g. polar project).

22 Precip anomalies : 26 July– 01 August 2010 Sub-seasonal Prediction of Pakistan Floods (2010)

Recent developments The WMO executive council has approved the creation of a sub- seasonal to seasonal prediction project. It also approved the creation of a project office and a trust fund for sub-seasonal to seasonal prediction. The project will last 5 years, starting in 2013 with the option to extend based on a review of progress, achievements and remaining gaps. Next S2S meeting in February: - Finalize the definition of the database - Identify demonstration projects - Plan a workshop on "Sources of predictability at the subseasonal timescale- windows of opportunity for applications"

Possible links with PPP Sub-seasonal to seasonal prediction of sea-ice cover Teleconnections from the polar regions Model errors in the polar regions

UnitAbbrev.Descript Geop. heightgpmghInst. 00Zxxxxxxxxx Spec. humidityKg/kgqInst. 00Zxxxxxx TemperatureKtInst 00Zxxxxxxxxx Um/suInst 00Zxxxxxxxxx Vm/svInst 00Zxxxxxxxxx

UnitAbbreviationDescription Potential vorticity at 320KK m 2 kg -1 s -1 pvInst 00Z 10 metre Um s -1 10uInst 00Z 10 metre Vm s -1 10vInst 00Z CAPEJ kg -1 capeDaily Av. 4x Land-sea maskProportionlsmOnce OrographygpmorogOnce Skin temperatureKsktDaily Av. 4x Snow depth water equivalentkg m -2 sdDaily Av. 4x Snow fall water equivalentkg m -2 sfAccumulated Soil moisturekg m -3 smDaily Av. 4x Surf. Air Max. Temp.KMx2t6Daily Max. Surf. Air. Min. Temp.KMn2t6Daily Min. Surf. Air. Temp.K2tDaily Av. 4x Surf. PressurePaSpDaily Av. 4x Outgoing long-wave radia.W m -2 sttrAccumulated Surface latent heat fluxW m -2 sshlfAccumulated Surface net solar radiationW m -2 sssrAccumulated Surface net thermal radia.W m -2 sstrAccumulated Surface sensible heat fluxW m -2 ssshfAccumulated Total cloud cover%tccDaily Av. 4x Total column waterkg m -2 tcwDaily Av. 4x Total precipitationkg m -2 tpAccumulated Convective Precipitationkg m -2 cpAccumulated North-South surface stressN m -2 snsssAccumulated East-west surface stressN m -2 sewssAccumulated Mean sea-level pressurePamslDaily Av. 4x

UnitAbbreviationDescription Sea surface temperatureKsstk Daily Av. 4x Sea surface salinitypsussts Daily Av. 4x Depth of the 20 deg isoth.m20d Daily Av. 4x Sea ice coverProportionci Daily Av. 4x Heat content top 300mDegrees Ctav300 Daily Av. 4x Salinity in top 300mpsusav300 Daily Av. 4x U surface currentm s -1 u Daily Av. 4x V surface currentm s -1 v Daily Av. 4x Sea surface heightmslDaily Av. 4x