The use and evaluation of GloFAS for operational flood forecasting GloFAS Map Viewer for TC IDAI 16 th March 2019 Web: http://www.globalfloods.eu Shaun Harrigan, Ervin Zsoter, Lorenzo Alfieri, Christel Prudhomme, Hannah Cloke, Peter Salamon, Elisabeth Stephens, and Florian Pappenberger GFP Annual Meeting, Guangzhou, China 11 th – 13 th June 2019
GloFAS operational chain (supported 24/7 since April 2018) Hydro-met. Initial Conditions - ERA5-T, ENS-Crtl. Meteorological Post-processing Hydrological Web Interface Forecast Forcing - probability of Modelling - visualisation, - ECMWF ENS ( 46r1 ): exceedance at background - Daily 00UTC - HTESSEL, Lisflood different lead time, information - 51 members routing (~10 km) graphs, maps - Extended to 30d LT Input (static) Flood Thresholds Input Datasets - reference discharge Observations reanalysis - topography, soil, river - Satellite and in-situ (GloFASv2-ERA5) network etc. October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 2
New meteorological model cycle (46r1) operational today! Anomaly correlation of 500 hPa Geopotential reaching 85% • Major data assimilation upgrade • Many new products available (e.g. EFI Water Vapour Flux) day • Watch webinars here: 3 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS October 29, 2014
GloFAS upgraded to v2 on 14 November 2018 • A.) Scientific developments: – 1.) Global calibration of Lisflood routing & GW (Hirpa et al., 2018, JoH) – 2.) GloFASv2-ERA5 discharge reanalysis (1981 to NRT) – 3.) Improved initialisation of real-time forecasts (ERA5-T, 2-5 day latency) • B.) User enhancements: – 1.) Version numbering system – 2.) Availability of datasets (reforecasts and reanalysis) ahead of launch date – 3.) More comprehensive documentation (see: http://www.globalfloods.eu/) October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 4
GloFASv2 Evaluation Datasets Datasets GloFASv2 GloFASv1 - 1997-2016 - 1997-2016 - Initialised 2 per wk. - Initialised 2 per wk. from Reforecasts from ERA5 ERA-Interim/L (ECMWF IFS 43r1/43r3) - 11 ens. members - 11 ens. members - Global 0.1° grid - Global 0.1° grid - Calibrated - Not calibrated GloFASv2-ERA5 Discharge reanalysis Not used (1981-2017) Discharge observations Yes Yes October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 5
Forecast performance GloFAS v2 versus v1, w.r.t. obs. v2 performance at 10 day LT as good as v1 at 5 day LT Pearson Correlation Lead time (days) Correlation(ensMean, obs.) 0=None; 1=Perfect October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 6
Overall ensemble forecast skill of GloFASv2 CRPSS Lead time (days) CRPSS = 1 – ( 𝐝𝐬𝐪𝐭_𝐠𝐝)/𝐝𝐬𝐪𝐭_𝐜𝐟𝐨𝐝𝐢 ) (w.r.t. Reanalysis) October 29, 2014 0=No Skill; 1=Perfect skill EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 7
… spatial distribution of skill CRPSS = 1 – ( 𝐝𝐬𝐪𝐭_𝐠𝐝)/𝐝𝐬𝐪𝐭_𝐪𝐟𝐬𝐭𝐪𝐬𝐩𝐜 ) (w.r.t. Reanalysis) 0=No Skill; 1=Perfect skill CRPSS CRPSS 1 day 5 day lead lead CRPSS CRPSS 10 day 30 day lead lead October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 8
Ensemble skill for high flow events (Q10 threshold) 5 day lead Perfect discrimination ROC Area Skill Score ROCSS = 2 × ROCA – 1 (w.r.t. obs.) 0=No Skill; 1=Perfect skill October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 9
CEMS in action during Malawi & Mozambique floods Flood Forecast from GloFAS CEMS Rapping Mapping October 29, 2014 10
Using GloFAS forecasts to aid decision makers • DfID (UK) requested emergency reports to aid response to TC Idai humanitarian disaster • ECMWF, Uni. Reading, Uni. Bristol • TC Idai (7 reports between 21 st and 1 st April): • TC Kenneth (5 reports between 24 th April and 3 rd May) October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 11
Global flood forecast guidance & impact going operational! Aristotle multi-hazard activation Likelihood prepare of impact monitor act High X monitor prepare nil Medium nil nil monitor Low Required Resources Sub- National Inter- national national October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 12
Summary GloFAS Map Viewer: http://www.globalfloods.eu/ 1.) GloFASv2 operational since 14 November 2018 (Datasets freely available 😁 ) 2.) GloFASv2 more skilful than v1 in majority of catchments (extend lead time) 3.) GloFASv2 ensemble forecast evaluation, skilful against persistence + climatology 4.) GloFASv2 skilful during high flow events 5.) Flood forecast guidance & impact going operational at the global scale 6.) The road towards GloFAS 3.0 – Lorenzo Alfieri’s talk tomorrow! Questions? Shaun Harrigan shaun.harrigan@ecmwf.int
Extra slides…
Performance of GloFASv2-ERA5 discharge reanalysis correlation Hydrological performance with KGE mod (Gupta et al., 2009; Kling et al., 2012) bias See Zsoter et al. (2019) JHM! variability KGE mod KGE mod (sim., obs.) 0=No Skill; 1=Perfect skill October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 15
GloFAS Hydrological Model – HTESSEL + LISFLOOD routing • Runoff from 18-km H-TESSEL • 10-km resolution routing module • Calibrated at ~1300 locations using KGE Improvement KGE GloFAS v2 compared with GloFAS v1 (Hirpa et al., 2018, Journal of Hydrology) October 29, 2014
Q3: GloFASv2 Evaluation: Best benchmark to use? Tougher to beat CRPSS = 1 – ( 𝐝𝐬𝐪𝐭_𝐠𝐝)/𝐝𝐬𝐪𝐭_𝐜𝐟𝐨𝐝𝐢 ) (w.r.t. Reanalysis) 0=No Skill; 1=Perfect skill 1 day 10 day 30 day lead lead lead October 29, 2014
GloFAS discharge observations network 20 yr reforecast period (1997-2016) Observations maintained by Joint Research Centre (JRC) [2041 stations with at least 1 data entry] Sources include: GRDC, National Hydro. Met. Services, GloFAS partners] October 29, 2014
Forecast Bias (reanalysis) 1 day 5 day lead lead 10 day 30 day lead lead October 29, 2014 EUROPEAN CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS 19
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