Norwegian Meteorological Institute met.no LAMEPS – Limited area ensemble forecasting in Norway, using targeted EPS Marit Helene Jensen, Inger-Lise Frogner, Trond Iversen and Ole Vignes

Norwegian Meteorological Institute met.no Limited area ensemble forecasting in Norway - outline Ensembles using Norways operational version of the HIRLAM model – LAMEPS Perturbing initial state and lateral boundary conditions with a dedicated version of EPS from ECMWF - TEPS Combining these two systems gives NORLAMEPS Main focus is precipitation, especially extreme precipitation events Running storm surge from EPS,TEPS and LAMEPS

Norwegian Meteorological Institute met.no TEPS – Targeted EPS A dedicated version of ECMWF EPS. – ensemble members, as opposed to for EPS –Target area Northern Europe and adjacent sea areas, as opposed to NH north of 30°N –Starts at 12 UTC every day –Runs to +72h, as opposed to +240h for EPS T255L40(~80 km), Since Feb 1st: T399L62(~55 km)

Norwegian Meteorological Institute met.no LAMEPS HIRLAM in ensemble set-up Quasi-operational at met.no since 14 February members + Control, –Control based on Norwegian HIRLAM analysis –20 Initial and open boundary perturbations from TEPS –Starts at 18UTC every day (fresh HIRLAM analysis), i.e. a 6 hour delay compared to TEPS and EPS –Forecast Range: +60h Resolution: 0.2 deg (20km), 40 levels

Norwegian Meteorological Institute met.no NORLAMEPS Combines simply IFS TEPS and HIRLAM LAMEPS A simple multi-model, multi-initial-state ensemble ensemble members

Norwegian Meteorological Institute met.no Verification area Target area for TEPS SVs Integration area HIRLAM

Norwegian Meteorological Institute met.no Generation of perturbations Running TEPS to +72h members 12 UTC TEPS is automatically transferred to met.no TEPS is made ready to run in the Norwegian model environment TEPS is transferred to Trondheim Generation of HIRLAM perturbations LAMEPS running 18 UTC, to +60h Results from LAMEPS transferred back to met.no Generation of products for users/customers ~02 UTC ~22 UTC 50 minutes ECMWF

Norwegian Meteorological Institute met.no LAMEPS Precip, Reliability diagrams, percentiles - precip 70% 80% 95%90% Norw. synop sites Sep05-April06

Norwegian Meteorological Institute met.no Wind +24 LAMEPS Reliability diagrams, percentiles - wind 70% 95% 90% 80% Norw. synop sites Sep05-April06

Norwegian Meteorological Institute met.no Verification of Precip. Verify precipitation against super-observations. (Ghelli and Lalaurette): –All precipitation sites in Norway inside the verification area are aggregated using the method of Kriging Distribution of precipitation in Norway is dominated by sharp gradients –We verify in sub-regions with grossly different precipitation climatology separately. –Inside each sub-region precipitation climatology is fairly uniform

Norwegian Meteorological Institute met.no 1 West 2 East 3 North Average annual precipitation amounts in Norway from 1961 – 90 (mm).

Norwegian Meteorological Institute met.no Reliability diagrams, 20mm, 60h NORLAMEPS TEPS Annual Feb05-Feb06 EPS LAMEPS

Norwegian Meteorological Institute met.no BRIER SKILL SCORE all three regions Annual Feb05-Feb06

Norwegian Meteorological Institute met.no ROC and Value(C/L), all three regions 5 mm/24h LAMEPS TEPS EPS NORLAMEPS Annual Feb05-Feb06

Norwegian Meteorological Institute met.no LAMEPS TEPS EPS NORLAMEPS ROC and Value(C/L), all three regions 20 mm/24h Annual Feb05-Feb06

Norwegian Meteorological Institute met.no Area under ROC-curve all three regions Annual Feb05-Feb06

Norwegian Meteorological Institute met.no PRECIP. Rms error and bias error of control forecast Jan.-April 2006

Norwegian Meteorological Institute met.no Spread around ensemble mean (Jan-Apr 2006)

Norwegian Meteorological Institute met.no 100 year precipitation event in the middle part of Norway January 2006 >90mm/24h 130mm/24h

Norwegian Meteorological Institute met.no LAMEPS P24 > 50mm TEPS P24 > 50mm +12h - +36h +18h - +42h

Norwegian Meteorological Institute met.no LAMEPS P24 > 60mm TEPS P24 > 60mm

Norwegian Meteorological Institute met.no Future developments Contribute to HIRLAM Ensemble Predictions (GLAMEPS) Include perturbations of model physics in LAMEPS Increase the time resolution of the boundary fields (now every 6 hour) Develop a range of probability products Compute meso-scale initial perturbations in HIRLAM- domain Increase resolution (0.1 degrees or finer) Non-hydrostatic downscaling

Norwegian Meteorological Institute met.no Test LAMEPS on a new configuration for TEPS A system that combines targeted SVs and hemispheric SVs (Martin Leutbecher, ECMWF) –10 leading targeted singular vectors –40 leading hemispheric singular vectors computed in the subspace orthogonal to the targeted singular vectors –Ensemble size –Initial perturbations constructed with (revised) Gaussian sampling Results in increased spread for TEPS after day 2, without increasing the error of the ensemble mean

Norwegian Meteorological Institute met.no