Extended Abstract

een done but much i s s till needed t o p rogress in th is direction. Weather t ype oriented verifi cation isextremely important and inter national cooperati on is necessary to co nstitute the necessary obser vationaldatabases. Evaluate the g eneral performan ce of regional EPS sy stems of LAMs c oupled to app licationmodels (hydrology, air quality , …), and asse ss the benefit of the non-atmospheric uncertainty informationto end users is also part of a comprehensive estimation of the added value coming from LAM EPS.Data assimilation at the convective-permitting (and down to res olving) scale is a big issue also due tothe l ack of defined balances driving p hysical p rocessing a t the f iner mesoscale. The i mportance ofassimilating h igh resolution non conventional dat a make this br anch of present N WP e ven morechallenging. Duri ng the last decad e, E nsemble Bas ed data assimilation is doing big pro gresses b ut,especially at th e fine scales in the scope of LAM EPS, research is still young and the i mpact of ensemblebased technique still to be fu lly exploited. Both Hybrid techniques and fully Ensemble Based sy stems areunder development and testing in many centres and european consortia.LAM EPS and TIGGE LAMThe TIGGE-LAM panel was se t up by the GIFS-TIGGE working group to coordinate the contributionfrom LAM EPS to the THORPEX In teractive Grand Global Ense mble (TIGGE; h ttp://tigge.ecmwf.int/ )and to the p roposed Gl obal In teractive Fo recast System ( GIFS). A ccording to the TH ORPEX coreobjectives, GIFS-TIGGE is focussed on the optimization of the use of Ensemble Forecasting to maximizethe forecast sk ill. TIGGE LAM is inte nded to coordinate acti ons to ev aluate which are t he events whosepredictability can be i mproved by th e use of LAM EPS. TIGGE LAM(http://www.smr.arpa.emr.it/tiggelam/) should define how best t o implement ensemble prediction systemsto ad dress r egional and loc al situations and sp ecific hi gh-impact weat her types. TI GGE LAM acti vityshould b e d eveloped by pro viding g uidelines, coordi nating activities and f ostering res earch with th efollowing main objectives:◦ to contribute to the definition of scientific issues to advance LAM EPS◦ to reinforce the link and cooperation with the other WWRP working groups with crossingcompetences.◦ to support and foster research on LAM EPS by promoting actions to make the access toLAM EPS products easier and by coordinating / stimulating / participating to specificinitiatives to address the relevant scientific issues◦ to coordinate the archiving of limited-area ensemble forecasts by providing standards andguidelines and as a complement to the TIGGE archive◦ to facilitate the interoperability of the different LAM-EPS◦ to facilitate the implementation of new LAM EPSTo foster the Regi onal Fo cus, the Panel is being restructured in Regional Su b-Groups to make moreefficient the interactions with t he TH ORPEX Regiona l Committees, re gional forec ast ce ntres and t henational hydro meteorological services.The different LAM EPS gro ups have been included in the TIGGE LAM mailing list and the metadataon the different LAM EPS sy stems (at least some of the m) have been collected and ar e available on t heTIGGE LAM web site (at: http://www .smr.arpa.emr.it/tiggelam/?search&Metadata). In Table 1, presentLAM EPS systems are listed.TIGGE LAM activ ities connected to TIGGE were m ainly related to products archiving and form atstandardization. F ollowing w hat alre ady do ne by TIGGE a lis t of TI GGE LAM output par ameters wasdefined tog ether with the specific fo r the GRIB2 codi ng (http://www.smr.arpa.emr.it/tiggelam/?search&parameters). A sub-set of these output parameters have been classified as High Priority, and thePanel proposed to archive them at the three TIGGE Archiving Centres, NCAR, ECMWF and CMA. Europeis working to implement this archive; CMA is also planning to follow the Panel proposal. A good link withother Working Groups, Programmes and initiatives have also been established. It is envisaged that regionalensembles from TIGGE LAM will con tribute to the development of the GIFS, by optimizing the use of theproducts of the existi ng systems and via the participation to relevant RDPs and FDPs. Products based onLAM EPS systems, where av ailable, will supplement products available from the global TIGGE data, anddemonstrate the additional benefit obtainable from higher resolution ensembles.-289-