Assimilation of LandSAF albedo product in a limited area NWP model

Transcription

1 1/16 Assmlaton of LandSAF albedo product n a lmted area NWP model Jure Cedlnk Envronmental Agency of Slovena / RC-LACE Domnque Carrer Jean-Franços Mahfouf Jean-Lous Roujean Météo France Assmlaton of LandSAF albedo product n a lmted area NWP model

2 LandSAF Albedo Product 2/16 In preoperatonal phase, routnely produced snce 2005 Daly product BB BH albedo, Obs error Qualty flag Age of pxel SEVIRI resoluton -> Assmlaton of LandSAF albedo product n a lmted area NWP model

3 ALADIN NWP model 3/16 Local counterpart of ARPEGE, French global model, dynamcal core same as n IFS (ECMWF) Used operatonaly at many European met. servces ISBA [Nolhan and Planton 1989, Mahfouf 1995] used as surface scheme (a swtch to SURFEX and ECOCLIMAP s planned n near future) pre-ecoclmap albedo dataset [Webb 1991, Champeaux 1999] radaton scheme uses only one short wave band Assmlaton of LandSAF albedo product n a lmted area NWP model

4 4/16 Kalman Flter Based Albedo Analyss by Domnque Carrer LSAF provdes total broadband albedo and ts uncertanty, model uses vegetaton and bare sol albedo analyss step forecast step state vector: clm clm saf obs. vector: [ ] T x a A = ( 1 K H ) A a b +1 = x x y a b = = + K a a a [ a, a ] T a x = Mx + w veg veg b a T A +1 = MA M + b [ y Hx ],a Q bs b bs, a tot M K = A b = I, w = 0 H T b T [ HA H + R ] 1 R = obs. operator: 1 H = 0 veg veg obs. error: clm 2 ( σ ) veg ( ) ( ) clm 0 σbs 0 saf σ model. error (Q) s such that: 2/(1 veg ) t ( 2 ) + 1 t b 0 A + 1 = veg t t A 2/ ( 2 ) tot a Assmlaton of LandSAF albedo product n a lmted area NWP model

5 Analysed albedo tmeseres 5/16 cloudy days Assmlaton of LandSAF albedo product n a lmted area NWP model

6 6/16 Experment set-up ALADIN cycle 32, wth a set-up smlar to Meteo France operatonal one of 2007 only dynamc adaptaton (IC and LBCs from Arpège no data assmlaton) computatonal doman coverng central Europe and part of Medterranean (~9.5 km, 250x270) 01/02/2007 -> 31/12/2007, forecast length +54h ntalzaton at 00UTC (use prevous day albedo retreval) albedo assmlaton perfomed offlne new albedo nformaton s njected n the ntal fle albedo s analyzed n model space one nterpolaton of LSAF data from SEVIRI to model LCC grd (nearest neghbour) only grdponts wth no snow were modfed Assmlaton of LandSAF albedo product n a lmted area NWP model

7 Impact on surface temperature 7/16 Assmlaton of LandSAF albedo product n a lmted area NWP model

8 Net radaton valdaton 8/16 Assmlaton of LandSAF albedo product n a lmted area NWP model

9 Sensble heat flux and PBL heght tmeseres 9/16 Assmlaton of LandSAF albedo product n a lmted area NWP model

10 10/16 Evoluton of average latent heat flux always negatve, but less negatve n experment less precptaton n experment compared to reference - > convecton Assmlaton of LandSAF albedo product n a lmted area NWP model

11 Impact on precptaton and latent heat flux 11/16 Assmlaton of LandSAF albedo product n a lmted area NWP model

12 Postve correlaton of albedo and surface temperature found when analysng the greatest mpact of the albedo analyss ~ 10 C 12/16 on a grd-pont near Venna, end of June experment actually has lower albedo and also lower daytme temperature maxmum! Ths s a 3D model! Assmlaton of LandSAF albedo product n a lmted area NWP model

13 13/16 Objectve verfcaton Objectve verfcaton agans SYNOP data over Europe (roughly 80 observatons) Usng relable COMPASS software (MeteoFrance verfcaton department) Greatest mpact on temperature scores (2m), almost no sgnal on other varables (except correlaton wth mosture) and no sgnal for temps Assmlaton of LandSAF albedo product n a lmted area NWP model

14 Scores for 2m temperature March(I) RMSE June 14/16 Blue = LandSAF albedo assmlaton Red = reference bas September forecast tme -> December Assmlaton of LandSAF albedo product n a lmted area NWP model

15 Scores for 2m temperature (II) 15/16 Blue = LandSAF albedo assmlaton Red = reference day n March > Assmlaton of LandSAF albedo product n a lmted area NWP model

16 16/16 Conclusons relatvely large mpact of Land SAF albedo assmlaton larger mpact than purely mproved clmatology (e.g. ECOCLIMAP) acts as a sort of a systematc bas correcton reducng cold bas for T2m sometmes too pronounced (ntroducng addtonal warm bas) least of mpact s n late sprng and summer months (Aprl - July) -> probably connected to stablty and actvaton of turbulence and convecton schemes Assmlaton of LandSAF albedo product n a lmted area NWP model