Exploring and Validating LM Performances at Very High Resolution M. Didone, D. Lüthi, H.C Davies Institute for Atmospheric and Climate Science, ETH Zürich

IACETH Outline Introduction to MAP IOP15 Case Domain Issue - Aim –Approach –Data –Results Model Error in Precipitation Field Conclusions and Outlook

IACETH MAP IOP15 – Geopotential at 500hPa 00UTC November 06, UTC November 07, UTC November 06, 1999 ECMWF analysis interpolated on 7Km LM grid

IACETH Domain Issue The aim of the first part of the study is to examine how the large scale flow at 2km is influenced by the domain size of the coarser simulation which is arbitrarily chosen The availability of MAP Reanalysis data provides a suitable chance to also have indications on the effects of initial data on the model Indications of the quality of ECMWF analysis versus MAP Reanalysis

IACETH Approach - 1 We defined: 3 different domains for the 7 Km resolution simulation (L,M,S) 1 domain for the 2 Km simulation, so called “Alpine Domain”

IACETH Approach - 2 Initial conditions of ECMWF operational analysis 7Km resolution simulation for L,M,S domains 2Km resolution simulation on the Alpine Area nested on L,M,S Low pass filter Difference between model [at 7/2km] and AN always on Alpine Area and RMS calculation The same procedure has been repeated with MAP RE data as initial and boundary conditions

IACETH RMS of Geopotential at 500 hPa LM at 7KmLM at 2Km

IACETH RMS of Geopotential at 850 hPa LM at 7KmLM at 2Km

IACETH Model Error in Precipitation Field Analyses of Alpine High-Resolution Rain-Gauge Observations for the MAP Special Observing Period (Frei C. and Häller E.,2001)

IACETH 7Km – Domain L ECMWF ANMAP RE 24hrs precipitation on November 06, 1999

IACETH 2Km – Alpine Region 24hrs precipitation on November 06, 1999 ECMWF ANMAP RE

IACETH Conclusions The RMS values of the geopotential are extremely low Decrease of RMS values from L to S The use of MAP RE has a strong impact: –Lower RMS in the lower troposphere –Much better precipitation forecast A higher horizontal resolution produces better precipitation forecasts maintaining low RMS values The model performs quite well for this case driven with “perfect” boundary conditions, but…

IACETH Outlook … the introduction of Prognostic Precipitation 3D-Turbulence Scheme in the 2Km simulation might help to improve the results!