14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

Evaluation of ALADIN mesoscale Evaluation of ALADIN mesoscale precipitation forecasts in the precipitation forecasts in the

southern Alpine areasouthern Alpine area

Christoph WittmannChristoph Wittmann

IMG, University of Vienna

(master thesis)

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

TopographyTopography

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

MethodMethod

Selection of heavy and moderate wintertime/fall precipitation events (1999 – 2003) in connection with a southerly flow → 62 days belonging to 13 periods (duration: 3 – 8 days)

Analysis of typical observed precipitation patterns (rain gauge, areal averages)

Comparison of observed and modelled precipitation patterns, analysis regarding systematical deviations in the different areas

Comparison of observed and modelled inflow soundings (Udine,...) → additional prognostic information?

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

DataData

OBSERVATIONS:

• TAWES: rain gauge, areal average

• HZB: rain gauge, areal average

• Soundings (especially Udine)

• Weather charts archive (ZAMG, GFS)

• Radar

ALADIN-VIENNA (AVI)(resolution: 9.6 km)

• Model output (AVI00, AVI12): selected fields

• AVI: areal average• Pseudotemps

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

AreasAreas

1516 17

1918

14

25

24

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

Results (a)Results (a)Observed precipitation patterns: Areas 18 and 16 with the highest areal means Area 17 with the lowest areal means

Stations with highest precipitation amounts (52 overall):

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

Results (b)Results (b)

Observed precipitation pattern:

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

Results (c)Results (c)

Systematical analysis:

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

Results (d)Results (d)

OBSERVATION ↔ ALADIN:

14th Aladin Workshop, Innsbruck14th Aladin Workshop, Innsbruck

Preliminary Conclusions & OutlookPreliminary Conclusions & Outlook

• Analysis of observational data gives clear idea regarding primary affected regions in the south of Austria (area, stations)

• Observed precipitation pattern with highest variability in eastern part of area 18 and western part of area 19

• Three areas can be outlined, showing significant tendencies with respect to over/underestimation of areal averages

• Comparison observation ↔ Aladin reveals existence of a “problem-area” (responsible for major part of underestimation in areas 18 and 19)

Information from upstream soundings (observed, modelled) → additional prognostic information ( → “p.a.”) ?

Further analysis: Relation between flow direction, precipitation patterns and deviations observation – Aladin (especially “p.a.”)

Information from radar data → role of convection?