Wolfgang Gepp ICAM 2003

A New 4D Variational Data Analysis Scheme in the Framework of VERA

University of Vienna Department of Meteorology

and Geophysics

Wolfgang Gepp

Department of Meteorology and Geophysics, University of Vienna

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

concept of VERA

interpolation of irregularly distributed data to a regular grid

data quality control (error correction)

a priori knowledge of small scale physical processes(Fingerprints)

variational algorithm using a form of thin plate splines

+

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

„old“ VERA

already in operational use

valuable analysis and nowcasting tool

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

Problems with „old“ VERA

restricted to 2D

insufficencies

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

we want

more reliable results

avoid insufficencies

include vertical sounding data

analyse 3D phenomena

temporal extrapolation

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

extend

algorithm to 3D and 4D

VERAXX

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

why a new scheme?

old algorithm becomes expensive for 4D

keep algorithm simple

for usual commercial PC platforms

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

VERAVERAXX

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

10x10x10x10

10000 gridpoints

10000 equations

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

solution

Partial Grid Calculation

5x5x5x5 subdomain

max. 625 equations

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

Partial Grid Computation

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

how get data into calculation?

VERA

VERAXX

pentagons out of stations

stations usually not at gridpoints

derive gridpoint values from stations

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

Deriving Grid Point Values

A

4 3

1 2

dx

dy

4321 )1()1()1)(1( yxyxxyyxA

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

First VERAXX results

only 3D calculations so far

no Fingerprints used

error correction from VERA

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

Horizontal Cross Section

H=220m

Zell am See, 15. Nov. 2002, 1800 UTC

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

Vertical Cross Section

Zell am See, 15. Nov. 2002, 1800 UTC

S N

Wolfgang Gepp ICAM 2003

University of Vienna Department of Meteorology

and Geophysics

More Information?

http://www.univie.ac.at/img-wien/vera

http://www.alpenwetter.net