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Ash cloud modelling using FALL3D

A. Folch

Volcanic Ash Awareness Workshop, Catania, June 23-24, 2009

Barcelona Supercomputing Center(BSC), Barcelona, Spain

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Overview

Eulerianmodelbasedontheadvectiondiffusionsedimentationequation.

Multipurposemodel:

Computesthedeposit(ashfalloutforecast,elaborationofhazardmaps,etc).

Computesairborneconcentration(FL,integrated,etc.).

Canbeusedtoforecastortostudypastevents.

Admitsdifferentparameterizationsfor:

i)Verticalandhorizontaldiffusion(atmosphericturbulence).

ii)Terminalsettlingvelocities(severalsemiempiricalmodelsavailable).

iii)Sourceterm(e.g.buoyantplumetheory).

Multiscalemodel:runsatscalesfromsynoptic(1000skm)toverylocal(fewkm).

Followsanoff-lineapproach.However,NMMb(NCEP)on-linecouplinginprogress...

Multipleclassesorbins(fromtephratoveryineash;lithicsorjuvenilecomposition).

Testedfor:Ves.(44),MSH(80),Chichn(86),Spurr(92),Etna(98;01;02),Chaitn(08).

Soonoperationalat:BsAsVAAC,COPAIRE(Quito),IGN(Spain).

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Meteorological inputs

Global

Mesoscale

Local

Database

FALL3D

0.5o2.5o

220km

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Postprocessstrategy

1)Resultsatground:

Depositload.Depositthickness.

PM10,PM5,PM2.5.

2)Resultsonair:

Columnmass(load).

Concentrationatlightlevels.3DConcentration.

*Cuts.

*Verticalproiles.

3)Trackingatselectedpoints:

(e.g.anairport).

Ashaccumulationrates.

AirQuality.

FALL3D

NetCDF Tracking

Images

Animations

GoogleEarth

GRD GIS

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Numericalperformance

Serialandparallelversions.

Solvingalgorithm:

Finitedifferences.

Terrainfollowing.

Secondorderschemewithlimiters.

Parallelizationattwolevels(speedupacceptable125proc.,block256proc.):

i)Classes(bins).ii)Domain.

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VAACs:

Regionalashcloudtracking/forecast.Largedomains,lowresolutionmodelling.

Europe:Denselypopulatedareas(localeffectsalsoimportant!!).

Likelytohavesmallscaleevents.

e.g.Etna,Vesuvius,Aores,Tenerife

Teide

2kmheightplume.Considerthesmallestexplosiveevent24h

WRFwindsat2kmresolution(PBL,localeffects,etc.)

Whyamultiscalemodelisnecessary?

1x1

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Tenerife

airport

airport

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