Atmospheric Transport Modelling (ATM): Atmospheric Transport Modelling (ATM):

On the PTS in-house capacity building in atmospheric transport modelling during the past decade with On the PTS in-house capacity building in atmospheric transport modelling during the past decade with

an outlook on scheduled improvements in support of the noble gas verification regimean outlook on scheduled improvements in support of the noble gas verification regime

Andreas BECKERand Gerhard WOTAWAAndreas BECKERand Gerhard WOTAWAPreparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Organization, Vienna International Centre, P.O. Box 1200, A-1400 Vienna, Austria

Role and Mandate of Atmospheric Transport Modelling

The verification of the ComprehensiveNuclear Test Ban Treaty (CTBT)

Source Attribution for the Radionuclide NetworkFour Layer ATM System

The verification of the ComprehensiveNuclear Test Ban Treaty (CTBT)includes, beside the three different waveform technologies, the radionuclidetechnologycomprisingglobal monitoring of radioactiveaerosolsand noble

A database of these SRS fields substantially helpsto improve the interpretation of the RN samples'

Left: Displayed is the colourcoded PSR field in term ofcorrelation coefficients. Thetechnologycomprisingglobal monitoring of radioactiveaerosolsand noble

gases within the International Monitoring System (IMS). Incontrast to thewaveform technologies the automated and interactive analysis andcategorizationof radionuclidesignals (see Fig. 1 for 2005 event analysis)

to improve the interpretation of the RN samples'measurements because it enables a time efficienttesting of source-hypothesis’s. In doing so aninversion problem is solved on basis of the SRS

correlation coefficients. Thehigher the PSR value the moreconsistently a singular sourcethere would reproduce the event

categorizationof radionuclidesignals (see Fig. 1 for 2005 event analysis)cannot provide information on the geo-location of the pertaining source regionwithout thesupporttechnologyof atmospherictransportmodelling(ATM) that

inversion problem is solved on basis of the SRSdata base in order to determine the so calledpossible source region (PSR, Figure 3, left) of a

scenario (bottom). The actual*

source location (red object) ofthe virtual nuclear scenarioconducted during the 2nd

without thesupporttechnologyof atmospherictransportmodelling(ATM) thatrelates these signals to the extend possible with what we call their ‘Field-of-Regards’ (FOR, Fig. 2) and ‘Possible Source Region’ (PSR, Fig. 2). Moreoverthefollowing additionalareasrequireIDC activitiesin thefield of ATM:

possible source region (PSR, Figure 3, left) of ascenario of treaty relevant RN measurements(Figure 3 bottom). Provided a user has access to

conducted during the 2ndCTBTO-WMO Experiment isspotted very well by the PTSsource location methodology.thefollowing additionalareasrequireIDC activitiesin thefield of ATM:

• Determine the global coverage of the radionuclide network (Fig. 5)

(Figure 3 bottom). Provided a user has access tothe relevant SRS fields, the global source attributioncan be performed in a pure post-processing stepeven bundled within a “thick client” visualisation tool

source location methodology.

*Geo-temporal event location: 18 Jan 2005 • Determine the global coverage of the radionuclide network (Fig. 5)• Enable Data Fusion (co-locate RN and SHI events)• Supply wind field data for infrasound wave propagation models• Support event screening for Noble Gas Stations

even bundled within a “thick client” visualisation toolsuch as WEB-GRAPE (CTBTO, 2005) developed bythe PTS (Figure 1, left).

*Geo-temporal event location: 18 Jan 2005 from 16:12 to 19:12 UTC at λ=174.86E, φ=41.89S

• Support event screening for Noble Gas Stations• Guide and safeguard On-Site Inspection campaigns• Predict plume dispersion from release locations of special interest

Figure 1: Flow -chart of the 4-layer ATM system (Kalinowski et al., 2008). The final analysistool WEB-GRAPE is also capable to export any visualization into zipped kml (=kmz) files forwatching in Google Earth.

the PTS (Figure 1, left).

The WEB-GRAPE based analysis is feasible onhardware with specifications comparable to currently

The 4 Layer Atmospheric Transport Modelling Systemwatching in Google Earth. hardware with specifications comparable to currently

available PC/Notebook, and allows also for aparametric inter-comparison among SRS fields

Figure 3: Snapshot from the GUIclient tool capable to host and

Since August 2002, the IDC calculates based on a four layer ATM workflowconcept(Fig. 1; Beckeret al., 2004) socalledsource-receptorsensitivityfields

parametric inter-comparison among SRS fieldscalculated by different LPDM systems on the samebacktracking problem.

client tool capable to host andperform all SRS fields based post-processing (inversion) andbacktracking results.

Source location estimation with the PSR product; two examplesCS-137concept(Fig. 1; Beckeret al., 2004) socalledsource-receptorsensitivityfields

in order to describe the transport of nuclear debris from possible eventlocations to the 80 radionuclide IMS stations scheduled fordaily sampling.The techniqueapplied is to numerically track the pathsof particlesinserted

backtracking problem. backtracking results.

2

3

4 PSR computations for Yellowknife

The techniqueapplied is to numerically track the pathsof particlesinsertedinto a high quality global wind field analysis provided by the European Centrefor Medium-Range Weather Forecasts (ECMWF). In CTBT verificationcontextthe numberof 80 radionuclidemeasurementsper day is much lower

IMS RN Threshold Monitoring for Ba/La140 across 2008 as determined by ATM and MDC

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ug Improving the horizontal ATM resolutioncontextthe numberof 80 radionuclidemeasurementsper day is much lowerthan the global number of 518400 possible 1º×1º×3h sized sources to becheckedper day. Therefore,it is moreefficient to performthe ATM receptor

across 2008 as determined by ATM and MDCOptions to change the computational basis of source-receptor sensitivity

checkedper day. Therefore,it is moreefficient to performthe ATM receptororiented, hence backward in time. Therefore the transport paths of 0.5 millionparticles are backtracked across the 2 weeks prior to the collection stop of eachsample. Theparticleconcentrationsarethenstoredat theaforementionedgeo-

137Cs Detections in Continuous source scenariosample. Theparticleconcentrationsarethenstoredat theaforementionedgeo-

temporal resolution yielding a database of SRS fields. Downto this step thebelongingcomputationaleffort demandsacentralizedoperation.

Cs Detections in Yellowknife/Canada

in summer 2003Continuous source scenario

belongingcomputationaleffort demandsacentralizedoperation.

The remaining generation and visualization of the ATM products, however, ispurepost-processingof the SRSfields databasefeasibleevenon a notebook Fire spots across Eurasia as purepost-processingof the SRSfields databasefeasibleevenon a notebookprovided it has access to this data. Nevertheless the samplespecific ‘Field-of-Regard' product is operationally post-processedand attachedto the IDC

Fire spots across Eurasia as detected by Terra/Aqua

Regard' product is operationally post-processedand attachedto the IDCReviewed Radionuclide Report in terms of jpeg images. An event periodspecific ‘Possible Source Region’ product pertaining to a scenario of treatyrelevantRN measurementsis undertestingandshowspromisingbacktracking Backtracking of CS-137 measurements in 1986 at relevantRN measurementsis undertestingandshowspromisingbacktrackingperformance for historic cases (Fig. 2). The product allowsfor assemblingthose RN detections belonging to the same nuclear event, forthe so-called

Backtracking of CS-137 measurements in 1986 at Stockholm towards the Chernobyl region by means of the PSR product under development. PTS proposal in modifying the basis of calculation of SRS Data

standard screened radionuclide event bulletin (SSREB). For those usersauthorized to access the SRS fields data base, IDC has developed the userfriendly WEB-GRAPE (Becker and De Geer, 2005) hosting the entirefriendly WEB-GRAPE (Becker and De Geer, 2005) hosting the entireprocessing required for the source region estimate of radionuclide eventdetections in an interactive mode.

Ensemble Dispersion Modelling and Quality AssuranceFigure 5: Monthly median of minimum detectable source strengths for theparticulate network

References Becker, A., G. Wotawa and L.-E. De Geer., 2004: Review on New PTS modelling capabilities supporting the emerging

CTBTO-WMO response system including a proposal for standardised model inter-comparison. WMO, WWW,

Based on the CTBTO-World Meteorological Organization CooperationAgreement the IDC has created the CTBTO – WMO responsesystem

PSR if date/time of explosion would be known (Main release 12-18 hours after main explosion that happened CTBTO-WMO response system including a proposal for standardised model inter-comparison. WMO, WWW,

CBS/ERA-CG/INF.1/Doc.8(3). http://www.wmo.ch/web/www/ERA/Meetings/ERACG-Geneva2004/Doc8-3.pdfBecker, A. et 19 al., 2007: Enhanced Global Backtracking of Anthropogenic Radionuclides by Means of a Receptor

Oriented Ensemble Dispersion Modelling System Supporting Nuclear-Test Ban Treaty Verification. Atmos. Env. (2007), doi:10.1016/j.atmosenv.2006.12.048

Agreement the IDC has created the CTBTO – WMO responsesystemproviding PTS with the capability to perform backward ensemble dispersionmodelling (Becker et al., 2007) yielding so-called multi-model versions of theFORandPSRproducts. In additionto addressingtheuncertaintiesinherentto

release 12-18 hours after main explosion that happened at April 25 1986, 21 UTC)

doi:10.1016/j.atmosenv.2006.12.048Becker, A. and L.-E. De Geer, 2005: A new tool for NDC analysis of atmospheric transport calculations. CTBTO Spectrum

Newsletter 7, December 2005, pages 19 & 24.Draxler, R.R. and Hess, G.D., 1998: An overview of the HYSPLIT_4 modelling system for trajectories, dispersion and

deposition. Australian Met. Magazine 47, 295-3-8.

FORandPSRproducts. In additionto addressingtheuncertaintiesinherenttoany kind of ATM calculation, these products also serve quality assurancepurposes. The SRS field concept developed by the IDC (Wotawaet al., 2003)

Figure 2: Backtracking of Cesium-137 measurements using the new IDC productdevelopment called Possible Source Region, PSR. Green box: Detection at the IMSstation CAP17 (Yellowknife, Canada) in summer 2003 backtracked to forest fires in central

deposition. Australian Met. Magazine 47, 295-3-8.Stohl, A., C. Forster, A. Frank, P. Seibert, and G. Wotawa, 2005: Technical Note : The Lagrangian particle dispersion

model FLEXPART version 6.2. Atmos. Chem. Phys. 5, 2461-2474.Wotawa, G. et 12al., 2003: Atmospheric Transport Modelling in Support of CTBT Verification – Overview and Basic

Concepts. Atmos. Env. 37(18), 2529-2537.

provides for this purpose the ideal standard to harmonize the backtrackingresults delivered by the external meteorological centres.

station CAP17 (Yellowknife, Canada) in summer 2003 backtracked to forest fires in centraland east Asia (Wotawa et al., 2006). Yellow box: Utilization of NDC analysis tool WEB-GRAPE for the Chernobyl disaster case.

Figure 4: Recent proposal to change the time basis of the SRS dataand to introduce a second type of SRS field

Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization, Provisional Technical Secretariat, Vienna International Centre,P.O. Box 1200, A-1400 Vienna, Austria Telephone: +43 1 26030 6415 - Facsimile: +43 1 26030 5973 - E Email Address: Andreas.Becker@ctbto.org Disclaimer: The views expressed on this poster are those of the authors and do not necessarily reflect the views of the CTBTO Preparatory Commission

Concepts. Atmos. Env. 37(18), 2529-2537.GRAPE for the Chernobyl disaster case.