FALL3D-6.2
Contents
1. References Arastoopour H Wang C Weil S 1982 Particle particle interaction force in a diluite gas solid system Chem Eng Sci 37 9 1379 1386 Aschenbrenner B 1956 A new method of expressing particle sphericity J Sediment Petrol 26 15 31 Byun D Schere K 2006 Review of the governing equations computational algorithms and other components of the Models 3 Community Multiscale Air Quality CMAQ modeling system Applied Mechanics Reviews 59 51 Collins W Rasch P Boville B Hack J McCaa J Williamson D Kiehl J Briegleb B 2004 Description of the NCAR Community Atmosphere Model CAM 3 0 Technical Report NCAR TN 464 STR National Center for Atmospheric Research Boulder Colorado Costa A Folch A Macedonio G 2010 A model for wet aggregation of ash particles in volcanic plumes and clouds I Theoretical formulation J Geophys Res in press Costa A Macedonio G Folch A 2006 A three dimensional Eulerian model for transport and depo sition of volcanic ashes Earth Planet Sci Lett 241 634 647 Dellino P Mele D Bonasia R Braia L La Volpe R 2005 The analysis of the influence of pumice shape on its terminal velocity Geophys Res Lett 32 L21306 Folch A Costa A Durant A Macedonio G 2010 A model for wet aggregation of ash particles in volcanic plumes and clouds II Model application J Geophys Res in press Folch A Costa A2. 4 1 The results file filename res nc in netCDF format This file can be processed using several open source programs e g ncview Panoply ncl etc to generate plots and animations The log file filename 10g contains information about the run including summary of input data error and warning messages etc The tracking points files filename pts contain information about evolution of variables at the tracked points There exist an output file for each point specified in the input file filename pts The FALL3D 6 2 Input files The control file filename inp The control input file is an ASCII file made up with a set of blocks that define all the computational and physical parameters needed by FALL3D 6 2 and the rest of utility programs Each program reads only the necessary blocks of the file Parameters within a block are listed one per record in arbitrary order and can optionally be followed by one or more blank spaces and a comment Maximum allowed lenght is 256 characters including comments A detailed description of each record is given below Real numbers can be expressed following the FORTRAN notation e g 12e7 12 x 107 BLOCK TIME_UTC Defines variables related to time BLOCK GRID Defines the characteristics of the FALL3D 6 2 computational mesh BLOCK FALL3D Defines the variables needed by FALL3D 6 2 program BLOCK GRANULOMETRY Defines the variables needed by SETGRN program BLOCK SOURCE Defines the variabl
3. Macedonio G 2009 FALL3D A computational model for transport and deposition of volcanic ash Comput Geosci 35 6 1334 1342 Ganser G 1993 A rational approach to drag prediction of spherical and nonspherical particles Powder Technol 77 143 152 Mastin L Guffanti M Servranckx R Webley P Barsotti S Dean K Durant A Ewert J Neri A Rose W Schneider D Siebert L Stunder B Swanson G Tupper A Volentik A Waythomas C 2009 A multidisciplinary effort to assign realistic source parameters to models of volcanic ash cloud transport and dispersion during eruptions J Volcanol Geotherm Res 186 10 21 Pfeiffer T Costa A Macedonio G 2005 A model for the numerical simulation of tephra fall deposits J Volcanol Geotherm Res 140 273 294 Pielke R Cotton W Walko R Tremback C Nicholls M Moran M Wesley D Lee T Copeland J 1992 A comprehensive meteorological modeling system RAMS Meteor Atmos Phys 49 69 91 Scire J Robe F Fernau M Yamartino R 2000 A User s Guide for the CALMET Meteorological Model Tech Rep Version 5 Earth Tech Inc 196 Baker Avenue Concord MA 01742 Ulke A 2000 New turbulent parameterization for a dispersion model in atmospheric boundary layer Atmos Environ 34 1029 1042 Wadell H 1933 Sphericity and roundness of rock particles J Geol 41 310 331 Walker G Wilson L Bowell E 1971 Explosive v
4. Vy my Vertical velocity Vz Vsj J7 o Usj m v3 v3 Diffusion Coefficients Kx K Ky K Kz2 K J Concentration C cJ m Density px pJ m Source Term Sa SJ m Table 1 Scaling factors for a terrain following coordinate system x mX y mY z gt Z x y z are the Cartesian coordinates m the map scale factor for the UTM coordinate system m 1 and J is the determinant of the Jacobian of the coordinate system transformation 2 Option SIMILARITY In this case inside the Atmospheric Boundary Layer ABL FALL3D 6 2 evaluates K as h 1 Kusz 1 Teen a h L gt 0 stable _ h Lh 2 1 tegt i h L lt 0 unstabl KUZ h En S unstable where is the von Karman constant k 0 4 ux is the friction velocity h is the ABL height and L is the Monin Obukhov length see Costa et al 2006 The expression above comes from an extension of the Monin Obukhov similarity theory to the entire ABL Ulke 2000 On the other hand above the ABL 2 h gt 1 K is considered a function of the local vertical wind gradient a characteristic length scale le and a stability function Fe which depends on the Richardson number Ri au K l cl Oz where U y u For le and Fe FALL3D 6 2 adopts the relationship used by the CAM 3 0 model Collins et al 2004 i IN le 4 a gt 4 1 So stable Ri gt 0 F Ri 1 10Ri 1 8Ri 5 V1 18Ri unstable Ri lt 0 where
5. http www unidata ucar edu software netcdf already installed version 3 6 or later It is manda tory to compile FALL3D 6 2 using the same FORTRAN compiler that has been used to compile the NetCDF library 5 1 1 Unix Linux Mac X OS For Unix Linux Mac X OS the package comes with an automatic installation script Proceed as follows 1 Enter the directory Install and edit the Install script file Set up the variables HOMEFALL3D FALL3D 6 2 home directory path Libmetcdf path of the NetCDF library in your computer and COMPILER name of the FORTRAN compiler NOTE Automatic installation is possible for the following standard compilers gfortran ifort f90 x1f90 If you want to compile using a different compiler it is necessary to modify the Makefiles and the Scripts manually 2 Run the Install script This will compile FALL3D 6 2 and the utility programs modify the scripts introducing your FALL3D 6 2 path and check the installation process 3 Optionally create an alias to the Script manager file located in the folder Scripts This script allows for launching FALL3D 6 2 and the utility programs directly from the command line 5 1 2 Windows OS Not yet available for the current versions 5 2 Execution To create a new run named problemname simply create a new directory problemname in the folder Runs copy the control input file from the example run rename it as problemname inp and modify it depending on your needs FALL3D
6. 6 2 USER S MANUAL 14 Level 1 Level 2 Level 3 Description Fal3d Documents Contains the manual Install Contains installation scripts Runs Run name Contains the examples one folder each Scripts Contains the script files Sources_ser FALL3D 6 2 sources PUB version Utilities LibMaster Master library SetDbs SETDBS utility program SetGrn SETGRN utility program SetSrc SETSRC utility program Table 4 Default structure of FALL3D 6 2 folders 5 2 1 Unix Linux Mac X OS FALL3D 6 2 and the utility programs can be launched using the Script manager with a series of argu ments It is recommended to use an alias for this script that can be called directly from any location in the following it is assumed that the alias is Launch From any location e Type Launch SetGrn problemname to run the SETGRN utility program for problemnane e Type Launch SetDbs problemname meteo to run the SETDBS utility program for problemnane Here meteo is one of the following profile calmet62 ncep1 e Type Launch SetSrc problemname to run the SETSRC utility program for problemnane e Type Launch Pub problemname to run the PUB version of FALL3D 6 2 for problemname 5 2 2 Windows OS Not yet available for the current versions Appendices Appendix A Format of the meteo profile file filename profile For the profile option the utility SetDbs needs an ASCII file containing the definition of the vertical wind profile and a topography file of the domain
7. end hour after OOOOUTC of the starting day If the SETSRC program is used to generate the source term this is the time slice at which source term is switched off i e the time at which the last eruptive phase ends RUN_END_ HOURS_AFTER_00 Run end hour after OOOOUTC of the starting day Must be equal or lower than the value of the record END METEO_DATA_ HOURS_AFTER_00 Note that in general a run should continue even when the source term is switched off i e when the eruption has stopped in order to allow the remaining airborne particles to sediment completely 4 1 2 BLOCK GRID This block of data defines the variables needed by SETDBS program to generate the FALL3D 6 2 grid Note that time and spatial coverage of the database must include the FALL3D 6 2 simulation interval COORDINATES Defines the map projection Possibilities are UTM or LON LAT Note that the UTM option can only be used if the domain is within a unique UTM zone The use of the UTM coordinate system in large domains covering more than one UTM zone is not allowed in this case the LON LAT option accounting for Earth s curvature must be used instead The sub blocks UTM or LON_LAT are read in each case respectively LONMIN Minimum longitude in decimal degrees of the domain i e longitude corresponding to the bottom left corner Only used in the LON LAT option LONMAX Maximin longitude in decimal degrees of the domain i e longitude corresponding to top ri
8. in GRD format see Appendix B In this case wind velocities are assumed constant on all the domain in a terrain following coordinate system The remain ing variables are assumed with the values of the Standard Atmosphere The format of the profile file filename profile is described in Table 5 and the meaning of the used symbols is the following e pcoord Coordinates where the profile was measured either as UTM or lon lat coordinates e pdate Starting time when the profile was measured the format of the date is yyyymmdd i e year month day e itime1 Initial time in sec after the starting time pdate of validity of the meteo data contained in the following nz layers e itime2 Final time in sec after the starting time pdate of validity of the meteo data contained in the following nz layers e nz Number of the database vertical layers e z Vertical coordinate of the layer in m a s l e ux wind z velocity in m s e uy wind y velocity in m s FALL3D 6 2 USER S MANUAL 15 pcoord pdate itimel itime2 nz z 1 ux 1 ux 1 T 1 z nz ux nz ux nz T nz itime3 itime4 Table 5 Format of the meteo data file filename profile dat for the PROFILE case Repeat this block for each meteo time increment Appendix B The GRD format The structure of a GRD format file is described in Table 6 and the meaning of the used symbols is the following e NX Number of grid points along x direction e NY Number of grid p
9. in m above the vent for the nt eruptive phases Note that the plume heights must be lower than the top of the computational domain specified in the record ZLAYER_ M of the GRID block If not the program will stop In the case SOURCE_TYPE SUZUKI only the sub block SUZUKI_SOURCE is used e MASS_FLOW_RATE_ KGS Array of values of the mass flow rate in kg s for the nt eruptive phases Alternatively the user can use the word estimate and SETSRC automatically computes the MFR from the column heights based on empirical fits Mastin et al 2009 This is the typical situation during an eruption when column height is likely to be the only observable available e HEIGHT_ABOVE_VENT_ M Array of heights of the plume in m above the vent for the nt eruptive phases Note that the plume heights must be lower than the top of the computational domain specified in the record ZLAYER_ M of the GRID block If not the program will stop e A Array of values of the parameter A in the Suzuki distribution for the nt eruptive phases Pfeiffer et al 2005 e L Array of values of the parameter A in the Suzuki distribution for the nt eruptive phases Pfeiffer et al 2005 In the case SOURCE_TYPE PLUME only the sub block PLUME_SOURCE is used e SOLVE_PLUME_FOR Possibilities are MFR or HEIGHT In the first case SETSRC solves for the mass flow rate given the column height whereas in the second does the opposite Since the plume equations use the mas
10. 002 eee 13 5 Program Setup 13 pel Installation id io G aig Get et Be a BS wed A a ik AA eee BS 13 5 1 1 Unix Linux MacX OS ee ee 13 5122 Windows OS aair tinka eB aR ee SR eee be Se ee 13 DD mi MOCUULONE ic A AAA SRA ses hd OP RG amp amp amp bs 13 5 2 1 Unix Linux Mae X OS a ai ee a a a ba a ee ee 14 52 2 Windows OS i ieli e eg SE eae Aa ii cee a 14 Appendices 14 Appendix A Format of the meteo profile file filename profile 14 Appendix B The GRD format aaau 15 Appendix C The NetCDF format 0 ee 15 FALL3D 6 2 USER S MANUAL 3 1 Introduction FALL3D 6 2 is a 3 D time dependent Eulerian model for the transport and deposition of volcanic ash The model solves the advection diffusion sedimentation ADS equation on a structured terrain following grid using a second order Finite Differences FD explicit scheme Different parameterizations for the eddy diffusivity tensor and for the particle terminal settling velocity can be chosen The code written in FORTRAN 90 is available for Unix Linux Mac X Operating Systems OS A set of pre and post process utility programs and OS dependent scripts to launch them are also included in the FALL3D 6 2 distribution package Although the model has been designed to forecast volcanic ash concentration in the atmosphere and ash loading at the ground it can also be used to model the transport of other kinds of airborne solid particles The mod
11. Ae is the so called asymptotic length scale A 30m The available choices for describing the horizontal component Ky Kz Ky are 1 Option CONSTANT i e Kp constant where the constant value is assigned by the user 2 Option RAMS In this case a large eddy parameterization as that used by the RAMS model Pielke et al 1992 can be used for evaluating Kp Ove 2 Ovy TA 6 se ar where Pr is the turbulent Prandtl number typically Pr 1 km 0 075A 4 3 A YAzAy Az and Ay are the horizontal grid spacings and C s is a constant ranging from 0 135 to 0 32 nH K P lem CgA 2 2 dy y 2 h F Tt Max m CsA 20 D FALL3D 6 2 USER S MANUAL 5 3 Option CMAQ In this case the horizontal diffusion is evaluated as in the CMAQ model Byun and Schere 2006 1 1 1 7 Kn Kv Kan 7 where v Ov Ov Ov 2 ESOR AE p eU apc Kni a AzxAy 2 wu dx e 8 z Aas Ayr Knn Kaf Achy 9 where a 0 28 and the values of Ka and Ax Ayf depend on the algorithm Using this parameterization for a large grid size the effect of the transportive dispersion is minimized whereas for a small grid size the numerical diffusion term is reduced Byun and Schere 2006 Thanks to the heuristic relationship 7 the smaller between Ky and Khan dominates In our case we set Kaf 8000 m s for Ary Ays 4km and also a minimum value for K equal to km 0 075A4 3 was imposed 2 3
12. FALL3D 6 2 User Guide Arnau Folch Antonio Costa 1 Earth Sciences Division Barcelona Supercomputing Center Centro Nacional de Supercomputaci n Edifici Nexus II c Jordi Girona 29 08034 Barcelona Spain Istituto Nazionale di Geofisica e Vulcanologia Via Diocleziano 328 80124 Napoli Italy March 2010 FALL3D 6 2 USER S MANUAL 2 Contents 1 Introduction 3 2 Ash transport model 3 21 Governing equations ise Tena eo PRA wea a A eee ae ee 3 2 2 Eddy Diffusivity Tensor 0 ee 3 2 3 Settling velocity models 2 0 60h eek we 5 2 4 Meteorological variables s icsse eR RRA EO a ee eee a 6 QO OUTES ETM re of dhe is 4 otk BO A PE A Sete wea da dod cad 6 2 6 Particle ageregati D ii acess ewe A BE dd he a AA Ge hw ee ee h 6 3 Overview of the program FALL3D 6 2 6 4 The FALL3D 6 2 Input files 7 4 1 The control file filename inp ee ee 7 R BLOCK TIME U TO iiba i a E E oe oe ede AS LEA ele RI o 8 AEZ BLOCK GRID hoe ab Ada a eye de Be nh Phd 8 4103 BLOCK FALESD 206000 RD Adah chews Se ke WU A eevee dk BGO 9 4 1 4 BLOCK GRANULOMETRY 0 0 000000 040 eee 9 4 15 BLOCK SOURCE 6 colon de a A ee 10 4 1 6 BLOCK OUTPUT sret Go ae ae ee ee ee ee 11 4 2 The database file filename dbs nc e 11 4 3 The granulometry file filename grn 0000000 0000004 12 4 4 The source filefilename src 2 00 eee ee 12 4 5 The points file filename pts 0 0 0 00000000
13. FALL3D 6 2 solves Eq 1 for each particle class j using a curvilinear terrain following coordinate system X maz Y my z gt Z where m is the map scale factor and Z z h x y with h x y denoting the topographic elevation and x y z are the Cartesian coordinates The scaling factors for this particular transformation are given in Table 1 Byun and Schere 2006 The generic particle class j is defined by a triplet of values characterizing each particle dp Pp Fp that are respectively diameter density and a shape factor For d we use the equivalent diameter d which is the diameter of a sphere of equivalent volume For the shape factor Fp we choose the sphericity 4 which is the ratio of the surface area of a sphere with diameter d to the surface area of the particle In our approximation each triplet d pp Y is sufficient to define the settling velocity Effect of Earth s curvature are considered when the lat lon coordinate system is used through the Jacobian of the transformation 2 2 Eddy Diffusivity Tensor In FALL3D 6 2 only the diagonal components of the Eddy Diffusivity Tensor i e the vertical K and the horizontal Kp Kz Ky components are considered The available choices for describing the vertical component K are 1 Option CONSTANT i e K constant where the constant value is assigned by the user FALL3D 6 2 USER S MANUAL 4 Coordinates X mx Y my Z z h z y Horizontal Velocities Vx muz
14. Settling velocity models There are several semi empirical parameterizations for the particle settling velocity vs if one assumes that particles settle down at their terminal velocity 4g Pp Pa d 1 3CaPa 0 Us where pa and pp denote air and particle density respectively d is the particle equivalent diameter and Ca is the drag coefficient Cy depends on the Reynolds number Re dus Va Va Ha pa is the kinematic viscosity of air Ha the dynamic viscosity In FALL3D 6 2 different options are possible for estimating settling velocity such as 1 ARASTOOPOUR model Arastoopour et al 1982 24 1 0 15Re 687 Re lt 988 947 Ci Re 11 0 44 Re gt 988 947 valid for spherical particles only 2 GANSER model Ganser 1993 qe 0 6567 0 4305K2 Ca Beg 1 0 1118 Re Ki Ko jt E a Re Kk Ko where K 3 dn d 21p70 5 Kz 101 8148 Logy are two shape factors dn is the average between the minimum and the maximum axis d is the equal volume sphere and y is the particle sphericity yw 1 for spheres For calculating the sphericity is practical to use the concepts of operational and working sphericity work introduced by Wadell 1933 Aschenbrenner 1956 which are based on the determination of the volume and of the three dimensions of a particle respectively P2Q 1 P 1 Q 6 1 4 P2 14 Q with P S I Q I L where L is the longest particle dimension J is the longest dime
15. a database file in NetCDF format This file can be created by an external utility program SETDBS This strategy allows FALL3D 6 2 to be used from micro to meso scale In the PUB distribution version there are a few options to generate this database depending on the scale of application For the possible choices see Section 4 2 2 5 Source term FALL3D 6 2 reads the time dependent source term mass released per unit time at each grid point from an external file This file can be generated by the SETSRC utility program as i a point source ii imposing a mushroom like shape Suzuki option or iii by using a model based on the Buoyant Plume Theory BPT see Section 4 4 2 6 Particle aggregation A subroutine describing particle aggregation in presence of water is being tested Aggregation model and validation tests are presented in Costa et al 2010 Folch et al 2010 3 Overview of the program FALL3D 6 2 FALL3D 6 2 needs the following input files e An input file where control parameters and options are specified filename inp This file is read by FALL3D 6 2 and the utility programs e A database file in NetCDF format see Appendix C containing all meteorological data and the topography filename dbs nc e A granulometry file specifying the characteristics of the particles emitted into the atmosphere filename grn FALL3D 6 2 USER S MANUAL 7 A source file specifying the discharge rates at the source points typically al
16. al Prognostic Models MMPM to a finer scale In this case only the UTM coordinate system can be used Note that the output of CALMET is a binary file that depends on the architecture of the machine were it was generated Moreover note that this option is compatible only with a CALMET output time step equal to an hour i e nsecdt 3600 The third choice NCEP 1 option uses data from NCEP re analysis 1 see http www esrl noaa gov psd data gridded data ncep reanalysis html Other choices available only in the PROF version contemplate several global and mesoscale me teorological models such as ARPA SIM ETA GFS or NMMb FALL3D 6 2 USER S MANUAL 12 ne diam 1 rho 1 sphe 1 fe 1 diam nc rho nc sphe 1 fe nc Table 2 Format of the granulometry file filename grn 4 3 The granulometry file filename grn The granulometry file is an ASCII file containing the definition of the particle classes a class is character ized by particle size density and sphericity This file can be created by the utility program SETGRN Note that SETGRN only generates distributions which are Gaussian or bi Gaussian in y log normal in d and linear in p and y FALL3D 6 2 can handle more general distributions but in this case the granulometry file filename grn has to be defined directly by the user The file format is described in Table 2 and the meaning of the used symbols is the following e nc Number of particle classes e diam Class diam
17. are YES or NO If YES FALL3D 6 2 writes results for all the classes If NO only total results are written TRACK_POINTS Possibilities are YES or NO If YES FALL3D 6 2 writes the tracking points files The database file filename dbs nc This file written in NetCDF format see Appendix C contains time dependent meteorological data wind field air temperature and density humidity etc needed by FALL3D 6 2 The file can be created by the external utility program SETDBS which reads meteo data and interpolates to the FALL3D 6 2 space time domain There are a several options to generate this database depending on the scale of application This strategy allows FALL3D 6 2 to be used from micro to meso scale The possible choices are described below The simplest option consists of using a horizontally uniform wind derived from a vertical profile typically obtained from sounding measurements or from indirect reconstructions The vertical profile needs to be specified in the file filename profile in the format described in the Appendix A In this case in addition to the profile filename profile it is also necessary to furnish a topography file filename top in GRD format see Appendix B The second choice CALMET option uses data derived from the output of the meteorological diag nostic model CALMET Scire et al 2000 This option is used for assimilating and interpolating short term forecasts or re analysis from Mesoscale Meteorologic
18. el inputs are meteorological data topography grain size distribution shape and density of particles and mass rate of particle injected into the atmosphere The FALL3D 6 2 model can be used as a tool for short term ash deposition forecasting and for volcanic fallout hazard assessment FALL3D 6 2 is available in two versions called PUB Public version and PROF Professional version More information on http www bsc es projects earthscience fal13d and http datasim ov ingv it Fal13d html 2 Ash transport model In this section we briefly describe the governing equations and the main assumptions used in FALL3D 6 2 For further details see Costa et al 2006 Folch et al 2009 2 1 Governing equations The main factors controlling atmospheric transport of ash are wind advection turbulent diffusion and gravitational settling of particles Neglecting particle particle interaction effects collisions aggregation etc the Eulerian form of the continuity equation written in a generalized coordinate system X Y Z is Byun and Schere 2006 Costa et al 2006 aC ac ac OC V a ox y OENE i 1 OC px OC px C px Fox 1x IX DY oxy DY OZ pxKz OZ S where C is the transformed concentration V Vx Vy Vz is the transformed wind speed Kx Ky and Kz are the diagonal terms of the transformed eddy diffusivity tensor p is the transformed atmospheric density and S is the transformed source term
19. es needed by SETSRC program BLOCK OUTPUT Defines the FALL3D 6 2 strategy for dumping of results FALL3D 6 2 USER S MANUAL 8 4 1 1 BLOCK TIME_UTC This block of data defines variables related to time and is used by FALL3D 6 2 and by the utility programs SETDBS and SETSRC YEAR Database starting year MONTH Database starting month 1 12 DAY Database starting day 1 31 BEGIN_METEO_DATA_ HOURS_AFTER_00 Time in h after OOOOUTC of the starting day at which meteorological data starts in the database file TIME_STEP_METEO_DATA_ MIN Time step in min of the meteo data in the database file END_METEO DATA_ HOURS_AFTER_00 Time in h after OOOOUTC of the starting day at which me teorological data ends in the database file This time slice has to be larger than time slices defined by the records ERUPTION_START_ HOURS_AFTER_00 and RUN_END_ HOURS_AFTER_00 If not the program will stop ERUPTION_START_ HOURS_AFTER_00 Eruption start hours after OOOOUTC of the day These are nt values nt gt 1 that indicate the starting times of the different eruptive phases Any type of transient behavior can be contemplated by adding a sufficient number of intervals Eruptive conditions plume height MFR etc are assumed constant during each phase i e a quasi steady approximation is used The first value must be equal or larger than the value of the record BEGIN_METEO_DATA_ HOURS_AFTER_00 ERUPTION_END_ HOURS_AFTER_00 Eruption
20. eter in mm e rho Class density in kg m sphe Class sphericity fc Class mass fraction 0 1 It must verify that Y fc 1 4 4 The source file filename src The source file filename src is an ASCII file containing the definition of the source term The source can be defined for different time phases during which source values are kept constant The number position and values i e Mass Flow Rate of the source points can vary from one time slice to another and cannot overlap There is no restriction on the number and duration of the time slices It allows in practise to discretize any kind of source term This file can be defined directly by the user in the format described in Table 3 or created by using the utility program SETSRC In the last case the filename src is created in accord to the parameter specified in the SOURCE block of the filename inp The options to be chosen in the filename inp are i a point source ii a mushroom like shape Suzuki option or iii an eruption column model based on the Buoyant Plume Theory BPT The format of the file filename src is described in Table 3 and the meaning of the used symbols is the following e itime1 Starting time of the time slice in sec after OOUTC of the starting day e itime2 End time of the time slice in sec after OOUTC of the eruption starting day e nsrc Number of source points can vary from one interval to another depending on the column height e nc Nu
21. ght corner Only used in the LON LAT option LATMIN Minimum latitude in decimal degrees of the domain i e latitude corresponding to bottom left corner Only used in the LON LAT option LATMAX Maximin latitude in decimal degrees of the domain i e latitude corresponding to top right corner Only used in the LON LAT option LON_VENT Vent longitude Only used in the LON LAT option LAT_VENT Vent latitude Only used in the LON LAT option FALL3D 6 2 USER S MANUAL 9 UTMZONE UTM zone code in format nnL e g 335 Only used in the UTM option XMIN minimum z coordinate of the domain bottom left corner UTM coordinates must be given in m Only used in the UTM option XMAX maximum zx coordinate of the domain top right corner UTM coordinates must be given in m Only used in the UTM option YMIN minimum y coordinate of the domain bottom left corner UTM coordinates must be given in m Only used in the UTM option YMAX maximum y coordinate of the domain top right corner UTM coordinates must be given in m Only used in the UTM option X_VENT x coordinate of the vent UTM coordinates must be given in m Only used in the UTM option Y_VENT y coordinate of the vent UTM coordinates must be given in m Only used in the UTM option NX Number of grid nodes in the x direction NY Number of grid nodes in the y direction ZLAYER_ M Array of heights in m of the vertical z layers in terrain following c
22. mber of particle classes e MFR Mass flow rate in kg s e x Longitude or x coordinate of the source isrc e y Latitude or y coordinate of the source isrc e z z coordinate of the source src above ground level a g 1 in m e src Mass flow rate in kg s of each granulometric class for this point source It must be verified that Y src isre ic MFR FALL3D 6 2 USER S MANUAL 13 itimel itime2 nsrc nc MFR x y zsrc 1 1 sre 1 nc x y zsrc nsrc 1 src nsrc nc Table 3 Format of the source file filename src Repeat this block for each time slice 4 5 The points file filename pts This file contains the names identifiers and coordinates of the points to be tracked Tt is used only when the record TRACK_POINTS in the input file filename inp is set to YES The format of the file filename pts consists of lines one line per point with three columns specifying the point name the point longitude or x coordinate if UTM coordinates are used and the point latitude or y coordinate if UTM coordinates are used There is no limit on the number of points 5 Program Setup 5 1 Installation To install FALL3D 6 2 and the utility programs uncompress and untar the file Fa113d 6 2 PUB tar gz It will create the folder structure shown in Table 4 The package contains the source codes scripts documentation and a run examples e For Unix Linux Mac X OS it is necessary to have a FORTRAN compiler and the NetCDF library
23. nsion perpendicular to L and S is the dimension perpendicular to both L and I Vwork 12 8 13 FALL3D 6 2 USER S MANUAL 6 3 WILSON model Walker et al 1971 Wilson and Huang 1979 using the interpolation suggested by Pfeiffer et al 2005 Zp oe PON TE Re lt 102 Ca 4 q 17 Calre Calne 103 Re 10 lt Re lt 103 14 Re gt 10 where y b c 2a is the particle aspect ratio a gt b gt c denote the particle semi axes 4 DELLINO model Dellino et al 2005 Uy 1 26055 Arg ope 15 where Ar gd pp Pa pa p2 is the Archimedes number g the gravity acceleration and is a particle shape factor sphericity to circularity ratio It is recommended to not extrapolate this option for particle diameter beyond the range used in the experiments by Dellino et al 2005 Since for FALL3D 6 2 the primary particle shape factor is the sphericity y for sake of simplicity y in 14 and in 15 are calculated approximating particles as prolate ellipsoids the same approximation is used for estimating dn 2 4 Meteorological variables FALL3D 6 2 uses an off line strategy i e the meteorological variables are calculated independently by a different meteorological model or information and interpolated to the spatial and temporal grid of FALL3D 6 2 FALL3D 6 2 reads time dependent meteorological data wind field air temperature Monin Obukhov length L friction velocity ux and ABL height h and topography from
24. oints along y direction e XO x coordinate UTM in m of the grid bottom left corner e XF z coordinate UTM in m of the grid top right corner point e YO y coordinate UTM in m of the grid bottom left corner point e YF y coordinate UTM in m of the grid top right corner point e VAL Value at each grid point It consists of an array of NXxNY values stored starting from the bottom left corner and moving towards right then up towards the top right corner NX NY XO XF YO YF MAX v MIN v VAL i 1 bas vo i 1 NX VAL i j Khs vo i 1 NX VAL i NY vo i 1 NX Table 6 Format of a GRD file filename grd Appendix C The NetCDF format NetCDF network Common Data Form is a set of software libraries and machine independent data formats that support the creation access and sharing of array oriented scientific data available at http www unidata ucar edu software netcdf FALL3D 6 2 uses the standard NetCDF format for both database input file filename dbs nc and results output file filename res nc Only the PROF version comes with the utility to view manipulate or transform NetCDF files However there is a good number of open source codes to do so For example e ncview and ncdump http opendap org download nc clients html e Panoply http www giss nasa gov tools panoply FALL3D 6 2 USER S MANUAL 16 e GrADS http www iges org grads e NCL the NCAR Command Language http www ncl ucar edu
25. olcanic eruptions I Rate of fall of pyroclasts Geophys J Roy Astron Soc 22 377 383 Wilson L Huang T 1979 The influence of shape on the atmospheric settling velocity of volcanic ash particles Earth Planet Sci Lett 44 311 324
26. ong the eruptive column filename src Optionally a file specifying a list of points filename pts where tracking of variables is performed e g to compute ash arrival times accumulation rates etc The formats of the input files are described in Section 4 The FALL3D 6 2 package comes with a set of utility programs that can be used to generate the input files The utility SETDBS can be used to generate the database file filename dbs nc created in accord to the parameters specified in the blocks TIME_UTC and GIRD of the input file filename inp This util ity program reads meteo data from different sources and interpolates variables onto the FALL3D 6 2 computational grid The time slice of the database must be equal or larger than the simulation time slice The utility SETGRN can be used to generate the granulometry file filename grn in accord to the parameters specified in the block GRANULOMETRY of the input file filename inp This program generates only Gaussian and Bi Gaussian distributions For other distributions the user must provide the granulometry file The utility SETSRC can be used to generate the source file filename src in accord to the parameters specified in the blocks TIME_UTC and SOURCE of the input file filename inp The use of these utilities although recommended is not necessary if the user provides some of the necessary files directly Once a simulation is concluded FALL3D 6 2 outputs the following files A
27. oordinates It is not necessary to specify the number of vertical layers since it is automatically calculated by the program The vertical layers can be specified manually as an array of values or for equally spaced vertical discretization simply indicating the limits and the increment e g FROM 0 TO 10000 INCREMENT 1000 4 1 3 BLOCK FALL3D This block of data defines the variables needed by FALL3D 6 2 program TERMINAL_VELOCITY_MODEL Type of terminal settling velocity model Possibilities are ARASTOOPOUR GANSER WILSON and DELLINO VERTICAL_TURBULENCE_MODEL Type of model for vertical diffusion Possibilities are CONSTANT or SIMILARITY VERTICAL_DIFFUSION_COEFFICIENT_ M2 S Value of the diffusion coefficient in m s Only used if VERTICAL_TURBULENCE_MODEL CONSTANT HORIZONTAL_TURBULENCE_MODEL Type of model for horizontal diffusion Possibilities are CONSTANT RAMS or CMAQ HORIZONTAL_DIFFUSION_COEFFICIENT_ M2 S Value of the diffusion coefficient in m s Only used if HORIZONTAL_TURBULENCEMODEL CONSTANT RAMS_CS Value of Cg in the RAMS model see eq 6 Only used if HORIZONTAL_TURBULENCE_MODEL RAMS 4 14 BLOCK GRANULOMETRY This block of data defines the variables needed by SETGRN program DISTRIBUTION Type of distribution Possibilities are GAUSSIAN or BIGAUSSIAN NUMBER_OF_CLASSES Number of granulometric classes FI_MEAN Mean value of Gaussian distribution For Bi Gaussian distributions two values mu
28. s flow rate as an input the first option requires an iterative procedure e MFR_SEARCH_RANGE Two values n and m such that 10 and 10 specify the range of MFR values admitted in the iterative solving procedure i e it is assumed that 10 lt MFR lt 10 Only used if SOLVE_PLUME_FOR MFR e MASS_FLOW_RATE_ KGS Values of the mass flow rate in kg s for the nt eruptive phases Only used if SOLVE_PLUME_FOR HEIGHT FALL3D 6 2 USER S MANUAL 11 HEIGHT_ABOVE_VENT_ M Heights of the plume in m above the vent for the nt eruptive phases Note that the plume heights must be lower than the top of the computational domain specified in the record ZLAYER_ M of the GRID block Only used if SOLVE_PLUME_FOR MFR EXIT_VELOCIY_ MS Values of the magma exit velocity in m s at the vent for the nt eruptive phases EXIT_TEMPERATURE_ K Values of the magma exit temperature in K at the vent for the nt eruptive phases EXIT_VOLATILE FRACTION_ IN Values of the magma volatile at the vent for the nt eruptive phases in weight percent 4 1 6 BLOCK OUTPUT This block of data defines the output strategy of the FALL3D 6 2 program 4 2 POSTPROCESS_TIME_INTERVAL_ HOURS Postprocess time interval in hours POSTPROCESS_3D_VARIABLES Possibilities are YES or NO If YES FALL3D 6 2 writes 3D concentration in the output file filename res nc If NO only 2D variables are written to the output file POSTPROCESS _CLASSES Possibilities
29. st be provided FALL3D 6 2 USER S MANUAL 10 e FI_DISP Value of o Gaussian distribution For Bi Gaussian distributions two values must be provided e FIZRANGE Minimum and maximum values of min and maz respectively e DENSITY_RANGE Values of densities Pmin and Pmax in kg m associated to min and max par ticles Lineal interpolation is assumed In particular if Pinin Pmax density is constant for all classes e SPHERICITY_RANGE Values of sphericity Wmin and Uma associated to Pmin and Pay particles Lineal interpolation is assumed In particular if min Ymax sphericity is constant for all classes 4 15 BLOCK SOURCE This block of data defines the variables needed by the SETSRC program This program generates the source term eruptive column for each of the nt gt 1 eruptive phases e VENT_HEIGHT Height of the vent a s l in m e SOURCE_TYPE Type of source distribution Possibilities are POINT SUZUKI or PLUME In the case SOURCE_TYPE POINT only the sub block POINT_SOURCE is used e MASS_FLOW_RATE_ KGS Array of values of the mass flow rate in kg s for the nt eruptive phases Alternatively the user can use the word estimate and SETSRC automatically computes the MFR from the column heights based on empirical fits Mastin et al 2009 This is the typical situation during an eruption when column height is likely to be the only observable available e HEIGHT_ABOVE_VENT_ M Array of heights of the plume
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