!********************************************************************** ! Copyright 1998,1999,2000,2001,2002,2005,2007,2008,2009,2010 * ! Andreas Stohl, Petra Seibert, A. Frank, Gerhard Wotawa, * ! Caroline Forster, Sabine Eckhardt, John Burkhart, Harald Sodemann * ! * ! This file is part of FLEXPART. * ! * ! FLEXPART is free software: you can redistribute it and/or modify * ! it under the terms of the GNU General Public License as published by* ! the Free Software Foundation, either version 3 of the License, or * ! (at your option) any later version. * ! * ! FLEXPART is distributed in the hope that it will be useful, * ! but WITHOUT ANY WARRANTY; without even the implied warranty of * ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * ! GNU General Public License for more details. * ! * ! You should have received a copy of the GNU General Public License * ! along with FLEXPART. If not, see . * !********************************************************************** subroutine initialize(itime,ldt,up,vp,wp, & usigold,vsigold,wsigold,xt,yt,zt,icbt) ! i i o o o ! o o o i i i o !***************************************************************************** ! * ! Calculation of trajectories utilizing a zero-acceleration scheme. The time* ! step is determined by the Courant-Friedrichs-Lewy (CFL) criterion. This * ! means that the time step must be so small that the displacement within * ! this time step is smaller than 1 grid distance. Additionally, a temporal * ! CFL criterion is introduced: the time step must be smaller than the time * ! interval of the wind fields used for interpolation. * ! For random walk simulations, these are the only time step criteria. * ! For the other options, the time step is also limited by the Lagrangian * ! time scale. * ! * ! Author: A. Stohl * ! * ! 16 December 1997 * ! * ! Literature: * ! * !***************************************************************************** ! * ! Variables: * ! h [m] Mixing height * ! lwindinterv [s] time interval between two wind fields * ! itime [s] current temporal position * ! ldt [s] Suggested time step for next integration * ! ladvance [s] Total integration time period * ! rannumb(maxrand) normally distributed random variables * ! up,vp,wp random velocities due to turbulence * ! usig,vsig,wsig uncertainties of wind velocities due to interpolation * ! usigold,vsigold,wsigold like usig, etc., but for the last time step * ! xt,yt,zt Next time step's spatial position of trajectory * ! * ! * ! Constants: * ! cfl factor, by which the time step has to be smaller than * ! the spatial CFL-criterion * ! cflt factor, by which the time step has to be smaller than * ! the temporal CFL-criterion * ! * !***************************************************************************** use par_mod use com_mod use interpol_mod use hanna_mod use random_mod, only: ran3 implicit none integer :: itime integer :: ldt,nrand integer(kind=2) :: icbt real :: zt,dz,dz1,dz2,up,vp,wp,usigold,vsigold,wsigold real(kind=dp) :: xt,yt save idummy integer :: idummy = -7 icbt=1 ! initialize particle to "no reflection" nrand=int(ran3(idummy)*real(maxrand-1))+1 !****************************** ! 2. Interpolate necessary data !****************************** ! Compute maximum mixing height around particle position !******************************************************* ix=int(xt) jy=int(yt) ixp=ix+1 jyp=jy+1 h=max(hmix(ix ,jy,1,memind(1)), & hmix(ixp,jy ,1,memind(1)), & hmix(ix ,jyp,1,memind(1)), & hmix(ixp,jyp,1,memind(1)), & hmix(ix ,jy ,1,memind(2)), & hmix(ixp,jy ,1,memind(2)), & hmix(ix ,jyp,1,memind(2)), & hmix(ixp,jyp,1,memind(2))) zeta=zt/h !************************************************************* ! If particle is in the PBL, interpolate once and then make a ! time loop until end of interval is reached !************************************************************* if (zeta.le.1.) then call interpol_all(itime,real(xt),real(yt),zt) ! Vertical interpolation of u,v,w,rho and drhodz !*********************************************** ! Vertical distance to the level below and above current position ! both in terms of (u,v) and (w) fields !**************************************************************** dz1=zt-height(indz) dz2=height(indzp)-zt dz=1./(dz1+dz2) u=(dz1*uprof(indzp)+dz2*uprof(indz))*dz v=(dz1*vprof(indzp)+dz2*vprof(indz))*dz w=(dz1*wprof(indzp)+dz2*wprof(indz))*dz ! Compute the turbulent disturbances ! Determine the sigmas and the timescales !**************************************** if (turbswitch) then call hanna(zt) else call hanna1(zt) endif ! Determine the new diffusivity velocities !***************************************** if (nrand+2.gt.maxrand) nrand=1 up=rannumb(nrand)*sigu vp=rannumb(nrand+1)*sigv wp=rannumb(nrand+2) if (.not.turbswitch) then ! modified by mc wp=wp*sigw else if (cblflag.eq.1) then ! modified by mc if(-h/ol.gt.5) then !if (ol.lt.0.) then !if (ol.gt.0.) then !by mc : only for test correct is lt.0 call initialize_cbl_vel(idummy,zt,ust,wst,h,sigw,wp,ol) else wp=wp*sigw end if end if ! Determine time step for next integration !***************************************** if (turbswitch) then ldt=int(min(tlw,h/max(2.*abs(wp*sigw),1.e-5), & 0.5/abs(dsigwdz),600.)*ctl) else ldt=int(min(tlw,h/max(2.*abs(wp),1.e-5),600.)*ctl) endif ldt=max(ldt,mintime) usig=(usigprof(indzp)+usigprof(indz))/2. vsig=(vsigprof(indzp)+vsigprof(indz))/2. wsig=(wsigprof(indzp)+wsigprof(indz))/2. else !********************************************************** ! For all particles that are outside the PBL, make a single ! time step. Only horizontal turbulent disturbances are ! calculated. Vertical disturbances are reset. !********************************************************** ! Interpolate the wind !********************* call interpol_wind(itime,real(xt),real(yt),zt) ! Compute everything for above the PBL ! Assume constant turbulent perturbations !**************************************** ldt=abs(lsynctime) if (nrand+1.gt.maxrand) nrand=1 up=rannumb(nrand)*0.3 vp=rannumb(nrand+1)*0.3 nrand=nrand+2 wp=0. sigw=0. endif !**************************************************************** ! Add mesoscale random disturbances ! This is done only once for the whole lsynctime interval to save ! computation time !**************************************************************** ! It is assumed that the average interpolation error is 1/2 sigma ! of the surrounding points, autocorrelation time constant is ! 1/2 of time interval between wind fields !**************************************************************** if (nrand+2.gt.maxrand) nrand=1 usigold=rannumb(nrand)*usig vsigold=rannumb(nrand+1)*vsig wsigold=rannumb(nrand+2)*wsig end subroutine initialize