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|
!**********************************************************************
! 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 <http://www.gnu.org/licenses/>. *
!**********************************************************************
subroutine init_domainfill
!
!*****************************************************************************
! *
! Initializes particles equally distributed over the first release location *
! specified in file RELEASES. This box is assumed to be the domain for doing *
! domain-filling trajectory calculations. *
! All particles carry the same amount of mass which alltogether comprises the*
! mass of air within the box. *
! *
! Author: A. Stohl *
! *
! 15 October 2002 *
! *
!*****************************************************************************
! *
! Variables: *
! *
! numparticlecount consecutively counts the number of particles released *
! nx_we(2) grid indices for western and eastern boundary of domain- *
! filling trajectory calculations *
! ny_sn(2) grid indices for southern and northern boundary of domain- *
! filling trajectory calculations *
! *
!*****************************************************************************
use point_mod
use par_mod
use com_mod
implicit none
integer :: j,ix,jy,kz,ncolumn,numparttot
real :: gridarea(0:nymax-1),pp(nzmax),ylat,ylatp,ylatm,hzone,ran1
real :: cosfactm,cosfactp,deltacol,dz1,dz2,dz,pnew,fractus
real,parameter :: pih=pi/180.
real :: colmass(0:nxmax-1,0:nymax-1),colmasstotal,zposition
integer :: ixm,ixp,jym,jyp,indzm,indzp,in,indzh,i,jj
real :: pvpart,ddx,ddy,rddx,rddy,p1,p2,p3,p4,y1(2)
integer :: idummy = -11
! Determine the release region (only full grid cells), over which particles
! shall be initialized
! Use 2 fields for west/east and south/north boundary
!**************************************************************************
nx_we(1)=max(int(xpoint1(1)),0)
nx_we(2)=min((int(xpoint2(1))+1),nxmin1)
ny_sn(1)=max(int(ypoint1(1)),0)
ny_sn(2)=min((int(ypoint2(1))+1),nymin1)
! For global simulations (both global wind data and global domain-filling),
! set a switch, such that no boundary conditions are used
!**************************************************************************
if (xglobal.and.sglobal.and.nglobal) then
if ((nx_we(1).eq.0).and.(nx_we(2).eq.nxmin1).and. &
(ny_sn(1).eq.0).and.(ny_sn(2).eq.nymin1)) then
gdomainfill=.true.
else
gdomainfill=.false.
endif
endif
! Do not release particles twice (i.e., not at both in the leftmost and rightmost
! grid cell) for a global domain
!*****************************************************************************
if (xglobal) nx_we(2)=min(nx_we(2),nx-2)
! Calculate area of grid cell with formula M=2*pi*R*h*dx/360,
! see Netz, Formeln der Mathematik, 5. Auflage (1983), p.90
!************************************************************
do jy=ny_sn(1),ny_sn(2) ! loop about latitudes
ylat=ylat0+real(jy)*dy
ylatp=ylat+0.5*dy
ylatm=ylat-0.5*dy
if ((ylatm.lt.0).and.(ylatp.gt.0.)) then
hzone=1./dyconst
else
cosfactp=cos(ylatp*pih)*r_earth
cosfactm=cos(ylatm*pih)*r_earth
if (cosfactp.lt.cosfactm) then
hzone=sqrt(r_earth**2-cosfactp**2)- &
sqrt(r_earth**2-cosfactm**2)
else
hzone=sqrt(r_earth**2-cosfactm**2)- &
sqrt(r_earth**2-cosfactp**2)
endif
endif
gridarea(jy)=2.*pi*r_earth*hzone*dx/360.
end do
! Do the same for the south pole
if (sglobal) then
ylat=ylat0
ylatp=ylat+0.5*dy
ylatm=ylat
cosfactm=0.
cosfactp=cos(ylatp*pih)*r_earth
hzone=sqrt(r_earth**2-cosfactm**2)- &
sqrt(r_earth**2-cosfactp**2)
gridarea(0)=2.*pi*r_earth*hzone*dx/360.
endif
! Do the same for the north pole
if (nglobal) then
ylat=ylat0+real(nymin1)*dy
ylatp=ylat
ylatm=ylat-0.5*dy
cosfactp=0.
cosfactm=cos(ylatm*pih)*r_earth
hzone=sqrt(r_earth**2-cosfactp**2)- &
sqrt(r_earth**2-cosfactm**2)
gridarea(nymin1)=2.*pi*r_earth*hzone*dx/360.
endif
! Calculate total mass of each grid column and of the whole atmosphere
!*********************************************************************
colmasstotal=0.
do jy=ny_sn(1),ny_sn(2) ! loop about latitudes
do ix=nx_we(1),nx_we(2) ! loop about longitudes
pp(1)=rho(ix,jy,1,1)*r_air*tt(ix,jy,1,1)
pp(nz)=rho(ix,jy,nz,1)*r_air*tt(ix,jy,nz,1)
colmass(ix,jy)=(pp(1)-pp(nz))/ga*gridarea(jy)
colmasstotal=colmasstotal+colmass(ix,jy)
end do
end do
write(*,*) 'Atm. mass: ',colmasstotal
if (ipin.eq.0) numpart=0
! Determine the particle positions
!*********************************
numparttot=0
numcolumn=0
do jy=ny_sn(1),ny_sn(2) ! loop about latitudes
ylat=ylat0+real(jy)*dy
do ix=nx_we(1),nx_we(2) ! loop about longitudes
ncolumn=nint(0.999*real(npart(1))*colmass(ix,jy)/ &
colmasstotal)
if (ncolumn.eq.0) goto 30
if (ncolumn.gt.numcolumn) numcolumn=ncolumn
! Calculate pressure at the altitudes of model surfaces, using the air density
! information, which is stored as a 3-d field
!*****************************************************************************
do kz=1,nz
pp(kz)=rho(ix,jy,kz,1)*r_air*tt(ix,jy,kz,1)
end do
deltacol=(pp(1)-pp(nz))/real(ncolumn)
pnew=pp(1)+deltacol/2.
jj=0
do j=1,ncolumn
jj=jj+1
! For columns with many particles (i.e. around the equator), distribute
! the particles equally, for columns with few particles (i.e. around the
! poles), distribute the particles randomly
!***********************************************************************
if (ncolumn.gt.20) then
pnew=pnew-deltacol
else
pnew=pp(1)-ran1(idummy)*(pp(1)-pp(nz))
endif
do kz=1,nz-1
if ((pp(kz).ge.pnew).and.(pp(kz+1).lt.pnew)) then
dz1=pp(kz)-pnew
dz2=pnew-pp(kz+1)
dz=1./(dz1+dz2)
! Assign particle position
!*************************
! Do the following steps only if particles are not read in from previous model run
!*****************************************************************************
if (ipin.eq.0) then
xtra1(numpart+jj)=real(ix)-0.5+ran1(idummy)
if (ix.eq.0) xtra1(numpart+jj)=ran1(idummy)
if (ix.eq.nxmin1) xtra1(numpart+jj)= &
real(nxmin1)-ran1(idummy)
ytra1(numpart+jj)=real(jy)-0.5+ran1(idummy)
ztra1(numpart+jj)=(height(kz)*dz2+height(kz+1)*dz1)*dz
if (ztra1(numpart+jj).gt.height(nz)-0.5) &
ztra1(numpart+jj)=height(nz)-0.5
! Interpolate PV to the particle position
!****************************************
ixm=int(xtra1(numpart+jj))
jym=int(ytra1(numpart+jj))
ixp=ixm+1
jyp=jym+1
ddx=xtra1(numpart+jj)-real(ixm)
ddy=ytra1(numpart+jj)-real(jym)
rddx=1.-ddx
rddy=1.-ddy
p1=rddx*rddy
p2=ddx*rddy
p3=rddx*ddy
p4=ddx*ddy
do i=2,nz
if (height(i).gt.ztra1(numpart+jj)) then
indzm=i-1
indzp=i
goto 6
endif
end do
6 continue
dz1=ztra1(numpart+jj)-height(indzm)
dz2=height(indzp)-ztra1(numpart+jj)
dz=1./(dz1+dz2)
do in=1,2
indzh=indzm+in-1
y1(in)=p1*pv(ixm,jym,indzh,1) &
+p2*pv(ixp,jym,indzh,1) &
+p3*pv(ixm,jyp,indzh,1) &
+p4*pv(ixp,jyp,indzh,1)
end do
pvpart=(dz2*y1(1)+dz1*y1(2))*dz
if (ylat.lt.0.) pvpart=-1.*pvpart
! For domain-filling option 2 (stratospheric O3), do the rest only in the stratosphere
!*****************************************************************************
if (((ztra1(numpart+jj).gt.3000.).and. &
(pvpart.gt.pvcrit)).or.(mdomainfill.eq.1)) then
! Assign certain properties to the particle
!******************************************
nclass(numpart+jj)=min(int(ran1(idummy)* &
real(nclassunc))+1,nclassunc)
numparticlecount=numparticlecount+1
npoint(numpart+jj)=numparticlecount
idt(numpart+jj)=mintime
itra1(numpart+jj)=0
itramem(numpart+jj)=0
itrasplit(numpart+jj)=itra1(numpart+jj)+ldirect* &
itsplit
xmass1(numpart+jj,1)=colmass(ix,jy)/real(ncolumn)
if (mdomainfill.eq.2) xmass1(numpart+jj,1)= &
xmass1(numpart+jj,1)*pvpart*48./29.*ozonescale/10.**9
else
jj=jj-1
endif
endif
endif
end do
end do
numparttot=numparttot+ncolumn
if (ipin.eq.0) numpart=numpart+jj
30 continue
end do
end do
! Check whether numpart is really smaller than maxpart
!*****************************************************
if (numpart.gt.maxpart) then
write(*,*) 'numpart too large: change source in init_atm_mass.f'
write(*,*) 'numpart: ',numpart,' maxpart: ',maxpart
endif
xmassperparticle=colmasstotal/real(numparttot)
! Make sure that all particles are within domain
!***********************************************
do j=1,numpart
if ((xtra1(j).lt.0.).or.(xtra1(j).ge.real(nxmin1)).or. &
(ytra1(j).lt.0.).or.(ytra1(j).ge.real(nymin1))) then
itra1(j)=-999999999
endif
end do
! For boundary conditions, we need fewer particle release heights per column,
! because otherwise it takes too long until enough mass has accumulated to
! release a particle at the boundary (would take dx/u seconds), leading to
! relatively large position errors of the order of one grid distance.
! It's better to release fewer particles per column, but to do so more often.
! Thus, use on the order of nz starting heights per column.
! We thus repeat the above to determine fewer starting heights, that are
! used furtheron in subroutine boundcond_domainfill.f.
!****************************************************************************
fractus=real(numcolumn)/real(nz)
write(*,*) 'Total number of particles at model start: ',numpart
write(*,*) 'Maximum number of particles per column: ',numcolumn
write(*,*) 'If ',fractus,' <1, better use more particles'
fractus=sqrt(max(fractus,1.))/2.
do jy=ny_sn(1),ny_sn(2) ! loop about latitudes
do ix=nx_we(1),nx_we(2) ! loop about longitudes
ncolumn=nint(0.999/fractus*real(npart(1))*colmass(ix,jy) &
/colmasstotal)
if (ncolumn.gt.maxcolumn) stop 'maxcolumn too small'
if (ncolumn.eq.0) goto 80
! Memorize how many particles per column shall be used for all boundaries
! This is further used in subroutine boundcond_domainfill.f
! Use 2 fields for west/east and south/north boundary
!************************************************************************
if (ix.eq.nx_we(1)) numcolumn_we(1,jy)=ncolumn
if (ix.eq.nx_we(2)) numcolumn_we(2,jy)=ncolumn
if (jy.eq.ny_sn(1)) numcolumn_sn(1,ix)=ncolumn
if (jy.eq.ny_sn(2)) numcolumn_sn(2,ix)=ncolumn
! Calculate pressure at the altitudes of model surfaces, using the air density
! information, which is stored as a 3-d field
!*****************************************************************************
do kz=1,nz
pp(kz)=rho(ix,jy,kz,1)*r_air*tt(ix,jy,kz,1)
end do
! Determine the reference starting altitudes
!*******************************************
deltacol=(pp(1)-pp(nz))/real(ncolumn)
pnew=pp(1)+deltacol/2.
do j=1,ncolumn
pnew=pnew-deltacol
do kz=1,nz-1
if ((pp(kz).ge.pnew).and.(pp(kz+1).lt.pnew)) then
dz1=pp(kz)-pnew
dz2=pnew-pp(kz+1)
dz=1./(dz1+dz2)
zposition=(height(kz)*dz2+height(kz+1)*dz1)*dz
if (zposition.gt.height(nz)-0.5) zposition=height(nz)-0.5
! Memorize vertical positions where particles are introduced
! This is further used in subroutine boundcond_domainfill.f
!***********************************************************
if (ix.eq.nx_we(1)) zcolumn_we(1,jy,j)=zposition
if (ix.eq.nx_we(2)) zcolumn_we(2,jy,j)=zposition
if (jy.eq.ny_sn(1)) zcolumn_sn(1,ix,j)=zposition
if (jy.eq.ny_sn(2)) zcolumn_sn(2,ix,j)=zposition
! Initialize mass that has accumulated at boundary to zero
!*********************************************************
acc_mass_we(1,jy,j)=0.
acc_mass_we(2,jy,j)=0.
acc_mass_sn(1,jy,j)=0.
acc_mass_sn(2,jy,j)=0.
endif
end do
end do
80 continue
end do
end do
! If particles shall be read in to continue an existing run,
! then the accumulated masses at the domain boundaries must be read in, too.
! This overrides any previous calculations.
!***************************************************************************
if (ipin.eq.1) then
open(unitboundcond,file=path(2)(1:length(2))//'boundcond.bin', &
form='unformatted')
read(unitboundcond) numcolumn_we,numcolumn_sn, &
zcolumn_we,zcolumn_sn,acc_mass_we,acc_mass_sn
close(unitboundcond)
endif
end subroutine init_domainfill
|
