SUBROUTINE gastoparticle(pdtphys, zdz, zrho, xlat, pplay, t_seri, &
        id_prec, id_fine, tr_seri, his_g2pgas, his_g2paer)
  USE dimphy
  USE lmdz_infotrac
  USE lmdz_YOECUMF
  USE lmdz_yomcst
  USE lmdz_dimensions, ONLY: iim, jjm, llm, ndm
  USE lmdz_chem, ONLY: idms, iso2, iso4, ih2s, idmso, imsa, ih2o2, &
          n_avogadro, masse_s, masse_so4, rho_water, rho_ice
  USE lmdz_chem_spla, ONLY: masse_ammsulfate

  IMPLICIT NONE

  REAL :: pdtphys
  REAL :: zrho(klon, klev)
  REAL :: zdz(klon, klev)
  REAL :: tr_seri(klon, klev, nbtr)   ! traceurs
  REAL :: tend                 ! tendance par espece
  REAL :: xlat(klon)       ! latitudes pour chaque point
  REAL :: pi
  !   JE: 20140120
  REAL :: his_g2pgas(klon)
  REAL :: his_g2paer(klon)
  REAL :: tendincm3(klon, klev)
  REAL :: tempvar(klon, klev)
  REAL :: pplay(klon, klev)
  REAL :: t_seri(klon, klev)
  REAL :: tend2d(klon, klev)
  INTEGER :: id_prec, id_fine

  !------------------------- Scaling Parameter --------------------------

  !  REAL scale_param_so4(klon)  !Scaling parameter for sulfate

  INTEGER :: i, k
  REAL :: tau_chem     !---chemical lifetime in s

  !------------------------- Variables to save --------------------------

  !nhl      REAL fluxso4chem(klon,klev)
  !nhl      REAL flux_sparam_sulf(klon,klev)

  !======================================================================
  pi = atan(1.) * 4.

  IF (id_prec>0 .AND. id_fine>0) THEN
    DO k = 1, klev
      DO i = 1, klon

        !    tau_chem=scale_param_so4(i)*86400.*(8.-5.*cos(xlat(i)*pi/180.))    !tchemfctn2
        !nhl        tau_chem=86400.*(8.-5.*cos(xlat(i)*pi/180.))    !tchemfctn2
        tau_chem = 86400. * (5. - 4. * cos(xlat(i) * pi / 180.))    !
        tend = tr_seri(i, k, id_prec) * (1. - exp(-pdtphys / tau_chem)) ! Sulfate production
        !nhl        tend=(1.-exp(-pdtphys/tau_chem))
        !nhl        tend=scale_param_so4(i) !as this it works

        tr_seri(i, k, id_prec) = tr_seri(i, k, id_prec) - tend
        tr_seri(i, k, id_fine) = tr_seri(i, k, id_fine) + &
                tend / RNAVO * masse_ammsulfate  !--gAER/KgAir
        tend2d(i, k) = tend

        !nhl        fluxso4chem(i,k) = tend/RNAVO*masse_ammsulfate
        !nhl        flux_sparam_sulf(i,k) = tend/RNAVO*masse_ammsulfate
      ENDDO
    ENDDO

    tempvar = tend2d
    CALL kg_to_cm3(pplay, t_seri, tempvar)
    tendincm3 = tempvar

    DO k = 1, klev
      DO i = 1, klon

        ! his_g2pgas(i) = his_g2pgas(i) + tendincm3(i,k)*1e6*zdz(i,k)/pdtphys
        his_g2paer(i) = his_g2paer(i) + &
                tendincm3(i, k) / RNAVO * masse_ammsulfate * 1.e3 * &
                        1.e6 * zdz(i, k) / pdtphys    ! mg/m2/s
        his_g2pgas(i) = his_g2paer(i) * masse_s / masse_ammsulfate ! mg-S/m2/s

      ENDDO
    ENDDO
  ENDIF

  !

END SUBROUTINE gastoparticle