SUBROUTINE kg_to_cm3(pplay, t_seri, tr_seri)

  USE dimphy
  USE infotrac
  IMPLICIT NONE

  INCLUDE "dimensions.h"
  INCLUDE "YOMCST.h"

  REAL :: t_seri(klon, klev), pplay(klon, klev)
  REAL :: tr_seri(klon, klev)
  REAL :: zrho
  INTEGER :: i, k

  DO k = 1, klev
    DO i = 1, klon
      zrho = pplay(i, k) / t_seri(i, k) / RD
      tr_seri(i, k) = tr_seri(i, k) / 1.e6 * zrho
    ENDDO
  ENDDO

END SUBROUTINE kg_to_cm3