phylmd/Mobidic/o3_chem.f

module o3_chem_m

  IMPLICIT none

  private o3_prod

contains

  subroutine o3_chem(julien, gmtime, t_seri, zmasse, pdtphys, q)

    ! This procedure evolves the ozone mass fraction through a time
    ! step taking only chemistry into account.

    ! All the 2-dimensional arrays are on the "physics" grid.
    ! Their shape is "(/klon, llm/)".
    ! Index "(i, :)" is for longitude "rlon(i)", latitude "rlat(i)".

    use nr_util, only: assert, pi
    use dimphy, only: klon
    use dimens_m, only: llm
    use regr_pr_comb_coefoz_m, only: c_Mob, a4_mass, a2, r_het_interm
    use orbite_m, only: orbite, zenang

    integer, intent(in):: julien ! jour julien, 1 <= julien <= 360
    real, intent(in):: gmtime ! heure de la journée en fraction de jour
    real, intent(in):: t_seri(:, :) ! (klon, llm) temperature, in K

    real, intent(in):: zmasse(:, :) ! (klon, llm)
    ! (column-density of mass of air in a cell, in kg m-2)
    ! "zmasse(:, k)" is for layer "k".)

    real, intent(in):: pdtphys ! time step for physics, in s

    real, intent(inout):: q(:, :) ! (klon, llm) mass fraction of ozone
    ! "q(:, k)" is at middle of layer "k".)

    ! Variables local to the procedure:
    integer k

    real c(klon, llm)
    ! (constant term during a time step in the net mass production
    ! rate of ozone by chemistry, per unit mass of air, in s-1)
    ! "c(:, k)" is at middle of layer "k".)

    real b(klon, llm)
    ! (coefficient of "q" in the net mass production
    ! rate of ozone by chemistry, per unit mass of air, in s-1)
    ! "b(:, k)" is at middle of layer "k".)

    real dq_o3_chem(klon, llm)
    ! (variation of ozone mass fraction due to chemistry during a time step)
    ! "dq_o3_chem(:, k)" is at middle of layer "k".)

    real earth_long
    ! (longitude vraie de la Terre dans son orbite solaire, par
    ! rapport au point vernal (21 mars), en degrés)

    real pmu0(klon) ! mean of cosine of solar zenith angle during "pdtphys"

    !-------------------------------------------------------------

    call assert(klon == (/size(q, 1), size(t_seri, 1), size(zmasse, 1)/), &
         "o3_chem klon")
    call assert(llm == (/size(q, 2), size(t_seri, 2), size(zmasse, 2)/), &
         "o3_chem llm")

    c = c_Mob + a4_mass * t_seri

    ! Compute coefficient "b":

    ! Heterogeneous chemistry is only at low temperature:
    where (t_seri < 195.)
       b = r_het_interm
    elsewhere
       b = 0.
    end where

    ! Heterogeneous chemistry is only during daytime:
    call orbite(real(julien), earth_long)
    call zenang(earth_long, gmtime, pdtphys, pmu0)
    forall (k = 1: llm)
       where (pmu0 <= cos(87. / 180. * pi)) b(:, k) = 0.
    end forall

    b = b + a2

    ! Midpoint method:

    ! Trial step to the midpoint:
    dq_o3_chem = o3_prod(q, zmasse, c, b) * pdtphys  / 2
    ! "Real" step across the whole interval:
    dq_o3_chem = o3_prod(q + dq_o3_chem, zmasse, c, b) * pdtphys
    q = q + dq_o3_chem

    ! Confine the mass fraction:
    q = min(max(q, 0.), .01)

  end subroutine o3_chem

  !*************************************************

  function o3_prod(q, zmasse, c, b)

    ! This function computes the production rate of ozone by chemistry.

    ! All the 2-dimensional arrays are on the "physics" grid.
    ! Their shape is "(/klon, llm/)".
    ! Index "(i, :)" is for longitude "rlon(i)", latitude "rlat(i)".

    use regr_pr_comb_coefoz_m, only: a6_mass
    use nr_util, only: assert
    use dimens_m, only: llm
    use dimphy, only: klon

    real, intent(in):: q(:, :) ! mass fraction of ozone
    ! "q(:, k)" is at middle of layer "k".)

    real, intent(in):: zmasse(:, :)
    ! (column-density of mass of air in a layer, in kg m-2)
    ! ("zmasse(:, k)" is for layer "k".)

    real, intent(in):: c(:, :)
    ! (constant term during a time step in the net mass production
    ! rate of ozone by chemistry, per unit mass of air, in s-1)
    ! "c(:, k)" is at middle of layer "k".)

    real, intent(in):: b(:, :)
    ! (coefficient of "q" in the net mass production rate of ozone by
    ! chemistry, per unit mass of air, in s-1)
    ! ("b(:, k)" is at middle of layer "k".)

    real o3_prod(klon, llm)
    ! (net mass production rate of ozone by chemistry, per unit mass
    ! of air, in s-1)
    ! ("o3_prod(:, k)" is at middle of layer "k".)

    ! Variables local to the procedure:

    real sigma_mass(klon, llm)
    ! (mass column-density of ozone above point, in kg m-2)
    ! ("sigma_mass(:, k)" is at middle of layer "k".)

    integer k

    !-------------------------------------------------------------------

    call assert(klon == (/size(q, 1), size(zmasse, 1), size(c, 1), &
         size(b, 1)/), "o3_prod 1")
    call assert(llm == (/size(q, 2), size(zmasse, 2), size(c, 2), &
         size(b, 2)/), "o3_prod 2")

    ! Compute the column-density above the base of layer
    ! "k", and, as a first approximation, take it as column-density
    ! above the middle of layer "k":
    sigma_mass(:, llm) = zmasse(:, llm) * q(:, llm) ! top layer
    do k =  llm - 1, 1, -1
       sigma_mass(:, k) = sigma_mass(:, k+1) + zmasse(:, k) * q(:, k)
    end do

    o3_prod = c + b * q + a6_mass * sigma_mass

  end function o3_prod

end module o3_chem_m
1	guez	3	module o3_chem_m
2
3			IMPLICIT none
4
5			private o3_prod
6
7			contains
8
9			subroutine o3_chem(julien, gmtime, t_seri, zmasse, pdtphys, q)
10
11			! This procedure evolves the ozone mass fraction through a time
12			! step taking only chemistry into account.
13
14	guez	18	! All the 2-dimensional arrays are on the "physics" grid.
15			! Their shape is "(/klon, llm/)".
16			! Index "(i, :)" is for longitude "rlon(i)", latitude "rlat(i)".
17
18	guez	36	use nr_util, only: assert, pi
19	guez	3	use dimphy, only: klon
20			use dimens_m, only: llm
21	guez	9	use regr_pr_comb_coefoz_m, only: c_Mob, a4_mass, a2, r_het_interm
22	guez	3	use orbite_m, only: orbite, zenang
23
24			integer, intent(in):: julien ! jour julien, 1 <= julien <= 360
25			real, intent(in):: gmtime ! heure de la journée en fraction de jour
26	guez	18	real, intent(in):: t_seri(:, :) ! (klon, llm) temperature, in K
27	guez	3
28	guez	18	real, intent(in):: zmasse(:, :) ! (klon, llm)
29	guez	3	! (column-density of mass of air in a cell, in kg m-2)
30	guez	18	! "zmasse(:, k)" is for layer "k".)
31	guez	3
32			real, intent(in):: pdtphys ! time step for physics, in s
33
34	guez	18	real, intent(inout):: q(:, :) ! (klon, llm) mass fraction of ozone
35			! "q(:, k)" is at middle of layer "k".)
36	guez	3
37			! Variables local to the procedure:
38	guez	7	integer k
39	guez	3
40			real c(klon, llm)
41			! (constant term during a time step in the net mass production
42			! rate of ozone by chemistry, per unit mass of air, in s-1)
43	guez	18	! "c(:, k)" is at middle of layer "k".)
44	guez	3
45			real b(klon, llm)
46			! (coefficient of "q" in the net mass production
47			! rate of ozone by chemistry, per unit mass of air, in s-1)
48	guez	18	! "b(:, k)" is at middle of layer "k".)
49	guez	3
50			real dq_o3_chem(klon, llm)
51			! (variation of ozone mass fraction due to chemistry during a time step)
52	guez	18	! "dq_o3_chem(:, k)" is at middle of layer "k".)
53	guez	3
54			real earth_long
55			! (longitude vraie de la Terre dans son orbite solaire, par
56			! rapport au point vernal (21 mars), en degrés)
57
58			real pmu0(klon) ! mean of cosine of solar zenith angle during "pdtphys"
59
60			!-------------------------------------------------------------
61
62			call assert(klon == (/size(q, 1), size(t_seri, 1), size(zmasse, 1)/), &
63			"o3_chem klon")
64			call assert(llm == (/size(q, 2), size(t_seri, 2), size(zmasse, 2)/), &
65			"o3_chem llm")
66
67	guez	7	c = c_Mob + a4_mass * t_seri
68	guez	3
69			! Compute coefficient "b":
70
71			! Heterogeneous chemistry is only at low temperature:
72			where (t_seri < 195.)
73	guez	7	b = r_het_interm
74	guez	3	elsewhere
75			b = 0.
76			end where
77
78			! Heterogeneous chemistry is only during daytime:
79			call orbite(real(julien), earth_long)
80			call zenang(earth_long, gmtime, pdtphys, pmu0)
81			forall (k = 1: llm)
82			where (pmu0 <= cos(87. / 180. * pi)) b(:, k) = 0.
83			end forall
84
85	guez	7	b = b + a2
86	guez	3
87			! Midpoint method:
88
89			! Trial step to the midpoint:
90	guez	7	dq_o3_chem = o3_prod(q, zmasse, c, b) * pdtphys / 2
91	guez	3	! "Real" step across the whole interval:
92	guez	7	dq_o3_chem = o3_prod(q + dq_o3_chem, zmasse, c, b) * pdtphys
93	guez	3	q = q + dq_o3_chem
94
95			! Confine the mass fraction:
96			q = min(max(q, 0.), .01)
97
98			end subroutine o3_chem
99
100			!*************************************************
101
102	guez	7	function o3_prod(q, zmasse, c, b)
103	guez	3
104			! This function computes the production rate of ozone by chemistry.
105
106	guez	18	! All the 2-dimensional arrays are on the "physics" grid.
107			! Their shape is "(/klon, llm/)".
108			! Index "(i, :)" is for longitude "rlon(i)", latitude "rlat(i)".
109
110	guez	9	use regr_pr_comb_coefoz_m, only: a6_mass
111	guez	36	use nr_util, only: assert
112	guez	3	use dimens_m, only: llm
113			use dimphy, only: klon
114
115			real, intent(in):: q(:, :) ! mass fraction of ozone
116	guez	18	! "q(:, k)" is at middle of layer "k".)
117	guez	3
118			real, intent(in):: zmasse(:, :)
119			! (column-density of mass of air in a layer, in kg m-2)
120	guez	18	! ("zmasse(:, k)" is for layer "k".)
121	guez	3
122			real, intent(in):: c(:, :)
123			! (constant term during a time step in the net mass production
124			! rate of ozone by chemistry, per unit mass of air, in s-1)
125	guez	18	! "c(:, k)" is at middle of layer "k".)
126	guez	3
127			real, intent(in):: b(:, :)
128	guez	18	! (coefficient of "q" in the net mass production rate of ozone by
129			! chemistry, per unit mass of air, in s-1)
130			! ("b(:, k)" is at middle of layer "k".)
131	guez	3
132			real o3_prod(klon, llm)
133			! (net mass production rate of ozone by chemistry, per unit mass
134			! of air, in s-1)
135	guez	18	! ("o3_prod(:, k)" is at middle of layer "k".)
136	guez	3
137			! Variables local to the procedure:
138
139			real sigma_mass(klon, llm)
140			! (mass column-density of ozone above point, in kg m-2)
141	guez	18	! ("sigma_mass(:, k)" is at middle of layer "k".)
142	guez	3
143			integer k
144
145			!-------------------------------------------------------------------
146
147			call assert(klon == (/size(q, 1), size(zmasse, 1), size(c, 1), &
148			size(b, 1)/), "o3_prod 1")
149			call assert(llm == (/size(q, 2), size(zmasse, 2), size(c, 2), &
150			size(b, 2)/), "o3_prod 2")
151
152			! Compute the column-density above the base of layer
153			! "k", and, as a first approximation, take it as column-density
154			! above the middle of layer "k":
155			sigma_mass(:, llm) = zmasse(:, llm) * q(:, llm) ! top layer
156			do k = llm - 1, 1, -1
157			sigma_mass(:, k) = sigma_mass(:, k+1) + zmasse(:, k) * q(:, k)
158			end do
159
160	guez	7	o3_prod = c + b * q + a6_mass * sigma_mass
161	guez	3
162			end function o3_prod
163
164			end module o3_chem_m