Changeset 5466 for LMDZ6/branches/contrails/libf/phylmd/lmdz_aviation.f90

Timestamp:

Jan 6, 2025, 5:34:43 PM (4 days ago)

Author:

aborella

Message:

Modification to the shearing process

File:

• LMDZ6/branches/contrails/libf/phylmd/lmdz_aviation.f90 (modified) (2 diffs)

LMDZ6/branches/contrails/libf/phylmd/lmdz_aviation.f90

@@ -108 +108 @@
 ! Local
 !
-! for Schmidt-Applemant criteria
+! for Schmidt-Appleman criteria
 REAL, DIMENSION(1) :: ztemp, zpplay, qzero, zqsatl, zdqsatl
 REAL :: Gcont, qsatl_crit, psatl_crit, pcrit
@@ -343 +343 @@
 
 !--The clouds are then sheared. We keep the shape and number
-!--assumptions from before. The clouds are sheared along their
-!--semi-major axis (a_mix), on the entire cell heigh dz.
-!--The increase in size is
+!--assumptions from before. The clouds are sheared with a random orientation
+!--of the wind, on average we assume that the wind and the semi-major axis
+!--make a 45 degrees angle. Moreover, the contrails only mix
+!--along their semi-minor axis (b), because it is easier to compute.
+!--With this, the clouds increase in size along b only, by a factor
+!--L_shear * SQRT(2.) / 2. (to account for the 45 degrees orientation of the wind)
 L_shear = coef_shear_contrails * shear * dz * dtime
 !--therefore, the fraction of clear sky mixed is
-!-- N_cld_mix * ( (a + L_shear) * b - a * b ) * RPI / 2. / cell_area
+!-- N_cld_mix * ( a * (b + L_shear * SQRT(2.) / 2.) - a * b ) * RPI / 2. / cell_area
 !--and the fraction of cloud mixed is
-!-- N_cld_mix * ( (a * b) - (a - L_shear) * b ) * RPI / 2. / cell_area
+!-- N_cld_mix * ( a * b - a * (b - L_shear * SQRT(2.) / 2.) ) * RPI / 2. / cell_area
 !--(note that they are equal)
-shear_fra = RPI * L_shear * a_mix * bovera / 2. * N_cld_mix / cell_area
+shear_fra = RPI * SQRT(2.) / 2. * L_shear * a_mix / 2. * N_cld_mix / cell_area
 !--and the environment and cloud mixed fractions are the same,
 !--which we add to the previous calculated mixed fractions.