NAM_PARAM_C2R2

It contains the control parameters for the C2R2 warm microphysical scheme (CCLOUD = “C2R2” or “KHKO” in NAM_PARAMn).

NAM_PARAM_C2R2 content

Fortran name	Fortran type	Default value
HPARAM_CCN	CHARACTER(LEN=3)	‘XXX’
HINI_CCN	CHARACTER(LEN=3)	‘XXX’
HTYPE_CCN	CHARACTER(LEN=1)	‘X’
XCHEN	REAL	0.0
XKHEN	REAL	0.0
XMUHEN	REAL	0.0
XBETAHEN	REAL	0.0
XCONC_CCN	REAL	0.0
XR_MEAN_CCN	REAL	0.0
XLOGSIG_CCN	REAL	0.0
XFSOLUB_CCN	REAL	1.0
XACTEMP_CCN	REAL	280.0
XALPHAC	REAL	3.0
XNUC	REAL	1.0
XALPHAR	REAL	1.0
XNUR	REAL	2.0
LRAIN	LOGICAL	.TRUE.
LSEDC	LOGICAL	.TRUE.
LACTIT	LOGICAL	.FALSE.
LSUPSAT	LOGICAL	.FALSE.
LDEPOC	LOGICAL	.FALSE.
XVDEPOC	REAL	0.02
LACTTKE	LOGICAL	.TRUE.

• HPARAM_CCN : Acronym of the CCN activation parameterization to use (‘CPB’,’TFH’ or ‘TWO’). The ‘TFH’ and ‘TWO’ need only to prescribe the XCHEN and XKHEN parameters.

  • ‘TWO’ refers to the classical activation spectrum of Twomey in the form \(N_{CCN}(s)= C s^k\)

  • ‘TFH’ includes some improvements brought by Feingold and Heymsfield [1992] to the original activation spectrum of Twomey.

  • ‘CPB’ refers to an activation spectrum in the form defined in Cohard et al. [1998] with

  \[N_{CCN}(s)= C s^k F(\mu,\frac{\displaystyle{k}}{\displaystyle{2}},\frac{\displaystyle{k}}{\displaystyle{2}}+1;-\beta s^2)\]

  where F is the hypergeometric function and \([C, k, \mu, \beta]\), four adjustable coefficients.

• HINI_CCN : If HPARAM_CCN=’CPB’ then the initial CCN characteristics are given in the ‘CCN’ or ‘AER’ format. In the ‘CCN’ case, the parameters XCHEN, XKHEN, XMUHEN and XBETAHEN must be given while it is the case for XCONC_CCN, XR_MEAN_CCN, XLOGSIG_CCN, XFSOLUB_CCN and XACTEMP_CCN if the ‘AER’ option is chosen.

  • ‘CCN’ The aerosols are directly characterized by their activation spectrum \(N_{CCN}(s)\) in the form \(C s^k\) or

  \[C s^k F(\mu,\frac{\displaystyle{k}}{\displaystyle{2}},\frac{\displaystyle{k}}{\displaystyle{2}}+1;-\beta s^2)\]

  • ‘AER’ The aerosols are particles which are characterized by a lognormal distribution law in the form:

  \[{\displaystyle N}/{\displaystyle {\sqrt {2 \pi}} {\rm ln}(\sigma)} exp \Big ( - {\displaystyle {\rm ln} (r/\overline{r})^2}/{\displaystyle 2 {\rm ln}(\sigma)^2} \Big )\]

  with distribution parameters (\(\overline{r}\) is the geometric mean radius, \(\sigma\) the geometric standard deviation and N the total particle number), by their solubility (\(\epsilon_m\)) and by their activation temperature (T) as described by Cohard et al. [2000].

• HTYPE_CCN : Aerosol type (‘M’ or ‘C’) if HPARAM_CCN==’CPB’ and HINI_CCN==’AER’ is chosen.

  • ‘M’: NaCl composition (large size maritime aerosols)

  • ‘C’: (NH4)2SO4 composition (small size continental aerosols)

• XCHEN : C parameter in the generic activation spectrum \(N_{CCN}(s)\)

• XKHEN : k parameter in the generic activation spectrum \(N_{CCN}(s)\)

• XMUHEN : \(\mu\) parameter in the hypergeometric function of the CPB form of the activation spectrum \(N_{CCN}(s)\)

• XBETAHEN:  :math:beta` parameter in the hypergeometric function of the CPB form of the activation spectrum \(N_{CCN}(s)\)

• XCONC_CCN : aerosol concentration number (N)

• XR_MEAN_CCN : geometric mean radius of the aerosol distribution (\(\overline{r}\))

• XLOGSIG_CCN : natural logarithm of the geometric standard deviation of the aerosol distribution (\({\rm ln}(\sigma)\))

• XFSOLUB_CCN : Mean solubility of the aerosols (\(\epsilon_m\))

• XACTEMP_CCN : Mean air temperature at which activation will occur.

• XALPHAC : First dispersion parameter (\(\alpha_c\)) of the \(\gamma\)-distribution law of the cloud droplets :

  \[\gamma_c (D)=\frac{\displaystyle{\alpha_c}}{\displaystyle{\Gamma(\nu_c)}} \lambda_c^{\alpha_c \nu_c} D ^{\alpha_c \nu_c -1} exp\big(-(\lambda_c D)^{\alpha_c}\big)\]

• XNUC : Second dispersion parameter (\(\nu_c\)) of the \(\gamma\)-distribution law of the cloud droplets

• XALPHAR : First dispersion parameter (\(\alpha_r\)) of the \(\gamma\)-distribution law of the rain drops

  \[\gamma_r (D)=\frac{\displaystyle{\alpha_r}}{\displaystyle{\Gamma(\nu_r)}} \lambda_r^{\alpha_r \nu_r} D ^{\alpha_r \nu_r -1} exp\big(-(\lambda_r D)^{\alpha_r}\big))\]

• XNUR : Second dispersion parameter (\(\nu_r\)) of the \(\gamma\)-distribution law of the rain drops

• LRAIN : Enables the rain formation (by cloud droplet autoconversion) if set to TRUE

• LSEDC : Cloud droplets are allowed to sediment if set to TRUE

• LACTIT : Activation by radiative cooling is taken into account if set to TRUE

• LSUPSAT : Pseudo-prognostic supersaturation according to Thouron et al. [2012] taken into account if set to TRUE

• LDEPOC : TRUE to enable cloud droplet deposition

• XVDEPOC : Droplet deposition velocity

• LACTTKE : TRUE to take into account TKE in the calculation of vertical velocity for activation