# UKCA Chemistry and Aerosol vn11.8 Tutorial 8

 Difficulty EASY Time to Complete Under 1 hour Video instructions https://youtu.be/6XqYfW2qHKY?t=641

Remember to run mosrs-cache-password in your Rose suite and UM branch terminals.

## What you will learn in this Tutorial

In this tutorial you will learn how the wet deposition of chemical species is handelled in UKCA. You will then add-in the wet deposition of one of your new tracers.

## Task 8.1: Add wet deposition of a species

Task 8.1: Add in wet deposition for BOB, using the following values:

$\ k(298)\$ $\ -\left({\Delta H}/R\right)\$ $\ k(298)$ for the 1st dissociation $\ -\left({\Delta H}/R\right)$ for the 1st dissociation $\ k(298)$ for the 2nd dissociation $\ -\left({\Delta H}/R\right)$ for the 2nd dissociation
$\ 0.21\times 10^{+06}\$ $\ 0.87\times 10^{+04}\$ $\ 0.2\times 10^{+02}\$ $\ 0.0\$ $\ 0.0\$ $\ 0.0\$

## Adding Wet Deposition

The formulation used in UKCA is described in Giannakopoulos (1999). This scheme uses the following formula to calculate the effective Henry's Law coefficient

$H_{eff}=k\left(298\right)\exp \left(-{\frac {\Delta H}{R}}\left[\left({\frac {1}{T}}\right)-\left({\frac {1}{298}}\right)\right]\right)$

where $k\left(298\right)$ is the rate constant at 298K.

During this tutorial you will be tasked with adding the wet deposition of one of your new tracers.

References

1. Giannakopoulos, C., M. P. Chipperfield, K. S. Law, and J. A. Pyle (1999), Validation and intercomparison of wet and dry deposition schemes using 210Pb in a global three-dimensional off-line chemical transport model, J. Geophys. Res., 104(D19), 23761–23784, doi:10.1029/1999JD900392.

## Turning on Wet Deposition for a Species

### Chemistry Scheme Specification

Within the UKCA code, whether a species is wet deposited or not is controlled in the ukca_chem_master.F90 module. In the chch_defs_master array there are lines like

!   9 DD:  6,WD:  4,
! No dry deposition for HO2NO2 in R and T schemes
chch_t1( 9,'HO2NO2    ',1,'TR        ','          ',0,1,r+t,0,0,107),          &
chch_t1( 9,'HO2NO2    ',1,'TR        ','          ',1,1,ti+s+st+cs,0,0,107),   &
!  10 DD:  7,WD:  5,   (20)
chch_t1(10,'HONO2     ',1,'TR        ','          ',1,1,ti+s+t+st+r+cs,        &
0,0,107),      &


Where the 1 in the 7th column turns on wet deposition of that species (being 0 otherwise). You will need to change the 0 to a 1 for the species that you wish to now wet deposit.

### Setting Henry's Law values

In the ukca_chem_master.F90 module the parameters required to calculate $H_{eff}$ are held in the henry_defs_master array (of defined size n_wet_master), and has format

 N 'SPECIES   ' $\ k(298)\$ $\ -\left({\Delta H}/R\right)\$ $\ k(298)$ for the 1st dissociation $\ -\left({\Delta H}/R\right)$ for the 1st dissociation $\ k(298)$ for the 2nd dissociation $\ -\left({\Delta H}/R\right)$ for the 2nd dissociation SCHEME QUALIFIER DISQUALIFIER VN

Columns 3 and 4 are used if the species dissociates in the aqueous phase. In this case, $H_{eff}$ is further multiplied by a factor of

$1+{\frac {k(aq)}{H^{+}}}$

where

$k(aq)=k\left(298\right)\exp \left(-{\frac {\Delta H}{R}}\left[\left({\frac {1}{T}}\right)-\left({\frac {1}{298}}\right)\right]\right)$

and column 3 contains the values of $k(298)$ and column 4 contains the value of $-{\Delta H}/R$. Similarly, if the species dissociates a second time then a further factor of $1+k(aq)/H^{+}$ is applied, where this value of $k(aq)$ is calculated from the values of $k(298)$ and $-{\Delta H}/R$ in columns 5 and 6.

Examples for this array are

! WD: 4
wetdep(4,'HO2NO2    ',                                                         &
(/0.13e+05,0.69e+04,0.10e-04,0.00e+00,0.00e+00,0.0e+00/),ti+t+st+r+cs,0,0,107),&
wetdep(4,'HO2NO2    ',                                                         &
(/0.20e+05,0.00e+00,0.10e-04,0.00e+00,0.00e+00,0.00e+00/),s,0,0,107),          &
! WD: 5
wetdep(5,'HONO2     ',                                                         &
(/0.21e+06,0.87e+04,0.20e+02,0.00e+00,0.00e+00,0.0e+00/),ti+t+st+r+cs,0,0,107),&
wetdep(5,'HONO2     ',                                                         &
(/0.21e+06,0.87e+04,0.157e+02,0.00e+00,0.00e+00,0.00e+00/),s,0,0,107),         &


## Solution to Task 8.1: Add wet deposition of a species

You were given the task

• Add in wet deposition for BOB, using the following values:
$\ k(298)\$ $\ -\left({\Delta H}/R\right)\$ $\ k(298)$ for the 1st dissociation $\ -\left({\Delta H}/R\right)$ for the 1st dissociation $\ k(298)$ for the 2nd dissociation $\ -\left({\Delta H}/R\right)$ for the 2nd dissociation
$\ 0.21\times 10^{+06}\$ $\ 0.87\times 10^{+04}\$ $\ 0.2\times 10^{+02}\$ $\ 0.0\$ $\ 0.0\$ $\ 0.0\$

For a working Rose suite that has completed this task, please see

• vm: u-ca024@182959

The specific Rose changes made are:

vm:

Index: app/fcm_make/rose-app.conf
===================================================================
--- app/fcm_make/rose-app.conf	(revision 182833)
+++ app/fcm_make/rose-app.conf	(revision 182959)
@@ -43,4 +43,4 @@
thread_utils=false
timer_version=3A
um_rev=\$BASE_UM_REV
-um_sources=branches/dev/lukeabraham/vn11.8_UKCA_Tutorial_Solns@94072
+um_sources=branches/dev/lukeabraham/vn11.8_UKCA_Tutorial_Solns@94120


These differences can be found in the file Tutorials/vn11.8/worked_solutions/Task08.1/Task08.1_rose.patch.

The specific UM changes made are:

Index: src/atmosphere/UKCA/ukca_chem_master.F90
===================================================================
--- src/atmosphere/UKCA/ukca_chem_master.F90	(revision 94072)
+++ src/atmosphere/UKCA/ukca_chem_master.F90	(revision 94120)
@@ -97,7 +97,7 @@
INTEGER, PARAMETER :: n_chch_master = 329 ! number of known species
INTEGER, PARAMETER :: n_het_master  =  18 ! number of heterogeneous reactions
INTEGER, PARAMETER :: n_dry_master  = 150 ! number of dry deposition reactions
-INTEGER, PARAMETER :: n_wet_master  = 106 ! number of wet deposition reactions
+INTEGER, PARAMETER :: n_wet_master  = 107 ! number of wet deposition reactions
INTEGER, PARAMETER :: n_bimol_master= 855 ! number of bimolecular reactions
INTEGER, PARAMETER :: n_ratj_master = 158 ! number of photolysis reactions
INTEGER, PARAMETER :: n_ratt_master =  76 ! number of termolecular reactions
@@ -847,7 +847,7 @@
! 272
chch_t1(272,'ALICE     ',1,'TR        ','          ',1,0,st,0,0,111),          &
! 273
-chch_t1(273,'BOB       ',1,'TR        ','          ',0,0,st,0,0,111)           &
+chch_t1(273,'BOB       ',1,'TR        ','          ',0,1,st,0,0,111)           &
/)

! ----------------------------------------------------------------------
@@ -2058,7 +2058,10 @@
(/2.30e+02,4.90e+03,0.00e+00,0.00e+00,0.00e+00,0.00e+00/),cs,0,0,107),         &
! WD: 96. Using MeOH Henry's Law Coeffs
wetdep( 96, 'ARNOH17   ',                                                      &
-(/2.30e+02,4.90e+03,0.00e+00,0.00e+00,0.00e+00,0.00e+00/),cs,0,0,107)          &
+(/2.30e+02,4.90e+03,0.00e+00,0.00e+00,0.00e+00,0.00e+00/),cs,0,0,107),         &
+!    UKCA Tutorial: wet deposition of BOB
+wetdep(97,'BOB       ',                                                        &
+(/0.21e+06,0.87e+04,0.20e+02,0.00e+00,0.00e+00,0.00e+00/),st,0,0,107)          &
/)

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


These differences can be found in the file Tutorials/vn11.8/worked_solutions/Task08.1/Task08.1_code.patch.

Sample output from this task can be found at Tutorials/vn11.8/sample_output/Task08.1/atmosa.pa19810901_00.

## Checklist

Put a 1 in the W column of the chch_defs_master in ukca_chem_master.F90.
Append the Henry's Law parameter values in the depvel_defs_master array, and increment n_wet_master.

Written by Luke Abraham 2021