UKCA Release Jobs

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This page contains documentation on UKCA standard jobs that have been released or will soon be released.

You may also wish to look at the bugfixes page.

Contents

Getting Started

PUMA

The UK Met Office's Unified Model (UM) is provided for the NERC community from NCAS Computational Modelling Services via the PUMA (Providing UM Access) resource. To use UKCA you must have an account on PUMA. To obtain one, please go to the NCAS-CMS PUMA page.

FCM

The UM uses code management software, built around subversion, called FCM (Flexible Configuration Management).

If you have not used the UM with FCM, we ask that you first familiarise yourself with the system by doing the UM FCM Tutorial.

As well as being a good introduction to FCM and the UM User Interface (UMUI), it will also teach you how to set-up some configuration files that will be needed in the day-to-day running of the UM and UKCA.

Standard Release Jobs

UKCA can be configured through the UMUI, via it's own configuration panel. This mostly controls all the options required to run UKCA, although some extra changes have been made with hand-edits. To make it easy to get started with UKCA, several standard jobs have been created at various resolutions. To get started with UKCA, it should be a simple matter to take a copy of the UKCA job that you wish to run, changing a few user-specific options, and submitting the job.

Code Changes

To run a UKCA standard job, please take a copy of one of the jobs listed below. If you need to make code changes, you must make a new FCM branch, and merge in the UKCA branch which is used in the job that you are taking, then use your branch instead.

Please do not take a checkout of the UKCA branch used in the UMUI FCM panel (e.g. fcm:um_br/dev/luke/VN7.3_UKCA_CheM) and run from this as a working copy. If the fcm commit command is run from this directory it would commit any changes you have made to this branch. In this case, this would affect the branch for other UKCA users.

Job List

Available release jobs are:

UM Version UMUI Job-ID Climate Model Horizontal Resolution Vertical Levels Model Top Scheme Used FCM Branch Revision Number
7.3 HECToR:xfvfa
MONSooN: xfvfb
QESM-A N48 (2.5°×3.75°) L60 ~84km Tropospheric Chemistry with Isoprene fcm:um_br/dev/luke/VN7.3_UKCA_CheM 6791
7.3 HadGEM3-A r2.0 N96 (1.25°×1.875°) L63 ~40km Tropospheric Chemistry with Isoprene fcm:um_br/dev/luke/VN7.3_UKCA_CheM 6791
7.3 HECToR:xfvga
MONSooN:xfvgb
QESM-A N48 L60 ~84km Stratospheric Chemistry fcm:um_br/dev/luke/VN7.3_UKCA_CheM 6791
7.3 HadGEM3-A r2.0 N96 L85   85km Stratospheric Chemistry fcm:um_br/dev/luke/VN7.3_UKCA_CheM 6791
7.3 QESM-A N48 L60 ~84km Simple Tropospheric Chemistry with MODE Aerosol
7.3 HECToR:
MONSooN:xfxlb
N96 L38 ~40km Simple Tropospheric Chemistry with MODE Aerosol fcm:um_br/dev/mdalvi/VN7.3_MODEBLN_Rad_Indir 5953
7.3 HECToR:
MONSooN:xfxld
N96 L38 ~40km Simple Tropospheric Chemistry with MODE Aerosol (Nudged) fcm:um_br/dev/mdalvi/VN7.3_MODEBLN_Rad_Indir fcm:um_br/dev/mdalvi/VN7.3_nudged_new 5953
5586

Required UMUI Changes

Before submitting a UKCA job, you must first alter several options in the UMUI:

  • User-id, Mail-id (email address), and Tic-Code:
    Model Selection -> User Information and Target Machine -> General Details
    The user-id is your username on the target machine (i.e. HECToR).
    The tic-code will be the HECToR charging code, e.g. n02-chem. This code can be found by logging into the HECToR SAFE pages, and viewing your account information.
  • Target machine root extract directory (UM_ROUTDIR):
    Model Selection -> FCM Configuration -> FCM Extract and Build directories and Output levels
    This needs to be the full path to one of your directories on the target machine (HECToR /home directory or MONSooN /projects directory).

Optional UMUI Changes

As well as the required changes above, you may also want to change the following, depending on your experiments:

  • Model start date and run length:
    Model Selection -> Input/Output Control and Resources -> Start Date and Run Length Options
    NOTE: For Stratospheric Chemistry, the CFC and other long-lived trace gas concentrations will be highly dependent on the date - you will need to think about your chemical tracer initial conditions if you change the start date of a Stratospheric Chemistry run.
  • Reference date for meaning:
    Model Selection -> Atmosphere -> Control -> Post processing, Dumping & Meaning -> Dumping and meaning
    If you have changed the start date (above), you may need to change the reference date. If you do not do this, climate meaning may not work. Climate means will only be produced for a date after the reference date.
  • Archiving:
    Model Selection -> Post Processing -> Main Switch + General Questions
    Currently archiving is switched ON for most jobs.
    On HECToR all model output will placed in a directory called archive which is a sub-directory of your run directory.
    ON MONSooN, all data is copied to /nerc/PROJECT/USERID/JOBID.
    Superseded model restart dumps will be deleted.
    You will also need to ensure that your Monsoon project group name is correct.
  • UKCA Surface Emissions (as user single-level ancillary file):
    Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies and potential climatologies -> User single-level ancillary files and fields
    The emissions data-sets are taken from those used for AR5 integrations, and represent the year 2000. You may wish to change these emissions - to do this we recommend the use of Xancil, provided by NCAS-CMS.
  • UKCA 3D Emissions (as user multi-level ancillary file):
    Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies and potential climatologies -> User multi-level ancillary files and fields
    The standard aircraft emissions data-set comes from the Aero2K project, and represents the year 2000. You may wish to change these emissions - to do this we recommend the use of Xancil, provided by NCAS-CMS.
  • Tracer Initial Conditions:
    Model Selection -> Atmosphere -> STASH -> Initialisation of User Prognostics
    The table in this UMUI panel gives a listing of all the initial conditions of the STASH items defined by the user. They are given a STASH code, which the UM uses to identify the field. The UKCA tracers have a 5 digit code beginning at 34001 and ending at 34150, although 34149 and 34150 need to be initialised to zero. Several (or all) tracers will be initialised to some initial conditions, contained in the file listed by each tracer.

Continuation Run

After the job has run the first step, you will probably wish to turn on a continuation run.

  • Turn off compilation:
    Model Selection -> Compilations and Modifications -> Compile options for the UM model
    Model Selection -> Compilations and Modifications -> Compile options for the UM reconfiguration
    Set to Run from existing executable, as named below in both panels
  • Set to CRUN:
    Model Selection -> Input/Output Control and Resources -> User hand edit files
    Find the hand-edit crun.ed and set this to Y

Running a Perpetual Year

For some experiments, you may wish to run a perpetual year (i.e. a simulation of multiple years in length, each one representing the same year). There are two ways to two this:

  1. Manually re-run the same year
    • In this case you would run up until you have the 1st January start dump, then manually restart the simulation from this dump, run for 1 year and then send a new job off, running from the new 1st January start dump. You would need to ensure that the date used for each of these steps is for the year that you are interested in. To do this you will need to change how reconfiguration is performed.
    • Reconfiguration:
      Model Selection -> Atmosphere -> Ancillary and input data files -> Start Dump
      You will need to alter the directory path and name of file to point to the start-dump you are interested in. You must then turn off the radio button Using the reconfiguation and make sure that the start-date (listed at the top of this panel) matches that in the dump file.
  2. Create a multi-year simulation where all the input files are for a single year
    • This method is particularly useful when you want to run a perpetual year for more than a few years, as might be the case for Stratospheric Chemistry when 15-20 year spin-ups are needed. There are a few changes that need to be made to several ancillary files and the UMUI:
    1. Change Ancillary files:
      • The following acillary files will need to be changed, since these are not climatologies by default, but time-series. You may find that the directory that these files are placed in is set by an environment variable (e.g. $ANCIL_ATMOS etc.). This environment variable points to a directory on the target machine (HECToR or MONSooN). To find out what these variables are set to, go to:
        Model Selection -> Input/Output Control and Resources -> Time Convention and SCRIPT Environment Variables.
        • The single-level and multi-level (see above) user ancillary files may need to be changed to the year you are interested in.
        • Sea-Surface Temperature:
          Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies & potential climatologies -> Sea surface temperatures
        • Sea-Ice:
          Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies & potential climatologies -> Sea ice fields
        • 2D Sulphur Emissions:
          Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies & potential climatologies -> Sulphur cycle emissions (2D)
          NOTE: you should not need to change the DMS emissions
        • Soot Emissions:
          Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies & potential climatologies -> Soot Emissions
        • Biomass Emissions:
          Model Selection -> Atmosphere -> Ancillary and input data files -> Climatologies & potential climatologies -> Biomass Emissions
      • To create perpetual-year ancillary files:
        1. For each of the the ancillary files specified in these UMUI panels above, open in Xconv and select only the year that you are interested in and export this as a NetCDF file.
        2. Use Xancil to create replacement ancillary files for each of the above files. You will need to make sure that these are made as periodic in time.
        3. In the UMUI, replace the time-series ancillary files with your climatologies.
    2. UKCA changes:
      These changes are describing code and UMUI changes specific to the branch fcm:um_br/dev/luke/VN7.3_UKCA_Chem.
      • The changes to UKCA are controlled by two hand-edits:
        Model Selection -> Input/Output Control and Resources -> User hand edit files
        1. CheM_aerosol_background_on.ed/CheM_aerosol_background_off.ed
          • This hand-edit either specifies using a background aerosol climatology for all years (_on), or using a time-series of atmospheric aerosols (_off). The default used is CheM_aerosol_background_off.ed.
        2. CheM_trgas_presentday_full.ed (a pre-industrial version is also supplied, CheM_trgas_preI_full.ed)
          • This hand-edit gives values of certain trace-gases to UKCA. Some are taken from the UMUI:
            Model Selection -> Atmosphere -> Scientific Parameters and Sections -> Spec of Trace Gases
            These are:
            • CO2
            • CH4
            • N2O
            • CFC11 (CFCl3)
            • CFC12 (CF2Cl2)
            • CFC113 (CF2ClCFCl2)
            • HCFC22 (CHF2Cl)
          • Some gases are used by UKCA to specify constant values for the chemical solver.
            These are:
            • CH4 (TropIsop chemistry only)
            • CO2
            • H2
            • N2
            • O2
          • Some trace-gases are used in Stratospheric Chemistry, to specify the surface concentration of certain UKCA species (N2O, CF2Cl2, CFCl3, CH3Br, H2, and CH4). Some species are lumped together, so the surface concentrations of the following species can be set by the hand-edit:
            • CH3Br (as MeBr)
            • CH3Cl (as MeCl)
            • CH2Br2
            • H2
            • N2
            • CFC114
            • CFC115
            • CCl4
            • CH3CCl3 (as MeCCl3)
            • HCFC141b
            • HCFC142b
            • H1211
            • H1202
            • H1301
            • H2402
          • A program to determine the mass mixing ratios of these species routine can be found at /home/ukca/bin/scenario on PUMA. It is run by typing
            scenario YYYY/MM/DD <which scenario>
            on the command line, where
            • <which scenario> can either be WMOA1, RCP2.6, RCP4.5, RCP6.0 or RCP8.5
            • The year (YYYY) is between 1950 and 2100 for the WMOA1 scenario and 1765-2500 for any of the RCP scenarios
            • The code uses a 360 day calendar (12 months, 30 days per month).
          • To allow the specification of these gases in this way to be uses by UKCA, you will also need to turn on this option in the UMUI: UMUI values for CFCs etc
            Model Selection -> Atmosphere -> Model Configuration -> UKCA Chemistry and Aerosols -> STRAT

Adding New UKCA Tracers

You may wish to add new UKCA tracers, possibly with associated reactions. This is possible for both the TropIsop and StratChem configurations. There are two steps that you need to do - first, set up the new tracers for the UM, and second set up these tracers for UKCA. Adding tracers will require both UMUI hand-edit, STASH, and source-code changes.

  1. UMUI Changes
    • While these jobs only use a small sub-set of the total number of tracers allowed by the UM (150), due to the number of different schemes used, many of these other slots will have been reserved. While it is possible to use them, it is recommended that you choose an empty slot. To find which tracer slots are free, look in the file ukca_setd1defs.F90 which is found in the src/atmosphere/UKCA directory. In this file, locate the array specification of nm_spec (non-families). This array contains all 150 currently considered tracers. Several of these slots are unused, and these are the ones labeled XXX. Work out which number these are in the array, e.g. in the VN7.3_UKCA_CheM branch, numbers 40, 60, and 96-100 are currently free.
    • Take a copy of the tracer pre-STASHmasterfile (PSM) used by the UKCA job, and add a section for the tracer you are adding. You will need to change 3 numbers and the tracer name:
      1. The item number (Item): line 1, entry 3 (should be 1-150)
      2. The option code (Option Codes): line 3, entry 1 (last 3 digits, same number as Item)
      3. The field code (PPFC) : line 5, entry 2 (tracers begin numbering at 501 for tracer 1)
      4. The name of the tracer (Name): line 1, entry 4 (this should be representative of the species you are adding for clarity)
      • An example of a PSM entry is below, with XXX marking the locations to be changed
      • You will need to make sure that the lengths of the lines remains the same, otherwise the UMUI will not be able to read the PSM.
      • Replace the previous tracer PSM with your new one in the UMUI STASHmaster Panel:
        Model Selection -> Atmosphere -> STASH -> User-STASHmasterfiles. Diags, Progs & Ancils.
      • Initialise this tracer to a value in the UMUI Initialisation Panel:
        Model Selection -> Atmosphere -> STASH -> Initialisation of User Prognostics
        Scroll down the list until you come to your new tracer. The Option column will be blank - either
        1. initialise to zero (option 3)
        2. initialise to a constant value (option 6, value specified in column 4)
        3. initialise to a 3D field (option 7, file containing field specified in column 5. You may wish to use Xancil for this option)
        • It may be best to set the tracer to zero or a constant value at this point.
        • You may also wish to add the tracer through STASH to the climate meaning stream:
          Model Selection -> Atmosphere -> STASH -> STASH. Specification of Diagnostic requirements
    • With your new PSM, run the script make_tracer_list, found in the /home/ukca/bin directory on PUMA on this file. The output should be similar to:
      TC_UKCA=1,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
      1,0,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,1,1,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,1,
      • Take a copy of the hand-edit that your job uses to add the UKCA tracers. For TropIsop jobs this will be add_s34_CheT_tracers_L60/63.ed and for StratChem jobs this will beadd_s34_CheS_tracers_L60/85.ed.
        1. Find the lines that have the TC_UKCA definition, and replace it with the line you have generated with your PSM.
        2. Find the lines that define the value of TR_UKCA and increment this by the number of tracers you are adding.
      • Replace the original hand-edit in the UMUI with the one you have just created:
        Model Selection -> Input/Output Control and Resources -> User hand edit files
    • Make sure reconfiguration is on:
      Model Selection -> Atmosphere -> Ancillary and input data files -> Start Dump
      The radio-button Using the reconfiguration should be on
    • SAVE, PROCESS and SUBMIT the job. This should run with the extra tracer added. Look in a dump file to be sure that the tracer is there, and that it's value is as was set in the initialisation panel.
  2. UKCA code changes
    1. Adding the tracer
      • Before making these changes, you should run through the UM FCM Tutorial.
      • Any code changes should be made to a branch that you own. Make a new branch and merge in the UKCA branch that you are using (e.g. fcm:br/dev/luke/VN7.3_UKCA_CheM)
      • For these changes, you must be a copy of the UKCA branch. We suggest using a working copy rather than committing the changes:
        Model Selection -> FCM Configuration -> FCM Options for Atmosphere and Reconfiguration
        Set the UKCA branch to N and select the radio-button Include modifications from user working copy and put the full path (on PUMA) to the local copy of your branch
      • You will need to make some changes to ukca_setd1defs.F90
        • Edit the nm_spec (non-Families) array so that the slot used for the PSM now contains your tracer
        • Increment n_chem_tracers for the scheme you are using by the number of tracers added
        • You may also be adding emissions or surface boundary conditions.
          • For emissions, you would also increment n_chem_emissions and make changes to em_chem_spec, and the emissions ancillary file.
          • For boundary conditions, you would also increment n_boundary_vals and make changes to lbc_spec, and you may also make changes to ukca_scenario_prescribed/wmoa1.F90.
      • Take a copy of the jp_for_CheT/S.ed (T = TropIsop, S = StratChem) hand-edit:
        Model Selection -> Input/Output Control and Resources -> User hand edit files
        • Increase the values of JPCTR and JPSPEC by the number of tracers you are adding
        • Add the tracers:
          • For StratChem: Edit the file ukca_chem1_dat.F90 to add your tracer(s) into the chch_defs_strat type array, making sure that you use the same name as in the nm_spec array.
          • For TropIsop: Edit the file ukca_chem1_tropisop.F90 to add your tracer(s) into the chch_defs_tropisop type array, making sure that you use the same name as in the nm_spec array.
      • This should now run with the extra tracer considered as such by UKCA. However, there are no reactions/deposition being performed on it, so the tracer still should not change when viewed in a dump file
    2. Adding reactions, deposition etc
      • You will need to edit the ukca_chem1_dat.F90 or ukca_chem1_tropisop.F90 as appropriate to add reactions. These are defined
        • ratb_defs: Bimolecular reactions (JPBK in jp_for_CheT/S.ed)
        • ratt_defs: Termolecular reactions (JPTK in jp_for_CheT/S.ed)
        • rath_defs: Heterogeneous reactions (for StratChem only) (JPHK in jp_for_CheT/S.ed)
        • ratj_defs: Photolysis reactions (JPPJ in jp_for_CheT/S.ed)
        • depvel_defs: Dry-deposition (JPDD in jp_for_CheT/S.ed)
          • For species which are dry-deposited, you will also need to edit the chch_defs type, and put a 1 in the first column of the block of three numbers
          • The ordering of the depvel_defs type is dependent on the ordering of the tracers in chch_defs, so you will need to make sure that this is correct
        • henry_defs: Wet-deposition (Henry's Law) (JPDW in jp_for_CheT/S.ed)
          • For species which are wet-deposited, you will also need to edit the chch_defs type, and put a 1 in the second column of the block of three numbers
          • The ordering of the henry_defs type is dependent on the ordering of the tracers in chch_defs, so you will need to make sure that this is correct
        • NOTE: Emissions are not considered in ukca_chem1_dat/tropisop.F90
          • Emissions for most tropospheric species are considered by adding a field to the user single-level ancillary file (see above), and adding code to src/atmosphere/UKCA/ukca_setd1defs.F90 and src/atmosphere/UKCA/ukca_emission_ctl.F90.
          • Most stratospheric species are set as lower boundary conditions to the species. These are set in src/atmosphere/UKCA/ukca_scenario_wmoa1.F90 and src/atmosphere/UKCA/ukca_scenario_prescribed.F90 and the lbc_spec array is altered in src/atmosphere/UKCA/ukca_setd1defs.F90
        • These configurations of UKCA are built using the ASAD chemical integration package. For documentation on using ASAD, please see the ASAD webpage.
      • Edit the jp_for_CheT/S.ed to increment the JP counter(s) (listed above) associated with your changes, and also increase the size of JPNR, the total number of reactions, accordingly (dry- and wet-deposition are not counted in JPNR):
        Model Selection -> Input/Output Control and Resources -> User hand edit files
      • You may also need to add the conversion factor from MMR to VMR for your tracer:
        1. If needed, add the conversion factor to src/include/constant/c_v_m.h
        2. If needed, add a line to the WHERE block to copy this conversion factor into the c_species array in src/atmosphere/UKCA/ukca_cspecies.F90
      • SAVE, PROCESS and SUBMIT the job. This should now be using the new tracer in UKCA.
Blank pre-STASHmasterfile

The XXX labeled sections are ones which should be changed when adding a new UKCA tracer.

1|    1 |   34 |  XXX | XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX |
2|    2 |    0 |    1 |    1 |    2 |   10 |   11 |    0 |    0 |    0 |    0 |
3| 000000000000000000000000000XXX | 00000000000000000001 |    1 |
4|    1 |    0 | -99  -99  -99  -99  -99  -99  -99  -99  -99  -99 |
5|    0 |  XXX |    1 |   65 |    0 |    0 |    0 |    0 |    0 |

UMUI UKCA Panel

The UKCA configuration panel can be found at:

Model Selection -> Atmosphere -> Model Configuration -> UKCA Chemistry and Aerosols

The settings in the UMUI UKCA panel have been chosen for that specific chemistry/aerosol scheme, and choosing other options may not work. If you require extra functionality, please contact Luke Abraham to check on the current code status.

Tropospheric Chemistry with Isoprene - TropIsop

See also Tropospheric Chemistry with Isoprene description page.
Comparison of Tropospheric Chemistry with Isoprene in a number of model resolutions and UM versions.
This scheme using the FCM branch fcm:um_br/dev/luke/VN7.3_UKCA_CheM at revision 6791 (updated). It has 56 species (49 of which are tracers), 115 bimolecular reactions, 35 photolysis reactions (using rates determined using a 2D look-up table) and 15 termolecular reactions. 23 species are wet-deposited and 32 are dry-deposited (using a 2D dry-deposition scheme). Tropospheric Ox and CO budgets are outputted as standard, as are other diagnostics of interest, such as the CH4 lifetime and Stratosphere-Troposphere Exchange of O3.

The chemistry is integrated using the ASAD chemical package, using a sparse-matrix Newton-Raphson solver. While the UM dynamical timestep is every 20 model minutes, chemistry is called every model hour, although emissions are still performed every dynamical timestep. Top boundary conditions are used for O3 and NOy and CH4 is treated as a constant. The tracers are initialised to spun-up fields from a previous TropIsop run, however, we recommend that a 15 month-spin-up should be performed.

The chemistry scheme used in these simulations is the same as in Telford et al, Atmos. Chem. Phys., 10, 7117-7125, doi:10.5194/acp-10-7117-2010 (2010). A model description paper is also in preparation (O'Connor et al, 2011).

The tropospheric ozone concentrations in UKCA-TropIsop are biased slightly high. This is improved with using an interactive photolysis scheme, which will be released for general use soon.

Timings

It should be noted that due to "jitter" on the HPC platform, all timings are approximate. As a simulation progresses the time per model month may increase as the fields spin-up from their initial state.

Machine No. of Cores No. of Nodes Resolution Time for 1 Model Month
HECToR Phase2b 96 4 N48L60 ~50 minutes
MONSooN 64 2 N48L60 ~59 minutes

Stratospheric Chemistry - StratChem

See also Stratospheric Chemistry description page.
Ozone column in Dobson Units (DU) calculated from a UM7.3 N48L60 UKCA-StratChem run using interactive UKCA ozone in the UM radiation scheme. This is the mean of 21 model years representing 1990.
This scheme using the FCM branch fcm:um_br/dev/luke/VN7.3_UKCA_CheM at revision 6791 (updated). It has 41 species (36 of which are tracers), 113 bimolecular reactions, 34 photolysis reactions (using rates determined using a 3D look-up table), 17 termolecular reactions and 5 heterogeneous reactions. 15 species are wet-deposited and 15 are dry-deposited (using a 2D dry-deposition scheme). A stratospheric O3 is standard (based on the budget of Lee et al, JGR 107 DOI:10.1029/2001JD000538 (2002)), as are other diagnostics of interest, such as the CH4 lifetime and Stratosphere-Troposphere Exchange of O3.

The chemistry is integrated using the ASAD chemical package, using a sparse-matrix Newton-Raphson solver. While the UM dynamical timestep is every 20 model minutes, chemistry is called every model hour, although emissions are still performed every dynamical timestep. By default, lower boundary conditions set for the tracer concentrations of N2O, CH4, H2, CF2Cl2, CFCl3, CH3Br, and CH2Br2 are specified for the years 1950-2100. These values are also used in the UM radiation scheme, along with CO2 concentrations. The tracers are initialised to spun-up fields from a previous StratChem run, however it can take time for a Stratospheric run to equilibrate and spin-up times as long as 20 model years may be required if significant changes are made.

The chemistry scheme used in these simulations is the similar to that described in Morgenstern et al, Geosci. Model Dev., 2, 43-57, (2009).

Timings

It should be noted that due to "jitter" on the HPC platform, all timings are approximate. As a simulation progresses the time per model month may increase as the fields spin-up from their initial state.

Machine No. of Cores No. of Nodes Resolution Time for 1 Model Month
HECToR Phase2b 96 4 N48L60 ~46 minutes
MONSooN 64 2 N48L60 ~51 minutes

Simple Tropospheric Chemistry with GLOMAP-mode aerosol - UKCA-MODE

See also MODE Aerosol description page.

The UKCA aerosol scheme 'GLOMAP-mode' (sometimes called UKCA-MODE when in the UM) is described in detail in Mann et al (2010) and simulates aerosol microphysics (nucleation, condensation,coagulation and cloud processing), dry deposition, sedimentation and in-cloud/below-cloud scavenging. The scheme simulates atmospheric aerosol in a size-resolved manner with the chemical and aerosol microphysical processes determining the evolution of the size and composition of several size modes. The scheme transports the mass of sulphate, sea-salt, black carbon, organic matter and dust, along with the particle number concentration in each size mode. The aerosol scheme is coded flexibly to allow the same code to run with several alternative aerosol configurations via FORTRAN-90 modules.

UKCA-MODE can be coupled to all of the various UKCA chemistry schemes, but in this standard job uses the simple tropospheric chemistry scheme, extended to treat the degradation of the aerosol precursor species: sulphur dioxide (SO2);dimethylsulphide (DMS); and a lumped monoterpene tracer.

An interface between UKCA-MODE and the Edwards-Slingo radiation scheme allows the aerosol concentrations to interact with the radiation both directly (through scattering and absorption of incoming solar and outgoing long-wave radiation) and indirectly via modified cloud albedo. In the standard jobs, both these effects are computed in a passive/ diagnostic mode via use of a double-call to the radiation scheme.

One of the standard jobs also includes Nudging, wherein the model dynamics variables are nudged or relaxed towards ECMWF Reanalysis data. This configuration is particularly useful for evaluating the MODE scheme against measurements.

Timings

When run with all the 31 aerosol tracers switched on, the UKCA-MODE code adds 12% to the cost of the Atmosphere model (see O'Connor et al, 2011 ICP report to DECC/DEFRA).

Machine No. of Cores No. of Nodes Resolution Time for 1 Model Month
MONSooN (non-nudged) 64 2 N96L38 ~2 hours
MONSooN (nudged) 64 2 N96L38 ~2.5 hours

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