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More information on some input arrays can be found when moving the cursor above the corresponding field in the questionnaire. Those fields are also explained in the glossary.

UM: Met Office Unified Model

General information

Model name and version

short nameUM
full nameMet Office Unified Model
revision6.1
date
last change

Responsible for this information

namePeter Clark
instituteMet Office
addressMet Office JCMM, University of Reading
zipRG6 6BB
cityReading
countryUnited Kingdom
phone+44 (0)118 378 6523
fax+44 (0)118 378 8791
e-mailpeter.clark(belongs-to)metoffice.gov.uk

Additional information on the model

Contact person for model code

same as person above
namePorted Unified Model Manager
instituteMet Office
divisions
streetFitzRoy Road
zipEX1 3PB
cityExeter
countryUnited Kingdom
phone+44 (0)1392 885680
emailportable_um@metoffice.gov.uk
fax+44 (0)1392 885681

Model developer and model user

developer and userMet Office

Level of Knowledge needed to operate model

basic
intermediate
advanced
remarksThe system includes a graphical user interface which hides much of the scripting and code management from the user.

Model use at your institution

operational
for research
other use

Model code available?

is available?yes
more detailsAvailable under license on DVD-ROM - Contact above

Minimum computer resources required

typeLinux single CPU
time needed for run2h for 24h on 50x50x76, 1 km
storage2GB

Further information

documentationFull documentation supplied with model (system and science). See also support web sites.
model referencesCullen, M.J.P., Davies, T., Mawson, M.H., James, J.A., Coulter, S.C. and Malcolm A., 1997 An overview of Numerical Methods for the Next Generation UK NWP and Climate Model Numerical Methods in Atmospheric and Ocean Modelling. In The Andre J.Robert memorial volume. Edited by Charles A Lin, Rene Laprise and Harold Ritchie, Canadian Meteorological and Oceanographic Society, Ottawa, Canada, 425-444 Davies, T.; Cullen, M.J.P.; Malcolm, A.J.; Mawson, M.H.; Staniforth, A.; White, A.A.; Wood, N., 2005, A new dynamical core for the Met Office's global and regional modelling of the atmosphere, Quarterly Journal of the Royal Meteorological Society, 608, 1759-1782
webpagehttp://www.metoffice.gov.uk/research/nwp/numerical/unified_model/index.html
additional informationSee also http://www.met.rdg.ac.uk/~uwern/UM/support/ and http://www.cgam.nerc.ac.uk/um/index.php

Model properties

Model type

2D
3D
meteorology
chemistry & transport

Model scale

microscale
mesoscale
macroscale
short term
long term

Meteorological variables

PrognosticDiagnostic
u
v
w
ζ
pv
T
θ
θl
p
Gph
ρ
qv
qt
qlc
qf
qsc
qlr
qsh
qsg
qss
N
E
ε
K
zi
other variables iPrognostic cloud scheme available.
other variables ii
other variables iii

Approximations

Boussinesq
anelastic
hydrostatic
flat earth
remarksNo significant approximations to continuous equations. This includes NOT using the shallow atmosphere/traditional approximation common in th emajority of models.

Parametrizations

Meteorology

turbulence schemeNon-local, 1st order multi-regime PBL scheme (Locke et al)
deep convectionMass flux with downdraughts and momentum transport, CAPE closure, based on Gregory and Rowntree. Not used at high resolution.
surface exchangeMOSES II 9 tile, flux blended surface exchange. Includes urban tile.
surface temperatureMOSES II subsurface soil temperature scheme (usually run with 4 layers), Penman-Monteith surface T with optional thermal canopy.
surface humidityMOSES II subsurface soil moisture scheme (usually run with 4 layers), includes soil moisture freezing. Penman-Monteith surface T with optional thermal canopy.
radiationEdwards-Slingo flexible multi-band two stream LW and SW.
unresolved orographic dragOrographic Roughness based on Grant and Mason. Gravity wave drag from Webster (not used at high resolution).
radiation in vegetation
radiation between obstacles
treatment of obstacles
clouds / rainWilson and Ballard microphysics extended (Forbes) to include prognostic ice and snow, rain and graupel (each optionally prognostic or diagnostic). Smith diagnostic cloud scheme.
remarks

Initialization & boundary treatment

Initialization

chemistry & transport
meteorology3D-VAR: Nudging of analysis increments, weak balance constraint or digital filter all available. First used most generally.

Input data (name sources for data, e.g. website)

orographyglobe
land useIGBP (1km), CEH (25m) over UK
obstacles
vegetation
meteorologyMet Office operational analyses usually used as starting point. Can use ECMWF and others. Soil moisture from offline analysis over UK, climatology elsewhere.
concentrations
emissions
remarks

Data assimilation

Meteorology
nudging technique
adjoint model
3D-VAR
4D-VAR
OI
detailsCurrently 4D VAR at lower resolution, 3DVAR + latent heat nudging and moisture nudging at high resolution. Highest resolution operational analysis 12 km every 3 h. 4 km under test.

Boundary conditions

Meteorology
surfaceNo slip or free slip in dynamics, no slip via PBL.
topw=0
lateral inflowDavies relaxation
lateral outflowDavies relaxation

Nesting

Meteorology
one way
two way
other
variables nested
nesting online
nesting offline
data exchange by array
data exchange by file
time step for data exchangeFully flexible. Usually 5-15 min at 1km, 1-3h at 12 km.
explain methodDavies relaxation.
variables nestedAll prognostic
other

Solution technique

Coordinate system and projection

Horizontal

cartesian
Lambert conformal
latitude / longitude
rotated lat. / long.

Vertical

z coordinate
surface fitted grid
pressurecoordinate
sigma coordinate
remarksVertical coordinate is hybrid height based - terrain following near surface, flat at top. Gal-Chen and SLEVE can be implemented, but we use a slightly different formulation. Charney-Philips staggering in vertical to avoid compuation modes and improve balance.

Numeric

Meteorology

Grid

Arakawa A
Arakawa B
Arakawa C
Arakawa D
Arakawa E
uniform grid
nonuniform grid
Euler

Time integration

explicit
split-explicit
semi-implicit
other

Spatial discretisation

momentum equationsSemi-Lagrangian, non-interpolating in vertical. Eulerian continuity at present.
scalar quantitiesSemi-Lagrangian with monotone option and mass correction.
additional informationnon-uniform horizontal grid under test.
otherSemi-Lagrangian

Model resolution

Meteorology

HorizontalVertical
max300+5000
min0.1(-)5

Domain size

Meteorology

HorizontalVertical
maxglobal80000
min5025000

Model Validation and Application

Validation & evaluation

Used validation & evaluation methods

analytic solutions
evaluated reference dataset
model intercomparison
additional validation & evaluation efforts

Analytic solutions

Meteorology

u
v
w
T
qv
qlc
qsc
qlr
zi
other
testcase description
testcase references
used data set
reference for evaluation
remarksVarious standard dynamical core tests.

Evaluated reference dataset

Meteorology

u
v
w
T
qv
qlc
qsc
qlr
zi
other
testcase description
testcase references
used data set
reference for evaluation
remarksVarious standard dynamical core tests including global. GCSS intercomparisons with other CRM/LES models.
remarks

Application examples

application examplesConvective scale NWP (1 km) General mesoscale NWP (1-24 km) Input to emergency response Lagrangian dispersion model (NAME) Input to long term dispersion/deposition model (NAME) Generally run on NEX SX/6 or SX/8 supercomputers.

Participation in specific model evaluation exercises

AQMEII
List experiments (AQMEII)
Cost728
List experiments (COST728)
HTAP
List experiments (HTAP)
MEGAPOLI
List experiments (MEGAPOLI)