Transcript Driving UM-SCM with reanalysis / model data

Driving UM-SCM with
reanalysis / model data
Vaughan Barras
ACCESS
Model Development Group
Dynamically constrained simulations
Previous experience
constraining GCMs
dynamically with
reanalyses, allowing other
model components to
evolve
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d18O in hydrological cycle
eg: Melbourne Uni Network
of Isotopes in Precipitation
3rd IOP
(Jun 11, 2005)
See also:
Noone (2006) (WGNE Rep. 36; WMO/TD-No.
1347)
Yoshimura et al., 2008 (JGR, 113, D19108)
Barras and Simmonds, (submitted to JGR)
Use in SCMs?
…yes…provided it is set up carefully and SCM used appropriately.
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Idealised cases (equilibrium, constant forcings)
Targeted studies (Intercomparisons)
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Intensive Observational Campaigns (IOPs)
TWP-ICE, TOGA-COARE, GABLS, DYCOMS, RICO, Cabauw,…
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Alternative namelist generation?
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NWP forcings
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Useful - depending on what is under investigation
Complicated setup…
genesis
Software to create SCM namelists at a user-defined
location from reanalyses / model input.
Uses:
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Testing of parameterisations under a range of scenarios
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IOPs can be subjective in the conditions they represent
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Based on approximate ‘real-world’ conditions (reanalyses)
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Extract model conditions for detailed testing
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Efficiency enables creation of ensemble namelists
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Variable initial conditions, major forcing fields.
how it works
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Download global NetCDF fields of pmsl, F, U, V, T, q
for desired period
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ERA40
JRA25 (q > level 12 = 0.0)
NCEP (genesis converts RH to q)
UM
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User specifies lat / lon
Define ‘files.inp’ and ‘dates.dat’ files
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dumps from STASH (sub-periods of longer runs)
Use ‘Trans’ option in xconv to interpolate to P grid.
Simple list of input file names and dates matching inputs
Command line execution
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Can be scripted
genesis --help
gale/vjb> genesis
Usage: genesis
genesis [options]
-d
verbose, debug mode
-h
help
-t
no. of time increments (def=150)
-l
no. of levels of input data (def=20)
-x
no. of longitudes (def=29)
-y
no. of latitudes (def=17)
-X
user defined longitude (eg: 243.7)
-Y
user defined latitude (eg: 65.0)
-D
use date file (def = false)
-O
use offset file (def = false)
-E
ERA40 data (def = false)
-J
JRA data (def = false)
-N
NCEP data (def = false)
-U
UM data (def = false)
You also need a few files in the run directory for this to work.
a) files.inp - a file listing the *.nc file names in order: ps,z,u,v,t,q
b) offset.dat (optional) - list of offset parameters from
ncdump hdr [scale, add]
- if geopotential needs converting only (m2/s2 >> m)
then use -O with offset file set to 1 0 for each.
c) dates.dat (optional) - a list of dates/times corresponding to data records.
[generate using datetraj - yyyymmdd hhhh]
details
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Read NetCDF fields
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Finds nearest neighbour grid points for interpolation
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Calculates advective tendencies (T, q)
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Linear interpolation of fields (horizontally)
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Could incorporate other interpolation methods if desired
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Derivation of geostrophic wind profiles
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Assign dates / times to records
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Intermediate output field (*.scm)
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Initial profiles (P_IN, UI, VI, QI, THETA)
Increments (U_INC, V_INC, T_INC, Q_STAR)
Output ‘namelist.scm’
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Still needs to be checked before running!
Example – CASES 99
NWP forcing profiles compared with hi-res soundings from CASES 99
U
T
V
q
Example – CASES 99
ERA40 forced UM-SCM runs
t = 6hr
U*
Tsfc
t = 48hr
however…
Still requires user to set up cases carefully.
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SCM6.3 has constant Ūg
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No inclusion of ‘w’
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Restricted to short runs where synoptic circulation isn’t rapidly
changing (midlats can be a problem in this regard, tropics ok)
Variable setting in SCM7.1, enables longer simulations
SCMs sensitive to these settings, best if user defined / derived
by model continuity
Not comparable to observations, but…
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Genesis can provide framework for parameterisation sensitivity
studies, not restricted by IOP location.
Enables targeting of problem regions / conditions
[debugging…]