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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 d 18 O in hydrological cycle

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Driving UM-SCM with reanalysis / model data

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  1. Driving UM-SCM with reanalysis / model data Vaughan Barras ACCESS Model Development Group

  2. Dynamically constrained simulations Previous experience constraining GCMs dynamically with reanalyses, allowing other model components to evolve • 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)

  3. Use in SCMs? …yes…provided it is set up carefully and SCM used appropriately. • Idealised cases (equilibrium, constant forcings) • Targeted studies (Intercomparisons) • Intensive Observational Campaigns (IOPs) • TWP-ICE, TOGA-COARE, GABLS, DYCOMS, RICO, Cabauw,… • Alternative namelist generation? • NWP forcings • Useful - depending on what is under investigation • Complicated setup…

  4. genesis Software to create SCM namelists at a user-defined location from reanalyses / model input. Uses: • Testing of parameterisations under a range of scenarios • IOPs can be subjective in the conditions they represent • Based on approximate ‘real-world’ conditions (reanalyses) • Extract model conditions for detailed testing • Efficiency enables creation of ensemble namelists • Variable initial conditions, major forcing fields.

  5. how it works • Download global NetCDF fields of pmsl, F, U, V, T, q for desired period • ERA40 • JRA25 (q > level 12 = 0.0) • NCEP (genesis converts RH to q) • UM • dumps from STASH (sub-periods of longer runs) • Use ‘Trans’ option in xconv to interpolate to P grid. • User specifies lat / lon • Define ‘files.inp’ and ‘dates.dat’ files • Simple list of input file names and dates matching inputs • Command line execution • Can be scripted

  6. 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]

  7. details • Read NetCDF fields • Finds nearest neighbour grid points for interpolation • Calculates advective tendencies (T, q) • Linear interpolation of fields (horizontally) • Could incorporate other interpolation methods if desired • Derivation of geostrophic wind profiles • Assign dates / times to records • Intermediate output field (*.scm) • Initial profiles (P_IN, UI, VI, QI, THETA) • Increments (U_INC, V_INC, T_INC, Q_STAR) • Output ‘namelist.scm’ • Still needs to be checked before running!

  8. Example – CASES 99 NWP forcing profiles compared with hi-res soundings from CASES 99 U T V q

  9. Example – CASES 99 ERA40 forced UM-SCM runs t = 6hr U* Tsfc t = 48hr

  10. however… Still requires user to set up cases carefully. • SCM6.3 has constant Ūg • 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 • No inclusion of ‘w’ • SCMs sensitive to these settings, best if user defined / derived by model continuity • Not comparable to observations, but… • Genesis can provide framework for parameterisation sensitivity studies, not restricted by IOP location. • Enables targeting of problem regions / conditions [debugging…]

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