1. Objectives & generalities about phasing and The phasing roadmap Claude Fischer

2. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Content: Software interaction IFS-Arpège // LAM General overview and motivation Rules Phasing Validation Code management The phasing roadmap Appendices: Technical stuff (about VAR)

3. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Software interaction IFS-Arpège // LAM General view & motivation: IFS evolution forces a continuous, sometimes drastic, code optimisation and cleaning IFS provides powerful state-of-the-art software, both scientific and technological In detail, for the LAM: observation operators are IFS, basic configurations, singular vectors, CONGRAD etc… Sometimes, ideas are first tested in the LAM: NH model, digital filters Yet, not every development is easily transfered from the IFS to the LAM This « marriage » creates rights and duties

4. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Software interaction IFS-Arpège // LAM Rules or practice: IF (LELAM) THEN; CALL ETOTO; ELSE; CALL TOTO; ENDIF LAM-specific routines go into a separate fortran library, unseen from ECMWF No LELAM key below the level of gridpoint scan (SCAN2MDM/TL/AD) => LRPLANE Duplicated code must be avoided !! The issue(s) for modularity: with respect to a functionality or a desired degree of freedom, not with respect to IFS v/s LAM Any configuration which does have a sense for both global and LAM should not be coded as a by-product of LELAM !

5. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Software interaction IFS-Arpège // LAM Scientific « feeling »: apply basic logic ! Spectral space differences almost everywhere: Mean wind vector (SPUB, SPVB) since  ( m=0,n=0) is not defined in bi-Fourier space Allocations, pointers, do-loop indexes all are to be re-defined for the LAM -> most spectral routines are differentiated (eg: SUJBCOV/SUEJBCOV, SPCM/ESPCM) Gridpoint space: more subtle: Existence of lateral boundaries (eg: search of origin point in SL – ELARCHE) Plane geometry projection and associated map factor (eg: SL interpolation weights – ELASCAW) Existence of the E-zone (Extension zone for biperiodisation) Rotation of geographical North/South and East/West with respect to model grid N/S and E/W

6. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Phasing (1): practical matters When and how long ?: Twice per year (dates pending ECMWF/Météo-France discussions) 3-6 weeks (visits), but in practice 2-3 months for completion in Toulouse How many phasers ?: 4-6 initial phasers (= visitors from partner countries), plus 2-3 additional « late » phasers a ~ bigger investment of GMAP staff Phaser stays are financially supported by MF, LACE or HIRLAM Phasing is not very popular, and depends heavily on the people’s willingness to leave home … for a sacrifice Separate with/without observations (assimilation usually comes after forecast configurations)

7. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Phasing (2) Principles: At the very beginning: check and understand the modifications in a new IFS/Arpège cycle Perform code and scientific analysis, and then adapt to LAM setup and/or LELAM keyed code when needed (sometimes trivial … or not) Recode some Aladin at identical scientific content for code compliancy with Arpège Analyze and « uncode » code clashes

8. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Phasing (3) Phasing examples: SUBROUTINE TOTO(ZTAB,K) > SUBROUTINE TOTO(ZTAB,K1,K2) REAL ZTAB(K) > REAL ZTAB(K1,K2) CALL TITI(ZTAB) > SUBROUTINE ETOTO(ZTAB,K) > SUBROUTINE ETOTO(ZTAB,K1,K2) REAL ZTAB(K) > REAL ZTAB(K1,K2) CALL TITI(ZTAB)

9. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Phasing (4) Phasing examples: N is total wavenumber (Arpège)  function FKSTAR(N,M) (Aladin/LAM) SUBROUTINE TOTO WEIGHT=1.+MIN(1,M) > Y=X/S(N) > Y=WEIGHT*X/S(N) SUBROUTINE ETOTO WEIGHT=2**MIN(1,N) * 2**MIN(1,M) > Y=X/S(FKSTAR(N,M)) > Y=WEIGHT*X/S(FKSTAR(N,M))

10. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Validation Arpège and LAM sanity-check validation is done for both at the same time : Systematic validation of all model configurations, which do not use observation handling, is performed by the « mitraillette » tool for LAM’s: automatic launching of a number of configurations (forecast e001, TL and AD tests, fullpos, NH model, 2D plane vertical model, adiabatic or with physics, multi-processor etc…) Basic validation of screening and 3D-VAR minimisation, ideally at the same time as Arpège 4D-VAR (needs the observation handling to be validated before) Quality assurance (QA) tests: After the core phasing period, since this requires again ~2 months of work (run long assimilation experiments, test various operational versions) => both at MF and in partner centers (HIRLAM, LACE) Not all cycles are QA !

11. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Code management Source code repository in Toulouse: clearcase Arpège and LAM cycle numbers: CYxxTy IFS has its own cycles in Reading (CYxxRz) Support team for maintenance of cycles and libraries, and interfacing with operations: « GCO » -> 3 persons (2 involved in code and conf management) User-friendly compilation environment on the high performance platforms (« gmkpack ») Export versions are defined and made available for the Aladin/Hirlam partners (mostly for QA cycles)

12. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop The phasing roadmap for a common IFS-Arpège cycle … is a Word document (check on the Aladin website or ask for it !) Lists the sequences of tasks during phasing: Pre-phasing coordination (list the input contributions and fine-tune the dates) Installation of all codes under SCM and initial source code phasing; possibly some local porting of IFS version First compilations, validations, debugging Phasing of LAM code w/r to IFS changes After first validations are successful, start some porting to other platforms; resume validation Porting to ECMWF computer (usually with Hirlam) Send new (pre-)cycle to ECMWF; check numerical performances; prepare some reporting of phasing work

13. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Technical stuff

14. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Global // LAM code interfacing for VAR Architecture: obshortl coupling Slightly different code: LELAM key Completely different code Fully shared dataflow between IFS and Aladin (especially in gridpoint space), but quite separate dimensioning and addressing in spectral buffers (spherical versus bi-Fourier). Coupling code is of course only LAM.

15. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Global // LAM code interfacing for VAR Simulator and model: H.dx  Jo=B1/2. GradJo J=Jb+Jo;  J Minimisation Jb=  ;  Jb=2  GradJo=H*.R-1. (y-H(x)-H.dx) dx=B1/2.  einv_trans cpgtl obshortl obsvtl edir_trans ecoupl1 espcmtl H.dx Var inner loop (SIM4D)

16. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Global // LAM code interfacing for VAR Change of variable: chavarin cvar2insqrtbincvaru3ijgcori cv2spa ejgvcori jgnrsi cvargptl etransinv_jb etransdir_jb ebalstat ebalvert spa1=ylvazx%lamcv*tmeanuver addbgs ejghcori

17. Toulouse, Sept. 20-22, 2010 Aladin/LACE/Hirlam Maintenance training workshop Phasing of LAM 3D-VAR ODB & bator need to work (almost same as Arpège, plus LAMFLAG) At every new cycle with IFS, a careful inspection of B-matrix setup and change of variable routines, SPECTRAL_FIELDS and CONTROL_VECTOR structures, specific observation-related code is needed (~ 1 week of work). Additionally, TL and AD LAM code may need to be checked. LAM 3D-VAR does not use multi-incremental I/O prepared for IFS-Arpège: no WRMLPPADM/RDFPINC, no SAVMINI/GETMINI, NUPTRA>1, « traj » recomputation of innovations