PROGRAM IGCM3

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 What it does
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 Structure of Routine
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• call INI_GRAPHICS
• call INITAL
• 1 CONTINUE - label 1 is here
  • set tendencies to zero
  • IF (KOUNT.EQ.0) THEN
    • Initialise new tracer fields - IF (.NOT. LRSTRT) CALL ICTRAC
    • Add white noise perturbation - IF (LNOISE.AND..NOT.LRSTRT) CALL NOISE
    • Calculate restoration arrays - IF (.NOT. LRESTIJ) CALL SETRES
  • IF (DAY.LT.0.1) THEN set surface pressure to 976mb
  • Main loop over latitudes - DO 5 IH=1,JG
    • IF(JGL.EQ.1) READ(25) ALP,DALP,RLP,RDLP
    • Go from spectral space to grid point space using inverse Legendre and Fourier transforms - call to LTI and calls to FFT991
    • Calculate nonlinear terms - CALL MGRMLT
    • Save grid point fields for use in XSECT
    • Go from grid point space to spectral space using direct Legendre and Fourier transforms - calls to FFT991 and LTD
  • IF (LBALAN) and (KOUNT.LT.0) THEN
    • Balance spectral fields - IF (.NOT.LTBAL) CALL BALANC, IF ( LTBAL) CALL TBAL, CALL ENERGY, GO TO 1
  • First timestep - output history and diagnostics - IF (KOUNT.EQ.0) THEN
    • RODATA calculations
    • write to units 9, 2 and 13.
    • call XSECT, SPOP, ENERGY.
  • ELSE IF (KOUNT.EQ.KSTART) CALL ENERGY
  • IF (LRESTIJ) THEN - Write a restoration record to units 2 and 13
  • IF (KOUTR.EQ.KOUNTR) THEN - Write a restart record to units 2, 11 and 19
  • IF (KOUTH.EQ.KOUNTH) THEN - Write a history record to units 2 and 9
  • Output diagnostics -
    • IF (KOUTP.EQ.KOUNTP) THEN call XSECT, plotfields and SPOP
    • IF (KOUTE.EQ.KOUNTE) THEN CALL ENERGY
  • IF (KOUNT.LT.KTOTAL) THEN
    • add 1 to KOUTP, KOUTE, KOUTH, KOUTR and KOUNT, i.e. add one to timestep.
    • calc. DAY, i.e.
      • DAY=DAY+DELT/PI2
      • IF (.NOT. LPERPET) DOY=DOY+DELT/PI2
      • IF (DOY.GE.361) DOY = DOY-360.0
    • Adiabatic part of timestep - CALL TSTEP
    • Mass correction - IF (LMASCOR) CALL MASCOR ELSE IF(LRESTIJ) SP(1)=CMPLX(0.,0.)
    • Diabatic part of timestep. Preset tendencies to zero.
    • Set parameters for optional Newtonian cooling. - IF (LRESTIJ) CALL SETTEE
    • Preset accumulated diagnostics - IF (KOUTH.EQ.1) THEN ADDZ=0
    • IF (JGL.EQ.1) REWIND(25)
    • Loop over latitude for spectral transforms and calculation of diabatic tendencies. - DO 260 IH=1,JG
      • IF(JGL.EQ.1) READ(25) ALP,DALP,RLP,RDLP
      • Go from spectral space to grid point space using inverse Legendre and Fourier transforms - call LTI and calls to FFT991
      • Calculate diabatic terms - CALL DGRMLT
      • Write accumulated diagnostics to history file.
      • Go from grid point space to spectral space using direct Legendre and Fourier transforms - calls to FFT991 and call LTDDIA
    • Write zonally averaged diagnostics and spectral heating to history file - possible calls to plotfields2, netout2
    • 300 CONTINUE - there's no D0 300 ???
    • Apply dissipation and optional linear restoration - CALL DIFUSE
    • Update spectral fields in the diabatic timestep - CALL DSTEP
    • End of timestep - DO J=1,IGB, TAVE(j*2-1)=TAVE(J*2-1)+REAL(T(J)), TAVE(j*2)=TAVE(J*2)+AIMAG(T(J)), ENDDO
    • GO TO 1 ! time loop
• Write the final restart record - call end_netcdf, and write to units 2, 12, 13 or 17
• call end_graphics
• STOP

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 Program calls
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Called by	Calls
none	BALANC (summ) DIFUSE (summ) DGRMLT (summ) DSTEP (summ) END_GRAPHICS (summ) end_netcdf ENERGY (summ) FFT991 ICTRAC (summ) ini_graphics INITAL (summ) LTD (summ) LTDDIA (summ) LTI (summ) MASCOR (summ) MGRMLT (summ) netout2 NOISE (summ) plotfields plotfields2 SETRES (summ) SETTEE (summ) SPOP (summ) TBAL (summ) TSTEP (summ) XSECT (summ)

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