D. Temporal__Coordination__of__the__Fluxes_________________________

      Two  time  scales  will  be  resolved  by  nested  loops  in  the  coupler.   The  outer  loop
advances  all  models  one  day  per  iteration.  The  ocean  model,  which  will  not  resolve  the
diurnal cycle,  will be invoked only once per iteration of the outer loop.  Thus this model
will  use  one  fixed  set  of  input  fluxes  to  advance  one  day  each  time  it  is  invoked.   For
the  atmosphere,  land  and  sea-ice  models,  which  will  resolve  the  diurnal  cycle,  there  is
an inner loop which invokes/advances these models several times per outer loop iteration.
Each iteration of the inner loop will advance the atmosphere, land and sea-ice models one
atmospheric  time  step  (e.g.,  20  min  for  the  T42  CCM3  or  30  min  for  the  R15  CCM3).
Thus these models will use one fixed set of input fluxes to advance in the inner loop each
time they are invoked.

      The number of internal atmosphere model steps that correspond to one day is ndaya,
and  will  dictate  the  number  of  iterations  in  the  driver's  inner  loop.  When  invoked,  the
atmosphere model will advance for one atmosphere model step, after which it will provide
the  coupler  with  an  updated  model  state  "WA   (see  section  C.V),  along  with  the  fluxes  it
computes internally.

      The number of internal land model steps that correspond to one day is ndayl.  When
invoked, the land model will advance ndayl=ndaya steps (this must be an integer quantity),
after  which  it  will  provide  the  coupler  with  an  updated  model  state  "WB  ,  along  with  the
inner loop time average of the fluxes it computes internally (see section C.VIII).

      The  number  of  internal  ice  model  steps  that  correspond  to  one  day  is  ndayi.  When
invoked, the ice model will advance ndayi=ndaya steps, (this must be an integer quantity)
after  which  it  will  provide  the  coupler  with  an  updated  model  state  "WC  ,  along  with  the
inner loop time average of the fluxes it computes internally (see section C.VII).

      The number of internal ocean model steps that correspond to one day is ndayo.  When
invoked, the ocean model will advance ndayo steps, after which it will provide the coupler
with an updated model state W"H   , along with the daily average of the fluxes it computes
internally (see section C.VI).

      Input  flux  means  fluxes  given  by  the  coupler  to  a  model.  Output  flux  means  fluxes
computed  within  a  model  and  given  to  the  coupler.  All  input  fluxes  for  one  model  were
either  computed  by  the  coupler  or  were  the  output  flux  of  another  model.  In  general,  a
given  flux  field  between  any  two  component  models  may  have  been  computed  in  one  of
three places:  within either of the two models or within the coupler.

      One function of the coupler is to gather, merge, sum, and/or time-average various flux
fields  from  various  sources  and  form  a  complete  set  of  input  fluxes  for  each  component
model.   This  gathering  and  merging  process  will  generally  involve  mapping  flux  fields
between various model grids and combining like fields from several grids onto one grid.  A
summation might be required, e:g:, net heat flux = solar + latent + sensible + longwave
(see  encircled  crosses  in  Fig.  1).  Also,  for  some  flux  fields  the  coupler  might  be  required
to form time-averaged quantities.  Thus component fluxes are mapped, merged, summed,



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and/or time-averaged by the coupler in order to form complete input fluxes for the models.
Component fluxes that are gathered, merged, summed, and/or time-averaged to form the
complete input fluxes:



                                                                                                                   (Section C)
   o  F aid = atm/ice flux, computed by the drv                                                  (F1 d)
   o  F aia = atm/ice flux, computed by the atm model (an atm output flux)       (F1 a)
   o  F ald = atm/lnd flux, computed by the drv                                                 (F2 d)
   o  F ala = atm/lnd flux, computed by the atm model (an atm output flux)      (F2 a)
   o  F all = atm/lnd flux, computed by the lnd model (an lnd output flux)         (F2 l)
   o  F aod = atm/ocn flux, computed by the drv                                               (F3 d)
   o  F aoa = atm/ocn flux, computed by the atm model (an atm output flux)     (F3 a)
   o  F iod = ice/ocn flux, computed by the drv                                                   (F4 d)
   o  F ioo = ice/ocn flux, computed by the ocn model (an ocn output flux)         (F4 o)
   o  F ioi = ice/ocn flux, computed by the ice model (an ice output flux)             (F4 l)
   o  F lol = lnd/ocn flux, computed by the lnd model (an lnd output flux)          (F5 l)


Examples:                                                                         (Section C)
   o  F aid:  momentum flux between the atm and ice                  ("o1)
   o  F aia:  net shortwave radiation between the atm and ice       (S1 )
   o  F ald:  momentum flux between the atm and lnd                  ("o2)
   o  F ala:  net shortwave radiation between the atm and lnd       (S2 )
   o  F aod:  momentum flux between the atm and ocn                 ("o3)
   o  F aoa:  net shortwave radiation between the atm and ocn      (S3 )
   o  F iod:  momentum flux between the ocn and ice                    ("o4)
   o  F ioi:  net shortwave radiation between the ocn and ice         (S4 )
   o  F ioo:  ice formed within the ocn                                          (QH  )
   o  F lol:  ocean runoff formed within the lnd                            (FS )


Complete input fluxes (an overbar denotes a daily average):
   o  F axx = all atm model input fluxes:  a mapping/merging/summation of:  F aod, F aid,
      F ald, F all
   o  F lxx = all lnd model input fluxes:  a mapping/merging/summation of:  F ald, F ala
   o  F oxx__=__all_ ocn__model__input_ fluxes:_ a__mapping/merging/summation/time-averaging_
      of:  F aod   , F aoa   , F ioi  , F iod   , F lol
   o  F ixx = all ice_model_input fluxes:  a mapping/merging/summation/time-averaging of:
      F aid, F aia, F ioo  , F iod


These time-average_fluxes will need to be formed:
   o  F_aid___ = atm/ice fluxes, computed by the driver, time averaged by the driver
   o  F_aia___ = atm/ice fluxes, computed by the atm model, time averaged by the driver
   o  F_aoa___ = atm/ocn fluxes, computed by the atm model, time averaged by the driver
   o  F_aod___ = atm/ocn fluxes, computed by the driver, time averaged by the driver
   o  F_ioo__  = ice/ocn fluxes, computed by the ocn model, time averaged by the ocn
   o  F ioi   = ice/ocn fluxes, computed by the ice model, time averaged by the ice


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