RELEASE_NOTES   12 September 2003


The major changes and new features of this release are:

1) Modified the treatment of secondary organic aerosol (SOA) formation
   + The SOA algorithm has been modified to make the gas-particle
     partitioning of semi-volatiles reversible
   + Eliminated SOA production from anthropogenic alkenes
   + Adjusted yields of semi-volatiles from alkanes and aromatics to
     account for emissions of non-SOA producers being lumped with those
     from SOA-producers
   + Modified gas-phase monoterpene reactions rates in RADM2 and CB4

2) Modified the heterogeneous N2O5 reaction probability

3) Added an Euler Backward Iterative (EBI) gas-phase chemistry solver for
   the CB4 family of chemical mechanism

4) Implemented layer-dependent horizontal advection time-stepping

5) Changed the order of the time splitting science processes:
      Previous order                New order
      --------------------          --------------------
      advection              +----> vertical diffusion
      mass-adjustment        |      advection
      horizontal diffusion   |      mass-adjustment
      vertical diffusion ----+      horizontal diffusion
      clouds                        clouds
      chemistry                     chemistry
      aerosols                      aerosols

6) Updated all gas-phase chemical mechanisms (cb4, radm2, saprc)
   + New deposition velocity surrogates
   + New cloud scavenging surrogates
   + Zeroed reaction rate constant for N2O5 + H2O -> 2HNO3 in all /aero3
     mechanisms
   + Changed names of aero3/SOA NR species
   + For CB4, eliminated advection and diffusion of fast-reacting species

7) Cloud enhancements/updates
   + Modified to use effective Henry's Law constant for scavenging
   + Updated and added new coefficients to the Henry's Law constant table
   + Revised the timestep calculation in the aqueous chemistry subroutine
   + Updated the coarse-mode aerosol number washout

8) Other enhancements and bug fixes
   + Changed the units for aerosol for vertical diffusion to molar mixing
     ratio instead of mass density concentration
   + Updated the minimum aerosol concentration array and bug fix in
     coarse-mode aerosol standard deviation in the aerosol dry deposition
     subroutine
   + Added compatibility with emissions files that contain PM10 and
     speciated PM2.5 but do not contain PMC
   + Removed unused SUBST_GRID_ID
   + Fixed index bug in load_cgrid
   + Bug fix for no gas emissions species
   + Fixed NFS latency problems for parallel runs on an MPICH cluster