RELEASE NOTES for CAMx v6.30, 04/08/16 The Comprehensive Air Quality Model with extensions (CAMx) is available at http://www.camx.com. Overview of Version 6.30 ------------------------ V6.30 includes new features, modifications, and bug fixes from the previous release (v6.20). * Use the chemistry parameters files specifically labeled for v6.30. New files are available for Mechansims 4 (CB6r3) and 5 (SAPRC07TC). * A new version of TUV is available to support SAPRC07TC. * The 2D time-variant met file has changed to include new snow cover variables. CAMx remains backward compatible with the original snow cover input. * A new source apportionment region map file format supports fractional region definitions per grid cell. CAMx remains backward compatible with the original region map format. * The CAMx control file namelist has changed to support certain modifications. * There are no changes to other I/O file formats from v6.20. * The CAMx makefile now supports the Gnu Fortran compiler (gfortran). * The Makefile for 32-bit compilers is no longer supported. v6.30 New Features and Major Updates ------------------------------------ 1. Several modifications were implemented to improve model speed. Implications: Our tests without Probing Tools indicate speed increases by 15-50%, depending on model configuration (grid number and size, PiG, chemistry mechanism), compiler and chipset. These changes have minimal impacts on concentration results (e.g., ozone differences < 1 ppb). 2. OSAT has been expanded to include a more robust handling of O3-NOy interactions and to improve consistency with PSAT nitrate chemistry. Implications: OSAT now tracks odd oxygen and nitrogen through NOy chemistry to account for NOx recycling of ozone. OSAT is now more consistent with the PSAT nitrate treatment. Many more OSAT tracers are necessary, and this affects memory requirements and model speed. Expect to see slightly more ozone contributions from long range transport, and commensurately less contributions from local emissions. NOTE: With this update, source apportionment is not available for the following chemical mechanisms: 3 (CB6r2h); 5 (SAPRC07TC). 3. CAMx can now run on WRF Mercator and Polar projections. Implications: A parallel modification has been made to WRFCAMx (v4.4) to support the new projections. Some namelist variables have changed to support this update and to improve clarity. 4. A new snow albedo treatment has been incorporated based on the WRF/NOAH land surface model. Implications: Time/space-varying snow albedo is determined based on landuse, snow depth and age. Modifications have been made to WRFCAMx (v4.4) to read snow variables from WRF and to pass snow depth and age fields to CAMx via the 2-D time-variant input file. TUV includes an update to extend the range of albedo classes. Net surface albedo in snow-covered grid cells can be substantially different from the original constant value of 50%, and this can have a large impact on photochemical activity. 5. A new CB6 chemistry mechanism (CB6r3 -- mechanism 4) has been introduced that includes a temperature- and pressure-dependent organic nitrate branching ratio. Implications: This update was found to be important for photochemistry in cold and/or elevated conditions, such as wintertime in the US inter-mountain west. Generally, the effect of this change is to reduce ozone production slightly relative to CB6r2 in cold conditions. There are no appreciable effects in warm conditions that are more typical of the ozone season. 6. SAPRC07TC has replaced SAPRC99 (mechanism 5). Implications: SAPRC07 is a more recent gas-phase chemistry mechanism that has replaced the dated SAPRC99 mechanism. SAPRC07TC is a variant of SAPRC07 that includes extra model species for toxics and uses numerical expressions of rate constants that are compatible with the current chemistry mechanism solver. SAPRC07TC is consistent with the version in CMAQ so that emissions will work in either model. v6.30 Modifications ------------------- 1. The VBS organic aerosol option has been updated to add a basis set for organics from meat cooking, and to remove the internal allocation of POA emissions to individual POA and IVOC basis sets. Implications: Use the new VBS emissions preprocessor PREPVBS to develop POA and IVOC emissions for all basis sets. CAMx will stop with an error message if all needed emissions are not found on the emission input files. See the User's Guide for more information. 2. Heterogeneous reaction rates have been updated. Implications: The rate for N2O5+H2O->HNO3 has been updated, and a new rate calculation has been added for N2O5+HCl->CLN2+HNO3. 3. Source apportionment can now use a new source region map format that supports fractional (partial) area assignments for each grid cell. Implications: Previously, source region maps simply assigned each grid cell to a single source region. The addition of an optional partial region map allows the user to define multiple regions to each grid cell by source sector. See the User's Guide for more information. 4. Updated calculations of PiG dry and wet deposition for source apportionment tracers. Implications: This change improves upon inconsistencies found in treating dry and wet deposition from PiG puffs and deposition sums of source apportionment tracers. 5. The surface chemistry model has been extended to work with the Zhang dry deposition option and a new snow compartment has been added. Implications: Surface chemistry is now performed for a third (snow, if present) surface type on top of soil and vegetation. This update is tied to the snow albedo update. See the User's Guide for more information. 6. One of the definitions for the PiG shear flag (SHRFLG=1) has been updated. A PiG sampling criterion has changed. Implications: SHRFLG=1 now means puff growth by wind shear is always applied in the boundary layer (not just during neutral/ unstable conditions) and never applied above the boundary layer. PiG puffs are now sampled when puffs extend to within 10 m of the surface (rather than simply extending into the surface layer) to remove sensitivity to choice of layer structure. 7. A new user option called "ALLR" has been added to force the model to output gridded average concentrations for all species including radicals. Implications: The option "ALL" outputs all "state" (transported) species to the average and deposition output files. "ALLR" includes all radicals on the average concentration output files. 8. New flags have been added to the CAMx control (namelist) file to explicitly control the use of source apportionment and DDM point source override at runtime. Implications: Source apportionment and DDM point source override flags can be set for each stack to specify each stack's region assignment. These flags are set within the input point source files (a transparent feature), so users' may not know that such flags are set; this can lead to confusing SA or DDM results. The new namelist flags allow the user to explicitly turn the override feature on or off at runtime. See the User's Guide for more information. 9. The Implicit-Explicit Hybrid (IEH) chemistry solver option has been removed. Implications: IEH has been unnecessary since the introduction of the faster Euler-Backward Iterative (EBI) scheme, which is the default solver. 10. The source apportionment option "GOAT" has been removed. Implications: GOAT was an attribution option developed in early versions of OSAT, and is now considered obsolete. v6.30 Bug Fixes --------------- 1. Removed "-Mconcur=nonuma" from the PGF90 comiler flag list. Implications: This flag causes the model to run much slower (by factors of 10 or more) for later versions of PGF90 (v13+). 2. Fixed several MPI bugs found for PiG sampling grids. Implications: This bug led to clearly incorrect plume patterns on sampling grids relative to non-MPI simulations. MPI and non-MPI results are now equivalent. 3. Fixed a bug in the sign of v-component divergence in the calculations of PiG puff vertical advection. Implications: Minor impacts to puff elevation above ground. 4. Fixed two bugs related to RTRAC species names. Implications: A fix to the MPI pass of RTRAC species names resolved segmentation faults. Another minor bug was found when checking attributes for RTCMC species. Some species types may have been incorrectly assigned, depending on how species were ordered in the RTCMC/IMC chemistry parameters file. The check has been corrected and is now more robust. 5. Minor bug fix to the zenith angle routine GETZNTH in cases when cos(zenith) < -1. Implications: The cause for cos(zenith)<-1 remains unknown, but code has been modified to trap this, ensuring -1=