RELEASE NOTES for CAMx v7.00, 05/31/20 The Comprehensive Air Quality Model with extensions (CAMx) is available at http://www.camx.com. Overview of Version 7.00 ------------------------ V7.00 includes new features, modifications, and bug fixes from the previous release (v6.50) * Use the chemistry parameters files specifically labeled for v7.0. * The CAMx control namelist file has changed to support certain modifications. * CAMx now supports netCDF I/O files (v3 or v4 with optional compression). The original Fortran binary I/O format remains available. * The O3MAP and TUV input files include some format changes; see below for details. * The operation of the CAMx makefile has not changed since the last version. Type "make" or "make help" for more information. NOTE: RECENT VERSIONS OF THE GFORTRAN COMPILER WILL NOT COMPILE CAMx WITH OMP PARALLELIZATION BECAUSE OF AN INCOMPATIBILITY WITH BLOCK DATA IN ISORROPIA. THIS IS NOT AN ISSUE WITH OTHER SUPPORTED COMPILERS. OPTIONS: a) USE MPI ONLY WITH GFORTRAN b) REVERT BACK TO AN OLDER VERSION OF GFORTRAN c) USE A DIFFERENT COMPILER v7.00 New Features and Major Updates ------------------------------------ 1. CAMx now supports netCDF file formats for large gridded input fields including emissions, meteorology, and initial/boundary conditions. The model will accept a mix of netCDF or Fortran binary input files for maximum flexibility and backward compatibility. Implications: CAMx can be built with netCDF-3 or netCDF-4/HDF5; the latter allows for data compression using "data chunking". Uncompressed netCDF files are compatible with Models-3 software without the need to build CAMx with I/O API libraries. 2. CAMx supports a new 3-D gridded emissions file in netCDF format for certain non-point source sectors that are emitted above the surface and have traditionally been input to the model as elevated point sources. Implications: Now elevated emission sectors such as wildfires, lightning NOx, aircraft, etc. can be supplied directly in gridded format alleviating the need to characterize them as point sources. The Fortran binary format is not supported for 3-D emission files. 3. CAMx supports multiple point, 2-D and 3-D gridded input emission files. Implications: This new feature alleviates the need to merge all sectors into single input files. This capability is also extended to Probing Tools. Any point or 2-D input emissions file can be listed in any combination of netCDF or Fortran binary format (3-D files must be netCDF). NOTE on Source Apportionment Technology (SAT): With this change, SAT input emission files are used to define emissions for BOTH the core model and the SAT application. In earlier CAMx versions, separate sets of core and SAT files were listed and the model compared gridded and point emissions to core model inputs to ensure consistency. ALL SAT point emissions are always used for BOTH SAT and the core model. A "leftover" capability remains available for gridded emissions, based on differences between SAT emission inputs and core model emission inputs, but not for point emissions. It is no longer necessary to provide a consistent list of point sources among all of the SAT point source files. The list of points to model are now an internal concatonation of point source lists from each input SAT point source file. NOTE on DDM and RTRAC: With this change, DDM and RTRAC input point source emission files can include stack lists that are entirely unique to these Probing Tools. Earlier CAMx versions required a consistent list of point sources among the core model, DDM and RTRAC, which was onerous. This restriction is removed. 4. The bi-directional ammonia algorithm of Zhang et al. (2010) has been added as an option to the original uni-directional Zhang deposition algorithm. Implications: Only ammonia is treated in the bi-directional treatment. Default landuse-dependent “emission potentials” control ammonia “compensation points” (surface concentration) along the surface-air transport circuit. When atmospheric ammonia concentration exceeds the compensation point, the net flux is from air to surface; in the opposite case, the net flux is from surface to air. 5. Chemistry for dimethyl sulfide (DMS) has been added to the CB6r4 gas-phase mechanism. Implications: DMS from oceanic emissions oxidizes to form SO2 and SO4. Higher concentrations of particle sulfate will result over oceans and coastal areas of the modeling domain. Generate oceanic DMS emissions using the OCEANIC emissions pre- processor. Most global models include DMS; if using output from these models to generate CAMx IC/BC input files, be sure to map DMS concentrations to the CAMx IC/BC species list. PSAT adds DMS as an explicit tracer, and includes SO2 and SO4 formation from DMS, if DMS is listed in the chemistry parameters file. 6. Eight new primary PM2.5 elemental species (Fe, Mg, Mn, Ca, K, Al, Si, Ti) can be optionally included in the CF aerosol treatment. Implications: Separate chemistry parameters files for CB6r4+CF with and without the 8 elements are available. Avoid double-counting emissions by removing their mass from FPRM (fine primary) and FCRS (fine crustal) emissions. Five of the elemental species (Fe, Mn, Mg, Ca, K) influence aqueous PM chemistry (RADM-AQ), three (Mg, Ca, K) influence inorganic aerosol partitioning in EQSAM, and one (Ca) influences dust nitrate (CaNO3) in ISORROPIA. All 8 are used with FPRM and FCRS to determine aerosol surface area for heterogenous reactions of SO2 and N2O5. To calculate total PM2.5 mass, use the following summation: PM2.5 = PSO4 + PNO3 + PNH4 + PEC + FPRM + FCRS + NA + PCL + SOA1 + SOA2 + SOA3 + SOA4 + SOPA + SOPB + POA + PFE + PCA + PAL + PSI + PTI + PMN + PMG + PK To calculate total PM10 mass, use the following summation: PM10 = PM2.5 + CPRM + CCRS NOTE: The way to sum PM2.5 depends on how you define emissions of FPRM, FCRS and elements. If the emitted mass of FCRS and FPRM does not include the mass of emitted elements, then include FPRM + FCRS + elements. If the mass of elements were not removed from FRCS and FPRM, omit the elements from the summation. 7. OSAT/PSAT have been updated to support one-way nesting applications. Implications: CAMx can output 3-D fields of SA tracers, which can be translated to SA IC/BCs for a separate CAMx SA application on a smaller domain (referred to as one-way nesting). Preprocessors support CAMx-to-CAMx 1-way SA nesting, and global model-to-CAMx SA nesting, where global model sensitivity results (e.g., from “zero-out” brute-force cases) are translated to CAMx SA IC/BC inputs and tracked through the CAMx domain as separate tracers. v7.00 Modifications ------------------- 1. Updated SOAP2.1 to SOAP2.2: 1) Updated terpene SOA yields for RO2 autoxidation 2) SOA photolysis rate scaling from J(NO2) is reduced from 0.004 to 0.001 (Malecha et al. 2018) 3) Polymerization of anthropogenic SOA is deactivated 4) Loosened convergence tolerances and improved error trapping Implications: Change 1 reduces the terpene SOA yield, reducing SOA. Change 2 is based on more recent data and increases SOA by reducing a chemical removal mechanism. Change 3 reduces SOA. SOA concentrations predicted by SOAP are very sensitive to the choice of biogenic emission model. Change 4 should alleviate occasional model stops when SOAP solution does not converge, and provides more information in related error messages. NOTE: With this update, the CF aerosol scheme includes a version number: CF2 2. Several enhancements have been made to the DDM Probing Tool: - Introduction of chemical rate term sensitivities - DDM sensitivities can be calculated on sub-domains (like PA) - Updates to support core-model PM updates implemented in CAMx v6.4: * Revised aqueous-phase oxidation reaction rates * In-cloud SOA formation * SOA photolysis Implications: PM-DDM is now available for the CF aerosol treatment with the SOAP and ISORRPIA treatments. VBS and EQSAM are not yet supported. New namelist control variables have been added to configure rate term sensitivity. 3. Probing Tool arrays can be dimensioned to much larger sizes. Implications: Probing Tool arrays were dimensioned using single-precision integers, limiting the region/category/species memory space. Dimensioning is now performed with double-precision integers, greatly expanding the available Probing Tool space. 4. Updated the TUV/O3MAP system to report ozone column in Dobson Units (DU) rather than DU/1000. Implications: TUV and CAMx will expect to see the string "TUV4.8CAMx7.00" to ensure the latest versions were used to develop photolysis inputs with consistent DU units. CAMx will stop if the TUV label does not match; TUV will stop if DU/1000 units are read from the O3MAP file. For existing modeling datasets, you will need to rerun O3MAP and TUV for CAMx v7. 5. The SOA PSAT group has been reactivated for SAPRC07. Implications: Recent updates to SOAP were not extended to PSAT for SAPRC07, and so the PSAT SOA group was intentionally blocked when using SAPRC07. This feature is now fully functional. 6. Each grid of input wind fields can now be in a uniquely staggered or unstaggered arrangement. Implication: Input winds have been restricted to only staggered or unstaggered arrangements over all grids in a single run. Now each grid can be provided unique staggering arrangements. Those wind fields that are unstaggered (all winds at cell center) are interpolated to staggered arrangement as before. 7. The optional time-varying "flowrate" variable in point source input files is no longer used to define time-varying stack exit velocity. The time- invariant exit velocity is used exclusively for plume rise calculations. Implications: Flowrate has been an optional field in Fortran binary point source input files, where a positive value was used to re- calculate stack exit velocity each hour. This has been removed, but this variable remains available to define plume distribution override (see the CAMx UG); flowrate is not available in netCDF point source files. 8. Gas-phase chemical mechanism CB6r2 has been removed. Implications: The full-halogen mechanism CB6r2h remains available. We recommend using CB6r4, which includes important iodine reactions, if full halogen chemistry is not needed. v7.00 Bug Fixes --------------- 1. Fixed bug writing netCDF deposition file that was not considering in-line Ix emissions option. Implications: Model would crash with segmentation faults due to setting the wrong number of species in the output concentration arrays. 2. Fixed a bug that was not properly writing certain nested grid metadata in netCDF output files. Implications: Non-fatal error; some incorrect grid parameters were written to metadata variables in nested grid output files. 3. Fixed a bug that was not properly handling Source Apportionment "summary output" in netCDF output files. Implications: Non-fatal error; SA summary output concentrations were incorrect. 4. Fixed bug that was not properly checking grid dimensions before reading met input fields. Implications: This bug led to occasional model stops with a CAMx error message that did not correctly state the cause of the true problem: a mis-match between meteorological data dimensions and CAMx grid dimensions. 5. Fixed bug in timestep calculation that was improperly applying map scale factor. Implications: This bug resulted in occasional negative concentrations and model stop during 3-D advection due to exceeding CFL = 1, but only in cases where the map scale factor >>1. 6. Fixed bug that was not assigning CB6 species "INTR" to the "TPN" PSAT species class. Implications: Species INTR was not included in the TPN species class, which carries organic nitrates such as PAN and PNA. Impacts to PSAT and OSAT results are expected to be negligible to minor. 7. Fixed bugs in several routines that read Fortran binary point and gridded emission files that were not properly handling errors found in the ending hour interval at the end of a day. Implications: The routines now properly handle and report errors found in the ending date/time interval.