RELEASE NOTES for CAMx v4.51, 05/22/08 The Comprehensive Air Quality Model with extensions (CAMx) is available at http://www.camx.com. Join the CAMx User's Group by sending an e-mail message to Majordomo@environ.org with the words "subscribe CAMxusers" in the body of the message. When you subscribe, Majordomo will send you a reply that provides details on how to use this list server. The "camxusers" group is meant for broadcasting useful information about CAMx and its pre- and post-processors to all users that subscribe to this group, or to ask about available datasets or issues that other users may have come across. It is not meant for asking how to run CAMx or how to prepare inputs. Please direct specific comments or questions about problems or bugs with CAMx or its support software to ask-camx@environ.org, which comes directly to the developers. V4.51 is the official release of CAMx v4.5. A description of changes associated with v4.51 (relative to v4.50) is given below. This is followed by a description of changes associated with v4.50 (relative to the last public release, v4.42). Overview of Version 4.51 ------------------------ Version 4.51 includes Process Analysis for CB05 chemistry and modifications to PiG to improve model stability. It also includes a minor bug fix in the wet deposition routine. The CAMx v4.50 User's Guide should be used with v4.51. v4.51 Updates ------------- 1) Process Analysis (CPA, IRR, IPR) was added to CB05 chemistry and to LSODE and IEH chemistry solvers. This has included some other updates to the LSODE driver routines. Implications: PA tools are now available for any gas-phase chemical mechanism and all solvers. Affected routines: CPAMECH3-6.F, PASETUP.F, IEHSOLV.F, IERATE*.F, IERSN*.F, IEFAC*.F, LSRATE*.F, LSBOX.COM, LSCALL.F, LSODE.F, DSLDOE.F, CHEMDRIV.F, TRAP.F, IRONCHEM.F, LSJAC*.F (removed) v4.51 Modifications ------------------- 1) PiG was updated to improve the method by which puff PM increments are calculated. Implications: PiG is much more stable for PM chemistry. Affected routines: PIGDRIVE.F, IRONCHEM.F, PIGMSCL.F, PIGPREP.F, CHEMDRIV.F, TIMESTEP.F, AEROCHEM_CF.F READCHM.F PIGSTY.COM v4.51 Bug Fixes --------------- 1) Fixed a bug in the calculation of liquid water concentration reported to the deposition output file. Implications: An incorrect rain water volume was used in the calculation of deposited liquid concentration fields in the wet deposition routine. Liquid concentrations reported in the deposition output file are reduced by as much as an order of magnitude. There is no impact on air concentrations or other deposition fields reported in the dep output file. Affected routines: WETDEP.F, IRONWET.F Overview of Version 4.50 ------------------------ V4.50 is an extension from the previous release (v4.42). Version 4.50 introduces updates to incorporate CB05 chemistry and to improve the SOA PM algorithm. This version also provides several bug fixes. *** To use CB05 you must prepare photolysis rates using TUV. CB05 can be used with emissions prepared for CB4 but it is better to use emissions prepared for CB05. *** The updated SOA scheme needs new biogenic precursor emissions. Although an emission pre-processor is available to estimate them from traditional emissions, it is recommended to use the latest MEGAN biogenic model to generate the new emissions. *** The chemistry parameters files for v4.50 have been updated. You must use chemparam files specifically labelled "VERSION4.5" There are no changes to other input file formats from version 4.42. v4.50 Updates ------------- 1. Added CB05 gas-phase photochemical mechanism. Implications: You can now choose among CBM-IV (3 flavors), SAPRC99, or CB05 photochemistry. CB05 provides important updates based on recent research. Affected routines: New /CMC/ routines for mechanism 6, CHMSTRY.COM, IEHCHEM.COM, DDMCHEM.COM, CAMx.PRM, READCHM.F, CHEMDRIV.F, PIGDRIVE.F, IRONCHEM.F, SPCCB05SA.F, STABSA.F, CYCTPNSA.F, O3PRDSA.F 2. PM modules are linked to CB05 mechanism. Implications: Users can now simulate gas and PM species with CB05 mechanism. Affected routines: READCHM.F, AEROSET.F, AEROCHEM_CF.F, AEROCHEM_CMU.F, CAMx.PRM, CAMx_AERO.COM, CAMx_AERO.INC 3. Updated secondary organic aerosol (SOA) scheme. Implications: Improved science in SOA chemistry; users will see differences in SOA concentrations. Affected routines: Mech 4 routines in /CMC/ directory, CHMSTRY.COM, IEHCHEM.COM, DDMCHEM.COM, CAMx.PRM, READCHM.F, CHEMDRIV.F, AEROCHEM_CF.F, SOAP.COM, SOAPDAT.F, SOAP.F, SOACHEM.F, TRACER.COM, SPCCBIVSA.F, SPCSPRCSA.F, STABSA.F, SPECSA.F, CYCTPNSA.F, PSATSA.F, REPARTSA.F, OSATSA.F, APCASA.F, GOATSA.F, CLCIWT.F, RDSUMBC.F, CPAMECH4.F, AEROSET.F, AEROCHEM_CMU.F, CAMx_AERO.INC, DYNAMIC.INC, BLOCK.F, EQPARTO.F 4. Updated heterogeneous N2O5 hydrolysis. Implications: If PM is modeled, the rate of N2O5 hydrolysis depends on particle surface area and acidity; predicted PM nitrate will be slightly increased. Affected routines: CHMSTRY.COM, READCHM.F, CHEMDRIV.F, KHETERO.F v4.50 Modifications ------------------- 1. Added interpolation of temperature and pressure to PiG sampling grids. Implications: Improves concentration distrubtions on sampling grids in complex terrain. Affected routines: PIGSAMPL.F 2. Numerous small modifications to improve robustness of PM calculations in CF and CMU PM chemistry, and to simplify source code. Implications: No significant impacts on model speed or results. Affected routines: AEROSET.F, CHEMDRIV.F, AEROCHEM_CF.F, AEROCHEM_CMU.F, IRONCHEM.F 3. Numerous small modifications to improve robustness of gas-phase chemistry source code in OSAT, PA, and PiG. Implications: No significant impacts on model speed or results. Affected routines: LSCALL.F, CHEMDRIV.F, EXPTBL.F, PIGDRIVE.F, SPCSPRCSA.F, SPCCBIVSA.F, CYCTPNSA.F, O3PRDSA.F, CLCBWT.F 4. Revised the calculation of ozone destruction for OSAT to improve consistency across chemical mechanisms (CB4, CB05 and SAPRC99). Implications: Transparent to the user, improves code to handle any given gas mechanism. Affected routines: O3PRDSA.F 5. Revised the calculation of average OH rate constants in the OSAT and APCA source apportionment algorithms to be on a per carbon basis. Implications: Testing for a Los Angeles database found small impacts on ozone apportionments to VOC source categories. Affected routines: STABSA.F v4.50 Bug Fixes --------------- 1. Removed killing of PiG puffs when they grow into surface layer. Implications: A leftover diagnostic check was removed, which had been terminating PiG puffs whenever puffs grew into the surface layer. Puff behavior will change and higher sampling grid concentrations should be realized. Affected routines: PIGDRIVE.F 2. Fixed a typo in the code for OSAT/PSAT probing tools. Implications: Master grid boundary conditions for tracers were not updated at each timestep due to a typo, which is now fixed. Minor impact on OSAT/PSAT results. Affected routines: EMISTRNS.F 3. Fixed a bug in passing snow field to dry deposition routine. Implications: Incorrect snow values were passed to dry deposition routine for the nest grids. Minor impact on dry deposition velocities when optional snow field is used for nest grids. Affected routines: CAMx.F 4. Fixed a bug in RTRAC wet deposition routine. Implications: Incorrect order of argument variables was leading to NaNs in RTRAC wet deposition. Affected routines: WETDEPRT.F 5. Fixed a bug in rewinding/reading RTRAC point source file. Implications: When running CAMx continuously for more than 24 hours, RTRAC was not rewinding and synchronizing the RTRAC point source file correctly, leading to a model crash. This only impacted the case when users set the emissions date-insensitive flag = true. Affected routines: RDPTRT.F 6. Fixed minor Process Analysis bugs in vertical advective flux and wet deposition. Implications: Occasional large spurios relative errors are removed in the IPR outuput. Affected routines: VRTSLV.F, WETDEP.F