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CMAQ vs constants

A side-by-side editorial comparison of CMAQ and constants — release velocity, themes, recent moves, and the top alternatives to consider.

CMAQ vs constants: at a glance

FeatureCMAQconstants
SectorAnalyticsAnalytics
Velocity score0.00.0
Sparks · 30d00
Top themesair-quality, atmospheric-modeling, epa, scientific-computingphysical-constants, codata, units, uncertainty-propagation
Last editorial update2h ago49m ago
WebsiteVisit →Visit →

What is CMAQ?

CMAQ went global in v5.5, and has been patching that surface ever since.

CMAQ is the EPA's Community Multiscale Air Quality modeling system, used for regulatory and research air quality simulation. Its release rhythm is strictly two-tier: numbered major versions carry new science and fresh benchmark datasets, while the x.y.z.n updates carry bug fixes against documentation and benchmarks that stay pinned to the parent version. The current line is v5.5, which introduced CRACMM2 chemistry and coupling to MPAS-A meteorology, followed by three patch rollups.

Read the full CMAQ trajectory →

What is constants?

The R package for CODATA constants rebuilt its symbol table on NIST's naming so future updates stop being hand work.

constants exposes the CODATA recommended values of the physical constants to R, as a data frame plus symbol lists that carry units, uncertainties, or both. The package reached 1.0.0 on the 2018 CODATA release and has shipped once since, purely to track a units package update. Its surface is small and its release cadence is bound to CODATA, which revises every few years.

Read the full constants trajectory →

CMAQ vs constants: editorial side-by-side

C
CMAQ
ANALYTICS
0.0

CMAQ went global in v5.5, and has been patching that surface ever since.

◆ Current state

CMAQ is the EPA's Community Multiscale Air Quality modeling system, used for regulatory and research air quality simulation. Its release rhythm is strictly two-tier: numbered major versions carry new science and fresh benchmark datasets, while the x.y.z.n updates carry bug fixes against documentation and benchmarks that stay pinned to the parent version. The current line is v5.5, which introduced CRACMM2 chemistry and coupling to MPAS-A meteorology, followed by three patch rollups.

◆ Where it's heading

The v5.5 patches cluster around the newest and most sensitive components. ISAM source apportionment and DDM-3D sensitivity analysis account for corrections in every one of the three updates, and CRACMM2 needed fixes within months of release. That is the expected shape after a major version lands: the science is stable, the instrumentation built on top of it is not. Parallel I/O work in the latest patch suggests the global configurations are now being run at scales that expose throughput limits.

◆ Prediction

The next major version will fold these fixes in with new science, documentation and benchmark data — the release notes state this explicitly each time. Until then, expect further ISAM and DDM-3D corrections, which have appeared in every patch so far.

C
constants
ANALYTICS
0.0

The R package for CODATA constants rebuilt its symbol table on NIST's naming so future updates stop being hand work.

◆ Current state

constants exposes the CODATA recommended values of the physical constants to R, as a data frame plus symbol lists that carry units, uncertainties, or both. The package reached 1.0.0 on the 2018 CODATA release and has shipped once since, purely to track a units package update. Its surface is small and its release cadence is bound to CODATA, which revises every few years.

◆ Where it's heading

The direction set at 1.0.0 was to stop being a curated convenience wrapper and become a mechanical mirror of NIST. Hand-crafted symbol names were replaced with NIST's own ASCII symbols, categories adopted NIST's, and uncertainty switched from relative to absolute — all framed by the maintainer as necessary to make future CODATA updates routine. On top of that the package gained a correlation matrix and optional integration with the quantities package, moving it from a lookup table toward something that can propagate uncertainty.

◆ Prediction

Having rebuilt the symbol table specifically so CODATA revisions become mechanical, the next substantive release most likely tracks a new CODATA dataset rather than adding API. The experimental correlated-value support, disabled by default at 1.0.0, is the one part these entries flag as unfinished.

Alternatives to CMAQ and constants

Other Analytics products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either CMAQ or constants.

See all CMAQ alternatives → · See all constants alternatives →

Recent activity from CMAQ and constants

Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.

  1. 1y agoCMAQCMAQ 5.5.0.3 enables parallel I/O, fixes DDM-3D control files
  2. 1y agoCMAQCMAQ 5.5.0.2 corrects ISAM aerosol and cloud processing
  3. 1y agoCMAQCMAQ 5.5.0.1 fixes SAPRC mechanism runs and NLCD mapping
  4. 1y agoCMAQCMAQ 5.5 adds global simulation coupled to MPAS-A
  5. 1y agoCMAQCMAQ 5.4.0.5: minor ELMO output fixes
  6. 2y agoCMAQCMAQ 5.4.0.4 fixes RBSTATS under ROS3, corrects a molecular weight
  7. 5y agoconstantsCompatibility fix for units 0.7-0
  8. 5y agoconstantsconstants 1.0.0
  9. 8y agoconstantsUnit handling fixes ahead of the 1.0.0 rebuild

Frequently asked questions

What is the difference between CMAQ and constants?

They serve adjacent needs but don't currently overlap on shipped themes. CMAQ and constants are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.

Is CMAQ better than constants?

Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. CMAQ and constants are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other Analytics products to evaluate alongside.

What are the best alternatives to CMAQ?

Top CMAQ alternatives in Analytics are ranked by recent ship velocity. Browse the "CMAQ alternatives" section above for the current picks, or visit /alternatives/cmaq for the full list with editorial commentary on each.

What are the best alternatives to constants?

Top constants alternatives in Analytics are ranked by recent ship velocity. Browse the "constants alternatives" section above for the current picks, or visit /alternatives/constants-r for the full list with editorial commentary on each.