gSAM–Chem

large eddy simulation with interactive chemistry

A fast and modular platform to investigate atmospheric chemistry and transport at convective scales, resolving plume-scale chemistry.

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gSAM–Chem features

gSAM–Chem adds a fully coupled chemistry module to the global System for Atmospheric Modeling (gSAM)

Explicit Deep Convection

Resolves convective updrafts, cloud microphysics, and lightning at ~66 m horizontal resolution. Captures plume-scale isoprene–NOx segregation that is parametrized away in coarser models.

Interactive Emissions

Surface isoprene and soil NOx emissions respond to light, temperature, and precipitation-driven soil moisture. Lightning NOx is generated in real time from simulated convective intensity and cloud-to-ground/intracloud flash rates.

KPP-Compatible Chemistry

Plug-and-play gas-phase mechanisms via KPP. Ships with the CloudChem mechanism (44 gas-phase + 7 photolysis reactions) tuned for tropical isoprene–NOx–OH chemistry. Swap in any mechanism for other applications.

~50 m
spatial resolution
1 s
chemical time step
highly parallelized
linear strong-scaling speedup through 256 cores

Model architecture

gSAM–Chem couples a large eddy simulation dynamical core with interactive gas-phase chemistry, emissions, and deposition.

gSAM–Chem model schematic showing radiation, microphysics, chemistry, emissions, and deposition

Why gSAM–Chem?

Traditional chemical transport models parametrize convection whereas gSAM–Chem explicitly simulates it, enabling mechanistic studies of chemistry-meteorology interactions.

Use cases

gSAM–Chem supports a range of applications including:

Chemistry & convection

Simulate isoprene, NOx, OH, and related species in convective environments.

Subgrid process studies

Quantify chemistry–turbulence segregation, canopy-layer chemistry, or lightning NOx production.

Interpreting satellite observations

Generate high-resolution vertical profiles to interpret satellite trace gas retrievals.