[PULL REQUEST] Ecophysiology module that simulates stomatal resistance, plant productivity and isoprene emission #629
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Hi support team,
This PR is about incorporating the ecophysiology module into the GEOS-Chem. Details are described below. Please feel free to let me know if any additional information is required. Thank you!
Summary
Ground-level ozone (O3) is a major air pollutant that adversely affects human health and agricultural productivity. Removal of air pollutants including tropospheric O3 from the atmosphere by vegetation is controlled mostly by the process of dry deposition in the form of plant stomatal uptake, which in turn causes damage to plant tissues with ramifications for ecosystem and crop health. The openness of plant stomata is generally represented by a bulk stomatal conductance, which is often semi-empirically parameterized in many atmospheric and land surface models, and highly fitted to historical observations. A lack of mechanistic linkage to ecophysiological processes such as photosynthesis may render models insufficient to represent plant-mediated responses of atmospheric chemistry to long-term changes in CO2, climate and short-lived air pollutant concentrations. A new ecophysiology module is developed to mechanistically simulate land−atmosphere exchange of important gas species in GEOS-Chem, a chemical transport model widely used in atmospheric chemistry studies. We adopted the formulations from the Joint UK Land Environmental Simulator (JULES) to couple photosynthesis rate, bulk stomatal conductance and isoprene emission rate dynamically.
Key results
Code updates
The ecophysiology-related formulation is inside GeosCore/ecophy_mod.F90. Changes in drydep_mod.F, state_diag_mod.F90 and diagnostics_mod.F90 mainly deal with diagnostics. Updates in other files are mostly about enabling my module to work in GEOS-Chem. When the module is turned on, the dry deposition over vegetated land is generally lower and the resulting ozone concentration over land becomes higher.
Model structure
Currently, my module is called inside the drydep_mod.F when the bulk canopy stomatal resistance is calculated. If ecophysiology is turned on, it replaces the default parameterization of the stomatal resistance in Wesely scheme.
Clarifications on my changes in drydep_mod.F90
Most of those changes are involved to interchange the order of calculation of aerodynamic resistance RA and surface conductance RSURFC (which involves removing a DO loop) and include an IF-statement to call the ecophysiology module.
Data file update
To enable the parameterizations in the ecophysiology module, I included a map of some soil parameters. It is read by HEMCO.
References: