Following up on Eemeli's findings that the sulphate production is low in OpenIFS when simplified chemistry with climatological oxidants is used, I am checking subroutine AER_SO2SO4_V2. Looking at the constants used to define the Henry coefficients, it seems the temperature dependence for SO2 is incorrect:
REAL(KIND=JPRB), PARAMETER :: ZHCP_SO2_TD = 2100._JPRB ! temperature dependency for H^cp(SO2) [K]
According to Sander (ACP, 2015; https://doi.org/10.5194/acp-15-4399-2015), the value for this constant should be 2900. (see Table on p. 4416). Attached are two plots showing the temperature dependence of the Henry coefficient for the two cases and the corresponding relative error, respectively. Between -20 and +50 degrees Celsius, the relative error varies from ~ +60% to ~ -20%. By definition, the error is 0. at 25. degrees Celsius. For higher (lower) temperatures, less (more) SO2 will be dissolving from the gas phase into the cloud droplets, resulting in less (more) aqueous-phase sulphate production.
Following up on Eemeli's findings that the sulphate production is low in OpenIFS when simplified chemistry with climatological oxidants is used, I am checking subroutine AER_SO2SO4_V2. Looking at the constants used to define the Henry coefficients, it seems the temperature dependence for SO2 is incorrect:
REAL(KIND=JPRB), PARAMETER :: ZHCP_SO2_TD = 2100._JPRB ! temperature dependency for H^cp(SO2) [K]
According to Sander (ACP, 2015; https://doi.org/10.5194/acp-15-4399-2015), the value for this constant should be 2900. (see Table on p. 4416). Attached are two plots showing the temperature dependence of the Henry coefficient for the two cases and the corresponding relative error, respectively. Between -20 and +50 degrees Celsius, the relative error varies from ~ +60% to ~ -20%. By definition, the error is 0. at 25. degrees Celsius. For higher (lower) temperatures, less (more) SO2 will be dissolving from the gas phase into the cloud droplets, resulting in less (more) aqueous-phase sulphate production.