Articles | Volume 10, issue 3
Model description paper
29 Mar 2017
Model description paper |  | 29 Mar 2017

CLEPS 1.0: A new protocol for cloud aqueous phase oxidation of VOC mechanisms

Camille Mouchel-Vallon, Laurent Deguillaume, Anne Monod, Hélène Perroux, Clémence Rose, Giovanni Ghigo, Yoann Long, Maud Leriche, Bernard Aumont, Luc Patryl, Patrick Armand, and Nadine Chaumerliac

Abstract. A new detailed aqueous phase mechanism named the Cloud Explicit Physico-chemical Scheme (CLEPS 1.0) is proposed to describe the oxidation of water soluble organic compounds resulting from isoprene oxidation. It is based on structure activity relationships (SARs) which provide global rate constants together with branching ratios for HO abstraction and addition on atmospheric organic compounds. The GROMHE SAR allows the evaluation of Henry's law constants for undocumented organic compounds. This new aqueous phase mechanism is coupled with the MCM v3.3.1 gas phase mechanism through a mass transfer scheme between gas phase and aqueous phase. The resulting multiphase mechanism has then been implemented in a model based on the Dynamically Simple Model for Atmospheric Chemical Complexity (DSMACC) using the Kinetic PreProcessor (KPP) that can serve to analyze data from cloud chamber experiments and field campaigns.

The simulation of permanent cloud under low-NOx conditions describes the formation of oxidized monoacids and diacids in the aqueous phase as well as a significant influence on the gas phase chemistry and composition and shows that the aqueous phase reactivity leads to an efficient fragmentation and functionalization of organic compounds.

Short summary
The Cloud Explicit Physico-chemical Scheme (CLEPS 1.0) describes oxidation of water-soluble organic compounds resulting from isoprene oxidation. It is based on structure activity relationships (SARs) (global rate constants and branching ratios for HO• abstraction and addition) and GROMHE SAR (Henry's law constants for undocumented species). It is coupled to the MCM gas phase mechanism and is included in a model using the DSMACC model and KPP to analyze experimental and field data.