STRATAQ: A three-dimensional Chemical Transport Model of the stratosphere

• Main Authors: Grassi, B., Redaelli, G., Visconti, G.
• Other Authors: Dipartimento di Fisica L'Aquila, Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2002
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Arctic
• Online Access: https://hal.science/hal-00317041; https://hal.science/hal-00317041/document; https://hal.science/hal-00317041/file/angeo-20-847-2002.pdf

International audience A three-dimensional (3-D) Chemical Transport Model (CTM) of the stratosphere has been developed and used for a test study of the evolution of chemical species in the arctic lower stratosphere during winter 1996/97. This particular winter has been chosen for testing the model's capabilities for its remarkable dynamical situation (very cold and strong polar vortex) along with the availability of sparse chlorine, HNO 3 and O 3 data, showing also very low O 3 values in late March/April. Due to those unusual features, the winter 1996/97 can be considered an excellent example of the impact of both dynamics and heterogeneous reactions on the chemistry of the stratosphere. Model integration has been performed from January to March 1997 and the resulting long-lived and short-lived tracer fields compared with available measurements. The model includes a detailed gas phase chemical scheme and a parameterization of the heterogeneous reactions occurring on liquid aerosol and polar stratospheric cloud (PSC) surfaces. The transport is calculated using a semi-lagrangian flux scheme, forced by meteorological analyses. In such form, the STRATAQ CTM model is suitable for short-term integrations to study transport and chemical evolution related to "real" meteorological situations. Model simulation during the chosen winter shows intense PSC formation, with noticeable local HNO 3 capture by PSCs, and the activation of vortex air leading to chlorine production and subsequent O 3 destruction. The resulting model fields show generally good agreement with satellite data (MLS and TOMS), although the available observations, due to their limited number and time/space sparse nature, are not enough to effectively constraint the model. In particular, the model seems to perform well in reproducing the rapid processing of air inside the polar vortex on PSC converting reservoir species in active chlorine. In addition, it satisfactorily reproduces the morphology of the continuous O 3 decline as shown by the satellite ...