ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-4-1371-2004 3-D chemistry-transport model Polair: numerical issues, validation and automatic-differentiation strategy Mallet V. 1 Sportisse B. 1 CEREA, Joint Research Laboratory, Ecole Nationale des Ponts et Chaussées, EDF R&D, France 08 03 2004 4 2 1371 1392 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/4/1371/2004/acpd-4-1371-2004.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/4/1371/2004/acpd-4-1371-2004.pdf

We briefly present in this short paper some issues related to the development and the validation of the three-dimensional chemistry-transport model Polair. <br><br> Numerical studies have been performed in order to let Polair be an efficient and robust solver. This paper summarizes and comments choices that were made in this respect. <br><br> Simulations of relevant photochemical episodes were led to assess the validity of the model. The results can be considered as a validation, which allows next studies to focus on fine modeling issues. <br><br> A major feature of Polair is the availability of a tangent linear mode and an adjoint mode entirely generated by automatic differentiation. Tangent linear and adjoint modes grant the opportunity to perform detailed sensitivity analyses and data assimilation. This paper shows how inverse modeling is achieved with Polair.