GMD Geoscientific Model Development GMD Geosci. Model Dev. 1991-9603 Copernicus Publications Göttingen, Germany 10.5194/gmd-6-1029-2013 A mass-conserving and multi-tracer efficient transport scheme in the online integrated Enviro-HIRLAM model Sørensen B. 1 Kaas E. https://orcid.org/0000-0001-6970-2404 1 Korsholm U. S. 2 Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark Danish Meteorological Institute, Copenhagen, Denmark 22 07 2013 6 4 1029 1042 Copyright: © 2013 B. Sørensen et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://gmd.copernicus.org/articles/6/1029/2013/gmd-6-1029-2013.html The full text article is available as a PDF file from https://gmd.copernicus.org/articles/6/1029/2013/gmd-6-1029-2013.pdf

In this paper a new advection scheme for the online coupled chemical–weather prediction model Enviro-HIRLAM is presented. The new scheme is based on the locally mass-conserving semi-Lagrangian method (LMCSL), where the original two-dimensional scheme has been extended to a fully three-dimensional version. This means that the three-dimensional semi-implicit semi-Lagrangian scheme which is currently used in Enviro-HIRLAM is largely unchanged. The HIRLAM model is a computationally efficient hydrostatic operational short-term numerical weather prediction model, which is used as the base for the online integrated Enviro-HIRLAM. The new scheme is shown to be efficient, mass conserving, and shape preserving, while only requiring minor alterations to the original code. It still retains the stability at long time steps, which the semi-Lagrangian schemes are known for, while handling the emissions of chemical species accurately. Several mass-conserving filters have been tested to assess the optimal balance of accuracy vs. efficiency.

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