Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 8, 3247-3255, 2015
https://doi.org/10.5194/gmd-8-3247-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Development and technical paper
14 Oct 2015
A semi-Lagrangian advection scheme for radioactive tracers in the NCEP Regional Spectral Model (RSM)
E.-C. Chang1 and K. Yoshimura2 1Department of Atmospheric Science, Kongju National University, Gongju, South Korea
2Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan
Abstract. In this study, the non-iteration dimensional-split semi-Lagrangian (NDSL) advection scheme is applied to the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) to alleviate the Gibbs phenomenon. The Gibbs phenomenon is a problem wherein negative values of positive-definite quantities (e.g., moisture and tracers) are generated by the spectral space transformation in a spectral model system. To solve this problem, the spectral prognostic specific humidity and radioactive tracer advection scheme is replaced by the NDSL advection scheme, which considers advection of tracers in a grid system without spectral space transformations. A regional version of the NDSL is developed in this study and is applied to the RSM. Idealized experiments show that the regional version of the NDSL is successful. The model runs for an actual case study suggest that the NDSL can successfully advect radioactive tracers (iodine-131 and cesium-137) without noise from the Gibbs phenomenon. The NDSL can also remove negative specific humidity values produced in spectral calculations without losing detailed features.

Citation: Chang, E.-C. and Yoshimura, K.: A semi-Lagrangian advection scheme for radioactive tracers in the NCEP Regional Spectral Model (RSM), Geosci. Model Dev., 8, 3247-3255, https://doi.org/10.5194/gmd-8-3247-2015, 2015.
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In this study, the non-iteration dimensional-split semi-Lagrangian (NDSL) advection scheme is applied to the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) to alleviate the Gibbs phenomenon. The model runs for the Fukushima accident case study suggest that the NDSL can successfully advect radioactive tracers (iodine-131 and cesium-137) without noise from the Gibbs phenomenon.
In this study, the non-iteration dimensional-split semi-Lagrangian (NDSL) advection scheme is...
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