Assessing Tracer Transport Algorithms and the Impact of Vertical Resolution in a Finite-Volume Dynamical Core

James Kent*, Christiane Jablonowski, Jared P. Whitehead, Richard B. Rood

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Modeling the transport of trace gases is an essential part of any atmospheric model. The tracer transport scheme in the Community Atmosphere Model finite-volume dynamical core (CAM-FV), which is part of the National Center for Atmospheric Research's (NCAR's) Community Earth System Model (CESM1), is investigated using multidimensional idealized advection tests. CAM-FV's tracer transport algorithm makes use of one-dimensional monotonic limiters. The Colella-Sekora limiter, which is applied to increase accuracy where the data are smooth, is implemented into the CAM-FV framework, and compared with the more traditional monotonic limiter of the piecewise parabolic method (the default limiter). For 2D flow, CAM-FV splits dimensions, allowing overshoots and undershoots, with the Colella-Sekora limiter producing larger overshoots than the default limiter.

The impact of vertical resolution is also explored. A vertical Lagrangian coordinate is used in CAM-FV, and is periodically remapped back to a fixed Eulerian grid. For purely vertical motion, it is found that less-frequent remapping of the Lagrangian coordinate in CAM-FV improves results. For full 3D tests, the vertical component of the tracer transport dominates the error and limits the overall accuracy. If the vertical resolution is inadequate, increasing the horizontal resolution has almost no effect on accuracy. This is because the vertical resolution currently used in CAM version 5 may not be sufficiently fine enough to resolve some atmospheric tracers and provide accurate vertical advection. Idealized tests using tracers in a gravity wave agree with these results.

Original languageEnglish
Pages (from-to)1620-1638
Number of pages19
JournalMonthly weather review
Volume140
Issue number5
DOIs
Publication statusPublished - May 2012
Externally publishedYes

Keywords

  • SEMI-LAGRANGIAN TRANSPORT
  • SHALLOW-WATER EQUATIONS
  • ATMOSPHERIC TRANSPORT
  • HORIZONTAL RESOLUTION
  • MODEL
  • SCHEME
  • ORDER
  • SPHERE
  • ADVECTION
  • CLIMATE

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