Unresolved spatial variability and microphysical process rates in large-scale models
Article first published online: 21 SEP 2012
Copyright 2000 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 105, Issue D22, pages 27059–27065, 27 November 2000
How to Cite
2000), Unresolved spatial variability and microphysical process rates in large-scale models, J. Geophys. Res., 105(D22), 27059–27065, doi:10.1029/2000JD900504., and (
- Issue published online: 21 SEP 2012
- Article first published online: 21 SEP 2012
- Manuscript Accepted: 9 AUG 2000
- Manuscript Received: 14 APR 2000
Prognostic cloud schemes in large-scale models are typically formulated in terms of grid-cell average values of cloud condensate concentration q, although variability in q at spatial scales smaller than the grid cell is known to exist. Because the source and sink processes modifying q are nonlinear, the process rates computed using the mean value of q are biased relative to process rates which account for subgrid-scale variability. A preliminary assessment shows that these biases can modify instantaneous process rates by as much as a factor of 2. Observations of q at a continental site suggest that the bias is avoided in current practice through the arbitrary tuning of model parameters. Models might be improved if subgrid-scale variability in q were explicitly considered; several approaches to this goal are suggested.