The Sensitivity of Ageostrophic Circulations to Model Resolution: A Case Study Using NGM Forecasts of ERICA IOP-4.
Abstract
The effect of model resolution on the ageostrophic circulations and dynamics of a rapidly deepening extratropical cyclone that occurred during the Intensive Observing Period (IOP) 4 (4-5 January 1989) of the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) is examined using the psi-vector technique proposed by Keyser et al. (1989). A comparison of forecasts made by the National Meteorological Center's Nested Grid Model (NGM) using operational (C-grid) and double-resolution (D-grid) versions indicated central pressure and frontal evolution differences between the two forecasts IW IOP-4 cyclone was observed to deepen by 60 mb in 24 h to a central pressure of 936 mb. The NGM C-grid forecast attained a central pressure at 0000 UTC 5 Jan of 959 mb, while the D-grid forecast attained a central pressure of 949 mb. Differences in the laterally coupled jet streaks between the C- and D-grid forecasts enabled the D-grid forecast to depict stronger transverse ageostrophic circulations that produced stronger ascent and greater spin-up of the low-level cyclone.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1992
- Accession Number
- ADA262011
Entities
People
- James Berdeguez
Organizations
- Naval Postgraduate School