Sensitivity of three-dimensional trajectories to the spatial and temporal densities of the wind field

Abstract

Initialization and forecast fields from the National Weather Service's (NWS) Nested Grid Model (NGM) were archived on the 90 km calculational grid at 2-hour intervals out to 12 hours, twice per day, for the 3-month period of January-March 1987. The resulting time series of meteorological data were used to determine the sensitivity of calculated trajectories to changes in temporal and spatial density of meteorological data during a wide range of synoptic conditions. Trajectories were most sensitive to changes in temporal resolution when the grid resolution was 90 and 180 km. Trajectories computed on the coarser 360 km grid had substantially larger deviations from the base case and were no longer sensitive to changes in temporal resolution. Relative horizontal transport deviations ranged from 5-25% of the travel distance at 96 hours depending upon the spatial and temporal resolution. -from Authors