What wind data are used to calculate the trajectories?


All available 5-minute observations of wind speed and wind direction measured at the monitoring stations within the Corpus Christi surface monitoring network are used for the trajectory calculation.  Ideally, the trajectory would be based on continuous observations of wind speed and direction at monitoring stations located throughout the entire Corpus Christi area.  In reality, observations of wind speed and wind direction are only available from a limited number of monitoring stations so that winds at locations away from the monitoring stations must be estimated using the available observations. An interpolation scheme is used to make these estimates.


What is the trajectory calculation methodology?


At the trajectory starting location, an inverse distance interpolation is used to estimate the average wind speed and wind direction at the requested start time.  The inverse distance interpolation methodology is used so that wind data collected at nearby monitoring stations are more heavily weighted compared to wind data collected at more distant monitoring stations.  The average 5-minute wind speed and direction obtained from the interpolation is then used to advect (forward or backward in time) the hypothetical parcel over a 5-minute period.  The hypothetical air parcel is assumed to move along a linear path at the average wind speed and direction.  A new average wind speed and direction is then interpolated at the new trajectory location using all available wind data for the next 5-minute period.  The calculation procedure is repeated until the trajectory is complete for the requested duration.