Characteristics of plume Releases as Depicted by Balloon Launchings and Model Simulations

Abstract

On 12 May 1986, approximately 190 000 tagged helium balloons were released at 1330 EDT from locations scattered throughout the United States. An average of 4.5% of the balloon tags were recovered and sent to the American Geological Institute. A map of resultant balloon trajectories was then generated from the data. From an analysis of the surface and 500 mb maps on this data, synoptic conditions are defined and categorized. This along with the resultant motion map gives useful data for identifying the dispersion characteristics involved with a particular synoptic condition. The ARL-ATAD model, a single-layer trajectory model, was run for the 12 May balloon launch for a PBL and 750-660 mb layer simulation from seven sites across the, United States. These were compared with the balloon resultant motion map. The PBL approach produced poor comparisons with two of the seven sites showing balloon and trajectory motions transporting plumes in opposite directions. The layer approach did much better with only the Los Angeles, California comparison showing disagreement. Yet oven with the layer approach, the ability of the ATAD model to predict plume transport is highly questionable due to the lateral dispersion evidenced by the balloon resultant motions. This experiment is of great interest because of the uniqueness involved with the spatial extent and total number of released balloons.