NCAR ACD FLEXPART Backtrajectories (C-130 Flights)

The chaotic nature of the atmosphere and uncertainties in model estimates of wind vector, turbulence and convection requires a statistical approach to estimate all probable backtrajectories. Hence not only one, but a large number of particles (1e5 - 1e6) are released over a short time period (1 hr) and followed back in time. While the exact trajectory for each particle is used internally, the main model result is the number of particles and the time they spent within a 3D lat/lon/altitude grid, called a "sensitivity" or "residence time" field.

This is calculated at discrete intervals (every hour) in time since release. These fields are the raw output of the model calculations. For ease of use, deterministic backtrajectories as mass weighted mean of the plume at each hour, and 5 plume cluster centroids (Stohl et al., Atm.

Env., 2002) are calculated as well. NOTE: Narrowing your order by date will allow you to select from a smaller group of files. Please make sure to properly acknowledge this dataset in publications or presentations, or consider offering co-authorship if you deem it to be a substantial contribution to your work.