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NCAR ACD FLEXPART Backtrajectories (C-130 Flights)



This dataset contains output of FLEXPART, a Lagrangian Particle Dispersion Model (LPDM), including an updated version of the plots/ICARTT data. It provides information on the history of air sampled along the C130 flight track by releasing "particles" (infinitesimally small parcels of air) from the plane location and following its path backwards in time. Advection, turbulence and convection are the processes considered. A particle itself is "inert", processes like deposition, emission or chemical conversion are not considered. Thereby the result could be called "airmass history", as the particles behave like air. Its location back in time and space since released is called "backtrajectory". 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.

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Language English
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Temporal coverage

Begin datetime 2013-06-03 00:00:00
End datetime 2013-07-14 23:59:59

Spatial coverage

Map data from IBCSO, IBCAO, and Global Topography.

Maximum (North) Latitude: 45.00, Minimum (South) Latitude: 24.00
Minimum (West) Longitude: -105.00, Maximum (East) Longitude: -72.00

Primary point of contact information

EOL Data Support <>

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Example citation following ESIP guidelines:

Knote, C. 2013. NCAR ACD FLEXPART Backtrajectories. Version 1.0. UCAR/NCAR - Earth Observing Laboratory. Accessed 28 Oct 2021.

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Ancillary information

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