SEAC4RS Lightning Influenced Trajectory Plots
We computed encounters with NLDN-derivied lightning following the same general procedure as Fuelberg et al. (2007). Briefly, a trajectory was considered to be influenced by lightning if there was at least one NLDN flash within 0.5 degrees latitude/longitude and within +-30 min of its position. We also tested a spatial threshold of 0.25 degrees latitude/longitude. The distances of 0.5 and 0.25 degrees are used to account for the uncertainties in trajectory locations. Further, we used only the 36 km WRF data for these calculations. Because we are mixing model data with observed lightning, we wanted the model-produced convection to have little influence on the trajectory. Thus, the 36 km data was a compromise between accurately representing the synoptic-scale flow without over-emphasizing model-produced convection.
For each DC-8 flight, the plots show the flight track color coded by "time since lightning influence." For example, the color red indicates that back trajectories released from that location encountered NLDN lightning within 0-12 hours. Black indicates that the trajectories never encountered NLDN lightning. Text data for the lightning influence product is available for each flight and has the following format:
Flight leg, Traj # within that flight leg, starting lat, starting lon, starting height (m), starting month, starting day, starting hour, starting minute, time since convective influence (hours), ending lat, ending lon, ending height, ending month, ending day, ending hour, ending minute
In the description above, "ending" refers to the value the trajectory had when it encountered the NLDN lightning. "0" in the data indicates that the trajectory was not influenced by lightning during the 120 h back track.
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