828301.fig.003a
(a)
828301.fig.003b
(b)
828301.fig.003c
(c)
828301.fig.003d
(d)
Figure 3: Air mass back trajectories at 4000 m, 1500 m, and 500 m for February 4, 2009 (a), February 6, 2009 (b), March 5, 2009 (c), and March 6, 2009 (d).