Flight from Thule to Fairbanks on 4 April

• NA CO: Elevated plume of NA outflow from recirculated low, plume max at 8km altitude E of 80E, less at lower altitudes
• AS CO: Asian plume over most of Alaska, up to an alt of 6km
• BB CO: Not much along the flight track, but Siberian plume moving into Alaska
• EU CO: some EU CO dragged south along stratospheric filament. NW moving plume E of 100W at 5-6km altitude.

Flight from Thule to Fairbanks on 5 April

• NA CO, AS CO: not much pollution expected on direct return flight
• BB CO: Biomass plume moving into Alaska at 3-4km altitude. What is the origin of this? BB CO ahead of or mixed with EU SO4 plume.
• EU SO4: mid-level plume 3500m moving up on the west coast of GL on 5 April

Further evolution Asian CO plume moving across Alaska towards the pole, interesting target for continuous sampling? Chinese/Russian fire plume moving at 160E into the Arctic, branching, part moves into Russian waters, part passes south of Alaska/Aleutians. NA pollution moving up along W Greenland, strong CO plume moving in later. Flight track on April 5 Spiral over Summit for validation with radiation measurements. No flight across Greenland into African dust. Return over Hudson bay.