Volcanic Clouds over the North Atlantic? Nutshell: Multiple CALIPSO layers from PBL to 10 km on 8 May, mid-day. Layers extend from 40-60N. Notes: * CALIPSO feature ID is “cloud” for most of these layers. * Horizontal texture of these layers is smooth compared to extensive cloud features north of 60. * CloudSat picks up no echoes in curtain containing these layers. * CloudSat DOES pick up echoes in area of broad CALIPSO cloud north of 60. * CloudSat also gets echoes off of some stratoCu below the thinner CALIPSO layers. * Back trajectory from a 9km CALIPSO feature at ~44N matches in location and time the strong OMI AI feature on 6 May southeast of Iceland. * Ray Hoff posted some 7 May CALIPSO curtains he suspected of volcanic origin (http://alg.umbc.edu/usaq/archives/003768.html) Relevance: Large AI on 6 May implicates a strong and high absorbing aerosol plume. AI and SO2 (not shown) plumes on 7 and 8 May indicate movement in the direction of the 8 May CALIPSO layers. If the 8 May CALIPSO layers are not simply water-ice clouds, this suggests ash penetration to ~10 km and elevated layers over a large area of the Atlantic. It may me important to examine these layers critically to confirm or rule out ash. Mike Fromm, NRL, 9 May 2010

Cut to the chase… …next slide is CALIPSO/CloudSat composite showing the layers in question in the context of nearby certain water-ice clouds. … next next slide gives the trajectory and AI analysis …all the rest of the slides are just the original CALIPSO and CloudSat granules used.

Back Trajectory start point (next) Volcanic clouds? No CloudSat cloud except for strongest stratoCu Where on Earth we’re looking CloudSat cloud extent Back Trajectory start point (next) Land Feature synch Volcanic clouds?

Endpoint time is 14 UTC 6 May OMI AI 6 May 2010, ~11-14 UTC Image credit: Simon Carn Notice double-digit AI max near Trajectory endpoint

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