Arild Andersen found one of his clearest avenues of expression with Masqualero, a group that brought him notably together with trumpeter Nils Petter Molvaer, saxophonist Tore Brunborg, and drummer Jon Christensen. On Aero, the group’s second album for ECM, he is joined also by Frode Alnaes, whose looming drones ebb and flow throughout the title opener, which seems to materialize out of nothing into a looming figure of delicate comportment and elegant mind. It is this figure whose footsteps Andersen articulates. In “Science” this figure shows us it can dance, fashioning a partner out of snatches of rain and cloud, autumn and snowdrift. The confidence of that stride is expressed in the superb dynamic contrasts of the band, only to be unraveled through Brunborg’s platonic soprano into a sonorous vulnerability.