On the hemispheric symmetry in thermospheric nitric oxide

Middle atmosphere research has suggested the importance of charged particle precipitation for several minor species. To experimentally investigate the se effects requires observations of both the minor species and particle pre cipitation. Particle precipitation is organized in a geomagnetic coordinate system, yet data are persistently presented in geographic coordinates. Thi s has serious implications, as quantified here for nitric oxide observation s, which could lead to erroneous conclusions regarding particle effects. In geographic coordinates UARS/HALOE measurements of high latitude NO at equi nox show a 25% hemispheric asymmetry that disappears when the data are repl otted in magnetic coordinates. This result is applicable to all high latitu de particle effects and is important for understanding magnetospheric and s olar influences on various minor species in the mesosphere and stratosphere .