Polar cap mesosphere wind observations: comparisons of simultaneous measurements with a Fabry-Perot interferometer and a field-widened Michelson interferometer

Polar cap mesospheric winds observed with a Fabry-Perot interferometer with a circle-to-line interferometer optical (FPI/CLIO) system have been compar ed with measurements from a field-widened Michelson interferometer optimize d for E-region winds (ERWIN). Both instruments observed the Meinel OH emiss ion emanating from the mesopause region (similar to 86 km) at Resolute Bay, Canada (74.9 degrees N, 94.9 degrees W). This is the first time, to our kn owledge, that winds measured simultaneously from a ground based Fabry-Perct interferometer and a ground-based Michelson interferometer have been compa red at the same location. The FPI/CLIO and ERWIN instruments both have a ca pability for high temporal resolution (less than 10 min for a full scan in the four cardinal directions and the zenith). Statistical comparisons of ho urly mean winds for both instruments by scatterplots show excellent agreeme nt, indicating that the two optical techniques provide equivalent observati ons of mesopause winds. Small deviations in the measured wind can be ascrib ed to the different zenith angles used by the two instruments. The combined measurements illustrate the dominance of the 12-h wave in the mesopause wi nds at Resolute Bay, with additional evidence for strong gravity wave activ ity with much shorter periods (tens of minutes). Future operations of the t wo instruments will focus on observation of complementary emissions, provid ing a unique passive optical capability for the determination of neutral wi nds in the geomagnetic polar cap at various altitudes near the mesopause. ( C) 2000 Optical Society of America OCIS codes: 010.1290, 120.3180, 120.2230 , 120.4640.