Multi‐payload measurement of transverse velocity shears in the topside ionosphere

Using a multi-payload sounding rocket mission, we present the first direct measurement of velocity shear in the topside auroral ionosphere. In regions of large, similar to 200 mV/m, transient electric fields we directly measure differences in the plasma drift velocity. From these differences, shear frequencies reaching +/-6Hz are measured. These directly measured shears are compared with the shear inferred from single payload measurements. It is shown this traditional measurement of shear overestimates the shear frequency by a factor of two for this event, highlighting the importance of the temporal component of near-DC electric field structures. Coincident with these strong fields and shears are enhanced emissions of broadband, extremely low frequency (BB-ELF) plasma waves, and a narrowband wave emission near the H(+)-O(+) bi-ion resonant frequency. Citation: Lundberg, E. T., P. M. Kintner, K. A. Lynch, and M. R. Mella (2012), Multi-payload measurement of transverse velocity shears in the topside ionosphere, Geophys. Res. Lett., 39, L01107, doi:10.1029/2011GL050018.