Thermospheric planetary wave‐type oscillations observed by FPIs over Xinglong and Millstone Hill

Three-year (2010-2013) observations of thermospheric winds (at similar to 250 km) by Fabry-Perot interferometers at Xinglong (XL, 40.2 degrees N, 117.4 degrees E) and Millstone Hill (MH, 42.6 degrees N, 71.5 degrees W) are used to study the climatology of atmospheric planetary wave-type oscillations (PWTOs) with periods of 4-19 days. We find that (1) these PWTOs occur more frequently in the months from May to October. They are consistent with the summertime preference of middle-latitude ionospheric electron density oscillations noted in other studies. (2) The month-to-month variations in PWTOs show phase changes between MH and XL, switching from antiphase to in phase when PWTO periods vary from short to long. (3) Typical PWTOs show annual and semiannual variations. The relative intensity of annual over semiannual components for PWTOs is different between XL and MH. (4) Magnetic storms and substorms have little influences on the annual and semiannual variations of the typical PWTO amplitudes. (5) Meridional wind PWTOs with typical periodicity bands around 5, 8, and 16 days appear to be correlated to both solar wind speed and K-p oscillations, suggesting a possible influence of the solar wind corotating interaction regions on neutral wind dynamics.