Signatures of the 3‐day wave in the low‐latitude and midlatitude ionosphere during the January 2010 URSI World Day campaign

Recent studies of the equatorial ionosphere have found evidence of forcing by atmospheric Ultra Fast Kelvin (UFK) waves. This study investigates the quasi‐3‐day UFK wave and its effects on the variations of the ionosphere at low latitudes and midlatitudes using coordinated observations of both the atmosphere and ionosphere during the January 2010 URSI World Day campaign. The global maps of TEC from the IGS ground‐based GPS product demonstrate a 3‐day periodic variation during January 15–25. This variation has the largest amplitude at 15° magnetic latitude and extends into lower latitudes. Simultaneously, a 3‐day wave is observed in the mesosphere in the zonal wind measurements by a meteor radar at the magnetic equator. The latitudinal range of the TEC variation (20°S–20°N) is also consistent with that of the 3‐day wave. The Incoherent Scatter Radar (ISR) observations show a 3‐day signature in vertical ion drifts over Jicamarca (11.9°S, 76°W) and in the electron densities in the top side of ionosphere measured from Millstone Hill (42.6°N, 71.5°W). This signature is consistent with the fountain effect in the equatorial region, and shows the impact on the topside ionosphere at midlatitudes. The UFK wave is trapped within ±30° geographic latitude, but this study shows that the effects of the wave could reach the ionosphere at the higher latitude even as high as 40°N (50°N magnetic latitude).