Observations of the migrating semidiurnal and quaddiurnal tides from the RAIDS/NIRS instrument

In this paper we analyze temperature data from the Near-Infrared Spectrometer (NIRS) instrument on Remote Atmospheric and Ionospheric Detection System experiment on the International Space Station and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite during June and July 2010 to investigate structures of the migrating semidiurnal (12 h) and quaddiurnal (6 h) tides in the upper mesosphere and lower thermosphere. Temperature measurements from the NIRS and SABER instruments allow us to examine the tides from the stratosphere to the lower thermosphere. We find that the amplitude of the migrating 6 h tide grows from ~5 K near 100 km altitude to ~30 K near 130 km. The amplitudes of the tide at altitudes accessible by NIRS are much larger than those previously reported at lower altitudes from the Aura Microwave Limb Sounder and the SABER instruments. The amplitude of the 12 h tide in the NIRS data shows two peaks in the lower thermosphere (between 95 and 130 km) with a maximum around 60 K occurring in the winter hemisphere near 20° latitude and a second maximum around 40 K occurring in the summer hemisphere near 30° latitude. The structure of the migrating terdiurnal (8 h) tide is also investigated in the NIRS data and shows increasing amplitude with altitude over a broad range of latitudes, roughly between 50°N and 30°S. Altitudinal variations seen in the 6, 8, and 12 h tides suggest an evolving mix of various Hough modes.