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 6h tide grows from similar to 5K near 100km altitude to similar to 30K near 130km. 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 12h tide in the NIRS data shows two peaks in the lower thermosphere (between 95 and 130 km) with a maximum around 60K occurring in the winter hemisphere near 20 degrees latitude and a second maximum around 40K occurring in the summer hemisphere near 30 degrees 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 degrees N and 30 degrees S. Altitudinal variations seen in the 6, 8, and 12h tides suggest an evolving mix of various Hough modes.