2. Kelvin Waves as Observed by the SABER Instrument on the TIMED Spacecraft Jeffrey M. Forbes, Xiaoli Zhang, Saburo Miyahara, Scott E. Palo, James Russell, Christopher J. Mertens and Martin Mlynczak This Paper: Main Focus on Equatorial Temperatures, 20-120 km Wavenumber vs. Period Spectra as a Function of Height Ultra-Fast Kelvin Waves (UFKW), Periods 2.5-4.5 days Intraseasonal Oscillation (ISO) of UFKW and Zonal Mean Temperatures

3. Data processing Sliding 60-day window, 1 day at a time, covering all local times and longitudes Extract zonal mean, diurnal & semidiurnal solar & lunar tides, & stationary planetary waves Analyze residuals from above fit Raw Temperature Residuals at Equator ascending descending 30 km October-November, 2005 30 km: ~10-day eastward-propagating structures (Kelvin waves) clearly visible ascending descending 90 km October-November, 2005 90 km: Larger amplitudes, but no clear patterns. Kelvin waves probably masked by day-to- day variability of tides, gravity waves, etc.

4. Data processing: sliding fits performed zonal wavenumbers s = -6 (eastward) to s = +6 (westward) periods 2 to 20 days in increments of 0.5 days window length = 3 x wave period all data during 2002-2006 “Background spectrum” due to various sources of variability, e.g., tides, gravity waves 3.0-3.5 day Ultra-fast Kelvin Wave 6-7 day oscillation~16-day normal mode ISO, possibly driven by UFKW & diurnal tide EPFD (e.g.,Miyoshi & Fujiwara, GRL, 2006) Multi-Year Mean Spectrum

5. z = vertical wavelength x = zonal wavelength T = wave period N = buoyancy frequency u bar = zonal mean u (= 0) e.g. Holton et al. (2001) 35-42 47 21 14 30 18 10 Dominant Kelvin waves (s = -1, s = -2) transition from long-periods (5-10 days) and short-wavelengths (9-13 km) in the stratosphere, to shorter periods (2-3 days) and longer wavelengths (35-45 km) in the MLT Zonal phase speed ms -1 11638 15558

6. 13 9 9 37 30 Slow Kelvin waves Ultra fast Kelvin waves 21 17 14 35-42 In Addition to Kelvin Waves, Other Parts of the Spectrum also Vary with Height, e.g., s = 0

7. Results similar to the previous were obtained by examining the symmetric component of the temperature residuals No notable results were obtained when the anti-symmetric component of the temperature residuals was examined. We now concentrate on MLT Kelvin waves, periods 2.5-4.5 days, i.e., UFKW Characterizing IS variability of MLT UFKW, and possible connections with IS variability of the zonal mean state

8. In the context of a full-atmosphere GCM, Miyoshi and Fujiwara (2006) established connections between EPFD due to DT and UFKW, and 20-60 day ISO in zonal mean winds. Variations in DT and UFKW are connected with established troposphere ISO’s at 20-25 days (Hartmann et al., 1992) and 40-60 days (Madden and Julian, 1994) manifested in tropical convection, e.g., latent heating rates. Existence of UFKW are well-established in the tropical MLT: Lieberman and Riggin (1997), Riggin et al. (1997), Yoshida et al. (1999) Previous similar suggestions and supportive observations relating waves and ISO in the MLT provided by Eckerman et al. (1997), Isoda et al. (2004), Lieberman et al. (1998). Ultra-Fast Kelvin Waves (UFKW), Diurnal Tides (DT) and Intraseasonal Oscillations (ISO) in the MLT The SABER data provide the first look at the above that extends continuously from 20-120 km, -50 o to +50 o latitude, 2002 to 2006

9. ISO of 2.5-4.5 day Wave Amplitudes, 90 km, Eastward s = -1

10. 3.3 km day-1 Filtered zonal mean 20-60 days ~± 2-4K UFKW and Zonal Mean Variability at the Equator, 2003

11. UFKW Zonal Mean Spectra show some similarities, but not close correspondence. However, the “UFKW” omits the effects of longer-period and s  -1 KW & DT

12. SABER temperature data provide the first opportunity to “see” vertical coupling from the lower stratosphere to lower thermosphere in the equatorial region vis-à-vis vertically-propagating waves with periods > 2 days. The dominant waves responsible for this coupling are symmetric eastward- propagating waves, i.e., Kelvin waves. Dominant Kelvin waves transition from long-periods (5-10 days) and short- wavelengths (9-13 km) in the stratosphere, to shorter periods (2-3 days) and longer wavelengths (35-45 km) in the MLT. UFKW (periods 2.5-4.5 days) intermittently exist at similar amplitudes (3-10 K, 80-120 km) during all months of the year, with variability in the 20-60 day range. An ISO of zonal mean temperatures also exists with periods 20-60 days that may be driven by EPFD due, at least in part, to UFKW. The zonal mean ISO preferentially exists above 70 km, consistent with in- situ generation at these altitudes. Possible F-region effects of UFKW vis-à-vis dynamo, similar to DE3? (see Takahashi et al. Paper 4.2-10) SUMMARY & CONCLUSIONS