Examples of ALO Results Vincent B. Wickwar, Joshua P. Herron, Karen L. M. Nelson, Troy A. Wynn, Kristina Thomas, Eric M. Lundell Larisa, This is what I put together to show you some of the variability seen in the mesosphere. The big question is separating what comes from below from what comes from above. Vince CEDAR Workshop 2004 Santa Fe, NM June 27—July 2, 2004

Atmospheric Regions From Top to Bottom Hard to Observe Thermosphere Mesosphere Stratosphere Troposphere This is to emphasize that the Rayleigh lidar is practically unique in covering the mesosphere from ~45 km to ~90 km. Hard to Observe Rayleigh Lidar Spacecraft

ALO Temperature Climatology: 1993–2003 This is our climatology. Even it shows considerable variability. The top altitudes occur when the signal is 16 standard deviations above the noise. The temperature there is set to values from the CSU 8-year climatology. Our temperatures are most likely independent of this initial value 10 km lower down. The spring and fall equinoxes above 80 km are particularly variable with hotter regions creating cold islands in February and in November. Do you see any signs of this interesting equinox transition temperature behavior? The contours show signs of the inversion layers in the winter data. Do you see signs of the inversion layers at your slightly higher altitudes. They might appear as another cycle in a temperature wave. The white lines mark interesting periods. The corresponding temperature profiles are shown on the next figure.

Examples of Temperature Profiles These are selected profiles from the climatology. The first 2 are from summer. The next 2 are from the fall equinox transition. The last two are from the winter periods.

Monthly Temperature Comparisons This shows how the monthly profiles vary. Above 60-65 km one clearly sees the dominant roll of dynamics with the summer temperatures so much cooler than winter temperatures.

Nightly Temperatures — Winter-Summer Comparison January June This is another type of variability. These are individual nightly temperature profiles superimposed for January and for June. The wave activity is enormous. It appears to cease at ~95 km. However that is an artifact of our starting the integration used to find the temperatures from the CSU 8-year climatology. This influences the wave amplitude for the first 5-10 km. The black curves are the means along with the standard deviation of the mean.

Mesospheric Inversion Layers at ALO These show 4 examples of month-long averages of the inversion layers. While these look big, they are reduced in size because of the month-long average. My impression is that they often “stick around” for 1 to 2 weeks and then can change significantly.

ALO Geophysical Variability — 31-day RMS This shows the geophysical variability more formally than in the June and July superposition of profiles. On a given day, we made a multiyear average covering a 31-day period. We then made the RMS calculation for the individual days in that 31-day window compared to the 31-day mean. We then advanced a day and did it again. [K]

Temperatures for June 23, 1995, NLC This and the next figure are to show the magnitude of waves in the upper mesosphere. These are profiles before, after, and during a NLC event. (During the NLC, we had to interpolate across the NLC.) All you should take in here is that the temperatures are very low near 83 km. Then look at the next figure.

Low Temperature — Result of a Wave June 23, 1995 For this figure, we subtracted the profiles in the previous figure from the 31-day multiyear mean centered on 23 June. What you see is a very large amplitude wave. This wave does not stand out like the inversion layers in winter, but it is every bit as big. (The wave may be bigger than shown here because we are starting the temperature integration for the previous figure from the usual CSU 8-year climatological values.)

ALO Variation of Density Differences Relative to the Climatological Mean This is a very different presentation. Here we are looking at densities instead of temperatures. We measure relative neutral densities (not absolute). We normalized our profiles to the MSISe00 values at 45 km. We then created a climatological mean density by averaging the mean densities from the 12 months. This is the fractional variation from that mean. This gives a view of the summer to winter density variations, as well as the variations in altitude. (Normalized to MSISe00 at 45 km)