Temperature responses to the 11 year solar cycle in the mesosphere from the 31 year (1979–2010) extended Canadian Middle Atmosphere Model simulations and a comparison with the 14 year (2002–2015) TIMED/SABER observations

Abstract

A recent 31 year simulation (1979–2010) by extended Canadian Middle Atmosphere Model (eCMAM30) and the 14 year (2002–2015) observation by the Thermosphere Ionosphere Mesosphere and Dynamics/Sounding of the Atmosphere using Broadband Emssion Radiometry (TIMED/SABER) are utilized to investigate the temperature response to the 11 year solar cycle on the mesosphere. Overall, the zonal mean responses tend to increase with height, and the amplitudes are on the order of 1–2 K/100 solar flux unit (1 sfu = 10−22 W m−2 Hz−1) below 80 km and 2–4 K/100 sfu in the mesopause region (80–100 km) from the eCMAM30, comparatively weaker than those from the SABER except in the midlatitude lower mesosphere. A pretty good consistence takes place at around 75–80 km with a response of ~1.5 K/100 sfu within 10°S/N. Also, a symmetric pattern of the responses about the equator agrees reasonably well between the two. It is noteworthy that the eCMAM30 displays an alternate structure with the upper stratospheric cooling and the lower mesospheric warming at midlatitudes of the winter hemisphere, in favor of the long‐term Rayleigh lidar observation reported by the previous studies. Through diagnosing multiple dynamical parameters, it is manifested that this localized feature is induced by the anomalous residual circulation as a consequence of the wave‐mean flow interaction during the solar maximum year.

Solar Response and Long‐Term Trend of Midlatitude Mesopause Region Temperature Based on 28 Years (1990–2017) of Na Lidar Observations

“…And more importantly, the seasonal variations of the both diurnal and semidiurnal total (migrating + nonmigrating) tides are dominated by the migrating tides, as shown in Figure 4 of Yuan et al (2014). Here, between 100 and 104 km, the former increases linearly while the latter remains nearly the same as altitude increases, suggesting that above 100 km, the lidar winter solar response without tidal contamination like the models, as seen in the eCMAM (Gan et al, 2017) and Figure 14b of Marsh et al (2007), also increases monotonically with altitude. Of course, there are day-to-day variations in nightly means, mainly resulting from (local) gravity wave interactions with tides and planetary waves ; though this has not been treated in our analyses, the manner that they affect the two nightly time series should be comparable as both data sets have observations on the same nights.…”

“…Because the terms α(z), β(z)t, and δ(z)Q 81 (t) are not orthogonal, the added constant will shift the value of α(z) by~1 K with very small shifts in β(z) on the order of 10 −5 K/decade or less. Gan et al (2017). Using the actual start and end observation times each night with data, we considered other scenarios of slowly varying phase and amplitude (limited to 1 K) and found the shift in trend up to 0.06 K/decade for _2MN, and 0.33K/decade for _Ngt.…”

“…On the other hand, the contribution of the same wave from the _Ngt time series adds various amounts to different nights with data, leading to a larger change in β(z) on the order of 10 −1 K/decade. We compare eCMAM and SABER data between 75 and 100 km read from Figure 3 of Gan et al (2017) to lidar data between 85 and 105 km plus the value at 81 km. The differences only depend upon the time-dependent proxy base functions in (1) and the times of observation and not on the long-term fitting parameters.…”

“…Though the shape of the trend profile from the 25-year data set is similar, the maximum trend, though still within the error bars of the two analyses, is cooler by more than 1.0 K/decade. The rarely reported response to the 11-year solar cycle based on the same SABER measurements (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) was also published (Gan et al, 2017). With global coverage (48°S to 48°N), the trend based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere Ionosphere Mesosphere and Dynamics temperatures (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) was published (Huang et al, 2014).…”

Production and transport mechanisms of NO in observations and models

“…This implies that it is not the shorter term smaller variations in Lyα that are causing the NO variations, but rather the variations on long timescales, similar to the 11 year solar cycle. It could also imply that the high latitude NO densities are not varying with irradiance changes, but rather with a process in the lower thermosphere that follows the 11 year solar cycle, such as for example temperature (Gan et al, 2017). This was also suggested by Marsh et al (2004) to explain a negative contribution of solar variability at high latitudes.…”