Seasonal variations of the vertical fluxes of heat and horizontal momentum in the mesopause region at Starfire Optical Range, New Mexico

Abstract

[1] Lidar observations of wind and temperature profiles between 85 and 100 km, conducted at the Starfire Optical Range (SOR), New Mexico, are used to characterize the seasonal variations of the vertical fluxes of heat and horizontal momentum and their relationships to gravity wave activity in this region. The wind and temperature variances exhibit strong 6-month oscillations with maxima during the summer and winter that are about 3 times larger than the spring and fall minima. The vertical heat flux also exhibits strong 6-month oscillations with maximum downward flux during winter and summer. The downward heat flux peaks near 88 km where it exceeds À3 K m s À1 in mid-winter and is nearly zero during the spring and fall equinoxes. The heat flux is significantly different from zero only when the local instability probability exceeds 8%, i.e., the annual mean for the mesopause region. The momentum fluxes also exhibit strong seasonal variations, which are related to the horizontal winds. Two-thirds of the time the horizontal momentum flux is directed against the mean wind field.

Seasonal and local time variability of ripples from airglow imager observations in US and Japan

“…5-11, Acott, 2009). This seasonal variation is in agreement with wind and temperature variances measured by radar and lidar at other locations (Nakamura et al, 1996;Gardner and Liu, 2007). We also see in Fig.…”

“…As a consequence of AGW dissipation, the wave momentum flux is deposited into the mean state and the local eddy diffusion is enhanced. Indeed, the mesosphere eddy diffusion coefficient and momentum flux divergence show greater values during solstices than equinoxes (Fukao et al, 1994;Gardner and Liu, 2007). From observed seasonal dependent AGW activities, in particular the associated dissipations, one can deduce a seasonal distribution of the eddy diffusion coefficient.…”

“…For this purpose, we read from the altitude-month contour plots of wind variances in Fig. 4 of Gardner and Liu (2007), and plot monthly mean AGW total wind variances at 87 km in Fig. 3 here.…”

Large-scale gravity wave perturbations in the mesopause region above Northern Hemisphere midlatitudes during autumnal equinox: a joint study by the USU Na lidar and Whole Atmosphere Community Climate Model

“…Except for a few studies in the polar region, long-period large-scale GWs, especially inertia GWs, which play critical roles in MLT dynamics, are not well studied, leaving contributions from most of these waves unchecked. The ground-based experimental studies on climatological GW perturbations (Gardner and Liu, 2007;Rauthe et al, 2006Rauthe et al, , 2008 have been limited to nocturnal observations as well with various de-trending algorithms developed, trying to remove tidal biases from the measurements. At the same time, several bandpass filter techniques are also be attempted and utilized in similar GW investigations.…”

Sodium lidar‐observed gravity wave breaking followed by an upward propagation of sporadic sodium layer over Hefei, China

“…Convective instability, which is associated with temperature inversion, usually occurs when there is a large negative temperature gradient. Gravity waves can dissipate in the middle atmosphere, transporting heat downward and thus cooling the breaking region [Walterscheid, 1981;Gardner and Yang, 1998;Gardner and Liu, 2007;Li et al, 2007].…”