Simultaneous, common‐volume lidar observations and theoretical studies of correlations among Fe/Na layers and temperatures in the mesosphere and lower thermosphere at Boulder Table Mountain (40°N, 105°W), Colorado

Abstract

[1] Simultaneous and common-volume observations of Fe density, Na density, and temperatures in the mesosphere and lower thermosphere were made for 12 nights with an Fe Boltzmann lidar and a Na Doppler lidar at the Table Mountain Lidar Facility (40.13°N, 105.24°W) near Boulder, Colorado, in August and September 2010. We derive the correlations among temporal variations of Fe/Na densities and temperatures, eliminating the covariance bias via computing the cross correlations between Fe (Na) density and Na (Fe) temperature perturbations. The Fe-Na density correlation is positive below the Fe layer peak and above the Na peak where the Fe/Na density gradients have the same signs but becomes negative in between the Fe and Na peaks where the gradients are opposite. The large correlation between temperature and density fluctuations is positive on the layer bottomside but negative on the topside with the transitions occurring near the layer peaks. The relative Fe/ Na variances reach minimum near the layer peaks but rapidly increase and exceed the relative temperature variance significantly toward edges. These observations can be largely reproduced by theoretically modeling the metal layer responses to the wave-induced perturbations only through dynamic processes with a Gaussian stationary density distribution. These results suggest that the dynamic effects (mainly the vertical displacement) induced by gravity waves or tides dominate the observed short-term density and temperature variations over a night. We explain the Fe/Na gradient difference observed at the bottomside via the chemical "shelf" around 80 km for reactive chemicals and the Fe/Na layer height difference.

Measurements of the vertical fluxes of atomic Fe and Na at the mesopause: Implications for the velocity of cosmic dust entering the atmosphere

“…The effective lifetime of the atomic species in the metal layer is defined as the layer abundance divided by the total meteoric influx. The mean abundances are 10.65 × 10 9 cm −2 and 3.45 × 10 9 cm −2 , respectively, for Fe and Na at Table Mountain for August–September 2010 [ Huang et al ., ]. The ratio of the Fe to Na column abundance equals 3.1, which is consistent with the measured flux ratio and also implies that the particle velocities must be slow.…”

“…In sections 3 and 4 of their paper, Huang et al . [] provide detailed descriptions of the lidar specifications and measurement capabilities, the observational scenarios, and the data processing for this unique data set. The vertical constituent flux is defined as the expected value of the product of the vertical wind and the constituent density.…”

A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper

“…This study was enabled by the coordinated observations with two Na Doppler lidars of the Consortium of Resonance and Rayleigh Lidars (CRRL) at Boulder, CO, and Logan, UT, in collaboration with an AMTM [ Pautet et al , ] located at Bear Lake Observatory (41.9°N, 111.4°W) nearby Logan, in the night of 27 November 2013, from ~1 to 13 UT. Under the CRRL umbrella, the Consortium Technology Center, hosted by the University of Colorado Boulder, operates a Student Training and Atmospheric Research (STAR) Na Doppler lidar from the Table Mountain Lidar Observatory (40.1°N, 105.2°W) north of Boulder [ Smith et al , ; Huang et al , ], while the Utah State University (USU) lidar group operates a Na Doppler lidar from the USU campus in Logan (41.7°N, 111.8°W) [ Yuan et al , ].…”

Simultaneous and common‐volume lidar observations of K/Na layers and temperature at Arecibo Observatory (18°N, 67°W)

“…They concluded that the overall correlation between Na and Fe could be well explained by their responses to wave dynamics, while chemistry played important roles in determining the structure of the metal layers. Huang et al [] further reported the correlations between temperature and Fe/Na. By using theoretical models of wave‐induced dynamics, they showed that these correlations between Fe and Na layers and those between temperature and Fe/Na layers could be largely reproduced assuming that the density fluctuation is induced only by dynamical effects of waves while ignoring the chemical effects.…”

“…Chen and Yi [] showed for the first time that the Fe and Na fluctuations are positively correlated on both the bottomside and the topside of the layers, whereas they are typically negatively correlated near 90 km. These features have also been verified by the simultaneous Fe and Na observations at Arecibo Observatory (AO), Puerto Rico (18.35°N, 66.75°W) [ Yue et al ., ] and at Boulder, Colorado (40°N, 105°W) [ Huang et al ., ]. Yue et al [] found that negative correlation occurred around the peaks of nightly mean Fe and Na densities only if there existed a distinguishable height difference between the Fe and Na peaks.…”