Direct measurements of vertical Fe, Na and heat fluxes in the MLT by lidar at Boulder: Implications for the Velocity of Cosmic Dust Entering the Atmosphere

Wentao Huang(1), Xinzhao Chu(1), Chester S. Gardner(2), Juan D. Carrillo-Sánchez(3), Wuhu Feng(3), John M. C. Plane(3), David Nesvorný(4), John A. Smith(1), Xian Lu(1), Weichun Fong(1), Zhibin Yu(1), Cao Chen(1) and Ian F. Barry(1)

Abstract
The vertical transport of heat and constituent by gravity waves and tides plays a fundamental role in establishing the thermal and constituent structures of the mesosphere and lower thermosphere (MLT), but has not been thoroughly investigated by observations. We attempt to directly measure the constituent and heat fluxes using lidar. Since summer 2010, we have been operating a Na Doppler lidar at Boulder, CO. In 2011, the efficiency of the lidar has been greatly improved, then the lidar was further upgraded in late 2013 with new frequency shifters and data acquisition scheme, which are optimized for estimating eddy and gravity wave fluxes. We also operated simultaneously an Fe Boltzmann lidar and an Fe Doppler lidar with the Na lidar in summer 2010 and late 2014, respectively. Our measurement of the Fe/Na flux ratio at 86 km (2.57±1.09) is used to constrain the velocity/mass distribution of the meteoroids entering the atmosphere and update the estimated global influx of cosmic dust to 150 t/d. We are analyzing the high-resolution Na lidar data to characterize the seasonal variations of heat and Na fluxes, and try to estimate the Eddy fluxes for the first time by lidar.