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Rayleigh and resonance lidar observations were made during the Turbopause experiment at Poker Flat Research Range, Chatanika Alaska (65° N, 147° W) over a 10 h period on the night of 17-18 February 2009. The lidar observations revealed the presence of a strong mesospheric inversion layer (MIL) at 74 km that formed during the observations and was present for over 6 h. The MIL had a maximum temperature of 251 K, amplitude of 27±7 K, a depth of 3.0 km, and overlying lapse rate of 9.4±0.3Kkm-1. The MIL was located at the lower edge of the mesospheric sodium layer. During this coincidence the lower edge of the sodium layer was lowered by 2 km to 74 km and the bottomside scale height of the sodium increased from 1 km to 15 km. The structure of the MIL and sodium are analyzed in terms of vertical diffusive transport. The analysis yields a lower bound for the eddy diffusion coefficient of 430m2 s-1 and the energy dissipation rate of 2.2mWkg-1 at 76-77 km. This value of the eddy diffusion coefficient, determined from naturally occurring variations in mesospheric temperatures and the sodium layer, is significantly larger than those reported for mean winter values in the Arctic but similar to individual values reported in regions of convective instability by other techniques. [ABSTRACT FROM AUTHOR]

The article focuses on tracking of the volcano ash cloud during the eruption of Mt. Augustine Volcano in southern Alaska. It provides information on the report of the Alaska Volcano Observatory (AVO), the office responsible for the monitoring of the 100 active volcanoes in the Northern Pacific. It talks on the ash dispersion model Puff developed by the University of Alaska Fairbanks (UAF), and Geophysical Institute (GI) at AVO to allow forecasters to predict the movement of volcanic ash clouds, and warn aircraft of potential hazards. Observations based on satellite data on the movement of ash clouds in the neighboring place of Mt. Augustine and across Alaska are also provided.