18.5
Modeling turbulence and seeing over Mauna Kea
Tiziana Cherubini, University of Hawaii, Honolulu, HI; and S. Businger, R. Okasawara, and R. Lyman
The Mauna Kea Weather Center at University of Hawaii has been providing weather forecasts to the Mauna Kea astronomy community since January 1999. To provide guidance to mountain weather forecasters, the Penn State/NCAR mesoscale model (MM5) has been run operationally over the summit of Mauna Kea during this time. In addition to potential negative impacts from large precipitable water and clouds, atmospheric turbulence is a primary concern for astronomers. Turbulence induces amplitude and phase fluctuations in electromagnetic waves propagating through the atmosphere, resulting in image degradation. The turbulent fluctuations of the atmospheric refractive index are described by the refractive index structure function, Cn2. The maximum telescope resolution is defined by a parameter called seeing, which is the full width at half-maximum of a long-exposure stellar image at zenith. Cn2 and seeing are commonly used by astronomers to describe the turbulent state of the atmosphere at the time of their observations. Small-scale turbulence structures are parameterized in terms of model observable bulk properties of the atmosphere within the planetary boundary layer parameterization scheme. In this paper we investigate the use of schemes based on turbulence kinetic energy calculations in order to predict Cn2 and seeing. Preliminary results of predicted seeing and Cn2 will be presented along with observations of seeing and Cn2 collected at the summit of Mauna Kea by recently installed instrumentation.
Session 18, Applications in Meteorology, Oceanography, Hydrology and Climatology
Thursday, 13 January 2005, 1:30 PM-5:30 PM
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