No abstract

No abstract

Estimates of turbulence energy dissipation rates and inner scale sizes have been obtained at altitudes of 80-90 km, using simultaneous rocket and radar data from the STATE experiments. Spectral widths from radar Doppler spectra and the rocket-derived temperatures were used to calculate the turbulence energy dissipation rate as a function of height: values generally ranged from 0.05 to 0.15 m 2 s 'z, with a long term average about 0.1 m 2 s 'z. The maximum observed energy dissipation rate was about 1.0 m 2 s 'z, but these occasional intense levels of turbulence lasted only a few minutes. The kinematic viscosity has been calculated from the rocket data, which was then used with the energy dissipation rates to estimate the turbulence microscale (T•) as a function of height; values of about 1.5--2.0 m were obtained from 80 to 87 km, with • increasing rapidly for heights above about 87 km. The inner scale for neutral turbulence is approximately 13 times T•, which therefore possibly ranges from 20 to 26 m, which is in approximate agreement with other estimates for the mesosphere. This result shows that the 3-m scattering wavelength for the Poker Flat Radar is well within the viscous subrange for neutral turbulence and raises questions as to why such large backscatterd signals are detected in the polar mesosphere. A companion paper (Kelley and Ulwick, this issue) discusses this within the context of the electron density fluctuation spectra measured during the STATE campaign. L INTRODUCI•ONconfidence in calculations using the radar data. Although three rocket salvos were launched on different During June 1983 the STATE series of experiments were days, only one salvo (on June 15, 1983) included measureconducted at the Poker Flat Research Range, Alaska; these ments of neutral atmosphere profiles using an accelerometer experiments are also described elswhere [Fritts et al., this experiment and the falling sphere technique. As a result of issue' Kelley and Ulwick, this issue]. The in situ rocket instrument malfunction, only electron density data was measurements were planned to complement mesospheric obtained in the other two experiments. Our analysis measurements from the nearby MST (mesospheric, concentrates on the June 15 data, although we will also stratospheric, tropospheric) radar. The objective of this paper is to use the spectral widths from the radar Doppler present some results from the final experiment on June 17, even though no accelerometer data was available. spectra to determine turbulence energy dissipation rates and inner scale sizes. Kelley and Ulwick [this issue] have also independently calculated these parameters from the rocket 2. CALCULATION OF TURBULEHT ENERGY DISSIPATION data. RATES AND IN•'F_• SCALE SIZES Although other authors have previously either suggested or attempted to use radar spectral widths to calculate The spectral widths can be obtained directly from the turbulence dissipation rates [e.g., Gage et al., 1980; Sato and Doppler spectra at each height. The spectral width is a Woodman, 1982; ...

No abstract

No abstract