Momentum flux determination using the multi-beam Poker Flat Incoherent Scatter Radar

Abstract

Abstract. In this paper, we develop an estimator for the vertical flux of horizontal momentum with arbitrary beam pointing, applicable to the case of arbitrary but fixed beam pointing with systems such as the Poker Flat Incoherent Scatter Radar (PFISR). This method uses information from all available beams to resolve the variances of the wind field in addition to the vertical flux of both meridional and zonal momentum, targeted for high-frequency wave motions. The estimator utilises the full covariance of the distributed measurements, which provides a significant reduction in errors over the direct extension of previously developed techniques and allows for the calculation of an error covariance matrix of the estimated quantities. We find that for the PFISR experiment, we can construct an unbiased and robust estimator of the momentum flux if sufficient and proper beam orientations are chosen, which can in the future be optimized for the expected frequency distribution of momentumcontaining scales. However, there is a potential trade-off between biases and standard errors introduced with the new approach, which must be taken into account when assessing the momentum fluxes. We apply the estimator to PFISR measurements on 23 April 2008 and 21 December 2007, from 60-85 km altitude, and show expected results as compared to mean winds and in relation to the measured vertical velocity variances.

Investigation of gravity waves using horizontally resolved radial velocity measurements

“…Former studies of PMSE investigated the physical processes leading to the formation of this mesospheric backscatter at VHF Bragg wavelengths (see, e.g., Rapp and Lübken, 2004, for a review) or focussed on the issue of the aspect sensitivity of this radar backscatter (e.g., Zecha et al, 2001;Chilson et al, 2002;Smirnova et al, 2010Smirnova et al, , 2012. There have also been many studies inferring the mesospheric dynamic situation by gaining valuable information about the neutral wind speed and wind variation inside the phenomenon itself (e.g., Zecha et al, 2001;Morris et al, 2006;Nicolls et al, 2010;Dalin et al, 2012;Stober et al, 2012;Nicolls et al, 2012). Due to the beam steering capabilities of MAARSY it is possible to investigate the wind field in much more detail, applying more sophisticated wind analysis methods such as VAD (Browning and Wexler, 1968) or VVP (Waldteufel and Corbin, 1979).…”

Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

“…4. Nicolls et al (2012), who applied an approach similar to that used in Fritts et al (2010a) to narrow-beam fixedlook phased array radars.…”

Observing Mesospheric Turbulence With Specular Meteor Radars: A Novel Method for Estimating Second‐Order Statistics of Wind Velocity

“…In the mesosphere, the mean winds and wind correlations as function of altitude have been measured with various types of radars: medium frequency (MF), mesosphere stratosphere troposphere, specular meteor, and incoherent scatter (e.g., Fritts et al, 1992;Hocking, 2005;Nicolls et al, 2012;Vincent & Reid, 1983). These components have been also measured with lidars (e.g., Gardner & Yang, 1998).…”

“…The technique was later extended to an arbitrary number of pointing positions by Thorsen et al (1997) using a wide-beam MF radar, and to all-sky monostatic specular meteor radars (SMRs) by Hocking (2005). The statistical uncertainties of the measured wind correlations have been studied by Kudeki and Franke (1998), Thorsen et al (2000), and Nicolls et al (2012), taking into account geophysical variability, spatial correlation, and the full covariance of line of sight velocities, respectively.…”