Global observations of 2 day wave coupling to the diurnal tide in a high‐altitude forecast‐assimilation system

We examine wave components in a high-altitude forecast-assimilation system that arise from nonlinear interaction between the diurnal tide and the westward traveling quasi 2 day wave. The process yields a westward traveling “sum” wave with zonal wave number 4 and a period of 16 h, and an eastward traveling “difference” wave with zonal wave number 2 and a period of 2 days. While the eastward 2 day wave has been reported in satellite temperatures, the westward 16 h wave lies outside the Nyquist limits of resolution of twice daily local time satellite sampling. Hourly output from a high-altitude forecast-assimilation model is used to diagnose the nonlinear quadriad. A steady state primitive equation model forced by tide-2 day wave advection is used to intepret the nonlinear wave products. The westward 16 h wave maximizes in the midlatitude winter mesosphere and behaves like an inertia-gravity wave. The nonlinearly generated component of the eastward 2 day wave maximizes at high latitudes in the lower thermosphere, and only weakly penetrates to low latitudes. The 16 h and the eastward 2 day waves are of comparable amplitude and alias to the same apparent frequency when viewed from a satellite perspective

Electric fields and meteor radar wind measurements near 95 km over South Pole

Meteor and auroral drift measurements by P. Prikryl et al. (Radio Sci., 21, 271, 1986) and theoretical estimates by G.C. Reid (Radio Sci., 18, 1028, 1983) suggest that sufficiently large electric fields may decouple meteor trail electron motions from that of the neutral gas, leading to erroneous measurement of the neutral wind during sufficiently disturbed conditions. In the present study, we seek evidence of such effects by comparing hourly meteor radar wind measurements V_N near 95 km over South Pole with overhead F-region drifts V, measured by the SuperDARN radar at Halley (76° S, 27° W). Within the parameter space of our data set, we find no relationship between V_1 and the zonal wavenumber s = 0 and s = 1 components of V_N, and only a weak relationship for the wind residuals from the combined s = 0 and s = 1 wind field. For the latter, an inferred wind residual of 5.8ms^ is implied for an F-region plasma drift of 1000ms^ (E-field &thkzp; 70mVm^). This value of 5.8 ms^ falls within the 2 to 20ms^ range of plasma drifts expected to be induced at 95km by F-region E-fields ranging between 20 and lOOmVm^ by G.C. Reid (ibid, 1983). Thus, we cannot discount the possibility that this inferred wind is actually a plasma drift. In any case, we conclude that electric field contamination of previous scientific analyses with this data set which focused on the s = 0 and s = 1 components of the wind field, are negligible. Future experimental and modeling work is required to ascertain the degree to which .E-field induced effects on winds inferred from advection of meteor trails exist under more extreme conditions, or perhaps over shorter time scales

Workshop on a future muon program at FNAL

International audienceThe Snowmass report on rare processes and precision measurements recommended Mu2e-II and a next generation muon facility at Fermilab (Advanced Muon Facility) as priorities for the frontier. The Workshop on a future muon program at FNAL was held in March 2023 to discuss design studies for Mu2e-II, organizing efforts for the next generation muon facility, and identify synergies with other efforts (e.g., muon collider). Topics included high-power targetry, status of R&D for Mu2e-II, development of compressor rings, FFA and concepts for muon experiments (conversion, decays, muonium and other opportunities) at AMF. This document summarizes the workshop discussions with a focus on future R&D tasks needed to realize these concepts

Workshop on a future muon program at FNAL

The Snowmass report on rare processes and precision measurements recommended Mu2e-II and a next generation muon facility at Fermilab (Advanced Muon Facility) as priorities for the frontier. The Workshop on a future muon program at FNAL was held in March 2023 to discuss design studies for Mu2e-II, organizing efforts for the next generation muon facility, and identify synergies with other efforts (e.g., muon collider). Topics included high-power targetry, status of R&D for Mu2e-II, development of compressor rings, FFA and concepts for muon experiments (conversion, decays, muonium and other opportunities) at AMF. This document summarizes the workshop discussions with a focus on future R&D tasks needed to realize these concepts

Workshop on a future muon program at FNAL

International audienceThe Snowmass report on rare processes and precision measurements recommended Mu2e-II and a next generation muon facility at Fermilab (Advanced Muon Facility) as priorities for the frontier. The Workshop on a future muon program at FNAL was held in March 2023 to discuss design studies for Mu2e-II, organizing efforts for the next generation muon facility, and identify synergies with other efforts (e.g., muon collider). Topics included high-power targetry, status of R&D for Mu2e-II, development of compressor rings, FFA and concepts for muon experiments (conversion, decays, muonium and other opportunities) at AMF. This document summarizes the workshop discussions with a focus on future R&D tasks needed to realize these concepts