Abstract. The newly-installed MFR (medium frequencyradarAnnual climatologies involving both height and frequency versus time contour plots for periods from 8 h to 30 days, show that the changes with longitude are very significant and distinctive, often exceeding the local latitudinal variations. Comparisons with models and the recent UARS-HRDI global analysis of tides are discussed. The fits of the horizontal wave numbers of the longer period oscillations are provided in unique frequency versus time contour plots and shown to be consistent with the expected dominant modes. Annual climatologies of planetary waves (16 day, 2 day) and gravity waves reveal strong seasonal and longitudinal variations.

[1] The newly installed medium frequency radar (MFR) at Platteville provides unique opportunities to assess latitudinal effects in both the ionosphere and mesosphere-lower thermosphere (MLT) by comparisons with the long-established MFR at Saskatoon. The influence of the D region ''winter anomaly'' is evident in both ionospheres, and descending ''sporadic layers'' (110-90 km) are identified, especially at 40°N, for the first time for MF radar systems. Preliminary comparisons with the wind measurements are made, and the processes are identified as complex. Contour plots of mean winds, tides (12-and 24-hour), and planetary waves (PW) (2-and 16-day) demonstrate significant trends over 12°of latitude (1100 km). The 24-hour tide dominates at 40°N, the 12-hour tide dominates at 52°N, and PW structures demonstrate spatial and temporal intermittency. The two radars are now part of a new network, Canada U.S. Japan Opportunity (CUJO), stretching from 81°W to 141°E.

In this paper, analysis of wind data detected by six ground‐based radar systems located in equatorial and midlatitude belts shows that a strong mesospheric 6.5‐day wave event occurred during April–May 2003. We compared the global distribution of the observed 6.5‐day wave event with the theoretical wave structure (Rossby normal mode (s, n) = (1, −2)). Additionally, we investigated several important wave characteristics to understand the mesospheric 6.5‐day wave event, i.e., wave period, vertical structure, relationship with background wind, propagating direction, and the zonal wave number. Our results are summarized into three points: (1) the latitudinal structure of the mesospheric 6.5‐day wave during April–May 2003 is basically in agreement with the theoretical Rossby mode (s, n) = (1, −2), although the wave amplitude of zonal wind peaked at the subequatorial latitude of Northern Hemisphere but not at the theoretical place, equatorial region; (2) the main wave periods and the altitude distribution of large amplitude of this wave event varied with latitude; (3) the downward propagating wave phases indicated that this wave event originated in the lower atmosphere and propagated upward to the upper region.

Abstract. New techniques are applied to measured Doppler velocity and angle of arrival to estimate horizontal wind vectors, variances, and momentum fluxes, from MF radar data. The approach used to estimate mean winds was first introduced as "time domain interferometry" (TDI) by Vandepeer and Reid [1995]. In the present paper, the algorithm is refined and used with data from the Urbana MF radar, which employs a single vertical antenna beam, to obtain a monthly mean wind climatology which is compared with the results from conventional spaced antenna full correlation analysis. The comparison validates the scattering model used in the development of the TDI technique and highlights instrumental and processing biases that differ between the two techniques. An extension of the TDI method that can provide estimates of the Reynolds stress tensor associated with propagating gravity waves is also proposed, and some preliminary results are presented.

A summary of the first 18 months of continuous wind observations using the Urbana medium frequency (MF) radar is presented. Emphasis is placed on height-time contours of monthly mean winds and on amplitudes and phases of 24 hour and 12 hour tides. Results are compared with data from other midlatitude stations and models. Below 85 kin, monthly mean winds are shown to agree closely with the zonal mean, geostrophic wind model CIRA86. Significant dis•ancies above 85 km have been noted in comparisons between CIRA86 and the other mesosphere-!ower-thermosphere (MLT) radar stations (including MF, meteor, and low-frequency (IF)refers)and are also sustained in the observations reported here. Tidal characteristics are generally consistent with other midlatitude observations, although significant differences are noted between Urbana and its closest MLT network neighbor station (Durham, 43øN, 71øW). The mean wind observations provide a context for the gravity wave climatology derived from Na lidar observations at Urbana and promise to contribute toward improvements of middle atmosphere wind and tidal models. INTRODUCTIONThe past 20 years have been characterized by rapid improvements in the quantity and quality of observational data pertaining to mean winds and tides in the middle atmosphere.A variety of radar techniques have contributed measurements of winds in the 60 to 100 km altitude region, and a few stations have been collecting such data for a number of years. Under the auspices of the Middle Atmosphere Program (MAP), techniques used for the extraction of information from winds measured by radar techniques were improved and standardized.These studies showed that continuous measurements in both height and time are extremely useful for studying the longperiod oscillations in the middle atmosphere. The MAP studies revealed a need for a more complete global network of radars that can provide temporally continuous wind data. Manson et al. [1985aManson et al. [ , 1990Manson et al. [ , 1991 have compiled a detailed comparison of the mean winds obtained from midlatitude radar observations, and Manson et el. [1991] report detailed comparisons between observations and CLRA1986. In another study, Manson et el. [1989] summarized and compared semidiurnal and diurnal tidal climatologies derived from radar measurements at middle latitudes. The radar climatologies were also compared with the most current tidal models. In this paper we concentrate on descriptive analysis of the monthly mean winds and tidal parameters at Urbana and also compare and contrast the observations with those reported by other midlatitude stations. The mean wind and tidal climatology data presented here are intended to complement those presented by Manson et at. [1989, I991] and add one more midlatitude data point to the developing picture of midlatitude mesospheric dynamics. It is expected that the continuous data set being collected at Urbana, when combined with data collected at other midlatitude stations, will provide much useful information on the Copyfight...