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[1] A function that approximates atmospheric tidal behavior in the polar regions is described. This function is fitted to multistation radar measurements of wind in the mesosphere and lower thermosphere with the aim of obtaining a latitude-longitude-height description of the variation of tides over the whole Antarctic continent. Archival wind data sets are combined with present-day ones to fill the spatial distribution of the observations and to reduce the potential effects of spatial aliasing. Multiple years are combined through the compilation of monthly station composite days, yielding results for each month of the year. Despite potential problems associated with year-to-year variations in the tidal phase, a useful climatology of Antarctic zonal and meridional tidal wind components is compiled. The results of the fits reproduce the major features of the high-latitude tidal wind field: the dominance of the semidiurnal migrating mode in the winter months and the presence of a semidiurnal zonal wave number one component in the summer months. It is also found that the summer semidiurnal tide contains a zonal wave number zero component.

Using the mesosphere-stratosphere-troposphere radar at Poker Flat, Alaska, the long-period waves (greater than 1.5 but less than 36 days) in the troposphere/lower stratosphere and mesosphere were analyzed for the first 340 days of 1984. A 16-day wave was significant the whole year in all regions resolved by the radar and had maxima in the winter lower stratosphere, consistent with the (1,3) Rossby normal mode. Contrm'y to the theory of the (1,3) normal mode, the observed 16-day wave had a maximum in the summer mesosphere Two possible explanations we given' r• • Tb.e !6-day ........ genermed in the •,i,,..,-hemisphere, th.., propagate. d ve•ica!!ny and toward the surmner pole following the westerly mean winds and (2) gravity waves from the summer troposphere modulated by the 16-day tropospheric wave propagated vertically into the mesosphere where the resulting momentum deposition varied in a 16-day cycle. The period of the 16-day wave varieo from 12 to 19 days in the summer mesosphere. The quasi 2-day period in the high summer mesosphere migrated from about 51 to 47 hours over midsurmner to midautumn.

"SuomiNet," a university-based, real-time, national Global Positioning System (GPS) network, is being developed for atmospheric research and education with funding from the National Science Foundation and with cost share from collaborating universities. The network, named to honor meteorological satellite pioneer Verner Suomi, will exploit the recently shown ability of ground-based GPS receivers to make thousands of accurate upper-and lower-atmospheric measurements per day. Phase delays induced in GPS signals by the ionosphere and neutral atmosphere can be measured with high precision simultaneously along a dozen or so GPS ray paths in the field of view. These delays can be converted into integrated water vapor (if surface pressure data or estimates are available) and total electron content (TEC), along each GPS ray path. The resulting continuous, accurate, all-weather, real-time GPS moisture data will help advance university research in mesoscale modeling and data assimilation, severe weather, precipitation, cloud dynamics, regional climate, and hydrology. Similarly, continuous, accurate, all-weather, real-time TEC data have applications in modeling and prediction of severe terrestrial and space weather, detection and forecasting of low-altitude ionospheric scintillation activity and geomagnetic storm effects at ionospheric midlatitudes, and detection of ionospheric effects induced by a variety of geophysical events. SuomiNet data also have potential applications in coastal meteorology, providing ground truth for satellite radiometry, and detection of scintillation associated with atmospheric turbulence in the lower troposphere. The goal of SuomiNet is to make large amounts of spatially and temporally dense GPS-sensed atmospheric data widely available in real time, for academic research and education. Information on participation in SuomiNet is available via www.unidata.ucar.edu/suominet.

The global distribution of latent heat released by the diurnal oscillations in deep convective precipitating clouds is investigated as a forcing mechanism of diurnal nonmigrating atmospheric tidal modes. The seasonal distribution of this forcing is deduced from 3‐hour temporal resolution infrared (11 μm) radiance measured by four geostationary and two polar orbiting satellites which was transformed into the zonal wavenumber domain yielding migrating and non‐migrating oscillations. The dominant wavenumbers in the forcing include the westward propagating 5, 2, and 1 oscillations, the eastward propagating 3 oscillation, and the standing oscillation. These dominant wavenumber oscillations were decomposed into Hough functions to describe their meridional structure. A vertical profile of latent heating rate was estimated and the dominant 22 tidal modes were used in an f plane model to determine the middle atmospheric response to this tropospheric forcing. The f plane model was also excited using heating rates associated with the solar insolation absorption by water vapor. The magnitude of the model atmosphere diurnal winds from both water vapor and latent heat is similar at certain locations. This response suggests that the superposition of many nonmigrating tidal modes forced by the latent heat release of precipitating clouds is important in understanding the middle atmospheric circulation.

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Abstract. The global-scale wave model (GSWM) is used to investigate the effects of mean winds and realistic dissipation on upward propagating nonmigrating diurnal tidal components. We explore the signatures of two plausible tropospheric sources of these waves, namely, latent heat release associated with deep convective activity and the absorption of solar infrared radiation which varies zonally with longitudinal variations in tropospheric water vapor. Our calculations suggest that while nonmigrating components are up to a factor of 3 times smaller than the migrating diurnal tide, they modulate the latter and introduce measurable (•10 m/s) longitudinal variability in the mesosphere and lower thermosphere. These effects are most pronounced in the GSWM for the latent heat source and during northern hemisphere winter.