Thermospheric wind data obtained from the Atmosphere Explorer E and Dynamics Explorer 2 satellites have been combined with wind data for the lower and upper thermosphere from ground‐based incoherent scatter radar and Fabry‐Perot optical interferometers to generate a revision (HWM90) of the HWM87 empirical model and extend its applicability to 100 km. Comparison of the various data sets with the aid of the model shows in general remarkable agreement, particularly at mid and low latitudes. The ground‐based data allow modeling of seasonal/diurnal variations, which are most distinct at mid latitudes. While solar activity variations are now included, they are found to be small and not always very clearly delineated by the current data. They are most obvious at the higher latitudes. The model describes the transition from predominately diurnal variations in the upper thermosphere to semidiurnal variations in the lower thermosphere and a transition from summer to winter flow above 140 km to winter to summer flow below. Significant altitude gradients in the wind are found to extend to 300 km at some local times and pose complications for interpretation of Fabry‐Perot observations.

Abstract. A new all-sky imaging, wavelength scanning Fabry-Perot spectrometer was used to record high-resolution (R ___ 200,000) spectra of the A630 nm thermospheric optical emission above Poker Flat, Alaska. These spectra were used to derive spatially resolved maps of the horizontal wind vector at approximately 250 km altitude. We describe the procedure used to infer vector winds from hue-of-sight Doppler shifts, along with its limitations. We present the time evolution of the vector wind fields obtained from this method for 6 nights of observation. Five of the 6 nights contained periods when we inferred the existence of significant curvature, divergence or shear in the thermospheric wind across our instrument 's 001000 km diameter field of view. The sixth night exhibited little spatial structure and is shown for comparison. We compare these results with a "generic" solar minimum winter time run of the National Center for Atmospheric Research's Thermosphere, Ionosphere, and Electrodynamics General Circulation Model. While agreement was good at the start and end of the night, considerable differences were found in the late evening and midnight sectors. Some possible origins for these discrepancies are proposed. In particular, we suggest that the F region horizontal wind may be deflected by upwelling vertical winds, which are in turn driven by E region heating in the auroral zone. We note that both the instrument used and our high-latitude implementation of the analysis procedure are new experimental techniques. Thus the data presented here should be regarded as prehminary and, if possible, be vahdated by comparison with results from other techniques.

A 12‐hour oscillation in the horizontal motion of the neutral mesosphere near the South Pole has been determined from optical measurements of the Doppler shift of the OH emission in this region of the upper atmosphere. The measurement of this wave's phase progression with longitude shows this wave to be a westward‐traveling zonal wavenumber one mode. The absence of significant oscillation at this periodicity in the simultaneously measured mesospheric temperature is consistent with the zonal wavenumber one determination. Tentative assignment of this oscillation to an inertio‐gravity wave has been made based on these findings. The observation of this 12‐hour periodicity oscillation as a zonal wavenumber one motion precludes its identification as a zonal wavenumber two semidiurnal tide.

Upper‐mesosphere combined optical measurements of wind and temperature fields at Amundsen‐Scott Station (South Pole) and wind radar measurements at Scott Base (78°S, 167°E) show the presence of large‐scale waves in this region of the atmosphere. At Amundsen‐Scott the largest amplitude wave observed with sub‐diurnal periodicity appears with a frequency near 2.4/day (∼10.1 hour period), with a westward phase progression of wavenumber one. The presence of a wave with this periodicity is confirmed by the observations at Scott Base. The combination of the experimentally‐found period, phase progression, associated small‐temperature oscillations, and theoretical considerations lead to the interpretation of this wave as a Lamb wave. The present combination of spatially‐resolved optical measurements and radar measurements illustrates the value of multiple‐station and multiple‐technique observations in elucidating the upper‐mesosphere dynamical state, as well as the properties of the waves propagating through the medium where the observations are being made.

Abstract.We present simultaneous measurements of thermospheric winds, auroral emissions, and ionospheric currents over Alaska, obtained from four separate instruments. Thermospheric (F region) wind maps were recorded by an all-sky imaging Fabry-Perot spectrometer located at Poker Flat and observing at A630.0 nm. Auroral images at •557.7 nm were obtained from the low-resolution visible imager on board the Polar satellite. White-light all-sky auroral images were recorded by ground-based all-sky cameras located in Alaska at Poker Flat (65 ø 07'N, 212 ø 34'E) and at Kaktovik (70 ø 06'N, 217 ø 24'E). Finally, the east-west component of the ionospheric F region plasma convection was inferred using the Alaskan meridian chain of magnetometers. Montage images of these four data sets are presented, projected onto a geographic map of the Alaskan region. We examine a 10-hour period during the Alaskan local nighttime of February 10, 1997. These montages illustrate a close relationship between spatial structures occurring in the aurora, in the ionospheric plasma convection, and in the F region wind field. Latitudinal shear of the geomagnetic zonal wind, often observed in the premidnight time sector, was seen to be associated with both the equatorward and poleward boundaries of the discrete aurora. We focus particularly on a period commencing just after 0900 UT, when a strong shear in the zonal wind was observed to sweep southward across Alaska. After magnetic midnight the wind field was dominated by the emergence of the "cross-polar jet" from the polar cap. This overwhelmed any wind features associated with local auroral processes.

We describe a new all-sky imaging spectrometer using a separation scanned Fabry-Perot étalon. It is intended for ground-based mapping of upper atmospheric wind and temperature fields in the auroral zone. Its major advantage is that recorded spectra are not distorted by spatial and temporal brightness fluctuations in the aurora. We present a discussion of previous approaches to field widening a Fabry-Perot spectrometer, then describe the principles underlying our method. This enables comparisons with the throughput and the response to brightness fluctuations provided by previous instruments. We also describe our instrument's optical layout, its calibration, and data analysis.

Cold intolerance can be severe and debilitating following injury to the hand. Little is known about its natural history and factors predicting symptom severity. We looked retrospectively at upper limb peripheral nerve injuries over a 12-year period. Information was obtained using a patient questionnaire and patient records. The incidence of cold intolerance was 83%. In 48% the onset of symptoms was within 1 month of the initial injury. At a mean follow-up of 51 months improved symptoms were reported by 21%, while 18% deteriorated. Patients were more likely to develop cold intolerance if they smoked and less likely if they suffered a sharp injury. A score defining the severity of cold induced symptoms, based on the information collected, was calculated for each patient. Significantly increased severity was associated with complete nerve division, median and ulnar nerve division and an associated vessel injury. Symptom improvement was significantly more likely in non-smokers and a deterioration most likely with a high severity score.

Objective-To investigate the suggestion that osteoarthritis (OA) of the hip joint is often caused by subclinical acetabular dysplasia among elderly British women. Methods-We examined 393 hip joints from the radiographs of a sample of women aged 60-75 years undergoing intravenous urography. Acetabular dysplasia was assessed using measurements of the centre-edge (CE) angle and acetabular depth (AD), which are both reduced in this condition. OA was assessed using an overall grade based on the Keligren and Lawrence system and by measurement of minimum joint space (MJS). Results-MJS was the more repeatable measure of OA, and showed a strong correlation with overall grade (Spearman rank correlation coefficient r, =-0-61, p < 0.01). MJS was significantly negatively correlated with CE angle (Pearson correlation coefficient r = -0 25, p < 0.001) and AD (r=-0.11, p<0.05). Consistent with these findings, there was a weak but significant positive correlation between overall grade of OA and one of the two measures (CE angle) of acetabular dysplasia. Conclusions-These results do not support the hypothesis that mild degrees of acetabular dysplasia account for a substantial proportion ofhip OA in elderly women. Changes in hip joint geometry as a result of OA may be responsible for the weak negative association observed. (Ann Rheum Dis 1995; 54: 179-181) investigated the relationship between OA and acetabular dysplasia in elderly women.Patients and methods A sample of women aged 60-75 years old undergoing intravenous urography during 1988-91 was identified from the records of the radiology department at Southampton General Hospital. Radiographs were retrieved and individual hip joints were assessed from postmicturition films. Hip joints were excluded if visualisation was inadequate or total hip replacement surgery had been performed.Observer 1 (RWS) examined the radiographs over a three month period. Angular and linear indices were measured to the nearest degree and 0-5 mm, respectively, using techniques described previously7 9 and the bony landmarks illustrated in figure 1