Semidiurnal tidal winds at Collm (52°N, 15°E) and Saskatoon (52°N, 107°W) over the decade 1978–1988

Mean winds and tides have been measured by the LF and MF radar systems at Collm and Saskatoon respectively. Semidiurnal tide amplitudes and phases near 90 km evidence very similar monthly variations. A detailed comparison of mean wind and tidal profiles (85–110 km) in the Septembers of 4 years shows some differences however, which are consistent with regional (Europe-Canada) differences in the mean background winds.     

Winds and waves in the middle atmosphere at Saskatoon (52°N, 107°W), Collm (52°N, 15°E) and Badary (52°N, 105°E)

Winds data from three radar systems in the U.S.S.R. G.D.R. and Canada, which are well-spaced along the 52°N latitude circle, are used to illustrate longitudinal/regional variations in the dynamics of the upper middle atmosphere 80–97 km. Responses to the stratospheric warming of 1982/3 are noted at all three locations, but the zonal wind does not reverse at Badary, consistent with the flow there being eastward during all months of the year. Planetary wave period oscillations (2–30 days) are observed at all locations, and highly significant cross-spectral coherences exist between the three stations.     

Winds oscillations (∼ 6h–6days) in the upper middle atmosphere at Monpazier (France, 45°N, 1°E) and Saskatoon (Canada, 52°N, 107°W) in 1979–1980

The medium frequency radar (∼ 2.2 MHz) at Saskatoon has been run continuously since 1978 and the Meteor Radar at Monpazier ran continuously for ∼ 10 day intervals in most months of 1979/1980. The radars are separated by ∼ 8000 km. Because of the excellent quality of the data, spectral and harmonic analyses have been completed from ∼ 70 to 100km and oscillations with periods of ∼ 6h–6days studied.There are substantial similarities in the mean zonal winds, both with regard to magnitudes and times of seasonal reversals; also in annual and semi-annual oscillations. In general, the semi-diurnal tide has similar amplitudes, phases and vertical wavelengths : there are consistent summer (long λ) and winter (short λ) characteristics, with rapid transitions between them. Differences between the timing of these transitions and in some of the mid-season tides are discussed. The diurnal tide is less regular and of smaller amplitude at both locations, often being too small to reliably characterize at Monpazier. However, seasonal variations between summer and winter months may be discerned.In addition to the 24 and 12 h tidal oscillations, which traditionally are studied in most detail, there is clear evidence for additional osculations near 6,8, ∼ 10 and ∼ 16 h and longer periods of ∼ 2 and ∼ 5 days. The amplitudes of these are often comparable or larger than the ‘dominant’ 24 and 12 h tides. The monthly and seasonal variations of these additional oscillations are studied, as a function of height, at the two locations. There is evidence for large scale (global) and small scale (local) disturbances in the wind field.     

Combination of Primrose Lake (54°N, 110°W) ROCOB winds (20–60 km) and Saskatoon (52°N, 107°W) M.F. radar winds (60–110 km): 1978–1983

Comparisons are made between data from the unique Saskatoon medium frequency radar set, which is continuous from mid 1978–1983 and the ROCOB data from Primrose Lake, which is only 340 km northwest of Saskatoon. Until 1981 there were 2–3 firings per week and now there are 4–5 per month. While the final agreement is satisfactory, special care was required when matching the two regions: particular problems are the low rocket sampling rate and the unexpectedly large amplitude of the diurnal tide. Combination of the two data sets is made.The Canadian zonal winds are quite similar to CIRA 72, especially in the summer months, however, the winter winds show much more systematic variability due to 12- and 6-month periods of oscillation and stratwarms. Canadian meridional winds differ significantly from existing data models.     

On the stability of the ozone layer at Tromsø

Long-term measurements of the thickness of the ozone layer in Tromsø since 1935 show that the annual mean value can vary by as much as 18%. However, no decreasing trend of the ozone content and no correlation with the increasing amount of chlorine and halogen compounds of the atmosphere are found in the Scandinavian sector of the Arctic.     

Ionospheric modification experiments with the Tromsø heating facility

The experiments performed up to mid 1984 with the heating facility at Ramfjordmoen near Tromsø, Norway, are summarized. These experiments comprise D-region modification, polar electrojet modulation at VLF, ELF and ULF frequencies, excitation of E-region small-scale irregularities and of F-region small- and large-scale irregularities, anomalous absorption of HF wave on long and short time scales, excitation of incoherent backscatter plasma and ion lines, stimulated radio wave emission and F-region in situ measurements.     

Variations of mean winds and tides in the upper middle atmosphere over a solar cycle,Saskatoon, Canada, 52°N, 107°W

Saskatoon (52 N, 107 W) medium frequency (MF) radar data from 1979 to 1990 have been analyzed to investigate the solar activity effects on upper middle atmospheric winds and tidal amplitudes. The period of study covers two solar maxima and a solar minimum; the continuous data allow a systematic analysis of solar cycle dependence on mean winds and tides. The height region of 79–97 km sampled in the study shows an apparent but very weak dependence of mean winds and tidal amplitudes on solar activity variation. The observed features are fairly consistent with the early results reported by Sprenger and Schmindkr [(1969) J. atmos. terr. Phy. 31, 217). The mean zonal wind and the semidiurnal tidal amplitudes appear to exhibit positive and negative correlations with the solar activity, respectively; the statistical significances of these correlations are generally low. There is a biennial periodicity evident in the zonal wind oscillations but this docs not have a consistent phase relationship with the equatorial stratospheric wind oscillations (QBO). The meridional winds and the tidal amplitudes are characterized with different and quite irregular periods of oscillations (2–5 yr). The diurnal tidal variations over the solar cycle are small and irregular, although amplitudes are slightly larger during the solar minimum years.     

Heights of MF radar scatter (1986/87) and the wind field (55–95 km): Saskatoon,Canada

The Saskatoon MF radar (2.2 MHz) at 52°N, 107°W, has been used to measure the heights of occurrence of radar scatter during four seasons, and twelve months of 1986/87. Mean winds, and gravity waves are also available, by the spaced antenna method and from the same radar echoes. Certain heights, called elsewhere ‘preferred heights’, are identified near 60km, 70km, 75km in summer, and 80–86 km. Several layers have seasonal and diurnal variations. Associations with electron density gradients (rocket data), mean wind shear in summer, and gravity wave amplitude-minima in the equinoxes are effectively demonstrated. Case studies, involving 3 h data sets of radar scatter and wind elaborate the comparison: gravity waves of long period (τ > 6 h) are shown to modulate the scattering process.     

Mean winds at 60–90 km observed with the MU radar (35°N)

Mean winds at 60–90 km altitudes observed with the MU radar (35°N, 136°E) in 1985–1989 are presented in this paper. The zonal wind at 70 km became westward and eastward in summer and winter, respectively, with a maximum amplitude of 45 m s⁻¹ westward in early July and 80 m s⁻¹ eastward at the end of November. The meridional wind below 85 km was generally northward with the amplitudes less than 10 m s⁻¹. In September to November, the meridional wind at 75–80 km becomes as large as 20–30 m s⁻¹. Those zonal wind profiles below 90 km show good coincidence with the CIRA 1986 model, except for the latter half of winter, from January to March, when the observational result showed a much weaker eastward wind than the CIRA model. The height of the reversal of the summer wind from westward to eastward was determined as being 83–84 km, which is close to the CIRA 1986 model of 85 km. The difference between the previous meteor radar results at 35–40°N, which showed the reversal height below 80 km, could be due to interannual variations or the difference in wind measurement technique. In order to clarify that point, careful comparative observations would be necessary. These mean winds were compared with Adelaide MF radar observations, and showed good symmetry between the hemispheres, including the summer reversal height, except for the short period of eastward winds above Kyoto and the long period over Adelaide.     

Tidal winds in the radio-meteor region over Trivandrum (8.5°N, 77°E)

Wind measurements using a meteor trail radar which performed during two June solstice and three December solstice months were analysed to study the tidal winds over Trivandrum (8.5°N). The ter-diurnal (8 h) component of wind was found to be as significant as the diurnal and semi-diurnal components. The modulations in the altitude profiles of amplitude and phase of the tidal wind components are interpreted to be due to higher order tidal modes. The amplitudes and vertical wavelengths of the tidal modes observed in the meteor zone are discussed.     

Asbjørn Følling and the discovery of phenylketonuria

In 1934, the Norwegian biochemist and physician Asbj?rn F?lling described an inherited metabolic disorder characterized by severe intellectual impairment, motor problems, and skin abnormalities. He found that affected individuals could be identified by the abnormal excretion of phenylpyruvic acid in their urine. The disorder, which F?lling initially termed imbecillitas phenylpyrouvica, would later come to be known as phenylketonuria or PKU. The present paper focuses on the story of F?lling's discovery and his subsequent contributions to the area of study. In the years that have followed, research on PKU has continued to play a major role in the neurosciences, shaping our understanding of genetic disorders, human metabolism, and brain development.     

Spain and the Partition Treaties (1697–1700)

This study takes an analytical approach to the diplomatic strategy adopted by the Spanish monarchy in confronting the challenge it faced associated with the Partition Treaties that were signed by Louis XIV, William III and the United Provinces in 1698 and 1700. By consulting Spanish sources to complete the understanding of the diplomatic process, this study analyses the political action that Spain mobilized in its defence around 1700 and describes the evolution of Spain's foreign policy as the product of the mistrust that had developed between the main powers of Europe. This mistrust was politically answered by Madrid with Carlos II's last will and other planned measures to ensure the viability of the project that contained a turning point in the policy underlying the alliances of the monarchy. Although, like that of the other powers, Spain's manoeuvrability was restricted, this study concludes that Spain was able to create policy action plans and rationally implement them; moreover, the dynamics resulting from the negotiation and signing of the Partition Treaties led the monarchy to oppose them at all costs and naturally led to the choice of a French heir as its only solution.     

Observations of ionospheric modification by the Tromsø heating facility with the mobile diagnostic equipment of IZMIRAN

Results are presented of ionospheric modification experiments carried out at Tromsø, Norway, in October and November 1988. These experiments were jointly conducted by IZMIRAN and MPAe. In these experiments, small scale electron density perturbations (having a vertical size ~ 1 km and a density variation ~0.1%) were found to be excited near the reflection and upper hybrid resonance (UHR) points of an O-mode pump wave. When the pump frequency was close to the triple electron gyrofrequency, there were no noticeable perturbations near the UHR point. This peculiarity correlated well with a decrease of the intensity of stimulated electromagnetic emission (SEE). When SEE is comparatively weak, the SEE intensity can vary quasi-periodically, with a quasi-period of approximately 1 s. When this happens, anticorrelations between different parts of the SEE spectrum become possible.     

Long period wind oscillations in the meteor region over Trivandrum (8°N, 77°E)

The spectra of long period wind oscillations in the meteor zone over Trivandrum are presented. The spectral amplitudes were found to be much larger during June 1984 when the QBO in the stratospheric zonal wind was in a strong easterly phase compared with June 1987 when the zonal winds at the altitude of maximum QBO were weak westerlies. Zonal wind amplitudes for periods of 15 and 5 days were found to be most significant during these two June months. The amplitudes of these two oscillations in meridional wind were found to be as large as the amplitudes in the zonal wind. The vertical wavelength in both zonal wind and meridional winds of the 15-day oscillation is very large whereas for the 5-day oscillation the vertical wavelengths were 80 and 65 km during June 1984 and June 1987, respectively. The results are discussed.     

Total ozone changes in the northern hemisphere mid-latitudinal belt (30–60°N) derived from Dobson spectrophotometer measurements, 1964–1988

A statistical analysis is presented of the daily values of total column ozone obtained during 1964–1988 from a network of 24 Dobson instrument stations located within the mid-latitudinal belt 30–60°N. The year-round-, as well as the summer- and the winter data have been analyzed to detect year-to-year changes in the annual pattern of the probability density function of total ozone (PDFTO) in the belt. Long-term variations in the PDFTO have been deduced from trend analyses of the following statistical characteristics of the annual pattern of the PDFTO: mean, standard deviation, median, 10 and 90 percentile, and the asymmetry coefficient. The trends have been calculated from a multiple regression model adjusted for serial correlations, the 11-yr solar cycle, and long-term stratospheric circulation fluctuation effects. We have found that the pattern of the PDFTO has been drifting uniformly (without changes in its shape) towards lower ozone values, with some seasonal peculiarities in the drift (the annual rate of total column ozone loss). The winter pattern of the PDFTO moves (with a drift of 2.3% per decade) towards lower ozone values faster than the year round pattern (drift equals 1.8% per decade) and the summer pattern of the PDFTO (drift equals 1.5% per decade).     

Solar flux and seasonal variations of the mesopause temperatures at 51°N

Observations of the OH (8-3) band airglow emission, using a multichannel tilting filter type photometer, have been carried out at Calgary (51°N, 114°W), Canada, since 1981. In this paper recent measurements of the nocturnal, seasonal and solar flux variations of the mesopause temperature, obtained from the rotational temperature of the OH (8-3) band observations, are presented. The data presented span the ascending phase of the present solar cycle viz. 1987–1988 (low solar activity) and 1990 (high solar activity). Good correlations (r = 0.73) between the OH (8-3) band rotational temperature and the 10.7 cm solar flux were observed. The mean temperature for the period investigated was about 210 K. The seasonally averaged nocturnal variations show only small irregular excursions, possibly associated with solar tides and the passage of gravity waves in the mesopause region. However, the observed rotational temperatures show considerable night-to-night changes.     

Some regularities of the lower thermosphre wind regime in summer and autumn from meteor radar measurements in obninsk (55°N, 38°E)

Meteor wind measurements made at Obninsk during MAC/SINE and MAC/EPSILON, and in the summer and autumn of other years since 1973, are reported. The zonal wind, which is presumed to be in the 93–95 km height region, is generally westerly, and the meridional wind is mainly northerly. Quasi-two-day oscillations are studied, as are semidiurnal tides. There is some evidence for a 22-yr periodicity in the amplitude of the semidiurnal tide