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1.
The orbit of Explorer 24 (1964–1976A) has been determined at 18 epochs during the five month period prior to its decay in October 1968, using the RAE orbit refinement computer program PROP6. As a balloon, the satellite was strongly influenced by atmospheric perturbations, despite its high perigee altitude near 490 km. It therefore provided an opportunity of determining atmospheric rotation rates at high altitude. The rotation rate, Λ rev day?1, was estimated from the observed variation in orbital inclination, after the removal of perturbations including those due to solar radiation pressure.The mean rotation rates, averaged over local time, are Λ = 0.98 for 18 May to 18 August 1968 at 542 km; Λ = 1.06 for 18 May to 13 October 1968 at 533 km.For morning conditions, Λ = 0.9 for 22 June to 20 July 1968 at 540 km; Λ = 0.8 during September 1968 at 513 km.For evening conditions, Λ = 1.1 for 18 May to 15 June 1968, and for 26 July to 7 September 1968, at 540 km and 536 km respectively; Λ = 1.3 for 28 September to 13 October 1968 at 484 km.Further, the maximum W to E zonal wind has been estimated to occur at 20.5 h local time, during the period of the analysis.  相似文献   

2.
The average rotation rate of the upper atmosphere can be found by analysis of the changes in the orbital inclinations of satellites, and results previously obtained have indicated that the atmospheric rotation rate appreciably exceeds the Earth's rotation rate at heights between 200 and 400 km.We have examined all such results previously published in the light of current standards of accuracy: some are accepted, some revised, and some rejected as inadequate in accuracy. We also analyse a number of fresh orbits and, adding these to the accepted and revised previous results, we derive the variation of zonal wind speed with height and local time. The rotation rate (rev/day) averaged over all local times increases from near 1.0 at 150 km height to 1.3 near 350 km (corresponding to an average west-to-east wind of 120 m/s), and then decreases to 1.0 at 400 km and probably to about 0.8 at greater heights. The maximum west-to-east winds occur in the evening hours, 18–24 h local time: these evening winds increase to a maximum of about 150 m/s at heights near 350 km and decline to near zero around 600 km. In the morning, 4–12 h local time, the winds are east to west, with speeds of 50–100 m/s above 200 km. We also tentatively conclude that, at heights above 350 km, the average rotation rate is greater in equatorial latitudes (0–25°) than at higher latitudes.  相似文献   

3.
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4.
The satellite NOAA-B (1980-43A) was launched in May 1980 into an orbit with perigee height near 260 km and apogee height 1440 km, at an inclination of 92.2°.The lifetime was 11 months. The orbit has been determined at 40 epochs between October 1980 and May 1981 from about 3000 radar and optical observations. The average orbital accuracy, radial and cross-track, was about 100 m, with rather better accuracy in the final 14 days.The variation of orbital inclination has been analysed to determine two good values of atmospheric rotation rate, namely 1.10 ± 0.10 rev day?1 at 300 km (average local time) and 1.15 ± 0.06 rev day?1 at 225 km (evening).The effect of atmospheric rotation on the precession of the orbital plane of an actual satellite has never previously been detected; it is clearly apparent for 1980-43A in its last days and conforms to the expected theoretical change.The variation of perigee height has been analysed to determine ten values of atmospheric density scale height, for heights of 280–370 km. These values, accurate to about 3%, exceed by 15% the values indicated by the COSPAR International Reference Atmosphere. Solar activity was higher in the years 1980–1981 than at any time since early 1958 and it appears that the CIRA model underestimates the density and density scale height at high levels of solar activity.  相似文献   

5.
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6.
The Agena B upper-stage rocket 1963-27A was launched into near-circular orbit, inclined at 82.3° to the Equator, on 29 June 1963. Its orbital elements were available at 52 epochs over the 16 month interval prior to its decay on 26 October 1969. During this period the satellite passed through 31:2 resonance and the variation in orbital inclination near this event was analysed to obtain two lumped geopotential harmonics of order 31. Since the resonance was a weak feature in the data, the resulting values are poorly defined.Either side of the resonance period, the inclination was used to estimate the mean atmospheric rotation rate Λ rev day?1. The values obtained were Λ = 0.85 ± 0.18 at a height of 440 km for the period June 1968 to February 1969 and Λ = 1.13 ± 0.10 at 338 km for the period June to October 1969.  相似文献   

7.
The orbit of Cosmos 482 has been determined at 55 epochs during the period August 1975–October 1977. Inclined at 52° to the Equator, of eccentricity exceeding 0.3 and perigee height near 210 km, this high drag and high eccentricity orbit is the most eccentric as yet analysed by PROP. The combination of the orbital characteristics, restricted global coverage of observational data, and the many observations of angular measurement at extreme range proved to be troublesome. Cleared of other perturbations, the inclination is analysed to determine the atmospheric rotation rate, λ rev day?1, of the zonal winds at a height near 235 km. Results reveal a diurnal and seasonal dependence, including a summer value, averaged over local time, of λ = 0.9 and an evening value of λ = 1.4 in the winter months. The resultant wind velocities vary between 48 m s?1 East to West and 193 m s?1 West to East, with an average of 48 m s?1 West to East.  相似文献   

8.
During the evening of 9 April and the morning of 10 April 1969, the twilight zenith intensity of the atomic oxygen red line OI(3P-1D) at 6300 Å was measured at the Blue Hill Observatory (42°N, 17°W). At the same time incoherent scatter radar data were being obtained at the Millstone Hill radar site 50 km distant. We have used a diurnal model of the mid-latitude F-region to calculate the ionospheric structure over Millstone Hill conditions similar to 9–10 April 1969. The measured electron temperature, ion temperature, and electron density at 800 km are used as boundary conditions for the model calculations. The diurnal variation of neutral composition and temperature were obtained from the OGO-6 empirical model and the neutral winds were derived from a semiempirical three-dimensional dynamic model of the neutral thermosphere. The solar EUV flux was adjusted to yield reasonable agreement between the calculated and observed ionospheric properties.This paper presents the results of these model computations and calculations of the red line intensity. The 6300 Å emission includes contributions from photoelectron excitation, dissociative recombination, Schumann-Runge photodissociation and thermal electron impact. The variations of these four components for morning and evening twilight between 90–120° solar zenith angles, and their relative contributions to the total 6300 Å emission line intensity, are presented and the total is compared to the observations. For this particular day the Schumann-Runge photodissociation component, calculated using the solar fluxes tabulated by Ackermann (1970), is the dominant component of the morning twilight 6300 Å emission. During evening twilight it is necessary to utilize a lower O2 density than for the morning twilight in order to bring the calculated and observed 6300 Å emission rates into agreement. The implication that there may be a diurnal variation in the O2 density at the base of the thermosphere is discussed in the light of available experimental data and current theoretical ideas.  相似文献   

9.
The orbit of Tansei 3rocket(1977-12B) has been determined at 47 epochs between 1 October 1977 and 19 March 1979 using over 1700 observations and the RAE orbit refinement program PROP6. The rate of change of the inclination was examined to evaluate values of the atmospheric rotation rate, Λ rev day?1. Analysis yielded the value Λ = 1.1 ± 0.05 at height 315 ± 30 km, average conditions; or alternatively Λ = 1.1 ± 0.1 at height 347 ± 12 km, slight winter bias and Λ = 1.07 ± 0.1 at height 270 ± 18 km, average conditions, supplying further evidence of a decrease in rotation rates from the 1960s to the 1970s.Analysis of the inclination at 15th-order resonance yielded the lumped harmonic values
109C0,115 = 13.4 ± 6.2, 109S0,115 = 0.7 ± 13.3
for inclination 65.485°.  相似文献   

10.
The orbit of China 2 rocket, 1971-18B, has been determined at 114 epochs throughout its 5-yr life, using the RAE orbit refinement program PROP 6, with more than 7000 radar and optical observations from 83 stations.The rocket passed slowly enough through the resonances 14:1, 29:2, 15:1 and 31:2 to allow lumped geopotential harmonic coefficients to be calculated for each resonance, by least-squares fittings of theoretical curves to the perturbation-free values of inclination and eccentricity. These lumped coefficients can be combined with values from satellites at other inclinations, to obtain individual harmonic coefficients.The rotation rate of the upper atmosphere, at heights near 300 km, was estimated from the decrease in orbital inclination, and values of 1.15, 1.05, 1.10 and 1.05 rev/day were obtained between April 1971 and January 1976. From the variation in perigee height, 25 values of density scale height were calculated, from April 1971 to decay. Comparison with values from the COSPAR International Reference Atmosphere 1972 shows good agreement between April 1971 and October 1975, but the observational values are 10% lower, on average, than CIRA thereafter.A further 1400 observations, made during the final 15 days before decay, were used to determine 15 daily orbits. Analysis of these orbits reveals a very strong West-to-East wind, of 240 ± 40 ms?1, at a mean height of 195 km under winter evening conditions, and gives daily values of density scale height in the last 7 days before decay.  相似文献   

11.
The calculation of number densities of CO2, H2O and N2 photolysis products was carried out for the Martian atmosphere at heights up to 60 km. The ozone distributed in the atmosphere as a layer of 10 km width with [O3] max = 2.5 × 109 cm3 at height of 35 km which agree well with the results of u.v. observations on the evening terminator from the Mars-5 satellite. The calculated densities of O2, CO and H2O are also in good agreement with the measured data. The eddy diffusion coefficient is equal to 3 × 106 in the troposphere (h ? 30 km) and 108 cm2 s?1 above 40 km. The dependence of the total ozone content on water vapour amount in the atmosphere is considered; the hypothesis about the influence of water ice aerosol on the ozone formation is proposed to explain the high concentrations of ozone in the morning.  相似文献   

12.
Partial reflection radiowave wind observations have been made continuously at Saskatoon for 1 year (September 1978–August 1979). The winds have been obtained in real-time from a twin micro-processor system, that produces profiles (32 heights from 49 to 142km) at 5-min intervals: daytime/night-time profiles normally involve values from 6070 to 120 km.These data have been analyzed to give the daily mean wind and the amplitudes and phases of planetary, tidal (24, 12 h) and internal gravity (I.G.) waves (0.20 ? τ ? 6h). There are oscillations in the mean daily wind, with periods of 2–30 days: the disturbance from 60 to 100 km caused by the stratwarm of February and March is documented. The characteristics of the semi-diurnal tide undergo significant changes in vertical wavelength and time of maxima between summer months (May–August) and winter months (November–February): during summer the S22 mode (λz ? 150km) seems to dominate, and in other months a mixture of modes (λz ? 50km) exist. The diurnal tide is less regular, but during winter and spring λz ? 30–60 km, and for other months is very large, suggesting the S?11 mode. Energy densities and scale heights (h0) are given, and the relative magnitudes of these for the various waves are discussed with respect to height and season: there is a general trend for the growth of the wave amplitude with height (shown by h0) to increase in the order planetary, tidal and I.G. waves (h0, ～3–15 km): largest values are in winter and spring. Wave energies are largest in winter, decrease during spring and increase throughout late summer and fall.  相似文献   

13.
Almost simultaneous height sequences of 69 spicules in the Hα line have been studied. The spectra are obtained at six heights during 6 s on the east side of the solar disk with the 53-cm Lyot coronagraph of Abastumani Astrophysical Observatory. Radial velocities V r, total intensities or equivalent widths W, full widths at half maximum of intensity (FWHM) at all heights are determined (about 300 profiles of the Hα line). It is found that:
  1. Absolute values of radial velocities increase linearly with the height (see Equation (1));
  2. variation of the sign of the radial velocity along single spicules was never observed.
These results combined with the findings on the spicules radial velocities and shifts obtained earlier (Kulidzanishvili and Nikolsky, 1978; Nikolsky and Platova, 1970) led us to the conclusion that the 5-min tangential oscillations of spicules involve the entire spicule at once. The intensity height scales for single spicules and for the chromosphere ‘in toto’ are determined; they turned out to be 2.5 × 103 km and 1.9 × 103 km respectively (see Equations (2) and (3)). The dependence curve of the Hα line half-widths Δλ on the height h is drawn. The Hα line half-width for those spicule groups which are traced at all heights (10 spicules) decreases with the height (Figure 4); for the majority (～60 spicules) it remains essentially constant. Non-thermal ‘turbulent’ velocities V t, in Hα spicules are defined. A mean value of the ‘turbulent’ velocity V t at T = 6000° appeared to be 20–30km s?1. The hydrogen concentration in the spicules at 5000 km is 6 × 1011 cm?3.  相似文献   

14.
COSMOS 1009 rocket was launched on 19 May 1978 into an orbit with initial perigee height 150 km and apogee 1100 km: its lifetime was only 17 days. The orbit has been determined daily during the final 14 days of its life, using the RAE orbit refinement program PROP6,with about 1100 observations supplied by NORAD. An average accuracy of about 60 m, radial and cross-track, was achieved.The orbits were analysed to reveal three features of the upper atmosphere at heights between 125 and 175 km. From the decrease in perigee height, five values of density scale height, accurate to ±4%, were obtained. The first three were within 10% of those from CIRA 1972; the fourth, after a magnetic storm, was higher than expected; the fifth gave evidence of the decrease in drag coefficient at heights below 130 km.Atmospheric oblateness produced a change of 4° in perigee position during the last four days of the life. Analysis showed that the ellipticity of the upper atmosphere was approximately equal to that of the Earth, f, for the first two of the four days, and about 12f in the last two.The orbital inclination decreased during the 14 days by about 50 times its standard deviation, and the observed variation was analysed to determine zonal winds at heights of 150–160 km at latitudes near 47° north. The zonal wind was very weak (0±30 m/s) for 23–28 May at local times near 03h; and 90±30 m/s east-to-west for 29 May to 4 June at local times near 01 h.  相似文献   

15.
The polar orbit of HEOS 2 second-stage rocket, 1972-05B, has been determined on each of the final 16 days before its decay in September 1978, using the RAE orbit refinement program, PROP 6, with about 1360 observations. An accuracy of 30–70 m, both radial and across track, was achieved.Eleven values of density scale height have been determined from the decrease in perigee height, with a 2% error; seven of these values are within 6% of the CIRA 1972 reference-atmosphere values, the rms value being 4% higher than CIRA.The rotation rate of the upper atmosphere, A, was determined from the decrease in orbital inclination as Λ = 1.40 ± 0.05 rev day?1; i.e. a strong west-to-east zonal wind of 160 ± 20m s?1, at a mean height of about 240 km. The local time was 01–02 h; solar activity was high; and the latitude of perigee moved steadily from 10°N to 67°S.  相似文献   

16.
The Venera 8 descent module measured pressure, temperature, winds and illumination as a function of altitude in its landing on July 22, 1972, just beyond the terminator in the illuminated hemisphere of Venus. The surface temperature and pressure is 741 ± 7°K and 93 ± 1.5kgcm?2, consistent with early Venera observations and showing either no diurnal variation or insignificant diurnal variation in temperature and pressure in the vicinity of the morning terminator. The atmosphere is adiabatic down to the surface. The horizontal wind speed is low near the surface, about 35m/sec between 20 and 40km altitude, and increasing rapidly above 48km altitude to 100–140m/sec, consistent with the 4-day retrograde rotation of the ultraviolet clouds. The illumination at the center of the day hemisphere of Venus is calculated to be about 1% of the solar flux at the top of the atmosphere, consistent with greenhouse models and high enough to permit photography of the Venus surface by future missions. The attenuation below 35km altitude is explained by Rayleigh scattering with no atmospheric aerosols; above 35km there must be substantial extinction of incident light.  相似文献   

17.
The IRAM Plateau de Bure Interferometer has been used to map the CO(1-0) rotational line in Mars' middle atmosphere. Absolute winds and thermal profiles were retrieved during the 1999, 2001, 2003 and 2005 planet's oppositions. The observations sampled various seasons (Ls=143, 196, 262, 317 and 322), and different dust situations (clear, global storm, regional storm). The absolute winds were derived by measuring directly the Doppler lineshifts. The main zonal circulation near 50 km is dominated by strong retrograde winds, with typical velocities of 70-170 m/s, strongly varying seasonally, latitudinally, and longitudinally (in particular between morning and evening). Comparison of the retrieved temperature with a general circulation model indicates that the model often underestimates the temperatures in the middle (20-50 km) atmosphere, and overestimates them above 50 km.  相似文献   

18.
《Icarus》1987,70(3):442-468
The predictions of an analytical steady thermally forced viscous model for the zonally averaged global circulation of the Martian atmosphere are compared to observations of atmospheric temperatures and eolian feature directions. The temperature of the winter polar atmosphere is a sensitive indicator of the value of the mean eddy diffusivity v of the atmosphere. For global dust storm season, the observed large warming of the atmosphere over the winter (north) pole during the 1977b storm as well as the distribution and azimuths of Type I(b) dust streaks can be well reproduced if v = 107−108cm2sec−1. Observed northeasterly surface winds at high northern latitudes could be produced by plausible fluxes of CO2 from the northern polar cap. The thermal structure at southern latitudes during this storm is satisfactorily produced, but a major discrepancy exists between observations and predictions of the temperature structure at middle northern latitudes. By comparing these results with those from previous inviscid models of the zonal mean circulation on Mars, we suggest v > 107cm2sec−1 at heights above 30 km and v ⪡ 107cm2sec−1 at lower altitudes may yield a meridional circulation which produces the dynamical warming necessary to account for the observed thermal structure at 0.6 mbar at all latitudes. For late southern summer when the dust content of the atmosphere has decreased to levels characteristic of much of the Martian year, the lack of dynamical warming of the winter pole implies v ≤ 106cm2sec−1. In addition, the predicted surface wind azimuths at this season agree well with the observed azimuths of Type I(d) dust streaks, which are observed to form at this season. The observed latitudinal concentration of the streaks is not explained by the model and may require additional processes which have not been included.  相似文献   

19.
A further year's observation of twilight Hel 10830 Å emission made in Brazil confirms the trend of seasonal variation found earlier. The 10830 intensities taken with concurrent ionosonde data are discussed in the context of recent model calculations of the emission rates. An increase with KP is attributable to changing production and loss rates of He 23S with changing thermospheric temperature. The morning intensities being greater than those of the evening can be due to several effects, an important one of which appears to be the much greater loss rate of photoelectron energy to ambient electrons in the evening, arising from the very high evening electron concentrations at the Appleton Anomaly ionization crests.  相似文献   

20.
Magnetic field intensity of the horizontal component (H) data measured from Magnetic Data Acquisition System (MAGDAS) at Ilorin (geographic latitude: 8.47°N, geographic longitude: 4.68°E, geomagnetic latitude: 1.82°S, geomagnetic longitude: 78.6°S), Nigeria in the year 2009 (a low activity year) was used to study the diurnal, monthly-median and standard deviation of the solar quiet of the horizontal component (S q H). The diurnal variation of S q H and its corresponding monthly median variation (MS q H) shows minima values at pre-sunrise hours between 0500 and 0600 LT. The S q H value shows a daytime maximum variation range between 20 and 91 nT and a nighttime minimum variation range from 1 to 4 nT. The occurrences of daytime maxima of the S q H values that were observed in all the months are between the hours of 1000 and 1200 LT. The daytime maximum of the MS q H values from the entire months were seen at 1100 LT with exceptions of January and December. The month of October has the highest value (61 nT) and the lowest value was observed in December (35 nT). It is clearer that the range in maximums of S q H and MS q H variations during the daytime period in all the months is greater than the range in minimums observed at nighttime period (post-sunset and pre-sunrise). The monthly standard deviation (STD) depicts the index of variability of all the day-to-day variations in each month. Counter electrojet (CEJ) events were observed in the morning and as well during the evening hours. The magnitudes and frequencies of CEJ events during the evening hours are greater than that of the morning hours. CEJ seen during the morning period around 0500–0600 LT is the consequence of late reversals of nighttime westward currents to daytime eastward currents. A semi-annual variation with peak values during March, April, September and October was observed. Seasonal variation that was characterized with CEJ was also investigated.  相似文献   

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