For the following coordinated analysis by means of both TAIYO and AEROS-B satellite, the description of TAIYO and its data basis are presented. Simple results of integrated data analysis of TAIYO are also described.

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With the two aeronomy satellites AEROS-A and B simultaneous observations of the main upper atmospheric and ionospheric parameters as well as of the solar ionizing radiation were conducted. The data basis is described with respect to orbit parameters, performance criteria of the spacecraft and experiments, and the time coverage of the various parameters measured. An outline is given on the various aspects and the major results of data analysis which is performed on an integrated scale.

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Electron temperatures measured by the AEROS retarding potential analyzer (RPA) and by the TAIYO electron temperature probe are compared when both satellites were close to each other. The selected data are in the height range 250 to 400km. During local nighttime good agreement is obtained between the measurements of both satellites. This allows to derive temperature gradients with respect to the altitude profile and the increase at sunrise. At daytime the temperatures from TAIYO are, on the average, 10% higher than from AEROS.

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Locally measured electron densities by means of impedance probes aboard the two satellites TAIYO and AEROS-B have been compared. After identifying suitable encounters the measured altitude variations of the density during nighttime showed to fit reasonable well with calculated height profiles in some cases. But remaining discrepancies reveal the factors by which the actual density deviate even than from monthly medians. Other cases with still larger differences with respect to the shape of the height profile above the F₂ layer and the peak density (NmF₂) and altitude (hmF₂) are observed as well.

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An EUV airglow photometer aboard the satellite TAIYO recorded the airglow radiance in the wavelength region of 75-100nm. The intensity profile of the airglow with respect to altitude measured in daytime and twilight shows good agreement with the model calculation of OII 83.4nm emission.

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From the currently observed data, the absolute intensity of the solar hydrogen Lyman-alpha (H Ly-α) was estimated as 3.2×10¹⁵ photons/m² sec at 1 A. U. and constant within ±4.2% during the period from February 24 to September 30 with some lacks of observation only. No remarkable correlations with other indices such as F_10.7 and Calcium plage indices were observed. The density distribution of hydrogen atoms in the altitude range from about 800km to 3, 000km was analysed. The observed absorption profile data agreed with the simulated calculation by referring to the CIRA '72 Model Atmosphere.

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As the mean perigee height of the satellite was 250km, the orbital decay of this satellite was available to study the changes of density and exospheric temperature during the flight of satellite.
Orbital decay of the satellite was observed for solar activity minimum conditions from March 1975 to November 1976.
We derieved coefficients of the experimental formula of temperature change due to F_10.7 and K_p which are a little different from those of the Jacchia's 1971 model.
As the local time of perigee changed during the flight, we could study the diurnal variation of exospheric temperature.
The semi-annual variation of exospheric temperature was observed, too. We discussed that this semi-annual change of exospheric temperature is due to heating by the charged particles, precipitated at high latitudes through the dayside polar cusp.
The total flux of the precipitation of the charged particles through the polar cusp in the northern dayside hemisphere is minimum at the summer and winter solstices and maximum at the equinoxes. Observed maximum and minimum of the semiannual change of the exospheric temperature is delayed about 15-20 days with respect to these dates.
Changes of exospheric temperature due to the southern hemisphere anomaly was discussed, too.

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The approach followed in deriving total gas density at perigee from the orbital decay of the AEROS satellites is described. Numerical integration of the drag force acting on the satellite along the orbit is used in an iterative procedure to compute thermospheric density. The continuously changing value of the product of drag coefficient and effective cross section is kept within the integrand of the drag integral. The variation of the drag coefficient with free molecule flow Mach number and accommodation coefficient is taken into account using the nearest possible approximation of the quasi-cylindrical satellite which can be treated by classical FMF-theory. A summary of the density results is given. The resulting density agrees on the average with the COSPAR International Reference Atmosphere 1972. Exceptions from this result are shown at southern polar latitudes in an oxygen dominated thermosphere.

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The comparison of perigee density data near 230km for satellite AFROS-A has been extended to the complete mission time. The average ratio between orbital drag derived density and mass spectrometer measurements is very near to 1 with a large scatter reflected by a standard deviation of the order of 20%. A method of comparison was developed and tested which uses the observed rate of change of orbital period in comparison with the orbital decay computed from the actual mass spectrometer data measured at discrete positions along the orbit. This method proves that deviations from the average ratio of 1 between perigee densities from drag and mass spectrometers are due to the smoothing and poor resolution of the orbital drag technique.

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Aboard AEROS-A and B the solar EUV radiation was monitored in the wavelength range from 106-16nm with a planar grating spectrometer. During the measuring periods three types of solar flux variations were recorded: Long-term variations with solar cycle activity, medium-term variations with solar rotation and short-term variations with solar events. These variations differ from those of the classical solar indices. The determination of the absolute values of the solar flux is based on the calibration by means of synchrotron radiation and an inflight calibration of the multipliers. Other instrumental modes of operation performed EUV extinction measurements to derive densities of atomic oxygen.

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Preliminary models of the annual variations of He, N, O, N₂, and Ar were derived from the neutral/ion mass spectrometer (NIMS) data of AEROS-A and AEROS-B in the altitude range 220-550km. The period covered by AEROS-A extends from December 26, 1972 to August 9, 1973 at the local times 3 and 15hr, while AEROS-B represents very quiet solar conditions (<F_10.7>=81) during July 23, 1974 to September 24, 1975 at 4 and 16hr local time. Using the analytical framework of the OGO-6 model, the number densities of the constituents were expanded into spherical harmonics with the exospheric temperature inferred from N₂ observations under the assumption of diffusive equilibrium.

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Analyses have been made on the electron density and ion sheath capacity data obtained by gyro-plasma probe installed on TAIYO. The data for 160 orbits provide various states of the electron density profile in the ionosphere, such as the local time dependence and the equatorial anomaly. The measured impedance values at 406kHz reveals the ion sheath thickness surrounding the probe. In the region of the South Atlantic anomaly of the geomagnetic field, quick changes of the ion sheath capacitance have been observed indicating charging up of the probe. These quick changes are separated into two types; the first is the quick sharp variation and the second is the gradual variation. The sharp variation of the sheath capacitance value is disclosed to be triggered by the telemetry radio wave in the region of the South Atlantic anomaly.

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Longitudinal and Latitudinal characteristics of the O⁺-H⁺ ion transition height in the topside ionosphere at the low latitudes during the sunspot minimum period (1975-76) were observed by a retarding potential analyzer aboard TAIYO.
The results indicate that:
1) A semi-empirical formula of the ion transition height (H in km) is expressed as a function of the solar zenith angle (χ in deg.) and the geomagnetic dip angle (I in deg.); H=591-87.1sin² I, (χ≥90°), and H=591-87.1sin² I+(217+473sin² I) cos^0.331χ, (χ≤90°).
2) The ion transition heights around the South Atlantic geomagnetic anomaly are rather variable than those at another region in the nighttime. The region with variable ion transition height roughly coincides with that of anomalous intense count observed with a high energy measuring instrument (SXR) aboard TAIYO in the ionosphere.
3) Discussions and comparisons with other experiments are given. The remarkable asymmetry of the ion transition heights between the southern and northern hemispheres is explained by the semi-empirical formula to some extent.

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The two plasma experiments aboard the AFROS-B satellite determined the main plasma quantities in the height range 220-880km. These complementary instruments, a Retarding Potential Analyser and an Impedance Probe, provided the electron and ion temperatures, the main ion constitutents, the suprathermal electron flux and the plasma density.
This paper summarizes a selection of the obtained results. Comparisons of several quantities with other observations demonstrate the high reliability of the AFROS plasma data. As a contribution to sensor theory a dependence of RPA measurements on the magnetic field vector has been established. The ion temperature and composition turn out to undergo a strong latitudinal variation, the highest hydrogen concentration in the upper atmosphere being located at ±20° latitude. Concerning the longitudinal variation of electron density discrepancies between measured data and existing models have been revealed. The statistical relation between the position of the mid-latitude trough and magnetic activity was studied for a fixed local time. First results of a synoptic study of the high latitude day-side ionosphere using AFROS-B and ISIS-II data are presented.

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