ALBERT

Description: This paper presents the results of a series of total and spectral solar irradiance measurements made at ground surface (Table Mountain Facility, Calif., altitude 2.18 km). The spectral irradiance data are presented for the 0.3-3.0-micron spectral region for air mass 1.5.

Description: A proposal for a multi-institutional investigation of the processes involved in the growth and maintenance of high level extended clouds is presented. Mapping of variability of the cloud and of its radiative characteristics in terms of the meteorological environment of the cloud; performance of case studies involving observation of the cloud microphysics and radiation characteristics; and investigation of the processes responsible for the generation, maintenance, and dissipation of the cloud system are recommended. Both modeling and monitoring activities are considered. The specific research projects which the author proposes to carry out are described. Suggestions for the administrative organization of the total effort are presented.

Description: The interplay of the various physical processes involved in the formation, maintenance, and decay of middle and upper tropospheric stratiform clouds is discussed. Ice phase fair weather cloud forms are considered. Simulations of cirriform clouds which attempt to incorporate the physical processes in an interactive manner were performed. A two dimensional time dependent Eulerian numerical model, which incorporates all of the important physical processes in a simplified way, is employed to investigate the role of these processes in the evolution of a cloud in an isolated atmospheric layer. Physical parameters considered are the eddy viscosity and the thermal, water vapor, and ice water eddy diffusivities.

Description: Stratospheric limb radiance profiles versus altitude of closest approach of the line of sight to the Earth's surface have been measured before and after the Mount St. Helens eruptions by means of photographs taken from a Sun-oriented balloon gondola floating above 35 km altitude over France. Preliminary data were reported for flights in October 1979 and in May and June 1980. The radiance integrated along the line of sight as in-situ radiance (R) can be derived taking into account absorption by ozone and air. The onion peeling inversion method was used to derive the vertical radiance (R) profiles respectively. The values of R were determined in the solar azimuth. The solar elevation angles are chosen larger for the backscattering observation than for the forward scattering observation to deal with as similar illumination conditions as possible despite the Earth's sphericity.

Description: Microscopical investigation of volcanic ash collected from ground stations during Mount St. Helens eruptions reveal a distinctive bimodel size distribution with high concentrations of particle ranges at (1) 200-100 microns and (2) 20-0.1 microns. Close examination of individual particles shows that most larger ones are solidified magma particles of porous pumice with numerous gas bubbles in the interior and the smaller ones are all glassy fragments without any detectable gas bubbles. Elemental analysis demonstrates that the fine fragments all have a composition similar to that of the larger pumice particles. Laboratory experiments suggest that the formation of the fine fragments is by bursting of glassy bubbles from a partially solidified surface of a crystallizing molten magma particle. The production of gas bubbles is due to the release of absorbed gases in molten magma particles when solubility decreases during phase transition. Diffusion cloud chamber experiments strongly indicate that sub-micron volcanic fragments are highly hygroscopic and extremely active as cloud condensation nuclei. Ice crystals also are evidently formed on those fragments in a supercooled (-20 C) cloud chamber. It has been reported that charge generation from ocean volcanic eruptions is due to contact of molten lava with sea water. This seems to be insufficient to explain the observed rapid and intense lightning activities over Mount St. Helens eruptions. Therefore, a hypothesis is presented here that highly electrically charged fine solid fragments are ejected by bursting of gas bubbles from the surface of a crystallizing molten magma particles.

Description: The direct solar radiation transmission record at Mauna Loa, dating from 1958 to the present, revealed with remarkable precision the presence of stratospheric aerosol from volcanic activity. This record can be used to quantify the intensity of the stratospheric volcanic aerosol perturbation following a significant eruption in reference to the Agung event in 1963. The Mount St. Helens' stratospheric cloud was first detected by lidar at 18 km over Mauna Loa on 17 July. The atmospheric transmission was seen to decrease slightly after that time, but only a few tenths of 1 percent. Although it is still fairly early to draw a definite conclusion on the ultimate magnitude of the Mount St. Helens stratospheric aerosol from the Mauna Loa results, it can be stated that the stratospheric aerosol optical depth presently observed is comparable with that observed from Fuego which erupted in 1974. At Boulder, Colorado, the atmospheric debris from Mount St. Helens was observed by lidar on a number of occasions. Also, observations of the diffuse, total and direct transmission of solar radiation were made on June 3 and 4. The latter set of observations is useful for deriving information on the scattering properties of the volcanic cloud. The lidar and solar radiation data are presented and some of their special features are discussed.

Description: Samples of stratospheric aerosols collected with U-2 aircraft for several months following the first three major eruptions of Mount St. Helens were analyzed for ash and liquid acid content. Ash grain sizes and compositions vary depending on collection altitude, location within the drifting cloud, and days following their injection. s computers Size distributions of ash particles vary with altitude. Generally small particles are depleted more rapidly at low altitudes (12 km) than at higher altitudes (17-18 km). Although samples collected 1 day after the first eruption of May 18, 1980, were dry, flow marks on the aircraft indicated parts of the cloud contained heavy acid concentrations. Indeed, all other samples obtained within 1 to 4 days after later eruptions (May 25 and June 12, 1980) were covered with copious amounts of liquid acid. Proportions of liquid to ash varied considerably depending on sampling location and cloud age. Because the acid-coated ash globules were large, they rapidly fell from the stratosphere until, by late June 1980, only a residue of acid droplets remained. Size distributions and concentrations of these droplets varied considerably.

Description: Raypaths for decametric wavelength radiation in Jupiter's magnetosphere were calculated. The model-dependent raypaths with the Voyager observations were compared. Characteristics of the source regions and the influence of propagation effects were deduced. A three dimensional ray tracing program was employed to calculate the raypaths. Families of rays were launched at particular angles with respect to the magnetic field lines to generate conical sheets of radiation for various frequencies and various source locations. As the planet's magnetic field rotates, these warped sheets of radiation sweep past the observer, producing signatures in frequency versus time plots. These signatures match some of those found in the Voyager data. The greatest propagation effects occur in and around the source regions in the Io auroral oval.

Description: Nineteen stratospheric samples from the eruption plumes of Mount St. Helens were collected in five flight experiments. The plume samples were collected at various altitudes from 13.1 to 20.7 km by using the Ames cryogenic sampling system on board the NASA U-2 aircraft. The enriched, cryogenically collected samples were analyzed by chromatography. The concentrations of aerosols precursor gases (OCS, SO2, and CS2), CH3Cl, N2O, CF2Cl2, and CFCl3 were measured by gas chromatography. Large enhancement of the mixing ratio of SO2 and moderate enhancement of CS2 and OCS were found in the plume samples compared with similar measurement under pre-volcanic conditions. A fast decay rate of the SO2 mixing ratio in the plume was observed. Measurement of Cl(-), SO2(2-), and NO3(-) by ion chromatography was also carried out on water solutions prepared from the plume samples. The results obtained with this technique imply large mixing ratios of HCl, (NO + NO2 + HNO3), and SO2, in which these constituents are the respective sources of the anions. Measurement of the Rn222 concentration in the plume was made. Other stratospheric constituents in the plume samples, such as H2O, CO2, CH4, and CO, were also observed.

Description: Mount St. Helens erupted somewhat less than 0.5 cu km of magma (dense rock equivalent) on May 18, 1980. The May 18 event was usually violent. As much 35% of the volume of the airfall material fell outside of the 2.5 mm isopach, which encloses about 88,000 sq km. This extraordinary dispersive power was transmitted by an eruption column which reached heights of more than 20 km. There was a lateral blast (or surge) of unusually large dimensions associated with the onset of the eruption. The magma is dacitic in composition and had a low ( 500 ppm) sulfur content. Distal ashes contain much nonmagmatic (lithic) material, but smaller ( 50 microns m) particles are mostly finely divided magmatic dacite. The grain size distributions of the ash are multimodal, frequently with peaks at 90, 25, and 10 microns. The finer populations fell out faster than their terminal velocities as simple particles would suggest. It is inferred that large proportions of the fine ash fell out as composite particles. This condition greatly reduces the atmospheric burden of silicate particles. Some of the unusual aspects (violence, intense surges, multimodal grain size distributions, lithic content of the ashes) of the eruption may be due to its phreatomagmatic character. The hydrothermal system above the magma may have infiltrated the magma body at the onset of the eruption. An "overprint" of the geochemistry of this hydrothermal system on the geochemistry of the magmatic gas system is likely. One important feature is that reduced gas species may be much more abundant than in many eruptions. Another is that fine ash may form aggregates more readily.

Description: Disturbances of the atmosphere at heights of 120 to 40 km by penetration of meteroids of meter and decameter dimensions were examined. Unbiased data on atmospheric penetration of large meteroids was acquired, and their supply of gas and dust components to the middle atmosphere and their connection with the noctilucent clouds were determined.

Description: The goals of map/wind (winter in Northern Europe) are to better understand: (1) the interaction of planetary waves of tropospheric origin; (2) the temporal and spatial development of sudden stratospheric warmings; (3) the temporal and spatial development of mesospheric cooling events in conjunction with stratospheric warmings; (4) the vertical and horizontal transport of minor constituents; (5) the effects on the chemistry of neutral and charged species of the large temperature changes occurring during stratospheric warmings and mesospheric cooling; (6) sources of turbulent energy; (7) the temporal and spatial development of turbulent layers; and (8) the contributions of dynamical processes to the heating and cooling of the mesospheric and turbopause region.

Description: Three general areas of study were identified: stratospheric composition; mesospheric and lower ionospheric structure and composition; and middle atmospheric dynamics. The role of chemical reactions and spectroscope in the study of the middle atmosphere is discussed.

Description: Organizations in the United States which are interested in MAP participation were surveyed. Satellites, rockets, balloons, and ground support systems are listed with available experimentation.

Description: The plans for India's participation in the middle Atmosphere Program are outlined.

Description: Contaminated impact crater formations are pertinent to the study of meteoritic contamination at the Cretaceous-Tertiary boundary and other Ir-enriched layers. Target mixing considerations and volumetric estimates of Rochechouart breccias are presently combined with the geochemistry of both major and siderophile trace elements, to evaluate how the chemistry of the preserved target rock-projectile mixture evolved since deposition. Over 99 percent of the mass of extraterrestrial Ir and Os in preserved formations at Rochechouart is located in suevite-like breccias and impact melts. Hydrothermal alteration and/or weathering are the most likely processes to explain both major and trace element redistribution in Rochechouart formations.

Description: Several hundred topside ionograms were used to study simulated wave-particle interactions in the ionosphere. The study combined the benefits of high-frequency-resolution Alouette 2 analog sounder data with advanced digital graphics techniques. The study shows that the sounder phase can cause significant plasma heating when the plasma parameter is confined to specific ranges. The observations support the Harris instability generation process and the nonlinear Landau damping maintaining process for long-duration diffuse resonances. The observations also suggest that the so-called Q resonances have characteristics which imply that generation processes in a sounder-stimulated plasma turbulence may be involved.

Description: Eight comets were observed with the IUE at various-heliocentric and geocentric distances. Their UV spectra are remarkably similar despite the large differences in the dust to gas ratios. Since all the dominant atomic species (except N) radicals and ions of the coma are detected in this spectral region, the total gaseous output of the nucleus can be estimated. The abundance of the carbon atom-bearing species is still not very well known and there are indications that the CO content of the coma could vary from comet to comet.

Description: The initial phase of the photometry which involved 17 meteor spectra consisting of eight Geminid spectra, six Orionid spectra and three Eta Aquarid spectra is discussed. Among these 17 spectra it is found that the Geminid spectra are of the best quality and are used for the identification of the atomic lines and molecular bands that normally appear on video tape spectra. The data from the Geminid records are used for developing calibration techniques in photometry. The Orionid and Eta Aquarid spectra are chosen for early analysis because of the current interest in all physical and chemical data relating to Comet Halley.

Description: The effects of chemical composition of the lava, physical processes of volcanic formation, and lava flow lengths on the morphology of Earth volcanoes were investigated. Difficulties in investigating volcanic morphology are discussed.

Description: The chemistry and evolution of Titan's atmosphere are reviewed, in light of the scientific findings from the Voyager mission. It is argued that the present N2 atmosphere may be Titan's initial atmosphere, rather than one photochemically derived from an original NH3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH4 is irreversibly converted to less hydrogen-rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of about 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N2 into hot, escaping N atoms to remove about 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar EUV energy deposition in Titan's atmosphere by an order of magnitude, and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region.

Description: Estimates are made showing that, as a consequence of rocket activity in the earth's upper atmosphere in the Shuttle era, average ice nuclei concentrations in the upper atmosphere could increase by a factor of two, and that an aluminum dust layer weighing up to 1000 tons might eventually form in the lower atmosphere. The concentrations of Space Shuttle ice nuclei (SSIN) in the upper troposphere and lower stratosphere were estimated by taking into account the composition of the particles, the extent of surface poisoning, and the size of the particles. Calculated stratospheric size distributions at 20 km with Space Shuttle particulate injection, calculated SSIN concentrations at 10 and 20 km altitude corresponding to different water vapor/ice supersaturations, and predicted SSIN concentrations in the lower stratosphere and upper troposphere are shown.

Description: The first measurements of the production of nitric oxide (NO) by a laboratory discharge in a simulated Venus atmosphere are presented. The average NO yield over a range of energies was found to be 3.7 + or - 0.7 x 10 to the 15th molecules/joule. Simultaneous measurements of carbon monoxide (CO) resulting from the lightning-induced dissociation of carbon dioxide (CO2) indicated a CO yield of about 4 x 10 to the 17th molecules/joule. These measurements suggest that at and below cloud level, a region where solar ultraviolet radiation cannot penetrate, the dissociation of CO2 by lightning may be a significant source of oxygen atoms. Depending on the assumed value for the total energy dissipated by lightning on Venus, the production of NO by lightning may be a significant sink of atmospheric nitrogen over the history of Venus.

Description: (Previously announced in STAR as N82-18106)

Description: The influence of the geographical distribution and the number of the surface stations in the ozone detecting network on changes in global ozone inferred from the surface measurements is investigated by comparison with information obtained from satellite backscattered UV observations on the Nimbus 4 with nearly complete global coverage for the period 1970-1972. Results show that the geographical distribution of the stations does not properly represent different latitudes. While the number of stations in the north temperate zone appears adequate to represent monthly ozone averages to within 0.5% except during the early phase of the Northern Hemisphere spring maximum, the resultant error in the derived change in north temperature zone ozone between 1970-1972 is 0.5%. In the tropical and south temperate zones the smaller number of stations reduces precision, and the ozone averages for use in deriving seasonal variability and trends are uncertain by about 1%. However, in the south temperature zone, the average from the sample may differ as much as 5% in some months from the averages derived from the full set. It is concluded that the resulting uncertainty in the global averages is comparable in size to typical yearly changes.

Description: The current understanding of the manner in which astronomical variations modulate the Martian climate and thereby lead to the occurrence of laminated polar terrain is considered. The seasonal cycles of dust, carbon dioxide and water, and their responses to astronomical variations, are studied. After an assessment of the way in which these cycles presently operate, for which pertinent spacecraft and ground-based observations are extant, attempts to predict how these cycles may differ under conditions of high and low obliquity and eccentricity are discussed. Attention is given not only to those areas in which there is broad agreement, but also to the controversial and speculative. Key questions include the proportion of dust and water ice in the laminae and its variations within individual layers, the relative importance of older laminae and lower-latitude material as sources of new laminae, and the factors responsible for the youth of the laminated terrain.

Description: Photoclinometry is useful for the determination of topography for areas which have a uniform albedo. The technique is applied to early spring Viking images of the Martian north polar cap, taken when the surface was covered by a nearly uniform frost cover. Unlike earlier approaches, the topographic profiling can be used for surfaces with any photometric function, but the strike of the planetary surface relative to the illumination angle must be specified along the profile. The resultant profiles are relatively insensitive to misestimation of the photometric function and slope orientation, but are quite sensitive to the assumed values of the reflectance of an equivalent level surface and the atmospheric opacity (if it is large).

Description: The boundary between the inner and outer parts of Saturn's B ring is located at the theoretical limit of stability of dust grains with large negative charge to mass ratio. A grain inside of this stability limit will move along magnetic field lines and strike Saturn if given a slight velocity component normal to the ring plane. Outside of this marginal stability radius, a perturbed grain merely oscillates back and forth through the ring plane. The theoretical location of the marginal stability radius is at 1.625 Saturn radius. Observations by Pioneer 11 and Voyager 2 in the infared see the boundary as a prominent change in ring brightness at this radius. The occultation of delta-Scorpii by the rings in the ultraviolet seen by Voyager 2 shows about a factor of two change in optical depth beginning very close to this radius.

Description: The effects of the earth's atmosphere on the Thematic Mapper (TM) measurements are studied with two radiative transfer models. A doubling model is used to compute the effective reflectance of the earth-atmosphere system, as measured by the TM for the reflective bands. An emission-transmission model is used to compute the satellite-received radiance for the thermal band. The influences of the aerosol loading, the amount of water vapor, and the solar illumination angle on the effective reflectance are investigated. The effect of varying atmospheric water vapor on the measurements of the thermal band is studied. The scattering and absorption effects on TM bands are compared with those on Multispectral Scanner System (MSS) bands. While the changes in the aerosol loading introduce comparable variation of the effective reflectance for both sensors, the changes in the water vapor amount give less impact on TM4 than MSS7.

Description: Solar ultraviolet flux data obtained within the atmosphere by using Fastie-Ebert double monochromators carried on a balloon-borne gondola and a rocket payload are analyzed. Both the direct and scattered components of the solar ultraviolet flux at wavelengths from 190 to 320 nm are measured at the balloon float altitude of 40 km. The nearly identical spectrometer carried on the rocket flight measures the direct solar flux from 60 to 38 km during a parachute descent. The ozone column content above 40 km and the temperature profile and ozone density below 40 km are deduced using the scattered and direct solar flux components. It is shown that the Nimbus 7 solar flux data are consistent with the present data and with the ozone absorption cross sections of Inn and Tanake (1959). The calculated and measured values of the scattered solar flux are found to agree fairly closely.

Description: The influence of the choice of the Lagrange multiplier on constrained linear inversions is explored, with reference made to applications in inferring the columnar aerosol size distributions from spectral aerosol optical depth measurements. A range of the Lagrange multiplier is examined to find all positive solutions for the solution vector, which represents modifying factors to the assumed form of the size distribution. An iterative method is devised to constrain the calculations to consideration of only positive quantities and a requirement that the regression fit to data be consistent with measurement errors. The determination of the variances and covariances is formulated and applied to existing data sets for optical depth. Variances in the solution are found to be large for particle radii when the information content of the data is small.

Description: Soil fines exposed on the lunar surface accumulate small metallic iron particles and solar wind-derived carbon. In previous work, it has been suggested that an intimate association exists between one particular carbon phase, hydrolysable carbon, and very fine iron droplets, where the carbon is in solid solution in the iron. The earlier hypothesis of a constant carbon in iron concentration across a broad range of droplet sizes is testable by combining hydrolysable carbon determinations with a variety of magnetic measurements sensitive to different droplet diameters. New measurements of ferromagnetic resonance response on density and magnetic separates from size fractions of soil 12023 are interpreted as evidence that hydrolysable carbon is preferentially associated with the larger, magnetically stable single-domain iron particles rather than with the smaller superparamagnetic droplets. For the former, there is a quite uniform ratio of iron to carbon both within a series of separates from a single soil, and among soils of widely varying FeO content.

Description: New line assignments in the spectrum of the stratospheric submillimeter emission, measured with unapodized resolution of 0.0033/cm, have been made. Positive evidence for the presence of symmetric and asymmetric ozone isotopes, water vapor excited to the (010) level, and HCN is given.

Description: During its April 1979 eruption series, Soufriere Volcano produced two major stratospheric plumes that the SAGE (Stratospheric Aerosol and Gas Experiment) satellite system tracked to West Africa and the North Atlantic Ocean. The total mass of these plumes, whose movement and dispersion are in agreement with those deduced from meteorological data and dispersion theory, was less than 0.5 percent of the global stratospheric aerosol burden; no significant temperature or climate perturbation is therefore expected.

Description: At the time of the Soufriere, St. Vincent, volcanic eruption of April 17, 1979, a NASA P-3 aircraft with an uplooking lidar (light detection and ranging) system onboard was airborne 130 kilometers east of the island. Lidar measurements of the fresh volcanic ash were made approximately 2 hours after the eruption, 120 kilometers to the northeast and east. On the evening of April 18, the airborne lidar, on a southerly flight track, detected significant amounts of stratospheric material in layers at 16, 17, 18, and 19.5 kilometers. These data, and measurements to the north on April 19, indicate that the volcanic plume penetrated the stratosphere to an altitude of about 20 kilometers and moved south during the first 48 hours after the eruption.

Description: The radio occultation technique, as applied to Saturn's rings, is developed as a new method for the study of the physical properties of planetary ring systems. The rings are treated as a Doppler-spread radar target composed of an ensemble of discrete scatterers. The mathematical formulation of the received signal as a random-phasor-sum process is carried out following a conventional radar theory approach, providing a convenient starting point for deriving coherent signal parameters. A classical result is rederived for the equivalent refractive index of the medium. The analysis is generalized to include ringlets of arbitrary width and it is shown that when the width is such that two adjacent rays are differentially perturbed in phase, ray bending that causes focusing of the coherent signal may result. The diffuse component is also treated in detail.

Description: Advances in satellite tracking data accuracy and coverage over the past 15 years have led to major improvements in global geopotential models. But the spacial resolution of the gravity field obtained solely from satellite dynamics sensed by tracking data is still of the order of 1000 km. Attention is given to an approach which will provide information regarding the fine structure of the gravity field on the basis of an application of local corrections to the global field. According to this approach, a basic satellite to satellite tracked (SST) range-rate measurement is constructed from the link between a ground station, a geosynchronous satellite (ATS 6), and a near-earth satellite (Apollo or GEOS 3). Attention is given to a mathematical model, the simulation of SST gravity anomaly estimation accuracies, a gravity anomaly estimation from GEOS 3/ATS 6 and Apollo/ATS 6 SST observations, and an evaluation of the mean gravity anomalies determined from SST.

Description: Data on the thermal structure of the nightside middle atmosphere of Venus, from 84 to 137 km altitude, have been obtained from analysis of deceleration measurements from the third Pioneer Venus small probe, the night probe, which entered the atmosphere near the midnight meridian at 27 deg S latitude. Comparison of the midnight sounding with the morning sounding at 31 deg S latitude indicates that the temperature structure is essentially diurnally invariant up to 100 km, above which the nightside structure diverges sharply from the dayside toward lower temperatures. Very large diurnal pressure differences develop above 100 km with dayside pressure ten times that on the nightside at 126 km altitude. This has major implications for upper atmospheric dynamics. The data are compared with the measurements of Keating et al. (1980) above 140 km, with theoretical thermal structure models of Dickinson, and with data obtained by Russian Venera spacecraft below 100 km. Midnight temperatures are approximately 130 K, somewhat warmer than those reported by Keating et al.

Description: Global magnetic component anomaly field maps have been derived from the Magsat vector magnetometer data obtained from November 1979 through May 1980. The amplitude of variations of the components over the maps are between 10 and 15 nT, well above the noise in the data. Averaged data, in 2-by-2 deg blocks, exhibit standard errors of the mean of about 1 nT over most of the X and Z maps, and about 2 nT over most of the Y maps. Errors rise to about twice these amounts near the auroral belts. Most of the anomalies in the component data are consistent with a crustal magnetization model which incorporates dipoles aligned only in the direction of the main field. However, there appear to be some regions which require dipoles aligned in some other direction i.e., remanent magnetization.

Description: Initial results of the Magsat mission are presented, in keeping with the categories of earth core field, the crustal or anomaly field of the earth, and external fields. It is noted that one major advantage of orbital magnetic field surveys is their ability to obtain a global set of magnetic field measurements of uniform precision and accuracy at a single epoch, aiding the derivation of the core field models that are a prerequisite for further data analysis. The ability to isolate fields from crustal sources was unexpected, because of the low amplitudes of such fields by comparison with those of the core and those external to the earth. The most significant external-field finding has been an east-west component variation near the dip equator.

Description: Studies of Birkeland current systems have been conducted primarily with low altitude satellite magnetometer data whereas electrojet current signatures have been usually analyzed with data from ground-based magnetometer chains. However, the Magsat magnetometer data set allows magnetic disturbances due to both field-aligned and electrojet currents to be examined simultaneously. This is mainly due to Magsat's approximately 400 km altitude, thus providing data closer to the electrojet current system than has been previously available from satellite measurements. Of additional importance are the superior accuracy, both in sensitivity and altitude, of the magnetic field measurements obtained by Magsat and last, but not least, the availability of an accurate magnetic field model of the concurrent epoch (based on the Magsat data set) that allows one to obtain a better baseline than previous models. The aforementioned points are emphasized and both Birkeland and electrojet currents have been analyzed in a case study for November 13, 1979.

Description: Transverse magnetic disturbances associated with Birkeland currents have been measured by the Magsat and TRIAD spacecraft, whose orbits were nearly coplanar from November to mid-December, 1979. A comparison of data received when the satellites were over the TRIAD/Chatanika receiving station shows that 75% of magnetic disturbance measurements are similar in shape and magnitude, with TRIAD peak disturbances being on average 7% larger than those of Magsat. This discrepancy is lower than measurement uncertainties due to baselines and calibration. During periods of higher Kp, despite time separations of as much as 45 min, better agreement is found in the large-scale and well-defined field-aligned current signatures.

Description: An analytical method for the analysis of absorption spectra obtained from the interferograms of an interferometer operated in the solar occultation mode, in which an interferogram is smeared with individual interferogram components generated by the passage of rays at different tangent altitudes, is described. The creation of strong sidelobes on absorption lines by the interferogram smearing leads to the recommendation of a strong apodization on the interferogram for the solar occultation experiment. The application of these concepts to the simultaneous retrieval of temperature and pressure from CO2 4.3-micron band stratospheric absorption spectra includes the analysis of the continuum absorptions by the pressure-induced N2 fundamental bands and by far wings of the CO2 v3 band. Agreement is reported between observed and simulated spectra.

Description: The effect of attenuation in precipitation regions of the sea, which must be considered in order to measure the radar backscatter from the ocean with sufficient accuracy to allow determination of the wind vector, can be ascertained from a knowledge of the brightness temperature observed by a microwave radiometer such as the Seasat multifrequency scanning radiometer. Two algorithms relating radiometric measurements and attenuation, and thereby correcting measured scattering coefficient values, were compared with wind vectors reported by surface observers and those determined by the Seasat scatterometer measurements with and without correction for atmospheric attenuation. Although the attenuation correction yields some improvements, it is constrained by both radiometer footprint differences and different scan patterns.

Description: It is found that the difference between the wet tropospheric corrections obtained with the Seasat Multichannel Microwave Radiometer (SMMR) algorithm and corrections based on near-coincident radiosonde meteorological measurements has a standard deviation of 2.79 cm, which is consistent with the independent value for water vapor determination accuracy reported by the SMMR Evaluation Team. Because the difference between the radiosonde corrections and those obtained by means of interpolated surface meteorological data has a standard deviation of 5.73 cm, the SMMR wet tropospheric correction is recommended for investigations sensitive to the wet tropospheric height correction accuracy.

Description: A nominal atmospheric model of Mars is presented, with detailed consideration being given to the various sources of variability in the Martian atmosphere. A basic model for the midlatitude summer is outlined for the northern and southern hemispheres. Attention is given to meteorological variability due to winds, diurnal and seasonal pressure variations, temperature changes, and the effects of dust opacity, particularly on temperature stratification. Viking lander IR thermal mapper data are examined in terms of diurnal and latitudinal temperature variations, and cloud and haze formation and locations are discussed. Mass spectrometry of the atmosphere is used to describe the molecular abundances, and water vapor measurements are reviewed. Finally, radio occultation, UV airglow, and mass spectrometry of the Martian upper atmosphere are investigated, along with the temperature structure of the upper atmosphere.

Description: Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.

Description: No evidence was found for an intrinsic magnetic field, nor for the development of a bow shock wave, as the corotating Saturnian magnetoplasma convected past Titan during the Voyager 1 close encounter of November 12, 1980. The observation of a well-developed, induced bipolar magnetic tail is evidence, however, of a strong electrodynamic interaction. Three thin, current-carrying regions were crossed which correspond to the inbound and outbound tail magnetopause and an imbedded tail neutral sheet. The interaction is unique among those observed to date in the solar system, in that it is intermediate with respect to sonic and Alfvenic Mach numbers by comparison with Titan in the solar wind and Io in the Jovian magnetosphere. The draping of the Saturnian magnetic field around the ionosphere of Titan is suggested by results of the analysis of magnetic field data.

Description: Rapid intensity fluctuations in the optical emission, N2/+/ (4278 A), H-beta (4861 A), and OI (5577 A) have been observed with rocket-borne photometers during a passage through a homogeneous auroral arc. The measurements indicate that relatively weak (2-5%) intensity fluctuations of random nature, with dominant frequencies in the 2-20 Hz range, do exist in the optical emissions of quiet-form auroras. These variations have well-defined averaged spectral characteristics and apparently differ from the strong quasi-periodic type of variations seen during pulsing auroras. It is argued that the observed fluctuations, which are usually composed of weak short-lived microbursts, reflect the temporal and spatial microstructure which apparently exists always within auroral arcs.

Description: The Allan Hills icefield is described by as a limited icefield that has large concentrations of meteorites. The meteorites appear to be concentrated on the lower limb of an ice monocline with other finds scattered throughout the field. In an attempt to understand the mechanisms of meteorite concentration, a triangulation chain was established across the icefield. This chain is composed of 20 stations, two of which are on bedrock, and extends westward from the Allan Hills a distance of 15 kilometers. The triangulation chain and its relationship to the meteorite concentrations is shown.

Description: The chemistry of Jupiter's atmosphere is reviewed. The various molecules that were discovered on Jupiter are summarized. The compounds: methane, ammonia water, ethane, acetylene, carbon monoxide, phosphine, and germane.

Description: The spectroscopy of the species H2O, H2O2, and HO2 are discussed. Their vibration rotation transitions are emphasized, but the pure rotational transitions in the vibrational ground state of H2O are also considered since they contribute to opacity in the middle infrared region.

Description: A review of recent progress in the theory of collisional line broadening, particularly the impact of recent advances in collision dynamics calculations is presented. Some new approaches to the interpretation of experimentally measured linewidths and their impact on planetary atmosphere research are discussed. Experimental techniques which may have some advantage in providing pressure broadening data at very low temperatures are also mentioned.

Description: Examples of the role which molecular spectroscopy played in the interpretation of the thermal emission spectra of Earth, Mars, and Jupiter are given. Some advantages of molecular spectroscopy from a spacecraft passing close to a planet, or from an orbiter, over ground based techniques are discussed. Specifically the possibility of obtaining spectra over a wide spectral range (1) without the obscuring effect of Earth's atmosphere, (2) at much higher spatial resolution, and (3) from directions and with phase angles inaccessible from Earth.

Description: A semiempirical physical model of the Jovian subnebula was developed by analogy with the primitive solar nebula itself. The chemical aspects of this model are developed according to the principles developed in the study of the thermochemistry and gas kinetic behavior of the solar nebula, but with important modifications to take into account the higher pressures and densities in the Jovian subnebula. The bulk compositions and densities of the inner satellites of Jupiter are calculated. It is proposed that Europa differs from Io chiefly in that in has suffered a less severe thermal history. The general features of this model are applicable with minor modification to the systems of Saturn and Uranus.

Description: The experimental data and theoretical work on the 7.7 micron band of methane are reviewed. This band is particularly relevant in studies of the atmospheres of Jupiter, Saturn and the other outer planets. Methane spectra taken from the infrared spectrometer (IRIS) aboard Voyager, and a temperature profile derived by inverting those data, both for hydrogen and methane are presented.

Description: Measurements were made of the aerosol size, height and geographical distribution, their composition and optical properties, and their temporal variation with season and following large volcanic eruptions. Sulfur-bearing gases were measured in situ in the stratosphere, and studied of the chemical and physical processes which control gas-to-particle conversion were carried out in the laboratory.

Description: The Instruments are divided into two groups, ground based instruments and satellite-borne instruments. The ground based instruments include a Dobson ozone spectrophotometer, a filter ozonometer, and ozonesondes. The satellite-borne instruments include: a backscatter ultraviolet spectrometer, a high resolution infrared radiation sounder, a infrared interferometer spectrometer, a limb radiance inversion radiometer, and multichannel filter radiometer. A list of investigations using stratospheric satellite data is presented.

Description: The present state of knowledge concerning the absolute magnitude and temporal variability of the solar spectral irradiance is outlined with emphasis on wavelengths relevant to the mesosphere and stratosphere. Reference spectra for the wavelength region 175 to 850 nm are presented including estimates for solar maximum and solar minimum conditions. Values for the Lyman alpha emission are given separately.

Description: A compilation of rate constant data for use in stratospheric modeling is presented. The tabulations are divided into two categories: bimolecular and termolecular. Explanations are given for anomalous pressure and temperature dependences.

Description: Tropospheric and stratospheric source gases and their distribution are reported. A comparison of measurements and model calculations for stratospheric gases is presented.

Description: The capability for obtaining four-dimensional data on stratospheric structure, dynamics, and zone is discussed. Progress in the development of multidimensional models of the stratosphere is reported. The discussion of multidimensional aspects of the stratosphere is divided into four major sections: observations, analysis and interpretation, modeling, and transport of trace species.

Description: Temperatures in the sensible regions of the atmospheres of the outer planets are quite cold. The temperature structures for Jupiter, Saturn, Uranus and Neptune, derived from the equilibrium models are presented in preparation. The vertical temperature profiles for Jupiter and Saturn, the molecular spectroscopic data which form the basis for this type of analysis, and the problems involved with these models for molecular absorption and with the recovery technique in general, are discussed. Results for Jupiter and Saturn from the Pioneer and Voyager infrared experiments are also presented.

Description: Measurements were made of the exact shape of CO2 absorption lines in Mars and Venus to determine the vertical pressure temperature structure using high resolution heterodyne spectroscopy. Accurate measurements of absolute wind velocities in both the mesosphere and stratosphere of Venus were made from Doppler shifts of narrow CO2 lines, and searches were made for minor molecular species of interest in modeling the stratospheric photochemistry for Mars and Venus.

Description: The similarities between the atmospheres of Earth, Venus, and Mars are discussed. The following species are highlighted: NOx, HOx, and COx. The concentrations of the species were examined for all three planets.

Description: About 97% of the Venusian atmosphere is CO2, with the balance comprised of various trace constituents. Species other than CO2 that are found in Venus' atmosphere or are being sought are discussed. The problems connected with the spectrum of CO2 itself are highlighted.

Description: Possibly important sources of infrared opacity in the Venusian atmosphere was identified. It is shown that which is the major atmospheric constituent comprising about 97 percent of the atmosphere, is the dominant infrared opacity source. Not shown is N2 which comprises about 3 percent of the atmosphere. The mixing ratio of water vapor varies considerably with altitude but falls in the range of about 20 to 200 parts per million (ppm). The mixing ratio of SO2 falls in the range of 100-200 ppm. This number is about 5000 times larger than estimates obtained earlier via Earth-based observations. The abundance of some of the other minor constituents is also shown.

Description: The catalog includes molecules of interest in the interstellar medium, in planetary atmospheres and in the Earth's atmosphere. Different units than those on the AFGL tape are used. For citing line frequencies in the microwave region. Either the experimental errors or the propagation of errors from the fit are included on the tape. This gives an estimate of how accurate the frequencies are. The intensity units are defined as follows: the logarithm of the intensity unit is the cross section times the frequency in MHz. This is essentially the same unit as on the AFGL tape, but contains fewer factors of the speed of light. The catalog is available to the scientific community either as a tape or on microfiche (filmed in frequency sorted and molecule sorted format).

Description: The region of planetary atmospheres upward of 1 millimeter is considered. The applications of this region, how microwave, millimeter, and submillimeter spectra (the so called rotational spectra) can fruitfully interact with infrared spectral measurements are described. Both the rotational bands and vibrational bands of molecules are considered. A typical rotational absorption coefficient for a linear molecule in a low J state with a dipole moment of about one Debye is plotted and evaluated. A vibrational case was chosen similarly: the transition dipole moment used for the vibrational case is typical of CO at the peak of its rotational distribution. Information on high altitude parameters that often cannot be obtained from higher frequency spectra, which can be provided by rotational spectra is discussed.

Description: Several Venus cloud condensates, including A12C16 as well as halides, oxides and sulfides of arsenic and antimony, are assessed for their thermodynamic and geochemical plausibility. Aluminum chloride can confidently be ruled out, and condensation of arsenic sulfides on the surface will cause arsenic compounds to be too rare to produce the observed clouds. Antimony may conceivably be sufficiently volatile, but the expected molecular form is gaseous SbS, not the chloride. Arsenic and antimony compounds in the atmosphere will be regulated at very low levels by sulfide precipitation, irrespective of the planetary inventory of As and Sb. Thus the arguments for a volatile-deficient origin for Venus based on the depletion of water and mercury (relative to Earth) cannot be tested by a search for atmospheric arsenic or antimony.

Description: A pure CH4 atmosphere would rapidly escape from Pluto. For such an atmosphere, even CH4 frosts on Pluto's surface would completely sublimate on a time scale short compared to Pluto's life. Observations of CH4 therefore imply that its atmosphere must also contain another gas in significant quantity.

Description: Near-infrared spectrophotometry of Triton and Pluto at low spectral resolution and signal precision reveals methane absorption on both bodies. The absorption on Triton is probably gaseous CH4, while that on Pluto is a combination of gas and ice of CH4. Using present detectors and telescopes, spectra of Triton and Pluto can be obtained which are 5-10 times better than those published, but such data will not be sufficient to distinguish between gaseous and solid methane on these bodies.

Description: Developments in the spectral analysis of ammonia are highlighted. Experimental techniques of diode laser spectroscopy were reviewed. It is shown that diode lasers give much better spectral resolution than even Fourier transform spectroscopy.

Description: Infrared spectra of methane and ammonia are taken. The methane data base accumulated is described. The spectral region from 4,000 to 6,500 cm is covered at moderate resolution (0.15 cm), working at three temperatures (118, 191, and 272K), and with the (pressure - pathlength) product ranging over a factor of a thousand. Methane spectra broadened by hydrogen and helium have also been taken. Normalized spectra are stored on magnetic tapes, at a resolution slightly better than 0.25 cm.

Description: The 3.5 micron region of methane was analyzed. The positions and strengths of approximately 9000 absorption lines in the region from 2400 to 3200 cm were measured. Spectra were obtained at a resolution of 0.1 cm using the Fourier transform spectrometer and at 0.02 cm resolution using the four passed grating spectrometer. The analysis of the 3.5 micron region required the use of spectra of CH4 in other regions, therefore the methane spectrum from 1200 to 4700 cm is indicated. The method used for the compilation of line lists is demonstrated.

Description: Spectroscopic work in acetylene, ethylene and ethane, are of particular interest since the Voyager IRIS observations of Jupiter. Acetylene and ethane but not ethylene were observed in the Jovian spectrum. Two fundamental bands of the observed gases are used to determine the spatial distribution of these hydrocarbons on Jupiter and to illuminate the photochemistry of these species. The 100 to 1000 cm region is discussed and selected examples of current laboratory work are given.

Description: The collision induced spectra of HD and H2 are studied. Their application to the study of planetary (and planetary satellite) atmospheres is investigated.

Description: The payloads, mission, and performance characteristics of the Galileo probe, to be launched by a Centaur boost from the Orbiter in 1985, are described. The Galileo is intended to determine the chemical compositions and physical states of the Jovian atmosphere and of the Jovian satellites, and to investigate the structure and dynamics of the Jovian magnetosphere. The orbiting part of the spacecraft will carry a near-IR mapping spectrometer, a photopolarimeter radiometer, a solid state imaging camera, a UV spectrometer, and five fields and particles instruments. A probe will be dropped for parachute descent into the Jovian atmosphere, carrying an atmospheric structure instrument, a neutral mass spectrometer, a He abundance interferometer, a nephelometer, and a radiometer. A retrorocket burn during the encounter with Jupiter will place the Galileo in an orbit calculated to pass close to all the Jovian moons over 12 orbits spanning 20 mos.

Description: The development and testing of two techniques for determination of apparent and rim crest volumes of impact and explosion craters are described. The accuracy of the techniques, their relative costs, and the time required to complete the volume calculations are compared.

Description: The use of a time domain reflectometer (TDR) for planetary exploration is considered. Determination of the apparent dielectric constant and hence, the volumetric water content of frozen and unfrozen soils using the TDR is described. Earth-based tests were performed on a New York state sandy soil and a Wyoming Bentonite. Use of both a cylindrical coaxial transmission line and a parallel transmission line as probes was evaluated. The water content of the soils was varied and the apparent dielectric constant measured in both frozen and unfrozen states. Advantages and disadvantages of the technique are discussed.

Description: Ephemerides computed from asteroid orbits and the 48 in. Palomar Schmidt log book were used to determine the number of objects that might have appeared in photographic plates taken in years other than 1979. Thus, new positions would be calculated aiding the refinement of the preliminary orbits of these asteroids, eventually leading to their permanent number of designation. From these 109 asteroids, 35 were potentially on 97 plates taken at Palomar between 1976 and 1981. Unfortunately, only 27 plates were readily available and the number of tentative asteroids was reduced to 10. Upon examination of the film, only six objects were found to be in the region predicted by their ephemerides. The position of these objects was measured to the one arcsecond precision.

Description: The sequence of events is described that occurred from the time that the ancient lunar crust solidified (about 4.4. billion years ago) and anorthositic high lands dominated the surface, until the global contraction (cooling) that began around 3.3 billion years ago when late stage basalts were emplaced at basin margins where fractures penetrated to subsurface tensional zones. The lunar intercrater plains may be linked with early KREEP volcanism, the LKFM basalt source region, and the first stages of mare volcanism. Ages of KREEP bracket the possible ages of the pre-Imbrian plains, and overlap the initial stages of mare basalt emplacement. Both plains are extruded under the same tensional tectonic regime.

Description: A steady state analysis has been made of the sources and sinks of sulfur in the remote marine atmosphere and of the steady state exhanges of SO2 and sulfate between the sea, boundary layer, and free troposphere. Two situations were examined: an area of high biological productivity (Gulf of Guinea) and an area of low productivity (tropical Atlantic). The results of the analysis suggest that about one-third of the background concentrations of SO2 and excess sulfate observed in the remote marine atmosphere mixes in from the free troposphere, with the balance, about 100 micrograms S/sq m per day, attributed to the local oxidation of reduced sulfur-bearing precursors in the boundary layer.

Description: (Previously announced in STAR as N81-31721)

Description: Data on the composition, thermal structure, and Lyman-alpha dayglow of Saturn, when analyzed in conjunction with photochemical models of the hydrocarbons and the atomic hydrogen production, yield the homopause value of the eddy diffusion coefficient to be approximately 100 million/sq cm per sec. The equatorial value of the eddy diffusion coefficient at the homopause of Saturn is thus found to be approximately 100 times greater than on Jupiter. The mesosphere (and presumably, troposphere) of Saturn appears to be considerably more turbulent than the upper atmosphere of Jupiter.

Description: The hypothesized responsibility of internal gravity wave breaking for upper atmosphere turbulence generation and the control of homopause level number density is considered. The lowest-order, equatorially trapped, westward-propagating diurnal tidal mode is the primary cause of the necessary turbulence on earth, while the lower-order, westward-propagating semidiurnal modes are the primary cause on Mars. The frequencies and vertical wavenumbers of the responsible modes determine the eddy diffusion coefficients, while energy density is only indirectly involved, by determining which modes can break. The breaking potential of tidal modes can be assessed by a general scale relationship between tidal heating and velocity amplitude which is presently employed as the basis for the suggestion that the number density of the Martian homopause is likely to have been stable over much of geologic time.

Description: A theory explaining Jupiter's banded whistler emission, in particular low-frequency hiss and chorus, is proposed. It is shown that superthermal electrons described by a kappa distribution function cause whistler instability below one-third of the electron gyrofrequency, whereas a two temperature Maxwellian leads to a band of unstable growing modes just below one-half of the electron gyrofrequency. A superposition of both yields almost exactly the structure of whistler mode hiss and chorus detected by the Voyager 1 and 2 plasma wave instrument.

Description: A large-amplitude traveling ionospheric disturbance (TID) was detected over Owens Valley, California, on May 18, 1980, by a highly sensitive very long baseline interferometry (VLBI) radio astronomy experiment. This TID is interpreted as the response of the ionosphere to a gravity wave excited in the neutral atmosphere by the explosion of Mount St. Helens that took place at 1532 UT on that day. A model, invoking the point-excitation of internal gravity waves in an isothermal atmosphere, which fits observations of the TID at several other stations, leads to identification of the features observed in the VLBI data. Small-amplitude higher-frequency changes in the ionosphere were detected for several hours after the passage of the large-amplitude Mount St. Helens TID, but it is not clear whether these were excited by the passage of the gravity wave or were background fluctuations.

Description: (Previously announced in STAR as N82-20718)

Description: Independent measurements of Jovian cloud motions confirm previously published results on the general structure of Jupiter's zonal mean circulation. The new results are based on Voyager 2 images and measurement techniques which are different from those used in previous studies. The latitudes of the zonal jets agree with previous results, but there are some differences in the measured speed of the jets which exceed uncertainty estimates. These differences may be due to differences in sampling strategies. The structure of the zonal mean meridional velocity profile has still not been clearly resolved: mean meridional velocities generally differ from zero by no more than their estimated uncertainty. An analysis of successive measurements of the same cloud targets shows that most of the variance of individual velocity measurements is due to true variability of the winds.

Description: Observations of the surface of Venus, carried out by the Pioneer Venus radar mapper at a wavelength of 17 centimeters, reveal a global mean reflectivity at normal incidence of 0.13 + or - 0.03. Over the surface, variations from a low of 0.03 + or - 0.01 to a high of 0.4 + or - 0.1 are found, with Theia Mons, previously identified as possibly volcanic, showing a value of 0.28 + or - 0.07. Regions of high reflectivity may consist of rocks with substantial inclusions of highly conductive sulfides.

Description: Remote sensing of solar system bodies using the JPL Goldstone facility and the radio telescope at Arecibo to characterize the surfaces of the objects is described in terms of present and planned studies. Moon observations proceed at wavelengths from 8.6 mm to 20 m, and are nominally in the centimeter range. Cross sections available from the radar data and apparatus are discussed, noting the practice of using backscattered signals to define the shape of terrain. A review is presented of polarization properties models of the moon's surface, and the design of an experiment using a spacecraft with bistatic radar to determine the dielectric constant of the moon's surface is outlined. Radar is noted to have been used to characterize the rotation period of Mercury, the absorption profile and the topography of Venus, and aided in choosing a landing site for the Viking spacecraft. The existence of higher-than-expected polarization near the Galilean satellites is mentioned as an unexplained phenomenon.

Description: Approximately six years of global ozone monthly mean data from the Nimbus 4 BUV instrument are compared with monthly values of solar activity using 10.7-cm flux, F(10.7), as a parameter. Several techniques are explored in calculating the correlation between the two data sets, and all are found to yield relatively high correlations, ranging from R = 0.68 for 'raw' monthly means to 0.94 using a six-month running mean for each data set. It is shown, however, that the bulk of the correlation derives from the long-term decreasing trends in both data sets. When the long-term trends are removed, a cross-correlation analysis produces a maximum with no phase shift or with the ozone variations leading the solar variations by one month, thereby reducing the likelihood of a cause and effect relationship on time scales of this order. In view of the current uncertainty in the long-term stability of the BUV instrument and the resulting uncertainty in any long-term trend derived from its data, it is considered unrealistic to draw firm conclusions about a solar cycle influence on total ozone from this satellite data set.

Description: A zonally averaged time-dependent primitive equation model is used to simulate the dispersion of both a carbon 14 injection and the volcanic aerosol from the 1974 Fuego eruption. It is noted that both injections occurred at low latitudes to midlatitudes in the Northern Hemisphere. The eddy flux terms, which account for the major portion of the transport in the lower stratosphere of this model, are specified in a manner similar to that of Harwood and Pyle (1975). Comparisons with data underline the ability of the model to simulate the vertical character of the tracer while maintaining reasonable meridional transport times. For the aerosol study, the simulated 1/e decay time at 37 deg N and for the 16- to 21-km altitude region is 9 months, whereas lidar measurements at the same latitude give a decay time of 8 months. The simulated vertical width at half-maximum for the aerosol tracer at 37 deg N and 19 deg N and for 6 months after the event possesses values of 5.0 km and 3.6 km, respectively, whereas the observed lidar values are 4.4 km and 3.0 km, respectively. The tracer transport to the Southern Hemisphere also is in qualitative agreement with the limited data that are available.

Description: Magnetic perturbations observed by the TRIAD magnetometer within two hours of an AE-C spacecraft pass provide field-aligned current data, from the same local time in the northern hemisphere, for a study of the polar cusp. The AE-C spinning mode has allowed the use of the Z-axis magnetometer for Birkeland current observations, in conjunction with particle and drift measurements. The average B(z) were found to be 1.9 nT and -1.1 nT during the first two hourly intervals on January 15, 1977. Measurements from the low energy electron experiment revealed intense fluxes of soft, cusp-like 100 eV Maxwellian electrons throughout the prenoon polar cap. The upward directed current can be identified as the dominant cusp current appropriate for B(y) values lower than zero, while the downward directed current, which has the appropriate sign of a dayside region 1 current, is observed to lie entirely within a westerly, antisunward-convecting plasma.

Description: The odd nitrogen (NOx) abundance of the high latitude mesosphere exhibits a large variability in response to energetic particle precipitation. Model calculations for a very large particle event predict increases in the NOx mixing ratio that can exceed a factor of ten over time periods of the order of one week in the summer hemisphere. A more typical sized event can still lead to an enhancement of a factor of three in summer. Relative changes in the winter hemisphere are less dramatic due to a larger ambient NOx mixing ratio predicted here. However, a factor of two increase in NOx is possible during a very large event. Owing to the large variability, it is difficult to define a physically meaningful mean state profile in the high latitude mesosphere. Rather, the NOx abundance likely displays an erratic behavior which is correlated with the level of solar activity.

Description: An analysis of the magnetic field of Saturn is presented which takes into account both the Voyager 1 and 2 vector magnetic field observations. The analysis is based on the traditional spherical harmonic expansion of a scale potential to derive the magnetic field within 8 Saturn radii. A third-order zonal harmonic model fitted to Voyager 1 and 2 observations is found to be capable of predicting the magnetic field characteristics at one encounter based on those observed at another, unlike models including dipole and quadrupole terms only. The third-order model is noted to lead to significantly enhanced polar surface field intensities with respect to dipole models, and probably represents the axisymmetric part of a complex dynamo field.

Description: From a selection Voyager IRIS spectra corresponding to cloud-free areas of Jupiter, the CH4/H2 volume ratio in the atmosphere of this planet has been determined to be equal to 0.00195 + or - 0.00022, which corresponds to 2.07 + or - 0.24 times the solar value of Lambert (C/H = 0.00047). The estimate of errors includes both instrument noise and systematic uncertainties. Implications of this result for the formation and evolution of Jupiter are discussed.

Description: (Previously announced in STAR as N82-14038)