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Infrared solar spectra were obtained from the ground at McMurdo, Antarctica, during September and October 1987. Absorption features due to HNO3 and HCl have been analyzed to determine the vertical column content of these compounds for the days when observations were made. The variation of these column amounts with time is presented and discussed.
The concentrations and the time development of chlorine and nitrogen trace gases in the Antarctic stratosphere before, during, and after the Airborne Antractic Ozone Experiment (AAOE) were simulated using photochemical models of the Antractic stratosphere during winter/spring. The initial conditions in the calculations were constrained using observations by the AAOE instrument. The comparison of calculated results with the AAOE measurements of HCl and ClO suggest that heterogeneous chemistry was maintained throughout the month of September 1987.
A photochemical model consisting of 40 species and 107 reactions is integrated along 80-day air parcel trajectories calculated in the lower stratosphere for the springtime Antarctic. For the trajectory starting at 58 deg S, which may be regarded as outside the circumpolar vortex, only a small change in O3 occurs in the model. In contrast, for the air parcel starting in the vortex at 74 deg S, the O3 concentration is reduced by 93 percent during the 80 days from the beginning of August to late October. The model results for several species are compared with measurements from the Airborne Antarctic Ozone Experiment and, in general, good agreement is obtained. In the model, the dentrification of the air parcels in polar stratospheric clouds increases the amount of chlorine present in active form. Heterogeneous reactions maintain high active chlorine which destroys O3 via the formation of the ClO dimer. Results of calculations with reduced concentrations of inorganic chlorine show considerably reduced O3 destruction rates and compare favorably with the behavior of total O3 since the late 1970s. The remaining major uncertainties in the photochemical aspects of the Antarctic ozone hole are highlighted.
The effect of transport on the springtime decline in ozone in the southern polar vortex was investiated using data on long-lived gas tracers (N2O, CH4, CCl4, CH3CCl3, CO, CFC-11, CFC-12, and CFC-113) obtained by the ER-2 aircraft in the period between August 23 and September 22 during the Airborne Antarctic Ozone Experiment. It was found that, while the concentrations of long-lived trace gases remained relatively constant for fixed potential temperature and latitude, the ozone mixing ratio over the same period declined by more than 50 percent inside the polar vortex near 18-km altitude. These data indicate a substantial photochemical sink of ozone. The evidence of the zero or negative time tendencies for long-lived trace gases and the meridional and vertical gradients of ozone imply that transport is supplying ozone to the polar region during springtime.
The likely photodissociation pathways of chlorine peroxide are examined. Reasoning by analogy between hydrogen peroxide and chlorine peroxide, it is shown that photodissociation of chlorine peroxide at wavelengths longer than 250 nm is not likely to give chlorine atoms as a primary product. Reasoning by analogy with molecules whose visible spectra are known, it is concluded that chlorine peroxide is also likely to photodissociate in the visible to give ClO radicals as primary products.
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The first experiment of the Stratosphere-Troposphere Exchange Project to identify modes of transport during large-scale cyclogenesis is reviewed. The U-2 aircraft instrument payload is described and the flight paths are shown in relation to their meteorological situations. The procedures used to predict large-scale cyclogenesis and associated tropopause folding and to direct the aircraft are reviewed.
Three papers are presented on the following topics: (1) a cerebellar-model associative memory as a generalized random-access memory; (2) theories of the cerebellum - two early models of associative memory; and (3) intelligent network management and functional cerebellum synthesis.
A one-day investigation of the atmospheric boundary layer (ABL) is reported in which an aircraft monitors the temporal and spatial variations of heat and moisture turbulent-flux divergences. Incoming solar radiation is similar over natural prairie land and agriculturally developed land although the heat and moisture values show significant differences over the surfaces. Other temporal variations are noted which demonstrate that ABL transport of sensible and latent heat is affected by complex variables even under simple synoptic conditions.
The symposium presented issues involved in the development of scheduling systems that can deal with resource and time limitations. To qualify, a system must be implemented and tested to some degree on non-trivial problems (ideally, on real-world problems). However, a system need not be fully deployed to qualify. Systems that schedule actions in terms of metric time constraints typically represent and reason about an external numeric clock or calendar and can be contrasted with those systems that represent time purely symbolically. The following topics are discussed: integrating planning and scheduling; integrating symbolic goals and numerical utilities; managing uncertainty; incremental rescheduling; managing limited computation time; anytime scheduling and planning algorithms, systems; dependency analysis and schedule reuse; management of schedule and plan execution; and incorporation of discrete event techniques.
The Dirac oscillator is a relativistic generalization of the quantum harmonic oscillator. In particular, the square of the Hamiltonian for the Dirac oscillator yields the Klein-Gordon equation with a potential of the form: (ar(sub 2) + b(L x S)), where a and b are constants. To obtain the Dirac oscillator, a 'minimal substitution' is made in the Dirac equation, where the ordinary derivative is replaced with a covariant derivative. However, an unusual feature of the covariant derivative in this case is that the potential is a non-trivial element of the Clifford algebra. A theory which naturally gives rise to gage potentials which are non-trivial elements of the Clifford algebra is that based on local automorphism invariance. An exact solution of the automorphism gage field equations which reproduces both the potential term and the mass term of the Dirac oscillator is presented.
The present conference discusses topics in orbit determination, tethered satellite systems, celestial mechanics, guidance optimization, flexible body dynamics and control, attitude dynamics and control, Mars mission analyses, earth-orbiting mission analysis/debris, space probe mission analyses, and orbital computation numerical analyses. Attention is given to electrodynamic forces for control of tethered satellite systems, orbiting debris threats to asteroid flyby missions, launch velocity requirements for interceptors of short range ballistic missiles, transfers between libration-point orbits in the elliptic restricted problem, minimum fuel spacecraft reorientation, orbital guidance for hitting a fixed point at maximum speed, efficient computation of satellite visibility periods, orbit decay and reentry prediction for space debris, and the determination of satellite close approaches.
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Experimental data are presented on the variation of the modulus of rigidity in the temperature range -20 to +50 degrees C. of a number of metals which are of possible use for elastic elements for aircraft and other instruments. The methods of the torsional pendulum was used to determine the modulus of rigidity and its temperature coefficient for aluminum, duralumin, monel metal, brass, phosphor bronze, coin silver, nickel silver, three high carbon steels, and three alloy steels. It was observed that tensile stress affected the values of the modulus by amounts of 1 per cent or less.
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