Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

Flight Center, USA; Moore, T. E., NASA Marshall Space Flight Center, USA; [2000]; 1p; In English; 1st; 1st S-RAMP Conference,
4 Oct. 2000, Sapporo, Japan; No Copyright; Avail: Issuing Activity; Abstract Only
We will present reported observations of up- and down-flows of topside ionospheric thermal plasmas from multiple near-simultaneous
tracks through the high-latitude topside ionosphere. From several Southern polar passes, it has been possible to
construct plots of field-aligned flows of O+ observed by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft
near 5000 km altitude together with vertical ion flow observations from one or more DMSP spacecraft near 800 km altitude. We
will also involve simulations from our Dynamic Fluid-Kinetic(DyFK) modeling of polar plasma transport and display resulting
altitude profiles of ion parallel velocities and densities, and overlay those profiles with the ”conjunction” measurements by
DMSP(800 km) and POLAR(approx. 5000 km altitude). We also will present simultaneous observations of POLAR auroral UVI
images with field-aligned flows.
Author
Satellite Observation; Thermal Plasmas; Auroras; Ionospheres
20000067657 Texas A&M Univ., Dept. of Atmospheric Sciences, College Station, TX USA
Transport and Mixing in the Stratosphere and Troposphere
Bowman, Kenneth P., Texas A&M Univ., USA; [2000]; 3p; In English
Contract(s)/Grant(s): NAG1-1896; No Copyright; Avail: CASI; A01, Hardcopy; A01, Microfiche
Long-term changes in the composition of the atmosphere are known to have significant effects on atmospheric chemistry and
stratospheric ozone. Increasing levels of greenhouse gases have the potential to change the global climate in the middle and upper
atmospheres, as well as in the troposphere. Volcanic eruptions, El Nino events, and other natural variations can also cause changes
in atmospheric composition and climate. Whether the causes are natural or manmade, changes in the global climate system can
have impacts on human society. In order to understand and predict the consequences of these changes, and of control measures
such as the Montreal Protocol, it is necessary to understand the complex interactions between radiation, chemistry, and dynamics
in the atmosphere. Much of the uncertainty in our understanding of atmospheric processes comes from an incomplete understanding
of atmospheric transport. A complete and self-consistent model of transport requires not only an understanding of trace-species
transport, but also the transport of dynamically active quantities such as heat and potential vorticity. Therefore, the goal of
the proposed research is to better understand large-scale transport and mixing processes in the middle atmosphere and troposphere.
Author
Atmospheric Composition; Upper Atmosphere; Stratosphere; Troposphere; Atmospheric Chemistry; Climatology
20000067672 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA USA
Antarctic Rebound and the Time-Dependence of the Earth’s Shape
Ivins, Erik R., Jet Propulsion Lab., California Inst. of Tech., USA; James, Thomas S., Geological Survey of Canada, Canada;
[2000]; 1p; In English; No Copyright; Avail: Issuing Activity; Abstract Only
Great strides have been made during the past 30 years in refining models of the last global glaciation. The refinements draw
upon a vastly expanded relative sea level and sedimentary core record. Furthermore, we now possess a sharpened understanding
of the mechanisms that drive climate changes associated with deglaciation. Some 15 years ago, using only 5.5 years of ranging
data, analyses of the drift in LAGEOS I node acceleration was used to infer that postglacial rebound was responsible for a secular
change in the Earth’s ellipsoidal shape (Yoder et al., .1983]. Today there exists a wealth of geodynamics satellite orbit data that
constrain the secular time-dependence of the Earth’s shape and low order gravity field, which includes mass redistribution from
present-day glacier and great ice sheet imbalance and from postglacial rebound. We have shown that an unambiguous determination
of the secular variation in the Earth’s pear shaped harmonic (l = 3, m = 0) might provide information that bears on the presentday
mass balance of Antarctica. This issue is revisited in light of new constraints on glacial loading during the late-Pleistocene
and Holocene. An especially critical issue for the interpretation of secular odd degree zonal harmonics, l = 3 to 7, is the timing
and magnitude of the deglaciation of Antarctica from Last Glacial Maximum. We explore ways in which the recovery of secular
variation in both zonal and non-zonal harmonics for l = 2 through 7 can improve constraints on both rebound and present-day ice
sheet balance.
Author
Glaciers; Secular Variations; Time Dependence; Climate Change; Glaciology; Zonal Harmonics
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