Intercomparison and calibration of wind and wave measurements at various frequencies

Radars are increasingly being used for determinations of the small-scale wave and turbulence fields of the atmosphere. It is important to understand as fully as possible the likely sources of error or bias in radar velocity determinations. This is especially true for the determination of wave and turbulence parameters which often rely on the measurement of first or second order deviations from the prevailing wind and therefore require better precision and time resolution than is usually required for measurements of the mean winds alone. The intercomparison of velocity measurements made with different techniques (e.g., radar and balloon) can be expected to help determine not only the relative effectiveness of the different methods, but also the degree of reliability

The Adelaide MF partial-reflection radar and VHF ST radar

The microwave frequency (MF) partial-reflection radar ran continuously since November 1983, with data being analyzed in real time. The spaced antenna technique was used routinely to produce a climatology of the mean circulation, atmospheric tides, and gravity waves. Since the beginning of 1985, the system was also used as a Doppler radar to measure the spectral widths of the mesospheric echoes. This has enabled the turbulence dissipation rates to be determined. The Stratosphere-Troposphere (ST) radar was operated in the spaced antenna mode to measure winds in November 1984, in conjunction with a cooperative campaign to study the propagation of cold fronts across SE Australia. Observations were also performed to study the structure of the more intense and deeper cold fronts, which occur in late winter

Mesospheric gravity-wave climatology at Adelaide

The MF Adelaide partial-reflection radar has been operating continuously since November 1983. This has enabled a climatology of gravity-wave activity to be constructed for the mesosphere. The data have been analyzed for a medium-period range of 1 to 8 hr. and a longer period range between 8 and 24 hr. covering the inertio-period waves. The tidal motions have been filtered out prior to analysis. For the data analyses so far (Nov. 1983 to Dec. 1984), a number of interesting features emerged. Firstly, the wave activity at heights above 80 km shows a small seimannual variation with season with the activity being strongest in summer and winter. At heights below 80 km however, there is a similar but more marked variation with the weakest amplitudes occurring at the time of the changeovers in the prevailing circulation. If breaking gravity waves are responsible for much of the turbulence in the mesosphere, then the periods March to April and September to October might also be expected to be periods of weak turbulence. The wave field appears to be partially polarized. The meridional amplitudes are larger than the zonal amplitudes, especially in water. It is found that the degree of polarization is about 15% in summer and 30% in winter. The polarized component is found to propagate in the opposite direction to the background flow in the stratosphere, which suggests that the polarization arises through directional filtering of the waves as they propagate up from below

Multiple port pressure scanner valve features greater accuracy, quicker data

Fast, accurate, multipressure measuring system, which employs a multiple port pressure scanning valve that connects a pressure transducer to many pressures, is described

Detecting illegal trade practices by analyzing discrepancies in forest products trade statistics : An application to Europe, with a focus on Romania

Discrepancies in bilateral trade statistics for forest products have recently attracted attention as potential indicators of illegal trade practices. For example, if exporters understate quantities to evade export taxes or quotas, then one might expect reported exports to be less than reported imports. Discrepancies in trade statistics can exist for reasons that have nothing to do with illegal activities, however, such as measurement error and shipment lags. Any attempt to infer evidence of illegal activities from statistical discrepancies must control for these other explanations. The author estimates the discrepancies between reported imports and exports for bilateral flows of sawnwood traded by Romania and other European countries. The author also examines whether these discrepancies reflect illegal activities by the traders. The mean discrepancy for sawnwood exported by Romania during 1982-97 was significantly different from zero for coniferous sawnwood but not for nonconiferous sawnwood. Yet the sign of the discrepancy for coniferous sawnwood-reported exports tended to be greater than reported imports-implies that illegal trade activities were more likely occurring in Romania's trading partners than in Romania. An econometric analysis of bilateral trade statistics for Romania and other European countries finds evidence that measurement error, shipment lags, and intentional underreporting all play a role in explaining discrepancies for both types of sawnwood. The econometric model is not sufficiently reliable, however, for estimating the portion that was due solely to illegal activities or determining whether those activities occurred primarily in Romania or in its trading partners. Moreover, given that it is based on observed discrepancies in bilateral trade statistics, it fails to detect illegal trade activities that occur simultaneously in both importing and exporting countries. For these reasons, econometric methods appear unlikely to be of practical use in revealing illegal trade activities in the Romanian forest sector.Environmental Economics&Policies,Economic Theory&Research,Development Economics&Aid Effectiveness,Trade Policy,Agribusiness&Markets,Trade Policy,Economic Theory&Research,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Environmental Economics&Policies,Agribusiness&Markets

Mapping exposed silicate rock types and exposed ferric and ferrous compounds from a space platform

There are no author-identified significant results in this report

Ratio maps of iron ore deposits Atlantic City district, Wyoming

Preliminary results of a spectral rationing technique are shown for a region at the southern end of the Wind River Range, Wyoming. Digital ratio graymaps and analog ratio images have been produced for the test site, but ground truth is not yet available for thorough interpretation of these products. ERTS analog ratio images were found generally better than either ERTS single-channel images or high altitude aerial photos for the discrimination of vegetation from non-vegetation in the test site region. Some linear geological features smaller than the ERTS spatial resolution are seen as well in ERTS ratio and single-channel images as in high altitude aerial photography. Geochemical information appears to be extractable from ERTS data. Good preliminary quantitative agreement between ERTS-derived ratios and laboratory-derived reflectance ratios of rocks and minerals encourage plans to use lab data as training sets for a simple ratio gating logic approach to automatic recognition maps

Time evolution of open quantum many-body systems

We establish a generic method to analyze the time evolution of open quantum many-body systems. Our approach is based on a variational integration of the quantum master equation describing the dynamics and naturally connects to a variational principle for its nonequilibrium steady state. We successfully apply our variational method to study dissipative Rydberg gases, finding excellent quantitative agreement with small-scale simulations of the full quantum master equation. We observe that correlations related to non-Markovian behavior play a significant role during the relaxation dynamics towards the steady state. We further quantify this non-Markovianity and find it to be closely connected to an information-theoretical measure of quantum and classical correlations.Comment: 5+3 pages, 8 figure

Securing the Peace after a Truce in the War on Inflation

Central bankers in the major industrial economies have come close to securing the peace, or in some cases, have secured it in the battle against inflation, hostilities that lasted almost as long as the Cold War. It is important to remember that this battle has been a good fight: both the theory and the empirics reviewed in this paper support the central tenet of central banking that lower inflation supports faster economic growth. However, the observation that low inflation is associated with a macroeconomic benefit does not imply that disinflation should be pursued without limit. A particularly compelling argument in the body of work on the optimal inflation rate is the view that price deflation, or even very low inflation, may pose unacceptable macroeconomic risks given the lower bound of nominal interest rates of zero. Empirical work in this paper suggests that the zero bound is not an artifact of theoreticians but a palpable reality. That said, the perils of the zero bound to nominal interest rates may be seen as less threatening if a central bank is willing to be both aggressive in providing policy accommodation when the economy may be nearing the zero bound and flexible in using the available tools of policy.