7,172 research outputs found
ETO lidar studies of cirrostratus altocumulogenitus: Another role for supercooled liquid water in cirrus cloud formation
Cirrus clouds have traditionally been viewed as cold, wispy, or stratiform ice clouds, typically displaying optical phenomena such as haloes. A composition entirely of hexagonal ice crystals, of one habit or another could only have a transitory existence in cirrus, since the concentrations of ice nuclei (IN) measured by various techniques (at the surface or in the lower troposphere) indicate an enormous number of IN that should be active at cirrus cloud temperatures. In light of recent instrumental aircraft and polarization lidar studies of cirrus clouds, it is clear that highly supercooled cloud droplets can sometimes be a component of cirrus clouds. It remains to be determined if supercooled liquid water (SLW) is present abundantly enough in cirrus to play a significant role in earth's radiance balance, or is merely a curious, infrequent occurrence. To help evaluate this issue, the UH polarization lidar FIRE Extended Time Observation (ETO) of cirrus clouds are being utilized to compile, among other parameters, a climatological record of SLW clouds associated with and within cirrus
An experimental investigation of the angular scattering and backscattering behaviors of the simulated clouds of the outer planets
A cryogenic, 50 liter volume Planetary Cloud Simulation Chamber has been constructed to permit the laboratory study of the cloud compositions which are likely to be found in the atmospheres of the outer planets. On the basis of available data, clouds composed of water ice, carbon dioxide, and liquid and solid ammonia and methane, both pure and in various mixtures, have been generated. Cloud microphysical observations have been permitted through the use of a cloud particle slide injector and photomicrography. Viewports in the lower chamber have enabled the collection of cloud backscattering data using 633 and 838 nm laser light, including linear depolarization ratios and complete Stokes parameterization. The considerable technological difficulties associated with the collection of angular scattering patterns within the chamber, however, could not be completely overcome
ETO cloud studies for FIRE 2, part 1
This research program in support of Project FIRE (First ISCCP Regional Experiment) involved two efforts. The results of the first effort, which were in direct support of the Extended Time Observations (ETO) component, are described here. Over the period from June 1990 through May 1991, our remote sensing systems were applied to providing ground-truth cirrus cloud observations for a total of 71 NOAA polar orbiting satellite overpasses. (Chronological tables of this effort are provided.) The primary remote sensor was a dual-polarization ruby (0.694 microns wavelength) lidar, although mid-way through the program we added a number of radiometers to assess the surface radiation budget and cirrus cloud infrared emittance, and some supplemental observations from a Ka-band (8.6 mm) radar were also collected. These studies were conducted from the Facility for Atmospheric Remote Sensing (FARS) at 40 degrees 46 minutes 00 seconds north latitude and 111 degrees 49 minutes 38 seconds east longitude. We also investigated the unusual characteristics of a subset of ETO case studies involving cirrus that generated solar and lunar corona displays. As we reported recently (reprint attached), these cirrus were atypically high and cold in relation to our total midlatitude cloud sample, and were comprised of unexpectedly small ice crystals from 10 to 30 microns in dimension. This finding lends some credence to the so-called cirrus small particle radiative anomaly, but only for very cold (less than -60 C) cirrus clouds. In a supplement, we will describe the design and testing of a prototype cirrus cloud polar nephelometer, which we constructed as part of our second research effort, to allow scattering phase functions to be obtained in future in situ cirrus research
An Alternative Approach to the Calculation and Analysis of Connectivity in the World City Network
Empirical research on world cities often draws on Taylor's (2001) notion of
an 'interlocking network model', in which office networks of globalized service
firms are assumed to shape the spatialities of urban networks. In spite of its
many merits, this approach is limited because the resultant adjacency matrices
are not really fit for network-analytic calculations. We therefore propose a
fresh analytical approach using a primary linkage algorithm that produces a
one-mode directed graph based on Taylor's two-mode city/firm network data. The
procedure has the advantage of creating less dense networks when compared to
the interlocking network model, while nonetheless retaining the network
structure apparent in the initial dataset. We randomize the empirical network
with a bootstrapping simulation approach, and compare the simulated parameters
of this null-model with our empirical network parameter (i.e. betweenness
centrality). We find that our approach produces results that are comparable to
those of the standard interlocking network model. However, because our approach
is based on an actual graph representation and network analysis, we are able to
assess cities' position in the network at large. For instance, we find that
cities such as Tokyo, Sydney, Melbourne, Almaty and Karachi hold more strategic
and valuable positions than suggested in the interlocking networks as they play
a bridging role in connecting cities across regions. In general, we argue that
our graph representation allows for further and deeper analysis of the original
data, further extending world city network research into a theory-based
empirical research approach.Comment: 18 pages, 9 figures, 2 table
Cloud boundary height measurements using lidar and radar
Using only lidar or radar an accurate cloud boundary height estimate is often
not possible. The combination of lidar and radar can give a reliable cloud
boundary estimate in a much broader range of cases. However, also this
combination with standard methods still can not measure the cloud boundaries in
all cases. This will be illustrated with data from the Clouds and Radiation
measurement campaigns, CLARA. Rain is a problem: the radar has problems to
measure the small cloud droplets in the presence of raindrops. Similarly, few
large particles below cloud base can obscure the cloud base in radar
measurements. And the radar reflectivity can be very low at the cloud base of
water clouds or in large regions of ice clouds, due to small particles.
Multiple cloud layers and clouds with specular reflections can pose problems
for lidar. More advanced measurement techniques are suggested to solve these
problems. An angle scanning lidar can, for example, detect specular
reflections, while using information from the radars Doppler velocity spectrum
may help to detect clouds during rain.Comment: Reviewed conference contributio
Regional conditions during the 25 October 1986 FIRE cirrus/altocumulus case study
The regional cloud and meteorological conditions are described for this case using satellite imagery (GOES), dual polarization lidar data, NWS radar, NMC analyses, rawinsonde data including special soundings, and analyzed vertical motions. These observations are interpreted with respect to relationships between the observed cloud characteristics and corresponding atmospheric structure. Similarities with the 27 to 28 Oct. FIRE Cirrus Case Study are noted
Investigation of vehicle glow in the far ultraviolet
To data, all vehicle glow observations have been conducted in the visible and near infrared wavelength regions. As the Space Telescope's wavelength coverage extends to the far ultraviolet range and current plasma theory of the spacecraft glow phenomena predicts bright glow intensities, a study of the ram glow effects in the 800-1400 angstrom region was undertaken. The data were collected between March 21-28, 1979, from 600 km altitude near local midnight by the University of California, Berkeley's extreme ultraviolet spectrometer on board the polar orbiting STP78-1 satellite. Data from several nighttime orbits obtained outside the South Atlantic Anomaly region and within + or - 30 deg magnetic latitude range were separated into forward (south viewing) and backward (north viewing) bins. Each of these binds was subdivided into three directional categories: (1) up (zenith angles 30-80 deg), (2) side (zenith angles 80-100 deg), and (3) down (zenith angles 120-150 deg). The maximum ram glow effects are expected in the side viewing directions. Our data include possible effects of ram glow signatures in the 800-1400 angstrom wavelength region
Lifetime of Kaonium
The kaon--antikaon system is studied in both the atomic and the strongly
interacting sector. We discuss the influence of the structures of the
and the mesons on the lifetime of kaonium. The strong
interactions are generated by vector meson exchange within the framework of the
standard invariant effective Lagrangian. In the atomic
sector, the energy levels and decay widths of kaonium are determined by an
eigenvalue equation of the Kudryavtsev--Popov type, with the strong interaction
effects entering through the complex scattering length for scattering
and annihilation. The presence of two scalar mesons, and ,
leads to a ground state energy for the kaonium atom that is shifted above the
point Coulomb value by a few hundred eV. The effect on the lifetime for the
kaonium decay into two pions is much more dramatic. This lifetime is reduced by
two orders of magnitude from sec for annihilation in a
pure Coulomb field down to sec when the strong
interactions are included. The analysis of the two photon decay width of the
suggests a generalization of the molecular picture which reduces the
lifetime of kaonium still further to .Comment: 33 pages, 12 figures;3 new figures and new comment concerning the a
Microphysical fundamentals governing cirrus cloud growth: Modeling studies
For application to Global Climate Models, large scale numerical models of cirrus cloud formation and maintenance need to be refined to more reliably simulate the effects and feedbacks of high level clouds. A key aspect is how ice crystal growth is initiated in cirrus, which has started a cloud microphysical controversy between camps either believing that heterogeneous or homogeneous drop freezing is predominantly responsible for cold cirrus ice crystal nucleation. In view of convincing evidence for the existence of highly supercooled cloud droplets in the middle and upper troposphere, however, it is concluded that active ice nuclei are rather scarce at cirrus cloud altitudes, and so a new understanding of cirrus cloud formation is needed. This understanding is sought through an examination of cirrus cloud growth models
Job creation and regional change under New Labour : a shift-share analysis
The paper examines changes in UK regional employment during the period of the New Labour administration, 1997–2010, with the Blair and Brown administrations considered separately. The paper employs a shift-share analysis of workplace employment data by industry and subregion, using annual data from the UK Labour Force Survey. The results reveal significant regional shifts, with interesting spatial dynamics in and around the capital and resilient employment growth in the provinces
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