524 research outputs found
Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini
We present an updated analysis of Jupiter's equatorial meteorology from
Cassini observations. For two months preceding the spacecraft's closest
approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the
atmosphere. We created time-lapse movies from this period in order to analyze
the dynamics of equatorial hot spots and their interactions with adjacent
latitudes. Hot spots are quasi-stable, rectangular dark areas on
visible-wavelength images, with defined eastern edges that sharply contrast
with surrounding clouds, but diffuse western edges serving as nebulous
boundaries with adjacent equatorial plumes. Hot spots exhibit significant
variations in size and shape over timescales of days and weeks. Some of these
changes correspond with passing vortex systems from adjacent latitudes
interacting with hot spots. Strong anticyclonic gyres present to the south and
southeast of the dark areas appear to circulate into hot spots. Impressive,
bright white plumes occupy spaces in between hot spots. Compact cirrus-like
'scooter' clouds flow rapidly through the plumes before disappearing within the
dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s
hot spot and plume drift speed. This raises the possibility that the scooter
clouds may be more illustrative of the actual jet stream speed at these
latitudes. Most previously published zonal wind profiles represent the drift
speed of the hot spots at their latitude from pattern matching of the entire
longitudinal image strip. If a downward branch of an equatorially-trapped
Rossby waves controls the overall appearance of hot spots, however, the
westward phase velocity of the wave leads to underestimates of the true jet
stream speed.Comment: 33 pages, 11 figures; accepted for publication in Icarus; for
supplementary movies, please contact autho
Investigation of Jupiter's Equatorial Hotspots and Plumes Using Cassini ISS Observations
We present updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the ISS onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial 5-micron hot spots and their interactions with adjacent latitudes. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but a diffuse western edge serving as a nebulous boundary with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-iike 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. This raises the possibility that the plumes and fast-moving clouds are at higher altitudes, because their speed does not match previously published zonal wind profiles. Most profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby waves controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed. Instead, our expanded data set demonstrating the rapid flow of these scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. This research was supported by a NASA JDAP grant and the NASA Postdoctoral Program
Ongoing Analysis of Jupiter's Equatorial Hotspots and Plumes from Cassini
We present updated results from our ongoing analysis of Cassini observations of Jupiter's equatorial meteorology. For two months preceding the spacecraft's closest approach of the planet, the ISS instrument onboard Cassini regularly imaged the atmosphere of Jupiter. We created time-lapse movies from this period that show the complex activity and interactions of the equatorial atmosphere. During this period, hot spots exhibited significant variations in size and shape over timescales of days and weeks. Some of these changes appear to be a result of interactions with passing vortex systems in adjacent latitudes. Strong anticyclonic gyres to the southeast of the dark areas converge with flow from the west and appear to circulate into a hot spot at its southwestern corner
Jupiter's visible aurora and Io footprint
Images obtained by the Galileo spacecraft's solid-state imaging (SSI) system represent the first survey of Jupiter's northern auroral emissions at visible wavelengths and on the nightside of the planet. These images captured the emissions with unprecedented spatial resolutions down to ∼26 km pixel^(−1). Four classes of emission were observed: (1) a continuous, primary arc associated with the middle/outer magnetosphere, (2) a variable secondary arc associated with the region just beyond Io's torus, (3) diffuse “polar cap” emission, and (4) a patch and tail associated with the magnetic footprint of Io. The primary arc emission occurs at an altitude 245±30 km above the 1-bar pressure level. Its horizontal width is typically a few hundred kilometers, and its total optical power output varied between ∼10^(10) and ∼10^(11) W in observations taken months apart. The location of the primary arc in planetary coordinates is similar to that on dayside images at other wavelengths and does not vary with local time. The morphology of the primary arc is not constant, changing from a multiply branched, latitudinally distributed pattern after dusk to a single, narrow arc before dawn. Emission from Io's ionospheric footprint is distinct from both the primary and secondary arcs. Measurements of its optical power output ranged from 2 to 7×10^8 W
Outcomes of Midurethral Slings in Women with Concomitant Preoperative Severe Lower Urinary Tract Voiding Symptoms
BACKGROUND: Women with stress urinary incontinence and concomitant obstructive (voiding) lower urinary tract symptoms (LUTS) represent a challenging patient population. Furthermore, their diagnosis and management remain incompletely studied and controversial. We evaluated the outcomes of midurethral sling procedures in women with severe obstructive LUTS. METHODS: We performed a post hoc analysis of women who were part of an institutional review board-approved study of midurethral sling surgery. Preoperatively and at 4-6 weeks postoperatively, patients completed the American Urological Association Symptom Score (AUASS) questionnaire. A postvoid residual urine test was obtained preoperatively, at the time of the voiding trial, and 4-6 weeks postoperatively. Three groups of patients with severe LUTS were then defined: Group A (AUASS \u3e/=20), Group B (voiding subscale \u3e/=12), and Group C (urodynamic obstruction). Patients could be included in more than one group. AUASS was again obtained at a medium-term follow-up of 31.6 months. RESULTS: Of 106 women completing follow-up, 30, 23, and 11 subjects met the criteria for groups A, B, and C, respectively. All had statistically significant improvements in storage and voiding subscales, as well as their stress urinary incontinence. No subject presented with retention or voiding dysfunction at follow-up. These improvements continued at medium-term follow-up with the exception of Group C that failed to demonstrate persistence of statistical improvement in AUASS subscales. CONCLUSION: Patients with stress urinary incontinence and severe voiding LUTS can be treated safely with midurethral sling procedures. In both the short and medium term, these symptoms improve dramatically in the majority of patients
The global energy balance of Titan
The global energy budget of planets and their moons is a critical factor to influence the climate change on these objects. Here we report the first measurement of the global emitted power of Titan. Long-term (2004–2010) observations conducted by the Composite Infrared Spectrometer (CIRS) onboard Cassini reveal that the total emitted power by Titan is (2.84 ± 0.01) × 10^(14) watts. Together with previous measurements of the global absorbed solar power of Titan, the CIRS measurements indicate that the global energy budget of Titan is in equilibrium within measurement error. The uncertainty in the absorbed solar energy places an upper limit on the energy imbalance of 6.0%
Effective Functional Form of Regge Trajectories
We present theoretical arguments and strong phenomenological evidence that
hadronic Regge trajectories are essentially nonlinear and can be well
approximated, for phenomenological purposes, by a specific square-root form.Comment: 29 pages, LaTeX. Published versio
Dynamics of Jupiter’s atmosphere
Giant planet atmospheres provided many of the surprises and remarkable discoveries of planetary exploration during the past few decades. Studying Jupiter's atmosphere and comparing it with Earth's gives us critical insight and a broad understanding of how atmospheres work that could not be obtained by studying Earth alone
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