636 research outputs found
Performance of Major Flare Watches from the Max Millennium Program (2001-2010)
The physical processes that trigger solar flares are not well understood and
significant debate remains around processes governing particle acceleration,
energy partition, and particle and energy transport. Observations at high
resolution in energy, time, and space are required in multiple energy ranges
over the whole course of many flares in order to build an understanding of
these processes. Obtaining high-quality, co-temporal data from ground- and
space- based instruments is crucial to achieving this goal and was the primary
motivation for starting the Max Millennium program and Major Flare Watch (MFW)
alerts, aimed at coordinating observations of all flares >X1 GOES X-ray
classification (including those partially occulted by the limb). We present a
review of the performance of MFWs from 1 February 2001 to 31 May 2010,
inclusive, that finds: (1) 220 MFWs were issued in 3,407 days considered (6.5%
duty cycle), with these occurring in 32 uninterrupted periods that typically
last 2-8 days; (2) 56% of flares >X1 were caught, occurring in 19% of MFW days;
(3) MFW periods ended at suitable times, but substantial gain could have been
achieved in percentage of flares caught if periods had started 24 h earlier;
(4) MFWs successfully forecast X-class flares with a true skill statistic (TSS)
verification metric score of 0.500, that is comparable to a categorical
flare/no-flare interpretation of the NOAA Space Weather Prediction Centre
probabilistic forecasts (TSS = 0.488).Comment: 19 pages, 2 figures, accepted for publication in Solar Physic
Third order superintegrable systems separating in polar coordinates
A complete classification is presented of quantum and classical
superintegrable systems in that allow the separation of variables in
polar coordinates and admit an additional integral of motion of order three in
the momentum. New quantum superintegrable systems are discovered for which the
potential is expressed in terms of the sixth Painlev\'e transcendent or in
terms of the Weierstrass elliptic function
An infinite family of superintegrable systems from higher order ladder operators and supersymmetry
We will discuss how we can obtain new quantum superintegrable Hamiltonians
allowing the separation of variables in Cartesian coordinates with higher order
integrals of motion from ladder operators. We will discuss also how higher
order supersymmetric quantum mechanics can be used to obtain systems with
higher order ladder operators and their polynomial Heisenberg algebra. We will
present a new family of superintegrable systems involving the fifth Painleve
transcendent which possess fourth order ladder operators constructed from
second order supersymmetric quantum mechanics. We present the polynomial
algebra of this family of superintegrable systems.Comment: 8 pages, presented at ICGTMP 28, accepted for j.conf.serie
Families of superintegrable Hamiltonians constructed from exceptional polynomials
We introduce a family of exactly-solvable two-dimensional Hamiltonians whose
wave functions are given in terms of Laguerre and exceptional Jacobi
polynomials. The Hamiltonians contain purely quantum terms which vanish in the
classical limit leaving only a previously known family of superintegrable
systems. Additional, higher-order integrals of motion are constructed from
ladder operators for the considered orthogonal polynomials proving the quantum
system to be superintegrable
The Star Blended with the MOA-2008-BLG-310 Source Is Not the Exoplanet Host Star
High resolution Hubble Space Telescope (HST) image analysis of the
MOA-2008-BLG-310 microlens system indicates that the excess flux at the
location of the source found in the discovery paper cannot primarily be due to
the lens star because it does not match the lens-source relative proper motion,
, predicted by the microlens models. This excess flux is most
likely to be due to an unrelated star that happens to be located in close
proximity to the source star. Two epochs of HST observations indicate proper
motion for this blend star that is typical of a random bulge star, but is not
consistent with a companion to the source or lens stars if the flux is
dominated by only one star, aside from the lens. We consider models in which
the excess flux is due to a combination of an unrelated star and the lens star,
and this yields 95\% confidence level upper limit on the lens star brightness
of and . A Bayesian analysis using a standard
Galactic model and these magnitude limits yields a host star mass , a planet mass of at a projected separation of AU. This result illustrates excess flux in a high
resolution image of a microlens-source system need not be due to the lens. It
is important to check that the lens-source relative proper motion is consistent
with the microlensing prediction. The high resolution image analysis techniques
developed in this paper can be used to verify the WFIRST exoplanet microlensing
survey mass measurements.Comment: Submitted to AJ on March 18, 201
Evaluation and recommendations for improving the accuracy of an inexpensive water temperature logger
Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 30 (2013): 1576–1582, doi:10.1175/JTECH-D-12-00204.1.Onset's HOBO U22 Water Temp Pros are small, reliable, relatively inexpensive, self-contained temperature loggers that are widely used in studies of oceans, lakes, and streams. An in-house temperature bath calibration of 158 Temp Pros indicated root-mean-square (RMS) errors ranging from 0.01° to 0.14°C, with one value of 0.23°C, consistent with the factory specifications. Application of a quadratic calibration correction substantially reduced the RMS error to less than 0.009°C in all cases. The primary correction was a bias error typically between −0.1° and 0.15°C. Comparison of water temperature measurements from Temp Pros and more accurate temperature loggers during two oceanographic studies indicates that calibrated Temp Pros have an RMS error of ~0.02°C throughout the water column at night and beneath the surface layer influenced by penetrating solar radiation during the day. Larger RMS errors (up to 0.08°C) are observed near the surface during the day due to solar heating of the black Temp Pro housing. Errors due to solar heating are significantly reduced by wrapping the housing with white electrical tape.This work is based on research
supported by Awards USA 00002 and KSA 00011 made
by King Abdullah University of Science and Technology
(KAUST) and by the Ocean Sciences Division of
the National Science Foundation under Grant OCE-
0548961.2014-01-0
FASINEX (Frontal Air-Sea Interaction Experiment) moored instrumentation
In 1986, FASINEX, a Frontal Air-Sea Interaction Experiment,
a multi-investigator cooperative experiment, was conducted
to study the role of horizontal variability in air-sea
interaction in the persistent front formed in the
subtropical convergence zone south of Bermuda. Aimed at
investigating all aspects of the atmospheric and oceanic
variables related to the formation and maintenance of the
front, an array of meteorological and current meter moorings
was deployed by the Woods Hole Oceanographic Institution
Buoy Group in 5400 meters of water . Two subsurface current
meter moorings were deployed in October, 1984; five surface
meteorological and current meter moorings and four Profiling
Current Meter (PCM) moorings were set in January 1986 . All
except one PCM mooring, which was lost, were recovered in
June 1986. This report discusses the extensive preparations
of, and modifications to, the Woods Hole Oceanographic
Institution Buoy Group instruments placed on the five
surface moorings. The equipment included 30 vector
measuring current meters, ten vector averaging current
meters and five vector averaging wind recorders .Funding was provided by the Office of Naval Research
under contract Number N00014-84-C-0134
Low-rate discharge of various electrochemical batteries for use with oceanographic instruments
The endurance of self-sustained oceanographic instruments is
generally limited to battery energy. Tests were initiated to measure the
capacities of several types of electrochemical batteries when discharged at
temperatures and rates typical of oceanographic use. Battery systems
represented are alkaline-manganese dioxide, mercuric-oxide, and lithium
sulphur oxychloride. Results of tests completed so far are presented. A
brief overview of those batteries best suited for use with self-sustained
oceanographic instruments is included as an appendix.Funding was provided by the Office of Naval Research under contract Number N00014-76-C-0197, NR 083-400
Superintegrability and higher order polynomial algebras II
In an earlier article, we presented a method to obtain integrals of motion
and polynomial algebras for a class of two-dimensional superintegrable systems
from creation and annihilation operators. We discuss the general case and
present its polynomial algebra. We will show how this polynomial algebra can be
directly realized as a deformed oscillator algebra. This particular algebraic
structure allows to find the unitary representations and the corresponding
energy spectrum. We apply this construction to a family of caged anisotropic
oscillators. The method can be used to generate new superintegrable systems
with higher order integrals. We obtain new superintegrable systems involving
the fourth Painleve transcendent and present their integrals of motion and
polynomial algebras.Comment: 11 page
Shelfbreak frontal structure and processes north of Cape Hatteras in winter
Author Posting. © Sears Foundation for Marine Research, 2008. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 66 (2008): 755-799.The circulation north of Cape Hatteras is complicated by the proximity of the shelfbreak front, the Gulf Stream, and convergent shelf flow from the Middle and South Atlantic Bights. A three-week cruise in this region in January/February, 2005 was undertaken in order to study the structure of the shelfbreak front as it terminates near Cape Hatteras and to quantify the freshwater transport from the Middle Atlantic Bight shelf into the Gulf Stream. Two strongly contrasting conditions were identified. Early in the cruise, the Gulf Stream directly abutted the shelfbreak at Cape Hatteras and drove a northward flow over the continental shelf as far north as 35°45′N. All of the Middle Atlantic Bight shelf water terminated by 35°30′N. Ten days later, the Gulf Stream had moved away from the shelfbreak south of Cape Hatteras and strong winds from the north were present. During this time, the shelfbreak frontal jet was strong (maximum southward velocity of approximately 0.5 m s-1 with a Rossby number of 2) and abruptly turned eastward and offshore between 35°35′N and 35°45′N. Freshwater transport eastward from the shelfbreak jet was 7.4 mSv and southward over the shelf was 19.9 mSv, giving a total freshwater transport of 27.3 mSv. This likely represents an upper bound due to the strong wind forcing. Implications of these results for the freshwater budget of the Middle Atlantic Bight shelf, stability properties of the shelfbreak front in this region, and the formation of “Ford water” in the Gulf Stream are discussed.Support for the Rutgers satellite archive is provided by NSF, ONR and NOAA.
This work was supported under NSF Grant Number OCE-0327249
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