Ternary forecast of heavy snowfall in the Honam area,Korea     

Keon Tae SOHN  Jeong Hyeong LEE  Young Seuk CHO 《大气科学进展》2009,26(2):327-332

The objective of this study is to improve the statistical modeling for the ternary forecast of heavy snowfall in the Honam area in Korea. The ternary forecast of heavy snowfall consists of one of three values, 0 for less than 50 mm, 1 for an advisory (50–150 mm), and 2 for a warning (more than 150 mm). For our study, the observed daily snow amounts and the numerical model outputs for 45 synoptic factors at 17 stations in the Honam area during 5 years (2001 to 2005) are used as observations and potential pre...  相似文献   

Model-based remote sensing algorithms for particulate organic carbon (POC) in the Northeastern Gulf of Mexico     

Young Baek Son  Wilford D. Gardner  Alexey V. Mishonov  Mary Jo Richardson 《Journal of Earth System Science》2009,118(1):1-10

Hydrographic data, including particulate organic carbon (POC) from the Northeastern Gulf of Mexico (NEGOM) study, were combined with remotely-sensed SeaWiFS data to estimate POC concentration using principal component analysis (PCA). The spectral radiance was extracted at each NEGOM station, digitized, and averaged. The mean value and spurious trends were removed from each spectrum. De-trended data included six wavelengths at 58 stations. The correlation between the weighting factors of the first six eigenvectors and POC concentration were applied using multiple linear regression. PCA algorithms based on the first three, four, and five modes accounted for 90, 95, and 98% of total variance and yielded significant correlations with POC with R ² = 0.89, 0.92, and 0.93. These full waveband approaches provided robust estimates of POC in various water types. Three different analyses (root mean square error, mean ratio and standard deviation) showed similar error estimates, and suggest that spectral variations in the modes defined by just the first four characteristic vectors are closely correlated with POC concentration, resulting in only negligible loss of spectral information from additional modes. The use of POC algorithms greatly increases the spatial and temporal resolution for interpreting POC cycling and can be extrapolated throughout and perhaps beyond the area of shipboard sampling.  相似文献   

Analysis of energetic electron drop-outs in the upper atmosphere of Titan during flybys in the dayside magnetosphere of Saturn     

Z. Bebesi  N. Krupp  K. Szego  M. Fränz  Z. Nemeth  S.M. Krimigis  D.G. Mitchell  G. Erdos  D.T. Young  M.K. Dougherty 《Icarus》2012,218(2):1020-1027

We discuss the high energy electron absorption signatures at Titan during the Cassini dayside magnetospheric encounters. We use the electron measurements of the Low Energy Measurement System of the Magnetospheric Imaging Instrument. We also examine the mass loading boundary based on the ion data of the Ion Mass Spectrometer sensor of the Cassini Plasma Spectrometer. The dynamic motion of the Kronian magnetopause and the periodic charged particle flux and magnetic field variations – associated with the magnetodisk of Saturn – of the subcorotating magnetospheric plasma creates a unique and complex environment at Titan. Most of the analysed flybys (like T25–T33 and T35–T51) cluster at similar Saturn Local Time positions. However the instantaneous direction of the incoming magnetospheric particles may change significantly from flyby to flyby due to the very different magnetospheric field conditions which are found upstream of Titan within the sets of encounters.The energetic magnetospheric electrons gyrate along the magnetic field lines of Saturn, and at the same time bounce between the mirror points of the magnetosphere. This motion is combined with the drift of the magnetic field lines. When these flux tubes interact with the upper atmosphere of Titan, their content is depleted over approximately an electron bounce period. These depletion signatures are observed as sudden drop-outs of the electron fluxes. We examined the altitude distribution of these drop-outs and concluded that these mostly detected in the exo-ionosphere of Titan and sometimes within the ionosphere.However there is a relatively significant scatter in the orbit to orbit data, which can be attributed to the which can be attributed to the variability of the plasma environment and as a consequence, the induced magnetosphere of Titan. A weak trend between the incoming electron fluxes and the measured drop-out altitudes has also been observed.  相似文献   

Multiresolution Analysis of Active Region Magnetic Structure and its Correlation with the Mount Wilson Classification and Flaring Activity     

J. Ireland  C. A. Young  R. T. J. McAteer  C. Whelan  R. J. Hewett  P. T. Gallagher 《Solar physics》2008,252(1):121-137

Two different multiresolution analyses are used to decompose the structure of active-region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are found. These lines are used as a mask on a map of the magnetic field gradient to sample the local gradient between opposite polarity regions of given scale sizes. It is shown that the maximum, average, and standard deviation of the magnetic flux gradient for α,β,β γ, and β γ δ active-regions increase in the order listed, and that the order is maintained over all length scales. Since magnetic flux gradient is strongly linked to active-region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all length scales in the active-region, and not just those length scales at which the strongest flux gradients are found. Further, it is also shown that the average gradients in the field, and the average length-scale at which they occur, also increase in the same order. Finally, there are significant differences in the gradient distribution, between flaring and non-flaring active regions, which are maintained over all length scales. It is also shown that the average gradient content of active-regions that have large flares (GOES class “M” and above) is larger than that for active regions containing flares of all flare sizes; this difference is also maintained at all length scales. All of the reported results are independent of the multiresolution transform used. The implications for the Mt. Wilson classification of active-regions in relation to the multiresolution gradient content and flaring activity are discussed.  相似文献   

HST spectral imaging of Titan's haze and methane profile between 0.6 and 1 μm during the 2000 opposition     

C.M. Anderson  E.F. Young  C.P. McKay 《Icarus》2008,194(2):721-745

We report on the analysis of high spatial resolution visible to near-infrared spectral images of Titan at Ls=240° in November 2000, obtained with the Space Telescope Imaging Spectrograph instrument on board the Hubble Space Telescope as part of program GO-8580. We employ a radiative transfer fractal particle aerosol model with a Bayesian parameter estimation routine that computes Titan's absolute reflectivity per pixel for 122 wavelengths by modeling the vertical distribution of the lower atmosphere haze and tropospheric methane. Analysis of these data suggests that Titan's haze concentration in the lower atmosphere varies in strength with latitude. We find Titan's tropospheric methane profile to be fairly consistent with latitude and longitude, and we find evidence for local areas of a CH₄-N₂ binary saturation in Titan's troposphere. Our results suggest that a methane and haze profile at one location on Titan would not be representative of global conditions.  相似文献   

Television photometry: The Mariner 9 experience     

A.T. Young 《Icarus》1974,21(3):262-282

Television photometry is compared to conventional techniques. Reduced data from the Mariner 9 cameras should, under optimum conditions, have been accurate to a few percent. However, a combination of unstable camera properties and various unfortunate circumstances (see Appendix A) produced serious nonlinearities (typically 20–40%) and other systematic errors. The means of estimating these errors are described in detail; they lean heavily on the fortuitous presence of a few specks of dust on the faceplate of one vidicon (see Appendix B). Crude corrections, shown in Figs. 2 and 4, will (if applied by hand to “reduced” data) probably improve the photometric quality from that of the Bonner Durchmusterung to nearly that of the Revised Harvard Photometry, for the two most-used filter positions of the A camera. It would be very difficult to improve the photometry further (Appendix C). In view of their low photometric accuracy and detective quantum efficiency (Appendix D), vidicons do not seem likely to replace conventional photography, except for special applications.  相似文献   

The Chalk area of North-East Surrey     

George William Young 《Proceedings of the Geologists' Association. Geologists' Association》1905,19(4):188-IN1

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Excursion to Lichfield and Cannock: Saturday,June 17th, 1899     

C. Lapworth  W.W. Watts  A.C. Young 《Proceedings of the Geologists' Association. Geologists' Association》1899,16(5):246-248

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Excursion to Godalming: Saturday,June 11th, 1898     

Thomas Leighton  A.C. Young 《Proceedings of the Geologists' Association. Geologists' Association》1898,15(10):445-450

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Excursion to Bishop's Stortford: Saturday,July 17th, 1897     

A. Irving  A.C. Young 《Proceedings of the Geologists' Association. Geologists' Association》1897,15(5):193-197

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