1,467 research outputs found

    Archived time-series of Atlantic Ocean meteorological variables and surface fluxes

    Get PDF
    Includes ErrataTime-series of monthly averages of latent, sensible and radiational heat fluxes and momentum fluxes at the surfaces of the North and South Atlantic Oceans were calculated from ship weather observations. These fluxes, together with values of meteorological variables have been averaged over entire Marsden squares (10X10° squares) for all months from January 1948 through December 1972. The method of computing fluxes from ship weather observations, listing of variables averaged, addition of sea-ice coverage of sub-polar regions, correction of albedos for the presence of sea ice, correction of infrared radiational exchange for humidity conditions of the upper atmosphere, and format of the data on magnetic tapes are described. Statistics of the fluxes and variables have been computed. Standard data tapes containing these time series and statistics are available.Prepared for Climate Dynamics Research Program~ Division of Atmospheric Sciences, National Science Foundation under Grant ATM 77-01475 A01

    Woods Hole Oceanographic Institution collection of Climatology and Air/Sea Interaction (CASI) data

    Get PDF
    Scientists at Woods Hole routinely collect and analyze a considerable amount of data relating to the oceans of the world. Of the many different kinds of data, one particular subset concerns those events occurring at the sea surface. A large number of sea surface environmental observations have been collected at Woods Hole. These data, and the subsequent analyses generated from the Air/Sea Heat Flux and the Climatology study projects, have been collected and archived. This document describes the W.H.O.I./ Climatology and Air/Sea Interaction (WHOI/CASI) data collection and provides an initial index to its various components.Prepared for the Office of Naval Research under Contract N00014-74-C-0262; NR 083-004 and for the National Science Foundation (Climate Dynamics Program, Atmospheric Sciences Division) under Grant ATM 77-014?5

    A note on the heat balance of the Mediterranean and Red Seas

    Get PDF
    The Mediterranean and Red Seas are used as test volumes in an attempt to assess the accuracy of estimates of climatological air-sea fluxes calculated using meteorological observations from merchant ships…

    Spin dynamics simulations of the magnetic dynamics of RbMnF3_3 and direct comparison with experiment

    Full text link
    Spin-dynamics techniques have been used to perform large-scale simulations of the dynamic behavior of the classical Heisenberg antiferromagnet in simple cubic lattices with linear sizes L≤60L\leq 60. This system is widely recognized as an appropriate model for the magnetic properties of RbMnF3_3. Time-evolutions of spin configurations were determined numerically from coupled equations of motion for individual spins using a new algorithm implemented by Krech {\it etal}, which is based on fourth-order Suzuki-Trotter decompositions of exponential operators. The dynamic structure factor was calculated from the space- and time-displaced spin-spin correlation function. The crossover from hydrodynamic to critical behavior of the dispersion curve and spin-wave half-width was studied as the temperature was increased towards the critical temperature. The dynamic critical exponent was estimated to be z=(1.43±0.03)z=(1.43\pm 0.03), which is slightly lower than the dynamic scaling prediction, but in good agreement with a recent experimental value. Direct, quantitative comparisons of both the dispersion curve and the lineshapes obtained from our simulations with very recent experimental results for RbMnF3_3 are presented.Comment: 30 pages, RevTex, 9 figures, to appear in PR

    The Evolution of the Stellar Hosts of Radio Galaxies

    Full text link
    We present new near-infrared images of z>0.8 radio galaxies from the flux-limited 7C-III sample of radio sources for which we have recently obtained almost complete spectroscopic redshifts. The 7C objects have radio luminosities about 20 times fainter than 3C radio galaxies at a given redshift. The absolute magnitudes of the underlying host galaxies and their scale sizes are only weakly dependent on radio luminosity. Radio galaxy hosts at z~2 are significantly brighter than the hosts of radio-quiet quasars at similar redshifts and the model AGN hosts of Kauffmann & Haehnelt (2000). There is no evidence for strong evolution in scale size, which shows a large scatter at all redshifts. The hosts brighten significantly with redshift, consistent with the passive evolution of a stellar population that formed at z>~3. This scenario is consistent with studies of host galaxy morphology and submillimeter continuum emission, both of which show strong evolution at z>~2.5. The lack of a strong ``redshift cutoff'' in the radio luminosity function to z>4 suggests that the formation epoch of the radio galaxy host population lasts >~1Gyr from z>~5 to z~3. We suggest these facts are best explained by models in which the most massive galaxies and their associated AGN form early due to high baryon densities in the centres of their dark matter haloes.Comment: To appear in A

    Three Emission-Line Galaxies at z~2.4

    Get PDF
    We present Keck near-infrared and WIYN optical photometry of a sample of galaxies detected by near-infrared narrowband imaging in the fields of quasar metal absorption line systems at z~2.4. Wide separations (0.6-1.6/h Mpc) from the quasars indicates that they are not directly responsible for the absorption systems. From the color excess of the galaxies we derived line fluxes, star formation rates, and equivalent widths. The data are consistent with one source having an active nucleus and two sources containing regions of star formation. The blue (R-K) colors for the sources suggest relatively lesser dust content. We discuss possible projects using current wide-field infrared instruments, which can cover an order of magnitude greater area with modest allocations of telescope time.Comment: 9 Pages, 3 figures LaTeX/AASTeX. ApJ accepted (est. March 2003

    Deep optical spectroscopy of extended Lyman alpha emission around three radio-quiet z=4.5 quasars

    Full text link
    We report the first results of a spectroscopic search for Lyman alpha, envelopes around three z=4.5 radio-quiet quasars. Our observational strategy uses the FORS2 spectrograph attached to the UT1 of the Very Large Telescope (VLT) in the multi-slit mode. This allows us to observe simultaneously the quasars and several PSF stars. The spectra of the latter are used to remove the point-like quasar from the data, and to unveil the faint underlying Lyman alpha, envelopes associated with the quasars with unprecedented depth. We clearly detect an envelope around two of the three quasars. These envelopes measure respectively 10" and 13" in extent (i.e. 67 kpc and 87 kpc). This is 5 to 10 times larger than predicted by the models of Haiman & Rees (2001) and up to 100 times fainter. Our observations better agree with models involing a clumpy envelope as in Alam & Miralda-Escude (2002) or Chelouche et al. (2008). We find that the brighter quasars also have the brighter envelopes but that the extend of the envelopes does not depend on the quasar luminosity. Although our results are based on only two objects with a detected Lyman alpha, envelope, the quality of the spatial deblending of the spectra lends considerable hope to estimate the luminosity function and surface brightness profiles of high redshift Lyman alpha, envelopes down to F= 2-3 10^{-21} erg/s/cm^2/A. We find that the best strategy to carry out such a project is to obtain both narrow-band images and deep slit-spectra.Comment: 8 pages, 5 figures, submitted to A&

    2D Kinematics and Physical Properties of z~3 Star-Forming Galaxies

    Full text link
    We present results from a study of the kinematic structure of star-forming galaxies at redshift z~3 selected in the VVDS, using integral-field spectroscopy of rest-frame optical nebular emission lines, in combination with rest-frame UV spectroscopy, ground-based optical/near-IR and Spitzer photometry. We also constrain the underlying stellar populations to address the evolutionary status of these galaxies. We infer the kinematic properties of four galaxies: VVDS-20298666, VVDS-020297772, VVDS-20463884 and VVDS-20335183 with redshifts z = 3.2917, 3.2878, 3.2776, and 3.7062, respectively. While VVDS-20463884 presents an irregular velocity field with a peak in the local velocity dispersion of the galaxy shifted from the centre of the galaxy, VVDS-20298666 has a well-resolved gradient in velocity over a distance of ~4.5 kpc with a peak-to-peak amplitude of v = 91 km/s . We discovered that the nearby galaxy, VVDS-020297772 (which shows traces of AGN activity), is in fact a companion at a similar redshift with a projected separated of 12 kpc. In contrast, the velocity field of VVDS-020335183 seems more consistent with a merger on a rotating disk. However, all of the objects have a high local velocity dispersion (sigma ~ 60-70 km/s), which gives v/sigma < 1. It is unlikely that these galaxies are dynamically cold rotating disk of ionized gas.Comment: 14 pages and 16 figure

    Measurement of [OIII] Emission in Lyman Break Galaxies

    Full text link
    Measurements of [OIII] emission in Lyman Break galaxies (LBGs) at z>3 are presented. Four galaxies were observed with narrow-band filters using the Near-IR Camera on the Keck I 10-m telescope. A fifth galaxy was observed spectroscopically during the commissioning of NIRSPEC, the new infrared spectrometer on Keck II. The emission-line spectrum is used to place limits on the metallicity. Comparing these new measurements with others available from the literature, we find that strong oxygen emission in LBGs may suggest sub-solar metallicity for these objects. The [OIII]5007 line is also used to estimate the star formation rate (SFR) of the LBGs. The inferred SFRs are higher than those estimated from the UV continuum, and may be evidence for dust extinction.Comment: 25 pages, including 6 figures. Accepted for publication in Ap
    • …
    corecore