Observations and a model of undertow over the inner continental shelf

Author Posting. © American Meteorological Society, 2008. 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 Physical Oceanography 38 (2008): 2341-2357, doi:10.1175/2008JPO3986.1.Onshore volume transport (Stokes drift) due to surface gravity waves propagating toward the beach can result in a compensating Eulerian offshore flow in the surf zone referred to as undertow. Observed offshore flows indicate that wave-driven undertow extends well offshore of the surf zone, over the inner shelves of Martha’s Vineyard, Massachusetts, and North Carolina. Theoretical estimates of the wave-driven offshore transport from linear wave theory and observed wave characteristics account for 50% or more of the observed offshore transport variance in water depths between 5 and 12 m, and reproduce the observed dependence on wave height and water depth. During weak winds, wave-driven cross-shelf velocity profiles over the inner shelf have maximum offshore flow (1–6 cm s−1) and vertical shear near the surface and weak flow and shear in the lower half of the water column. The observed offshore flow profiles do not resemble the parabolic profiles with maximum flow at middepth observed within the surf zone. Instead, the vertical structure is similar to the Stokes drift velocity profile but with the opposite direction. This vertical structure is consistent with a dynamical balance between the Coriolis force associated with the offshore flow and an along-shelf “Hasselmann wave stress” due to the influence of the earth’s rotation on surface gravity waves. The close agreement between the observed and modeled profiles provides compelling evidence for the importance of the Hasselmann wave stress in forcing oceanic flows. Summer profiles are more vertically sheared than either winter profiles or model profiles, for reasons that remain unclear.This research was funded by the Ocean Sciences Division of the National Science Foundation under Grants OCE-0241292 and OCE-0548961

The Implications of the Acquisition of a New Nationality for the Right of Return of Palestinian Refugees

This article examines the legal consequences of the acquisition of a new nationality for the right of return of Palestinian refugees. The article argues that since the right of return is independent of the refugee status, the cessation of the latter should not necessarily abrogate the former. By examining the underpinnings of the right of return to one’s own country, especially the link between the individual and her territory, this article argues that this link is somehow weakened in a situation of naturalization in a different country. However, this weakening of the link should not automatically lead to the deprivation of rights. The circumstances that lead refugees to leave their country of origin, the circumstances preventing their return, and the decisions made by the individuals in view of their available options should be examined

‘Orientalism is a partisan book’: applying Edward Said's insights to early modern travel writing

Since its publication in 1978, Edward Said's Orientalism has had a significant impact on postcolonial studies in a range of fields. This paper assesses his impact on the historiography of Anglophone travel writing concerning Ottoman Empire during the early modern period. Said's analysis of the relationship between representational power and colonial authority remains relevant to our understanding of early modern travel texts. Said's epistemology raises significant issues for historians of early modern intercultural encounters. This article summarises recent debates surrounding early modern travel narratives. It contrasts doctrinaire applications of Said's theory with more recent, particularistic studies. It provides a much-needed survey of travel writing historiography that considers the continuing impact of Said's postcolonial thought on the study of early modern travel narratives relating to the Ottoman Middle East. In so doing, it explores the lack of fit between early modern travel narratives and Said's methodology. I explore the methodological problems thrown up by conventional applications of Said's epistemology to precolonial travellers' texts. Based on a wide-ranging survey of Said's oeuvre, the article demonstrates that, more than 30 years on, Said's work remains relevant to the historiographical challenges presented by early modern English travel writing about Islam

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Infragravity Energy and Its Implications in Nearshore Sediment Transport and Sandbar Dynamics

Source: https://erdc-library.erdc.dren.mil/jspui/This report presents a tutorial on infragravity motions in the nearshore zone with particular attention given to the influence of infragravity motions on sediment transport and runup. This ubiquitous low-frequency wave motion, with periods from 30 sec to several minutes, often contributes a substantial portion to the surf zone energy especially during storms when erosion and sediment transport are most acute. The historical development of infragravity wave models and research is discussed as well as infragravity wave dynamics and theoretical generation mechanisms. Field studies identifying infragravity motions are discussed, including the various methods used to measure this complex phenomenon. Considerations for future research including studies to monitor the nearshore morphology, incident wind waves and swell, and infragravity waves are also discussed. These studies would help to understand the link between infragravity energy and nearshore processes (e.g. , sediment transport, sandbar generation, beach cusps and other periodic morphologies, rip currents, and runup). An annotated bibliography is included as an appendix

Annual Data Summary for 1988: CERC Field Research Facility Volume 2: Appendixes C through E

Source: https://erdc-library.erdc.dren.mil/jspui/This volume contains appendices C through E from Technical Report CERC-90-13 "Annual data summary for 1988 : CERC Field Research Facility". The Main text and Appendices A and B of the report can be found in Volume 1 of the report