Ship and Satellite Studies of Mesoscale Circulation and Sperm Whale Habitats in the Northeast Gulf of Mexico During GulfCet II

Eighty-three encounters with sperm whales (Physeter macrocephalus) occurred on two cruises that made expendable bathythermograph + conductivity-temperature-depth surveys of cyclone-anticyclone eddy pairs in the Northeast Gulf of Mexico (NEGOM). In late summer 1996, 41 sightings of sperm whales were made and 10 acoustic contacts were registered. Of these 51 encounters, 90% were in a cyclonic area of lower than average dynamic height offshore that was surveyed from space by near-real-time altimetric sea surface height anomaly and then mapped in high resolution with shipboard measurements or within 100 km of SW Pass of the Mississippi River. In midsummer 1997, 23 sightings and nine acoustic contacts were made. Of these 32 encounters, 81% were in an offshore cyclonic area of lower than average dynamic height or within 100 km of the mouth of the Mississippi River. Time series animation of the 1996 and 1997 altimetric data indicated these cyclones are typically associated with Loop Current excursions into the NEGOM and that the two cyclones we surveyed had spun up 4-6 mo previous to our fieldwork. Although cyclones in the NEGOM are temporally persistent, their geographic location is spatially variable: the cyclone surveyed in 1996 was centered 150-200 km south and east of the Mississippi River delta in water 2-3 km deep, whereas that surveyed in 1997 was centered farther east in water 2-3 km deep over DeSoto Canyon. Sperm whales appear to have affinity for cyclonic eddies because the largest numbers of encounters with sperm whales also shifted east in 1997 compared with 1996

The Loop Current: Observations of deep eddies and topographic waves.

Author Posting. © American Meteorological Society, 2019. 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 49(6), (2019):1463-1483, doi: 10.1175/JPO-D-18-0213.1.A set of float trajectories, deployed at 1500- and 2500-m depths throughout the deep Gulf of Mexico from 2011 to 2015, are analyzed for mesoscale processes under the Loop Current (LC). In the eastern basin, December 2012–June 2014 had >40 floats per month, which was of sufficient density to allow capturing detailed flow patterns of deep eddies and topographic Rossby waves (TRWs), while two LC eddies formed and separated. A northward advance of the LC front compresses the lower water column and generates an anticyclone. For an extended LC, baroclinic instability eddies (of both signs) develop under the southward-propagating large-scale meanders of the upper-layer jet, resulting in a transfer of eddy kinetic energy (EKE) to the lower layer. The increase in lower-layer EKE occurs only over a few months during meander activity and LC eddy detachment events, a relatively short interval compared with the LC intrusion cycle. Deep EKE of these eddies is dispersed to the west and northwest through radiating TRWs, of which examples were found to the west of the LC. Because of this radiation of EKE, the lower layer of the eastern basin becomes relatively quiescent, particularly in the northeastern basin, when the LC is retracted and a LC eddy has departed. A mean west-to-east, anticyclone–cyclone dipole flow under a mean LC was directly comparable to similar results from a previous moored LC array and also showed connections to an anticlockwise boundary current in the southeastern basin.The authors were supported by the Department of the Interior, Bureau of Ocean Energy Management (BOEM), Contract M08PC20043 to Leidos, Inc., Raleigh, NC. The authors also wish to acknowledge the enthusiastic support of Dr. Alexis Lugo-Fernández, the BOEM Contracting Officer’s Technical Representative, during the study into the Deep Circulation of the Gulf of Mexico, using Lagrangian Methods. Thanks go to the captains and crews of the R/V Pelican and B/O Justo Sierra, J. Malbrough (LUMCON), J. Singer (Leidos), J. Valdes (WHOI), B. Guest (WHOI), and the CANEK group (CICESE).2020-05-2

Hydrography of the Gulf of Mexico using autonomous floats

Author Posting. © American Meteorological Society, 2018. 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 48 (2018): 773-794, doi:10.1175/JPO-D-17-0205.1.Fourteen autonomous profiling floats, equipped with CTDs, were deployed in the deep eastern and western basins of the Gulf of Mexico over a four-year interval (July 2011–August 2015), producing a total of 706 casts. This is the first time since the early 1970s that there has been a comprehensive survey of water masses in the deep basins of the Gulf, with better vertical resolution than available from older ship-based surveys. Seven floats had 14-day cycles with parking depths of 1500 m, and the other half from the U.S. Argo program had varying cycle times. Maps of characteristic water masses, including Subtropical Underwater, Antarctic Intermediate Water (AAIW), and North Atlantic Deep Water, showed gradients from east to west, consistent with their sources being within the Loop Current (LC) and the Yucatan Channel waters. Altimeter SSH was used to characterize profiles being in LC or LC eddy water or in cold eddies. The two-layer nature of the deep Gulf shows isotherms being deeper in the warm anticyclonic LC and LC eddies and shallower in the cold cyclones. Mixed layer depths have an average seasonal signal that shows maximum depths (~60 m) in January and a minimum in June–July (~20 m). Basin-mean steric heights from 0–50-m dynamic heights and altimeter SSH show a seasonal range of ~12 cm, with significant interannual variability. The translation of LC eddies across the western basin produces a region of low homogeneous potential vorticity centered over the deepest part of the western basin.The authors were supported by the Department of the Interior, Bureau of Ocean Energy Management (BOEM), Contract M08PC20043 to Leidos, Inc., Raleigh, North Carolina.2018-10-0

Deep eddies in the Gulf of Mexico observed with floats

Author Posting. © American Meteorological Society, 2018. 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 48 (2018): 2703-2719, doi:10.1175/JPO-D-17-0245.1.A new set of deep float trajectory data collected in the Gulf of Mexico from 2011 to 2015 at 1500- and 2500-m depths is analyzed to describe mesoscale processes, with particular attention paid to the western Gulf. Wavelet analysis is used to identify coherent eddies in the float trajectories, leading to a census of the basinwide coherent eddy population and statistics of the eddies’ kinematic properties. The eddy census reveals a new formation region for anticyclones off the Campeche Escarpment, located northwest of the Yucatan Peninsula. These eddies appear to form locally, with no apparent direct connection to the upper layer. Once formed, the eddies drift westward along the northern edge of the Sigsbee Abyssal Gyre, located in the southwestern Gulf of Mexico over the abyssal plain. The formation mechanism and upstream sources for the Campeche Escarpment eddies are explored: the observational data suggest that eddy formation may be linked to the collision of a Loop Current eddy with the western boundary of the Gulf. Specifically, the disintegration of a deep dipole traveling under the Loop Current eddy Kraken, caused by the interaction with the northwestern continental slope, may lead to the acceleration of the abyssal gyre and the boundary current in the Bay of Campeche region.The authors were supported by the Department of the Interior, Bureau of Ocean Energy Management (BOEM), Contract M10PC00112 to Leidos, Inc., Raleigh, North Carolina.2019-05-0

The Meanings of Consonants

Proceedings of the Twenty-Ninth Annual Meeting of the Berkeley Linguistics Society: General Session and Parasession on Phonetic Sources of Phonological Patterns: Synchronic and Diachronic Explanations (2003

Dominant circulation patterns of the deep Gulf of Mexico

Author Posting. © American Meteorological Society, 2018. 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 48 (2018): 511-529, doi:10.1175/JPO-D-17-0140.1.The large-scale circulation of the bottom layer of the Gulf of Mexico is analyzed, with special attention to the historically least studied western basin. The analysis is based on 4 years of data collected by 158 subsurface floats parked at 1500 and 2500 m and is complemented with data collected by current meter moorings in the western basin during the same period. Three main circulation patterns stand out: a cyclonic boundary current, a cyclonic gyre in the abyssal plain, and the very high eddy kinetic energy observed in the eastern Gulf. The boundary current and the cyclonic gyre appear as distinct features, which interact in the western tip of the Yucatan shelf. The persistence and continuity of the boundary current is addressed. Although high variability is observed, the boundary flow serves as a pathway for water to travel around the western basin in approximately 2 years. An interesting discovery is the separation of the boundary current over the northwestern slope of the Yucatan shelf. The separation and retroflection of the along-slope current appears to be a persistent feature and is associated with anticyclonic eddies whose genesis mechanism remains to be understood. As the boundary flow separates, it feeds into the westward flow of the deep cyclonic gyre. The location of this gyre—named the Sigsbee Abyssal Gyre—coincides with closed geostrophic contours, so eddy–topography interaction via bottom form stresses may drive this mean flow. The contribution to the cyclonic vorticity of the gyre by modons traveling under Loop Current eddies is discussed.This work was supported by the Bureau of Ocean Energy Management (BOEM) under Contract M10PC00112 assigned to Leidos, Inc

Variability of satellite-derived sea surface height anomaly, and its relationship with Bigeye tuna (Thunnus obesus) catch in the Eastern Indian Ocean

We analyzed the variability of sea surface height anomaly (SSHA), and its relationship with Bigeye tuna catch in the eastern Indian Ocean (EIO) off of Java Island (Indonesia). Both time series of SSHA and Bigeye tuna HR show dominant signals corresponding to the annual and inter-annual variability. During the southeast monsoon the wind blows along southern coast of Java and produces coastal upwelling. This causes sea level to drop due to an offshore Ekman transport, and thermocline becomes shallower. During El Niño and Indian Ocean Dipole (IOD) positive phase, upwelling is more intense and a large cold eddy forms in the EIO off Java. Generally, Bigeye tuna HR tends to increase during upwelling seasons and becomes even higher during El Niño and the positive phase of the IOD. The increased Bigeye tuna HR during the southeast monsoon, El Niño and the IOD positive phase can be attributed to the shallower thermocline depth and the enhancement of biological productivity due to development of eddies and strong upwelling in the EIO. The spatial distribution of SSHA indicates that Bigeye tuna catches are abundant in the frontal regions between cold and warm eddies

Altimeter sampling characteristics using a single satellite

This is the published version. Copyright 1998 WileyAltimetric satellites have characteristic sampling patterns in both space and time based on their repeat period and orbit inclination. Aliased phenomena measured by altimetric measurements can appear as propagating waves with both wavelength and direction of propagation different from the underlying phenomena. All signals that contribute to the altimetric measurement can be aliased and produce such patterns, not just tidal signals. For example, mesoscale energy will be aliased as will unmodeled atmospheric variations. Past discussions of aliasing have only considered spatially homogeneous signals. This paper extends this work to phenomena with finite wavelengths and considers both the north-south and east-west components of the resulting aliases

Application to the Analysis of Germinal Center Reactions In Vivo

Simultaneous detection of multiple cellular and molecular players in their native environment, one of the keys to a full understanding of immune processes, remains challenging for in vivo microscopy. Here, we present a synergistic strategy for spectrally multiplexed in vivo imaging composed of (i) triple two-photon excitation using spatiotemporal synchronization of two femtosecond lasers, (ii) a broad set of fluorophores with emission ranging from blue to near infrared, (iii) an effective spectral unmixing algorithm. Using our approach, we simultaneously excite and detect seven fluorophores expressed in distinct cellular and tissue compartments, plus second harmonics generation from collagen fibers in lymph nodes. This enables us to visualize the dynamic interplay of all the central cellular players during germinal center reactions. While current in vivo imaging typically enables recording the dynamics of 4 tissue components at a time, our strategy allows a more comprehensive analysis of cellular dynamics involving 8 single-labeled compartments. It enables to investigate the orchestration of multiple cellular subsets determining tissue function, thus, opening the way for a mechanistic understanding of complex pathophysiologic processes in vivo. In the future, the design of transgenic mice combining a larger spectrum of fluorescent proteins will reveal the full potential of our method