Matthew K. Howard

Near-Resonant Ocean Response to Sea Breeze on a Stratified Continental Shelf

Abstract The spatial structure and temporal characteristics of sea breeze and the associated coastal ocean response in the northwest Gulf of Mexico are investigated using moored instruments, hydrographic stations, and wind measurements. Near the study area of 30°N, motions in the diurnal–inertial band (DIB) may be significantly enhanced by a near-resonant condition between local inertial and diurnal forcing frequencies. Wavelet analysis is used to quantify the results. Results indicate that diurnal sea-breeze variability peaks in summer and extends at least 300 km offshore with continuous seaward phase propagation. The maximum DIB oceanic response occurs in June when there is a shallow mixed layer, strong stratification, and an approximately 10-day period of continuous sea-breeze forcing. DIB current variance decreases in July and August as the consequence of the deepening of the mixed layer and a more variable phase relationship between the wind and current. River discharge varies interannually and can s...

Low‐Frequency Circulation Over the Texas‐Louisiana Continental Shelf

Low-frequency circulation over the Texas-Louisiana continental shelf is examined. Currents over the inner shelf are upcoast (Rio Grande to Mississippi River) in summer and downcoast in nonsummer and are driven by an annual cycle of winds. This results in an annual signal for salinity, with lowest salinity waters occurring (a) in late spring along the inner portion of the western shelf when downcoast flows carry the high discharges from the Mississippi-Atchafalya and other rivers to the Mexican border, and (b) in summer over the inner and outer eastern shelf when the upcoast flow causes a pooling of the discharges from the Mississippi-Atchafalya rivers over that shelf. Upcoast winds during summer also result in high salinities over the western shelf due to advection from off Mexico and upwelling. Currents over the outer shelf are variable, but predominantly upcoast throughout the year, probably a result of the integrated effects of anticy-clonic eddies impinging on the shelf edge. Comparison of currents in the weather band (2-10 d) with the mesoscale band (10-100 d) suggests the shelf is divided at approximately the 50-m isobath. The weather band predominates over the inner shelf, reflecting frequent passage of fronts over the region. The mesoscale band predominates over the outer shelf, indicating the presence of offshelf eddies that frequent this region.

Seasonal variation of wind-driven diurnal current cycling on the Texas-Louisiana Continental Shelf

We describe observations of large amplitude wind-driven current oscillations of 24-hr period occurring in the near-surface layer of waters of the Texas-Louisiana continental shelf. The near-surface anti-cyclonic current amplitudes can reach 60 cm s−1 and represent the largest non-storm induced high-frequency currents on the shelf. These currents can persist for a week or more, as long as driving diurnal winds persist with uninterrupted phase. The latitude of the shelf and the diurnal period of the wind-forcing combine to produce conditions for a near-resonant response of the surface currents to the wind stress, such that, the resulting currents are almost an order of magnitude greater than those found from steady Ekman drift. The oscillations are phase-locked to time of day suggesting a connection to the daily cycle of heating and cooling. The oscillations generally occur during the summer months when there is a shallow mixed layer, strong vertical stratification, maximum insolation, and infrequent frontal passages.

Eddy Forced Variations in On‐ and off‐Margin Summertime Circulation Along the 1000‐m Isobath of the Northern Gulf of Mexico, 2000–2003, and Links with Sperm Whale Distributions Along the Middle Slope

In summers 2000-2003, NOAA Ship Gordon Gunter and TAMU R/V Gyre dropped XBTs and logged ADCP data while carrying out visual and passive-acoustic surveys for sperm whales along the 1000-m isobath of the northern Gulf of Mexico. The ships also made CTD casts, particularly when/where the XBT and ADCP data indicated the ships were passing into or out of anticyclonic and/or cyclonic slope eddies. The fine-scale resolution of the ship surveys, when combined with the meso-scale resolution of remote sensing surveys of sea surface height and ocean color, document the summer-to-summer variability in the intensity and geographic location of Loop Current eddies, warm slope eddies, and areas of cyclonic circulation over this middle slope region of the northern Gulf of Mexico. These variations forced striking year-to-year differences in the locations along the 1000-m isobath where there was on-margin and off-margin flow, and in locations where sperm whales were encountered along the 1000-m isobath. For example, when there was on-margin flow into the Mississippi Canyon region in early summer 2003, sperm whales were very rarely seen or heard there. In contrast, later that summer and during other summers when flow was along-margin or off-margin there, sperm whales were locally abundant. In this report we describe how eddy-forced variations in on-margin and off-margin flow changed the meso-scale circulation along the 1000-m isobath, and we show that most sperm whales were encountered in regions of negative SSH and/or higher-than-average surface chlorophyll.

IOOS vocabulary and ontology strategy for observed properties

With the rapid growth of coastal ocean observations becoming available for integration by US Integrated Ocean Observing System (IOOS) Regional Associations and federal data assembly centers, there is a need for the establishment of IOOS Parameter Vocabulary strategy. Currently, different data naming conventions are being used by existing regional and subregional coastal ocean observing systems. This makes things complicated for the discovery, access and proper usage of the valuable data. To eliminate the misuse and misinterpretation of the data being made available and to facilitate the discovery and proper use of in data scientific research and other management applications, the authors have presented the development of IOOS Parameter Vocabulary and recommended a strategy to move this forward with ocean observing community engagement.

U.S. IOOS Program Office Quality Assurance of Real-Time Ocean Data Project

The Quality Assurance of Real-Time Ocean Data (QARTOD) Project is an activity of the U.S. Integrated Ocean Observing System (IOOS) Program Office designed to establish and document the minimum quality control and quality assurance procedures a non-federal Regional Information Coordination Entity must perform to meet certification criteria. Regional entities like the Gulf of Mexico Coastal Ocean Observing System Regional Association, and others, expect to benefit from certification by gaining federal protection from civil liability associated with dissemination and use of IOOS data and by becoming eligible to compete for future funding opportunities which may require certification. More importantly, these procedures will help ensure that only valid qualified data are inserted into and redistributed by the national data system.

Cabled ocean observatories in Sea of Oman and Arabian Sea

An ocean observatory—consisting of a real-time, cabled array in the Sea of Oman and an internally recording, autonomous mooring array recently upgraded to a cabled array in the northern Arabian Sea—celebrated more than 2500 days of continuous operation in July 2012. The observatory, which measures a range of properties, such as water current velocities, temperature, salinity, pressure, dissolved oxygen, and turbidity, is part of the Lighthouse Ocean Research Initiative (LORI) project [du Vall et al., 2011], which was designed as a pilot project and installed in 2005 in the region off Abu Bakara (Figures 1a and 1b). The initial goal of the project was to prove that an in situ, cabled ocean observatory can return high-quality scientific data on a real-time basis over longer time periods than conventional moored systems. That same year, an autonomous array was deployed off Ras al Hadd and on Murray Ridge in the Arabian Sea (Figure 1a).

One System, Many Societal Benefits: Building an Efficient, Cost-Effective Ocean Observing System for the Gulf of Mexico

Abstract During a decade of building the Gulf of Mexico Coastal Ocean Observing System (GCOOS), there has been convincing evidence that an integrated “system of systems” is an effective, efficient system that provides many societal benefits, including economic development opportunities. The Gulf community has come a long way toward establishing a regional ocean observing system, and with input from more than 700 stakeholders, the GCOOS Regional Association has developed a comprehensive blueprint for monitoring in the Gulf. This blueprint, the GCOOS Build-out Plan, can and should serve as a guide for future investments, including those intended to generate meaningful ecosystem indicators that inform the restoration process and ascertain the success of restoration efforts. With an unprecedented opportunity via The Clean Water Act penalty monies, the region is poised to build on extensive multi-institutional, interdisciplinary relationships to expand existing infrastructure into a comprehensive system that can address the myriad issues facing the Gulf.

Integrating Observing Systems to benefit stakeholders: A case study in the Gulf of Mexico

The U.S. Integrated Ocean Observing System is being designed to be an end-to Dend, integrated, sustained, operational System of Systems that provides data, information and products to benefit a broad range of stakeholders in their decision-making. These design concepts form the basis of pilot projects being undertaken by the Gulf of Mexico Coastal Ocean Observing System Regional Association (GCOOS-RA). This paper presents a case study of the GCOOS-RA Harmful Algal Bloom Integrated Observing System (HABIOS) Project. A set of research activities related to harmful algal blooms is examined for eventual transition from pilot project to an integrated operational system. The end-to-end nature of the system is explored from the perspectives of design and operation, data management and communication, modeling and analysis, decision-support tools and outreach, and benefits to stakeholders at national, regional, state, and local levels. The case study of the HABs pilot projects will demonstrate that HAB-related observations need to be both sustained and operational, and that progress is being may through the integration of the efforts of many entities concerned with detecting and monitoring HAB events and mitigating HAB impacts.

Making sense of ocean sensing: the Gulf of Mexico Coastal Ocean Observing System links observations to applications

The Gulf of Mexico Coastal Ocean Observing System Regional Association (GCOOS-RA) works to enhance our ability to collect, deliver and use ocean information. The GCOOS-RA Education and Outreach Council works to bring together industry, governments, academia, formal and informal educators, and the public to assess regional needs for coastal ocean information, foster cooperation, and increase utility of the data. Examples of data products in varying stages of development are described, including web pages for recreational boaters and fishermen, novel visualizations of storm surge, public exhibits focused on five Gulf of Mexico Priority Issues defined by the Gulf of Mexico Alliance, a Harmful Algae Bloom warning system, the Basic Observation Buoy project designed to engage citizen scientists in ocean monitoring activities, and the GCOOS Data Portal, instrumental in Deepwater Horizon mitigation efforts.