The second story in this multi-part feature focuses on Horizon Marine, Inc. glider operations in the Gulf of Mexico.

Check back later this summer to read the third story in this multi-part feature!

Horizon Marine’s Glider Operations in the Gulf of Mexico

The second story of this multi-part feature on gliders in the Gulf of Mexico (GOM) shifts from academic research projects to glider operations in industry. Horizon Marine, Inc. (HMI) is a GCOOS partner and a pioneer in operational oceanography. Horizon Marine utilizes state-of-art techniques for oceanographic data analysis and is most notably recognized for eddy monitoring in the GOM (aka Eddy Watch® program). In the recent years, Horizon Marine has added gliders to their operational fleet. This article highlights HMI’s services and how gliders are helping HMI achieve their monitoring goals in the GOM.

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HMI glider operating in the Gulf of Mexico.

HMI’s services concentrate on the location, intensity and evolution of strong ocean currents stemming from the Loop Current (LC) and Loop Current Eddies (LCE) in the GOM, particularly in deepwater (>1000 m) lease blocks across the northern Gulf. HMI specializes in the collection and analysis of real-time observational data throughout the GOM. Complete knowledge and prediction of the LC/LCE location and evolution remains a challenge because information about the subsurface structure of these features is so limited. High-resolution profile data are needed to fully describe the 4D interior the evolving LC system. Collecting such vital profile data can be an expensive and exhaustive process involving vessels, mooring arrays, technicians, and a great deal of time and money. Long-range autonomous underwater gliding vehicles (AUGVs) offer a means to collect high-resolution in situ ocean data from a wide range of sensors at a very low cost compared to conventional methods. Operating gliders demand few man-hours relative to equivalent operations conducted using vessels. Gliders can be re-tasked in an adaptive sense to focus on areas with data gaps, repeat a route, or approach new targets of interest.

HMI glider in preparation for deployment in the Gulf of Mexico

HMI glider in preparation for deployment in the Gulf of Mexico.

In 2009, HMI began experimenting with using gliders for commercial monitoring of the GOM circulation in support of the deepwater exploration and production. The HMI glider instrument facility is located in Houston, TX and flight operations are conducted from Marion, MA. Most glider deployments have been out of the Louisiana Universities Marine Consortium (LUMCON). As of 2013, the bulk of operations have been conducted using Slocum gliders manufactured by Teledyne-Webb Research. HMI conducts about 1-2 deployments each year with a typical deployment lasting 4-5 months. Deployments covers distances greater than 1500 nm, and data collected includes over 1000 vertical profiles to depths of 1000 m. Deployment objectives are generally focused on surveying the central and eastern GOM, from the northern GOM slope to as far south as Cuba and the Yucatan Channel. With long deployments that span a significant portion of the Loop Currents eddy shedding cycle (8-11 months), a single glider can revisit major mesoscale features and track their interior evolution. HMI takes maximum advantage of their existing observational tools (e.g. satellite-tracked drifters, satellite remote sensing data) to improve their ability to fly gliders efficiently and select appropriate survey targets. The data are used to support real-time monitoring of currents and to initialize numerical models of the GOM circulation. The most recent HMI glider deployment ended June 12 after a 4.5 month survey and another glider is scheduled to rotate into the GOM later this month.

HMI’s glider operations are a great example of how gliders are currently improving GOM operational oceanography. The activities highlighted also show the future potential of increasing the integration of gliders into GOM monitoring efforts. Stay tuned for next part of this GCOOS series as GCOOS continues to explore gliders operations in the GOM industry.

HMI Glider Data and Products for 2012 Gulf Operations

Track of HMI's Slocum glider from January to March, 2012 showing the depth-averaged currents.

Track of HMI’s Slocum glider from January to March, 2012 showing the depth-averaged currents.

Figure 2.  Temperature cross-section in the GOM collected by a glider from January-April 2011.  The glider path crosses through the Loop Current, the Yucatan Channel, and a detached Loop Current eddy. Blank areas indicate truncation of the glider dive profile to a maximum or minimum altitude below the sea surface. Every tenth dive is labeled on the upper x-axis and a dot placed every 25 m in the vertical.

Figure 2. Temperature cross-section in the GOM collected by a glider from January-April 2011. The glider path crosses through the Loop Current, the Yucatan Channel, and a detached Loop Current eddy. Blank areas indicate truncation of the glider dive profile to a maximum or minimum altitude below the sea surface. Every tenth dive is labeled on the upper x-axis and a dot placed every 25 m in the vertical.

Figure 3.  Cross-section from 24-31 May 2011 extending from west to east through the LC front region into the interior: potential density (top left), absolute geostrophic velocity relative to 1000 m (top right), temperature (bottom left), and salinity (bottom right).  Refer to Figure 4 for the glider path.  Distances are in km along the glider track except for the cross-stream distance (top right) which is the projected distance perpendicular to the LC stream flow.

Figure 3. Cross-section from 24-31 May 2011 extending from west to east through the LC front region into the interior: potential density (top left), absolute geostrophic velocity relative to 1000 m (top right), temperature (bottom left), and salinity (bottom right). Refer to Figure 4 for the glider path. Distances are in km along the glider track except for the cross-stream distance (top right) which is the projected distance perpendicular to the LC stream flow.

Figure 4.  Drift of the glider during the transmission cycle on the surface calculated from successive GPS positions (left), geostrophic velocity at 25 m (right).  The trajectory corresponds to the cross-sections presented in Figure 11 from 24-31 May. The trajectory and speed of a co-located satellite-tracked ocean drifter is overlaid on the right panel.

Figure 4. Drift of the glider during the transmission cycle on the surface calculated from successive GPS positions (left), geostrophic velocity at 25 m (right). The trajectory corresponds to the cross-sections presented in Figure 11 from 24-31 May. The trajectory and speed of a co-located satellite-tracked ocean drifter is overlaid on the right panel.