HawkEye Evaluation

This project was published in an article led by Mitch Torkelson in May 2026. For more information, check out Torkelson, M.*, Bresnahan, P.J., Rivero-Calle, S., Masud-Ul-Alam, M., Brewin, R.J.W., & Wells, D. (2026). Integrating In Situ Measurements and Satellite Imagery for Coastal Physical and Biological Analysis in the Cape Fear Coastal Region. Remote Sensing, 18(10), 1524. doi.org/10.3390/rs18101524.

Pre-Publication Background Info

As noted above, our manuscript on this work was accepted for publication; please see that article for published results and see below for Mitch’s description of the project from his graduate school days.

Project led by Mitch Torkelson. See Mitch’s full researchportfolio here: https://dinodiver.github.io/mitchtorkelson/.

Introduction

This ongoing project at UNCW evaluates the efficacy of the HawkEye satellite sensor in capturing ocean color (OC) imagery, specifically focusing on the Cape Fear River Estuary (CFRE) in southeastern North Carolina. Coastal and estuarine environments, which are vital for biodiversity and local economies, present unique challenges for remote sensing due to their optically complex waters. This research involves detailed comparisons of in-situ measurements with data from HawkEye and other satellite sensors to refine and enhance marine conservation and management strategies.

Methodology

Our approach leverages a multi-platform strategy that combines HawkEye satellite data with an array of other satellite-derived and in-situ “sea-truthing” chlorophyll a measurements from the CFRE. This integration allows us to assess the accuracy and utility of HawkEye in estimating chlorophyll concentrations, which are crucial for understanding estuarine dynamics.

Utilizing a 3D in-situ dataset for satellite matchup analysis can enhance satellite analysis since satellite sensors often provide a surface-level perspective, which can limit understanding of vertical variations within water bodies. Our 3D approach captures data across different depths, providing a comprehensive view that is essential for accurately interpreting satellite imagery. This depth-resolved data enables enhanced calibration and validation of satellite sensors, leading to improved accuracy in mapping and monitoring aquatic environments. The 3D dataset not only aids in understanding the spatial distribution of water quality parameters but also supports the development of models that predict ecological changes within these complex systems.

The Role of In-Situ Data

In-situ data collection provides ground-truth measurements that are essential for calibrating and validating satellite imagery data. By employing the Sea Sciences Acrobat, a towed oscillating vehicle, along with auxiliary sensors, we capture a detailed snapshot of the water column’s characteristics. The Acrobat allows for rapid, high-resolution, 3-dimensional profiling over large spatial areas, ensuring that we capture comprehensive information on the physical and chemical properties of the water column.

Figure: Deploying the Acrobat during an in-situ data collection mission.

Data Collection Method

During our field missions, we navigate along strategic transects using the R/V Cape Fear, collecting data up to depths of 10 meters. The paths are carefully chosen to capture a representative cross-section of the estuarine environment, including mixing zones and areas influenced by tides and river inflows. The Sea Sciences Acrobat, equipped with sensors for chlorophyll a, salinity, temperature, turbidity, and dissolved oxygen, continuously collects data as it moves up and down through the water column.

We then analyze this data to understand the three-dimensional variability of the estuarine environment. This allows us to identify critical gradients and hotspots that are indicative of dynamic water quality changes.

Figure: The path of our in-situ data collection at the mouth of the Masonboro Inlet.

Preliminary Results

Our 3D in-situ data collection method provides a comprehensive understanding of local water quality, crucial for environmental conservation. Initial analyses show significant spatial and temporal variability in indicators like chlorophyll a and salinity. The detailed maps created from this data reveal clear patterns and hotspots of environmental change, illustrating variations not apparent in surface measurements alone. By integrating these findings with satellite data, we enhance our understanding of estuarine processes and improve the monitoring of the ecosystem’s health and productivity.

Figure: Linearly interpolated chlorophyll a measurements collected along the transects.

Implications and Future Work

The preliminary findings from this study underscore the potential of advanced satellite sensors like HawkEye in improving our understanding of complex coastal waters. By providing more accurate and timely data, HawkEye can significantly aid in the management and conservation of aquatic resources. Ongoing research will focus on further integrating these insights into broader marine management practices and continuing to validate and refine our findings.

Collaboration and Resources

This research is part of a collaborative effort with the COAST Lab at UNCW. For more detailed information on methodologies and ongoing updates, please visit our GitHub Repository.

This research was presented at several conferences and gatherings, including:
· Cape Fear Astronomical Society - May 2024, UNCW, Wilmington, NC
· NC Water Resources Research Institute (WRRI) Annual Conference - March 2024, NC State Campus, Raleigh, NC
· CMS Research Showcase - February 2024, UNCW, Wilmington, NC
· CMS Research Showcase - April 2023, UNCW, Wilmington, NC