Satellite Imagery for Ocean Monitoring: Key Benefits
The oceans take up over 70 percent of the planet's surface, and they have a significant role to play in climate regulation, marine ecosystems, transportation, fisheries, and coastal economies. The monitoring of such a large dynamic environment cannot rely on ground surveying alone. Using satellite imagery to monitor oceans is a solution for efficiently observing the state of oceans.
State-of-the-art Earth observation satellites use optical, multispectral, hyperspectral, and SAR imagery, which can be analyzed to assess the state of oceans, coastlines, marine habitats, and anthropogenic activity. In combination with GIS, remote sensing, and spatial analysis, satellite imagery enables efficient ocean monitoring.
What Is Satellite Imagery for Ocean Monitoring?
Satellite imagery for ocean monitoring is defined as Earth observation data gathered by satellites for analysis and measurement of oceans' physical, biological, and environmental parameters.
Information provided by satellite imagery depends on the sensors and wavelength and includes such factors as:
Sea surface temperature
Ocean color and water quality
Concentration of chlorophyll
Suspended sediments
Harmful algal blooms
Extent of sea ice
Oil spills
Coastal erosion
Conditions of marine habitats
Ocean surface phenomena
Presence of ships and their location
Multi-temporal satellite imagery is especially useful since it allows comparing images taken at different time periods.
Key Benefits of Satellite Imagery for Ocean Monitoring
Wide-Area Coverage of the Ocean
First, satellites can observe an area of ocean, coast, or marine area over a very large geographic extent. This means that satellite imagery can be helpful in assessing areas where it is hard to access using ships or airplanes.
Furthermore, it can be helpful for regional and global assessment of the marine environment.
Repeated Monitoring Over Time
Earth observation satellites can acquire images repeatedly, providing opportunities for time-series observations for scientists and GIS practitioners.
Time-series of satellite images can help to recognize:
Seasonal changes in the water environment
Sea ice changes
Movement of the coastal shoreline
Sedimentation
Algal blooms
Changes in ecosystems
Weather phenomena
Thus, comparison of satellite images from various dates provides a practical way of recognizing environmental changes.
Water Quality of the Ocean
The use of satellite imagery is very helpful for assessing several indicators associated with the quality of ocean and coastal waters. Sensors in satellites use reflected electromagnetic radiation with different wavelengths to derive information regarding the water body properties.
Remote sensing technologies can detect any change in:
Turbidity
Suspension of sediment
Chlorophyll-a
Water color
Dissolved materials
Coastal pollution pattern
Various spectral indices and water quality algorithms could be applied to satellite data in order to convert the observations into indicators.
Monitoring Chlorophyll and Marine Productivity
The observations of ocean color are often utilized for the study of phytoplankton and marine productivity. Concentration of chlorophyll-a is a significant indicator, as phytoplankton is the base of many marine ecosystems.
The chlorophyll product derived from satellites could be useful for research on:
Primary productivity
Distribution of phytoplankton
Fisheries
Nutrients availability
Changes in the ecosystem
Harmful algal blooms
Detecting Harmful Algal Blooms
Harmful algal blooms may pose a threat to marine environments, the fishing industry, tourism, and people’s health. Satellite remote sensing can be used to determine and observe any large-scale changes in the ocean color caused by the presence of algal blooms.
This can be achieved by using spectral properties and algal pigment derivatives.
Satellite remote sensing becomes even more effective when it is complemented by field measurements and oceanic models.
Oil Spill Detection
Another application of satellite imagery is the detection of oil spills. In particular, SAR imagery is useful for this purpose because of its ability to acquire images at any time during the day and under cloudy conditions better than optical sensors.
The presence of an oil film at the sea surface may influence the roughness of the surface at smaller scales, causing the appearance of dark patches in the SAR images. This pattern can be used to detect oil spills and track their location.
It should be noted that dark SAR spots do not always indicate oil spills because there are other factors, such as wind, natural surface films, wind-shadow areas, and others, which may cause similar signatures.
Coastal Change and Erosion Monitoring
Monitoring changes on the coasts can be achieved by using satellite images. Shorelines that are extracted from satellite images captured at different times can show movement in the coastline, and areas that are eroding or accreting.
This data is important in:
Coastal zone management
Infrastructure planning
Climate change studies
Monitoring beaches
Conservation of habitats
Risk analysis in disasters
High-resolution satellite images can be used in localized coastal monitoring studies, whereas medium-resolution satellite images are important in regional coastal monitoring studies.
Sea Ice Monitoring
Monitoring sea ice can be done using remote sensing via satellites. Using optical sensors, visual information about the ice can be obtained in good lighting and atmospheric conditions, whereas using SAR data, ice observation can be done irrespective of weather conditions and lighting.
Satellite data can be used to estimate:
Extent of the sea ice
Ice concentration
Ice motion
Ice break-up
Seasonal variations
Long-term trends
These are very important in climate studies, navigation, ecological studies, and polar operations.
Monitoring Marine and Coastal Habitats
Remote sensing may be used in mapping and monitoring marine environments, including coral reefs, seagrass beds, and other coastal areas.
Differences in spectral reflectance that characterize various habitats may be observed through multispectral and hyperspectral imaging. Satellite images can assist in the mapping and change detection of habitat distribution when the appropriate atmospheric correction, water column correction, and classification techniques are used.
High-resolution images may also be beneficial for mapping of coastal habitats in clear and shallow waters.
Ship and Maritime Activity Monitoring
Monitoring of ships and maritime activities may also benefit from using satellite imagery. Optical satellite imagery can deliver visual data on vessels, whereas SAR images can be helpful to identify the presence of vessels under almost any weather and illumination conditions.
Satellite observations can be utilized to analyze:
Positions of vessels
Port activities
Offshore facilities
Shipping routes
Fishing activities
Maritime traffic patterns
Satellite imagery can also supplement Automatic Identification System (AIS) data.
Important Satellite Sensors for Ocean Monitoring
Diverse satellite sensors have various kinds of capabilities and functions. The choice of the sensor is determined by its purpose, resolution, atmosphere, and environment.
Optical and Multispectral Sensors
These satellites use sunlit radiation in the visible and near-infrared parts of the spectrum. They are beneficial in studying the oceanic color, shoreline, sediments, plants, and shallow waters.
It is worth mentioning that optical data may be distorted due to clouds, haze, atmospheric conditions, and low illumination.
Hyperspectral Sensors
These sensors obtain numerous spectral bands. These spectral details are useful in distinguishing the components and elements of the water.
The hyperspectral data is applicable for scientific purposes, such as the analysis of water quality, phytoplankton, sediment composition, and marine habitats.
Synthetic Aperture Radar
The SAR system transmits microwave signals and measures the backscatter from the target. The main advantage of SAR technology is that it does not require illumination by the sun.
Hence, SAR technology can be used at any time of day. Cloud-penetrating capability makes SAR an ideal choice for ocean observation tasks, including oil spill, sea ice detection, and ship detection.
Challenges and Limitations
Despite the advantages of satellite imagery, there are also some limitations associated with it. The optical sensors might be limited by the presence of clouds and atmospheric interference. Spatial resolution might not be adequate for the study of very small objects, while satellite revisits might limit the frequency of observations.
Some other challenges might include:
Atmospheric correction over water
Sun glint interference
Shallow water column effect
Resolution limitation of the sensor
Mixed pixels near the shore
Similarity of surface objects
Field validation data requirement
Volumetric raster datasets
For reliable analysis of the satellite observations, one should select the satellite observations according to environmental requirements and monitoring goals.
Accelerate Your Ocean Monitoring With GeoWGS84
GeoWGS84 provides access to very high-resolution satellite and aerial imagery that can be used to support several ocean and coastal monitoring projects. Utilizing current and historic imagery with GIS and remote sensing techniques, users are able to analyze marine environments, monitor coastal change, analyze water quality, and monitor areas of interest.
Uses of GeoWGS84 imagery include:
Coastal and shoreline change detection
Ocean and coastal environmental monitoring
Mapping of marine habitats
Water quality and sediment analysis
Oil spill and surface feature assessment
Coastal development monitoring
Disaster and storm impact analysis
Analysis of long-term environmental change
Access to very high-quality geospatial imagery enables users to integrate satellite imagery into their current GIS and remote sensing processes. Given the right type of spatial, spectral, and temporal resolution, imagery can turn large geographic areas into actionable spatial information for ocean and coastal applications.
The Future of Satellite-Based Ocean Monitoring
Progress in satellite sensors, cloud computing, AI, and geospatial analysis is enhancing the potential of ocean monitoring through satellites. Higher resolution imaging, enhanced revisit rates, and advanced processing techniques are allowing greater spatial and temporal analysis of marine environments.
Machine learning algorithms can be used to analyze large databases of satellite imagery for classification, identification of patterns, and detection of environmental changes. Analysis of satellite imagery along with GIS, oceanographic models, in situ observations, and other geospatial data can enhance the understanding of marine environments.
The use of satellite imagery in ocean monitoring allows one to have an efficient and scalable system for monitoring Earth’s oceans. Whether it is the assessment of water quality, chlorophyll content, oil spill identification, coastal erosion studies, sea ice mapping, or marine habitat monitoring, there are many uses of satellite images.
Through the use of satellite remote sensing, GIS, and sophisticated spatial analytics, organizations are able to turn Earth observation data into useful geographic information. With ongoing developments in satellite technology and AI-based geospatial analysis, satellite imagery will stay relevant for ocean monitoring in the coming years.
For more information or any questions regarding satellite imagery for Ocean Monitoring, please don't hesitate to contact us at
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