Table of Contents

About disaster management

RADARSAT images support activities related to the operational mapping and monitoring of natural disasters, such as:

• Prevention involves gathering baseline data, identifying potential hazardous sites and assessing the availability of facilities and equipment necessary to assist in emergency response activities
• Preparedness involves monitoring the high-risk area in order to provide early warning of potential disasters
• Emergency response to a specific incident involves identification of the location, assessment of the extent of the disaster and short-term monitoring of the event
• Recovery by monitoring of the affected areas for damage assessment and environmental impact for the reconstruction and rehabilitation of an area

For satellite imagery to be effective during disasters, three basic criteria must be met:

• the satellite sensor must be able to detect the phenomenon and subsequent changes
• the satellite must have reliable and frequent coverage over the area affected
• the satellite program must be able to deliver the data to the end-user in a timely fashion

RADARSAT's ability to operate independently of the weather and atmospheric conditions provides a level of reliability not available from optical sensors. The following table summarizes the features of the RADARSAT satellite program and their benefits for mapping and monitoring disaster events.

The following sections will help in understanding what is achievable with the RADARSAT satellite and what services are available to assist clients in incorporating RADARSAT into their information products.

• Planning: An Essential Step
• Commercial Services for Disaster Management
• Optimizing the RADARSAT Product for Disasters

Planning: An Essential Step

The management of disasters involves the timely coordination of different tasks and resources. The use of Earth observation satellite for disaster response management is now a reality. However, using remote sensing effectively and consistently in emergencies requires proactive and comprehensive planning. This includes incorporating the acquisition of satellite imagery into official emergency procedures, which can be activated at any time.

There are a number of steps required to successfully integrate remote sensing technology into decision making for emergency response. An implicit requirement to its successful integration is an understanding of the remote sensing system characteristics, capabilities and ordering process. Time is critical during the assessment of an emergency, therefore a clear procedure is essential to minimize the time required at each step of the process.

The steps/stages involved for successful use of remote sensing products in emergency situations include:

• the ordering of imagery over the disaster area from one or more systems
• the acquisition and reception of the imagery
• processing and delivery of image products
• the generation of information products to be delivered to the decision makers and field workers involved in the emergency response

Sufficient capability to utilize remote sensing data does not always reside within the organization responsible for managing response activities. Many industries/companies with remote sensing expertise deliver timely information products to support the organizations involved in emergency response activities.

The following diagram (Figure 1) describes the steps or processes involved in accessing RADARSAT for emergency response activities and must be addressed to effectively access timely information products over the disaster area. Planning for the future will ensure that at the time of the emergency, the best RADARSAT solution will be available.

Figure 2 graphically represents the various steps and organizations involved in providing a RADARSAT image to a client.

Data Ordering

The ordering of images is the first step in assessing the magnitude and impact of the disaster is the first critical step. All satellite remote sensing systems have fixed orbits, which directly influence the time at which an area can be imaged. RADARSAT has the advantage of having variable viewing geometries, which allow for repeat coverage of a location every one to five days (depending on latitude).

The ordering of RADARSAT imagery occurs through an official order desk. The RADARSAT acquisition planning timeline at the Mission Management Office (MMO) provides for emergencies. The process of placing an emergency acquisition request includes completing the Emergency Request Form. The order desks will assist the users in completing this form which is used to assess the status of the emergency. The information in the form will provide the Canadian Space Agency with appropriate information to decide whether to approve the emergency acquisition. 

CSA guidelines are used to determine if the request fulfills the emergency status requirements. The details of these guidelines (also available at the order desks), called The Guidelines for Emergency Data Acquisition, define the type of environmental and non-environmental situations which constitute an emergency. If the request is approved as an emergency, the MMO will take the necessary steps to program the satellite for the next available opportunity. 

When placing the order for an emergency acquisition, the following information must be provided to the order desk:

• nature and description of the disaster
• latitude and longitude coordinates of the disaster area to be imaged
• the scale (area covered) of the disaster and required resolution
• RADARSAT beam mode and position (support is provided in determining these parameters)
• frequency of imaging required to support the operations

Data Reception and Delivery

MDA Geospatial Services and the participating network stations will provide basic processing of the data from RADARSAT once it is has arrived at the processing facility. When the delivery of data products is time-critical, near-real time processing combined with electronic delivery is most effective. The product most often delivered for time-critical applications is Path Image (or SGF). This product contains latitude/longitude positional information but is still oriented in the direction of the satellite orbit. 

In addition to programming the acquisition, the MMO decides which network station will receive the raw data. Generally, data acquisitions occurring within the direct downlink area of a participating network station will receive the data. If a network station is not available, the data is stored on the on-board recorder and is downlinked to one of the Canadian network stations (Gatineau, Quebec or Prince Albert, Saskatchewan). 

Delivery and Utilization

The final stage to the successful integration of RADARSAT into decision support for emergency response activities is the delivery of the information product to the end-user and its actual use. In advance of an emergency situation, consideration should be given to:

• Who can make effective use of this information?
• What type of information product will be most effectively utilized?
• In what format will they require the product (digital or hardcopy, map or table, etc.)?
• How will they receive the product?

Questions such as these can provide the basis for effective information dissemination to all involved in the emergency response process. By building a pro-active comprehensive action plan from the time the image is ordered to its final delivery to an end-user, RADARSAT and other satellite remote sensing systems can play an important supporting role for disaster management and emergency response.

Commercial Services for Disaster Management and Monitoring

MDA Geospatial Services (MDA) offers services to support the management and monitoring of disaster events. These include:

• Priority and Urgent programming
• Rush and Near-real Time processing
• Electronic delivery
• RADARSAT Emergency Response Subscription Service (RERSS)

The specific services designed to meet the needs of disaster management, monitoring and mapping are described below. Additional information on these services is available from the Client Service department at MDA Geospatial Services, at tel: 1-604-244-0400, fax: 1-604-244-0404 or email: info@rsi.ca. MDA can provide information on the value added industry which can help deliver information products tailored to the users requirements.

Programming Services

MDA Geospatial Services provides a number of programming service options within the commercial user ordering system. MDA's priority programming service is well suited for monitoring programs and contingency plans. Urgent programming enables the RADARSAT satellite to be tasked for unexpected events. Under the Urgent programming service, 48 hours is required to finalize an acquisition plan. As well, MDA will assist clients in obtaining CSA Emergency Acquisition Programming if a genuine emergency occurs.

Processing Services

After the RADARSAT image has been acquired, it is processed into a product requested by an end-user. Near-Real Time processing is designed for emergencies when products must be delivered within hours of acquisition. Under this service, imagery is processed as soon as it has been received at the processing facility and is ready for delivery to the client within 4 hours. Rush processing service provides image products to the end-user within 48 hours of acquisition.

Electronic Delivery

In situations where products must be in the hands of the user within hours of acquisition, electronic delivery is available. Specialized information products to enhance transmission over the Internet is also available.

RADARSAT Emergency Response Subscription Service (RERSS)

MDA has formulated a RADARSAT Emergency Response Subscription Service (RERSS) to provide dependable, time-sensitive spatial information for natural disasters and crisis management. This service has been designed to ensure maximum effectiveness of RADARSAT data in responding to a client's urgent need for timely geographic information to incorporate into their decision support tools and operational responses. The service includes operational training to ensure clients are able to independently integrate information into all aspects of their current operations.

Optimizing the RADARSAT Product for Disasters

RADARSAT provides the unique capability of rapidly delivering a wide selection of SAR image products. The choice of product can be tailored for the particular type of disaster to ensure maximum information content is available. The following table summarizes the choices of products.

RADARSAT's strength for disaster mapping and monitoring is in the repeat coverage attainable through the satellite's multiple beam positions. In situations where the timing of the data acquisition is not critical, the beam mode and position can be tailored to maximize the information content of the image for the application. The information below identifies the optimum beam mode and position for some of the typical disaster applications. In emergency situations, the choice of beam mode and position may reflect what is available for the greatest repeat coverage of the region of interest. Therefore, there will be a trade-off between optimizing image information content and maximizing repeat coverage.

1. Mapping flood extent

RADARSAT beam mode. The choice of RADARSAT beam mode, which varies between 2,500 to 250,000 square kilometre coverage, will depend on the size of the river basin and expected flood conditions. Fine beam mode provides 8 metre resolution and is sufficient for detailed mapping (approx. 1:50,000) of flood extent in small river basins. In larger basins such as Manitoba's Red River, Standard and Wide beam mode with 25 metre resolution is considered a suitable trade-off between coverage and level of detail.

RADARSAT incidence angle

Shallow incidence angles create the greatest contrast between water and land; at these angles the water surface becomes more specular and the roughness from the land is enhanced. The optimum RADARSAT beam mode and positions to use for flood mapping are standard beam 4 to 7 (34 to 49 degree incidence angle range). However, the extraction of flood extent information is still possible using steep incidence angles (standard beams 1 to 3) and may be necessary for the quickest acquisition or to ensure the repeat coverage needed to monitor the flood.

Look direction. Using imagery from both descending and ascending orbit passes will increase the repeat coverage of an area as well as providing complementary information.

When to acquire RADARSAT data. Multi-date image acquisition is essential to monitor and map the dynamic evolution of a flooding event as the waters rise and recede.

2. Oil spill detection and mapping

RADARSAT beam mode. The optimum beam mode depends on the size of the oil spill (if known) and area of coverage required. Lower resolution beam modes (e.g. ScanSAR) provide the large area repeat coverage often needed when monitoring for potential oil spills. Wide, Standard and Fine beam mode products provide better resolution for detecting smaller spills and their extent. The better resolution may help in reducing false positive identification of spill locations. Research has demonstrated that any of the RADARSAT beam modes can detect the presence of oil on the water surface.

RADARSAT incidence angle. Steep incidence angles were originally recommended so as to maintain a high ocean clutter-to-noise ratio for signal suppression over an oil spill. With the better-than-expected noise performance, shallower incidence angles can also be considered.

Look direction. Look direction is not a critical factor for oil spill detection but using data from both look directions can significantly increase the revisit time for spill monitoring purposes.

When to acquire RADARSAT data. A critical factor affecting the success of detecting an oil spill is wind speed. Oil is detected on radar imagery because the oil dampens the capillary waves of the ocean surface. Very low wind speeds do not allow for sufficient contrast between ocean and oil-dampened waves. The contrast is also insufficient when wind speeds are high, which create wave action on both oil and non-oil ocean surfaces. The generally accepted wind speeds for optimum oil spill detection are 3 to 10 metres/second.

Please refer to the MDA Geospatial Services Web page for more information.