Aiding emergency response
In the event of a disaster, real-time monitoring through airborne chemical and radiological remote sensing not only improves safety of emergency responders, but also enables them better analyse the impact for planning and initiating rescue operations, says Paul E Lewis, National Geospatial-Intelligence Agency, USA
According to the United States Environmental Protection Agency (EPA), in the United States alone there are approximately 123 facilities where a release of chemicals could threaten more than 1 million people. There are approximately 750 additional facilities where a chemical release could threaten more than a 100,000 people. The utility of airborne chemical remote sensing became apparent to the EPA during a chemical plant explosion which occurred in Sioux City, Iowa in December of 1994. The facility produced ammonium nitrate fertiliser, and also produced its own ammonia for use in the process. The explosion at the chemical plant ruptured the main storage tank and spilled 3 million gallons of ammonia. This resulted in lethal vapour levels in and around the plant and created a plume of ammonia vapours estimated to be 35 miles long. Approximately 3,500 people were evacuated over a 50 square mile area. The EPA sent in vehicles with ground sampling crews dressed in Level A hazmat suits with 20-minute air packs to monitor the site. Due to heavy snow coverage on the ground and saturated soil conditions underneath the snow, all of the EPA vehicles became stuck. Ground sampling crews had to be rescued before air supplies ran out, consequently, no monitoring of vapour levels could be accomplished.
The lessons learned from responding to this accident along with the identified threat to population centres from potential chemical accidents prompted the EPA to begin evaluating the application, performance and feasibility of airborne infrared and gamma ray remote sensing spectroscopy for emergency responses involving chemical and radiological incidents. During this evaluation process, the following set of core requirements for an operational airborne emergency response capability also emerged:
• Cost-effective operation, maintenance and use of the aircraft
• Affordable COTS sensor technology
• Rapid dispatch/wheels up in under one hour after activation
• Airborne data collection under cloud ceilings
• Timely automated onboard data processing facilitating real or near-real-time chemical and radiological data analysis with low false alarm
• High-resolution day/night ortho-rectified imagery
• Data telemetry to and from the aircraft
• All data, analysis products, and information must be geospatially registered
• Seamless and direct integration of data and information to incident commanders: local, state, and federal joint operations centres
In 2001, the EPA implemented the United States’ only civilian operational airborne chemical and radiological detection and identification capability called the Airborne Spectral Photometric Environmental Collection Technology (ASPECT) Program. In 2003, the EPA and the National Geospatial- Intelligence Agency (NGA) agreed to collaborate in a cooperative research and development program focussed on evolving the capabilities of the ASPECT Program. This collaboration resulted in the following significant accomplishments:
• Near-real-time automated onboard chemical detection and identification for 78 (high probability of occurrence) chemical compounds with low false alarm rates
• Automated software producing near-real-time information on plume direction and concentrations
• Automated software producing day/night orthorectified imagery rapid response maps
• Automated software producing gamma ray survey information maps onboard the aircraft
• Data and information telemetry to and from the aircraft facilitating turnaround times and seamless integration of vital situational awareness information from the aircraft to the first responders or joint operations centres in 5 to 15 minutes after collection.
The emergency response event is always a unique event. The incident itself is often very fast paced, and site conditions can and do change very rapidly as the incident progresses. For any system to be useful in an emergency response incident, it must meet the following three requirements: 1) Respond to the incident in a timely fashion and provide a valued product to the incident management in a time frame that renders the product useful, 2) Collected data and analysis products must be immediately useful to the incident commanders and distributed in a form that does not require the incident management team to require outside expertise to use or understand the products, and 3) The system, while meeting these requirements, must be affordable.
The ability to get an airborne system to an incident in a timely fashion requires that the system be on a 24/7 standby basis. In the case of the ASPECT Program, the system is mandated to be airborne one hour after notification during normal business hours and within 1.5 hours after hours or on weekends. In the case of the ASPECT system, it is located in Texas, a geographical location in three-hour proximity of many potential chemical related incidents along the Gulf Coast of the United States. Once the system has transitioned to the incident site, a second time frame begins to drive the utility of the system; how fast can data be collected over the incident, processed, analysed, and transmitted to the incident managers. Based on how incidents have been managed in the past, any data that is older by about 30 minutes begins to become a history lesson and has minimal benefit to the emergency response. Accordingly, ASPECT has strived to develop a useful, validated product from collection to delivery in 5 to 15 minutes. While this has been a challenge, this is the benchmark that the Program uses and continues to evolve.
Meeting the time requirement is only part of a complete approach to delivering useful information and data. For the information and data to be truly useful, a delivery and presentation capability has to be in place that allows the incident management team to immediately take custody of, understand, and make use of the information and data in their decision process. This mandates that a timely and intuitively understandable product must be delivered that will satisfy the spectrum of emergency services. The ASPECT Program has addressed this requirement by using a combination of onboard automated data processing and satellite-based telemetry data, and sending automated data processing results to a reach back team of scientists and engineers. The ASPECT team’s subject area experts conduct additional analysis to verify all automated processing results and perform quality control checks on the data. Finally, all data is collapsed into a form that provides georeferenced immediate value to the responders and delivered using an intuitive geo-referenced organisational key to all data and information products in a Google Earth KML format (see Figure 4 for an example product). In situations which exclude the use of Google Earth (no remote Internet service), results are verbally transmitted to the incident managers with a follow-up reports as the situation
warrants and permits.
Figure 1: Radiance equation for passive infrared spectroscopy
Airborne remote sensing for chemical and radiological emergency response has become a critical tool for firefighters and emergency response personnel. Since 2001, the ASPECT Program has provided essential information during 115 emergency, disaster, and homeland security related incidents ranging from chemical plant explosions and train derailments to fires, floods, hurricanes and special events. The ASPECT Program played key roles in providing essential information to first responders and joint operations centres in response to the following historical events: 1) the Shuttle Columbia break up during reentry over Texas in February of 2003; 2) Hurricane Katrina in August of 2005; and 3) the Deepwater Horizon Oil Spill Disaster in the Gulf of Mexico from April to August in 2010.
Over the past decade, the APECT Program, the United States’ only operational civilian airborne emergency response remote sensing capability, has demonstrated the utility of having a timely, cost-effective operational airborne chemical and radiological remote sensing capability integrated seamlessly into to the local, state and federal emergency response and disaster recovery and remediation communities.
According to the State New Mexico Department of Homeland Security and Emergency Management, Response and Recovery Bureau Chief, Don Scott, “Real-time monitoring capabilities provided by overhead surveillance improves the safety margin for responders and the public. An airborne response platform offers responders the ability to understand the scope and magnitude of events quicker and over a wider area than ground monitoring, and provides a variety of technical remote sensing capabilities and coverage frequencies not available from satellites. First responders and emergency response operations personnel consider timely and affordable airborne chemical, radiological, and imagery analysis and mapping products essential to the safety of their personnel and an effective tool for optimising their resources during an event as well as subsequent recovery and remediation operations. The next step needs to be appropriation of funding for the implementation of multiple aircraft strategically located throughout the United States so that airborne chemical and radiological remote sensing capabilities can be on the scene of a disaster or event in less than three hours.”
Airborne chemical remote sensing: Passive infrared spectroscopy is an accurate and extensively validated methodology for identification and quantification of chemical plumes. It offers advantages in that chemical monitoring can be conducted quickly over a wide area while keeping monitoring personnel well removed from the actual hazard. Additional advantages are realised by the large number of compounds which can be automatically searched for and screened when compared to most point sensing methodologies. Figure 1 gives physical meaning to each of the components that affect the radiance L(λ) measured by a long wave infrared (LWIR) hyperspectral sensor such as the Fourier Transform Infrared Spectrometer (FTIS) onboard the ASPECT aircraft.
Digital filtering techniques are used to remove the radiance contributions from the background Lg(λ) and the atmosphere La(λ) and to isolate the chemical vapour plume radiance Lp(λ). Pattern recognition techniques are used to identify the chemical vapour species. The radiance contribution of the background is continually changing due to the movement of the aircraft. For this reason, no stable background radiance contribution Lg(λ) can be subtracted from the measured radiance L(λ). Therefore, a signal processing methodology is employed to digitally filter out the unwanted changing background contribution and retain the signature associated with the gas species to be detected. The ASPECT Program developed a matrix filter based signal processing approach to remove the background contribution and isolate the chemical vapour plume signature. Signal processing is performed on the raw data taking advantage of some very important properties the raw data known as the interferogram produced by the FTIS. A most useful inherent property of the interferogram is that spectral domain features are ordered in the interferogram. Broad spectral feature contributions from the background are separated from the narrow spectral feature contributions from the plume and thus, segmentation of the interferogram eliminates a dependence on computationally intense background suppression algorithms. The output of the digital filter is followed by a vector support machine based pattern recognition process which separates the observations into two classes, those which contain a spectral signature of interest and those that do not. The pattern recognition process then compares the signature of interest to a library of 78 (high probability of occurrence) chemical compounds. The digital filtering techniques and the vector support machine based pattern recognition techniques are applied to the set of compounds programmed into a library suitable for a specific incident.
Airborne gamma ray spectroscopy: The ASPECT aircraft sensor system incorporates a geospatially registered state-of-the-art gamma ray spectrometer capable of measuring the spectrum of energy emitted by radioactive isotopes at energy levels from 0 to 3,000 kilo-electron volts (KeV) known as the gamma ray wavelength region from 10-10 to 10-14 metres. These measured gamma ray spectra are unique to specific radioactive isotopes. The gamma ray spectrometer sorts the measured energy levels into 1,024 bins and sums these bins every one second to give a count value for each of the 1,024 measured energy levels as well as a total count sum. An exposure rate is estimated based on a calibration curve that is run at a test site prior to the airborne measurement using a known quantity of radiation. The effective exposure rate plot is the amount of radiation a person at a specific ground level would receive. The various isotope contributions are calculated using a statistical process for determining the measurement compared to a normal Gaussian distribution. The sigma values obtained from this process give an indication of when an isotope is detected and whether the measurement of a particular isotope is statistically significant. Figure 2 illustrates how this information is typically reported in the form of a geospatially registered map.
High-resolution orthorectified day/night imagery products: These products have to be produced and updated at a frequency deemed appropriate by the first responders or joint operations personnel in charge of the incident. These geospatial products ultimately become the universal frame of reference to which all relevant incident information, response recovery and remediation activities, progress, and resource optimisation for an incident are tied.
An onboard GPS system is used to obtain and track the position and altitude of the ASPECT aircraft. The orientation of the aircraft is obtained from an onboard INS system. Using this positioning information with pre-loaded digital elevation model data from the target area, high-resolution imagery is orthorectified for display.
The GPS/INS information is also used to accurately geolocate all airborne chemical and radiological detection results. Providing geospatial products to the first responders would be of little use unless the responders have the capability to display and use these products in their incident discovery and remediation process. ASPECT was a pioneer in using the Google Earth KML file format to deliver and disseminate its airborne emergency response data products to first responders and joint operations centres. The ASPECT Program chose to use the Google Earth KML format for two main reasons: 1) Google Earth maintains a publically accessible online database of high-resolution satellite imagery which has proved essential as a geospatial frame of reference for emergency response personnel; and 2) Google Earth software can be obtained free of charge or licensed for minimal cost and is available for a wide range of platforms thus eliminating any financial barrier. The software is immediately and intuitively usable by emergency response personnel, with it they can access, utilise, understand, geo-reference, update and ingest all ASPECT data into any existing GIS system.
The ASPECT products are delivered in an innovative multilayered approach that provides information tailored to the needs of the user. Figure 4 illustrates portions of a KML that was tailored to the needs of the Deepwater Horizon Incident Command. In Figure 4 for example, high-resolution imagery is first displayed using outlines in Google Earth that depict where imagery coverage is available. Each outline can display a thumbnail type image that provides a preview of what is in the imagery. These outlines are a small file and can be downloaded quickly. An outline of interest can be selected and a highresolution overlay is displayed in Google Earth providing a more detailed layer to the display. Since only images of interest are downloaded, the time required for downloading is minimised. For the first responders, imagery along with the chemical and radiological information within the context of the Google Earth background may be all that is required. However, the Google Earth interface also allows downloading imagery along with ancillary information that allows the ASPECT products to be put into almost any GIS system as an additional layer of delivery. An emergency response centre may have a larger GIS system containing additional data sources that are of use in managing the emergency. ASPECT products can be ingested into these systems from the Google Earth interface.
ASPECT innovative product delivery allows its products to be quickly and efficiently delivered to help serve the needs of emergency response and management at all levels.
The ASPECT’s airborne geospatial chemical and infrared mapping products have made significant contributions to the 2010 Deepwater Horizon Oil Spill Disaster recovery in the Gulf of Mexico. The ASPECT aircraft was deployed to the Gulf of Mexico in response to the Deepwater Horizon oil spill disaster from April 28 through August 10, 2010 and integrated directly into the Deepwater Horizon Incident Command (DHIC) structure. The United States Coast Guard (USCG) was in charge of oil recovery efforts and was the coordinating agency for all DHIC efforts.
The USCG commissioned private locally owned vessels to conduct oil skimming recovery operations. The objective of the oil skimming operations was to protect vulnerable wildlife and fishing areas by removing as much of the damaging floating oil as possible. In these operations, two boats were used to pull a boom on the sea surface to collect floating oil. After enough oil was collected between the boats and in the boom, it was either physically recovered or ignited to burn off the collected surface oil. Figure 3 shows two images taken by the ASPECT aircraft during a chemical emission air quality monitoring mission on May 26, 2010. The DHIC tasked the ASPECT Program with two primary missions: 1) monitoring chemical emission air quality during controlled oil burns and 2) improving the efficiency of skimmer vessel oil recovery operations.
The ASPECT’s chemical emission remote sensing capability was flown directly over and downwind of the fires and it provided operationally significant information to the DHIC. Analysis of the ASPECT’s FTIS data showed slightly elevated amounts of carbon dioxide (CO2), water vapour, carbon monoxide (CO), and ozone. Trace amounts of 1-3-butadiene and acetaldehyde were also identified. The insert in Figure 3 shows a representative spectrum acquired by the FTIS depicting the presence of aldehydes and carbon-hydrogen stretches in the infrared. Analysis of the FTIS data also provided the DHIC with significant information about the chemical content of the burning crude oil, namely, the absence of detected polyaromatic hydrocarbons (PAHs) in the air column over and downwind from the oil burn sites. PAHs are considered a health hazard and the analysis results meant that the crude oil pouring into the Gulf of Mexico has low PAH chemical content. This operationally significant information regarding the PAH health hazard was provided in near-real-time to the DHIC. This information was confirmed much later in the timeframe of the response by physical chemical analysis.
The ASPECT’s infrared imagery map products created and transmitted in near-real-time provided precise geospatial information about the location and quantity of recoverable surface oil. Initially, the DHIC was having difficulty getting their oil skimming vessels to the location of recoverable surface oil resulting in their operations being only 30 per cent effective. Several compounding reasons were responsible for the low oil recovery success rate: 1) DHIC’s analysts were not able to perform accurate and consistent characterisation of surface oil using available imagery sources; 2) Geospatial accuracy of available imagery varied;
3) Timelines for reporting interpreted oil locations were too long; 4) Oil drifted with wind and tide; and 5) Skimmer vessel transit times were too long.
To solve these difficulties, the ASPECT Program combined its airborne spectral infrared imagery, providing both day and night capability to locate and characterise the oil with a software analysis capability specifically designed to automatically create geospatially accurate surface oil characterisation and quantification maps. The software program automatically classifies each pixel of the ASPECT’s spectral imagery into four categories required for direction of oil skimming vessel operations: 1) Recoverable surface oil; 2) Mixed oil/water; 3) Water; and 4) Other. The timeline for collection of airborne spectral infrared imagery, onboard processing and creation of surface oil characterisation and quantification map products, and their direct transmission to DHIC was around ten minutes. Implementing this automated capability removed the human from the analysis loop resulting in an around-the-clock timely, accurate, consistent, continuous near-real-time reporting and updating of surface oil locations and quantities to the DHIC. The DHIC utilised this capability to direct its oil skimmer operations. Figure 4 illustrates the oil characterisation and quantification map product derived from ASPECT’s infrared spectral imagery. According to the USCG, use of the ASPECT near-real-time oil characterisation map products improved the efficiency of their oil skimmer vessel operations from 30 per cent to better than 90 per cent.
In the United States, Congressional Committees overseeing the regulation of homeland security activities are realising the need for a national civilian airborne remote sensing emergency response program in a nation of 300 million people, many of whom live in close proximity to chemical industries or nuclear power production facilities. The next step will require the United States Congress to appropriate funds and designate a lead organisation in order to create such a program. This realisation has been brought about in part by the 115 successful airborne emergency, disaster, and homeland security related responses documented by Dr Mark Thomas of the US Environmental Protection Agency (EPA) in his duties as the US EPA ASPECT Program Manager. Dr Thomas has documented a decade of successful airborne remote sensing emergency response operations along with how to keep operational costs affordable. His documentation provides a model and illustrates the process of building and maintaining a national civilian airborne remote sensing emergency response program as a balancing act between implementing adequate capability against the available and projected future funding resources.
A national program must provide the correct number of aircraft/ sensor systems to reach any incident in under three hours. Each system mustutilise a standard methodology that is cost-effective and scientifically valid to collect, process, and analyse the chemical and/ or radiological hazard data, and rapidly and efficiently transmit the data and analysis results to incident managers. This methodology must be balanced against available and sustainable organisational funding levels over the course of time. Careful assessment of the mission, scope, required detection capabilities, method of operation, and cost per flight hour of the targeted number of aircraft/sensor systems are fundamental considerations for a national program. The entire ASPECT system costs around $3 million distributed amongst sensors, support systems, data telemetry, and airframe integration. System operational costs include not only the time spent in the air collecting incident data, but time and resources expended on training and 24-hour standby. The ASPECT Program model compiled by Dr Thomas for controlling cost and maintaining a 24 hour a day 7 days a week operational capability is directly applicable and scalable to a national program. The author wishes to thank Dr Mark Thomas of the US Environmental Protection Agency’s ASPECT Program for his suggestions and contributions to this article.
Paul E Lewis
National Geospatial-Intelligence Agency,