Climate Monitoring | Predicting Public Health Threats with Space-based Sensors

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SAN FRANCISCO — Columbia University’s International Research Institute for Climate and Society (IRI) is using data drawn from space-based sensors to help public health officials around the world learn when climate conditions increase the risk of epidemics.

The researchers have created free, Internet-based tools designed to provide local officials with timely information on the climate conditions that contribute to diseases. For example, people who use the IRI website can use maps to identify areas where above-average rainfall, warm air temperatures, lush vegetation and the presence of standing water are likely to contribute to growth in local mosquito populations, and the spread of malaria and dengue fever.

IRI researchers are working with public health officials in Kenya, Ethiopia, Madagascar and Eritrea to assess where and when malaria epidemics are most likely to strike. They also are helping local officials identify the conditions that propel the spread of dengue fever in Brazil and Colombia. “We study places where environmental factors are driving the epidemics,” said Pietro Ceccato, a research scientist at Palisades, N.Y.-based IRI, which is part of Columbia University’s Earth Institute.

In 2004, Columbia University scientists began analyzing the relationship between environmental factors and malaria epidemics. Specifically, the researchers looked for correlations in regions where malaria epidemics do not occur every year to test their ability to predict and confirm local outbreaks of the disease. Those tests led to development of specific tools related to public health in the IRI-Lamont-Doherty Earth Observatory Climate Data Library, which offers users interactive maps and tools to monitor current climate conditions and view forecasts.

The climate reports and forecasts presented in the data library feature hundreds of data sets drawn from ground-based rain gauges as well as sensors onboard geostationary and polar-orbiting satellites. That information is then used to create simple, self-service tools, such as maps that users can click on to see changing rainfall patterns in a particular district or local area.

The goal is to make the tools so user-friendly that government health officials who have never used remote sensing data can obtain information easily through the website, Ceccato said. IRI also invites public health officials to visit its facility in New York for two-week training sessions to teach them to analyze the relationship between climate conditions and various diseases.

In addition to malaria and dengue fever, the Climate Data Library can help users study the conditions that heighten the risk in many parts of the world of diseases spread by ticks and famine aggravated by locust infestations.

While IRI researchers have access to the space-based data used in their current research, they would like to obtain more detailed information on bodies of water. The Moderate Imaging Spectral Radiometer, which flies on NASA’s Terra and Aqua Earth observation satellites, provides imagery with a resolution of 250 meters. Higher-resolution imagery would enable researchers to assess water quality, determining, for example, where turbid water in unused swimming pools is serving as a breeding ground for the mosquitoes that carry dengue fever, Ceccato said. IRI officials have discussed the characteristics they would like to see in future space-based instruments with scientists and engineers at the Jet Propulsion Laboratory in Pasadena, Calif.

In addition to sharing their models and maps with public health officials worldwide, IRI officials are working with the World Health Organization to assess the efficacy of campaigns designed to halt the spread of malaria with nets and pesticides. Instead of simply comparing the number of cases of malaria with those of previous years, IRI is using climate models to determine how frequently malaria epidemics would have been likely to occur without government intervention.

IRI is one of many organizations around the world using satellite data to develop surveillance and early warning tools to inform the public when changing environmental factors create conditions that could aggravate pulmonary diseases like asthma or encourage the spread of diseases carried by insects or contaminated water. The NASA Earth Science Applications Program is providing funding for many of those initiatives, said Steven Kempler, manager of the Distributed Archive Data Center at NASA’s Goddard Earth Sciences Data and Information Services Center (GES DISC) in Greenbelt, Md.

NASA officials also are developing Web-based tools to help students and researchers maximize use of the data. Information gathered by space agency sensors is distributed through 12 NASA Earth science data centers. Researchers and educators obtain data related to public health through GES DISC and the Socioeconomic Data and Applications Center (SEDAC), also located at Columbia University.

“SEDAC offers several interactive, data-visualization tools,” Kempler said in a Dec. 14 email. GES DISC developed Giovanni, a tool that enables researchers to display and download NASA satellite data without having to spend hours identifying the most pertinent information and downloading it. Through Giovanni, data can be accessed, viewed and downloaded with a few clicks of a computer mouse, Kempler said.