From People to Pixels: Integrating Data Across the NASA DAACs
A Blog post by Lindsey M. Harriman (SGT, Inc. Contractor to USGS EROS Center/LP DAAC) and Alex de Sherbinin (WDS Scientific Committee member)
Socioeconomic and Earth Sciences researchers in search of pertinent data can now reap the benefits of a recent collaboration between two Regular Members of the ICSU World Data System.
Today, our planet supports about 7.6 billion people, with a projected increase to nearly 10 billion by 2050, and more than 11 billion by 2100. These 7.6 billion people are using land and water resources to meet their basic needs. As the population increases, their use of, and their impact on, Earth’s resources is going to change. Researchers who study the dynamics between such human–land interactions and their changes over time will look at a range of variables, such as surface temperature, vegetation health, forest cover extent, and change in land cover and habitat, as well as impacts of natural disasters, and climate trends and extremes.
Research questions that often ask about such dynamics include:
- What is the proximity between populated areas and fire occurrences over time?
- What is the correlation between the increase of population and land surface temperature in urban areas?
- How has population affected land-cover change and vegetation growth over time in urban sprawl areas?
- How will land-cover changes affect flood and drought risk around rural and urban settlements?
To answer these types of questions, researchers need to integrate census data with Earth observation data, including data collected by NASA’s Earth Science Division Operating Missions. Recently, two NASA Distributed Active Archive Centers (DAACs)—the Land Processes DAAC (LP DAAC; WDS Regular Member) and the Socioeconomic Data and Applications Center (SEDAC; WDS Regular Member)—collaborated to make that integration much easier. LP DAAC and SEDAC worked together to provide access to georeferenced population data alongside land remote sensing data in the Application for Extracting and Exploring Analysis Ready Samples (AppEEARS). SEDAC’s Gridded Population of the World version 4 (GPWv4) aggregates census data from around the world into a globally consistent grid with 30 arc-second resolution (1 kilometer at the equator) for population density and counts. Soon researchers will also have access to age and sex distribution grids. LP DAAC disseminates land remote sensing data collected by several NASA missions—including from the popular Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard Terra and Aqua—and provides access to a selection of these datasets through AppEEARS.
Figure 1. Daily land surface temperature in Kelvin (K) and population trend, 2010–2017 for rural and urban points in North Carolina (based on MODIS MOD11A1 daily 1-km data and GPWv4, UN-Adjusted)
(a) Farm northwest of Nashville, North Carolina, USA. The red pin represents the location 36°N, 78°W. Image: Google Maps. Time series plots: output from AppEEARS.
(b) Suburban area of Charlotte, North Carolina, USA, experiencing rapid population growth. The red pin represents the approximate location 35°N, 81°W). Image: Google Maps. Time series plots: output from AppEEARS.
Figure 1 provides examples of time series plots of population growth and daily land surface temperature using the Point Sample function in AppEEARS. Users can interact with these visualizations within the application and also download the data values in comma separated value format.
Additionally, LP DAAC has collaborated with a third DAAC, the National Snow and Ice Data Center DAAC (NSIDC DAAC; WDS Regular Member), to provide MODIS snow-cover data from its archive for access through AppEEARS as an additional variable describing land dimension. SEDAC, LP DAAC, and NSIDC DAAC are all part of NASA’s Earth Observing System Data and Information System, and through their collaborations, AppEEARS now provides access to more than 100 data products from the three data centers in a single place, at no cost to the user. Many possible combinations of data can be extracted from AppEEARS for use in analyses of the dynamics between populations and ecosystems over time.
AppEEARS also provides benefits during the data preparation process. When performing a sample request, users drastically reduce the amount of data they ultimately need to download to perform their analysis. AppEEARS enables users to subset data based on geographic and temporal parameters, as well as by specific data layer. Since users can reformat the data and reproject within the application, the amount of post-processing required is reduced. Furthermore, AppEEARS not only provides data values, but also quality data values and their descriptions, when applicable. Lastly, users can visualize plots of the data values (point sample) or summary statistics (area samples) from the sample request within the application.
The collaboration around AppEEARS represents an initial step away from the idea that users need to download large amounts of data for local filtering, processing, integration, and analysis, and moves towards a model where analysis-ready data can be more immediately accessed. Coordinated tools and application development on the substantial holdings of all 12 DAACs is an important strategic direction for NASA’s Earth Science Data and Information System Project (WDS Network Member).
So, what’s your use case for AppEEARS?
Have questions about AppEEARS? Email: firstname.lastname@example.org.