GLOBE Observer and the GO on a Trail Data Challenge: A Citizen Science Approach to Generating a Global Land Cover Land Use Reference Dataset

Abstract

Land cover and land use are highly visible indicators of climate change and human disruption to natural processes. While land cover is frequently monitored over a large area using satellite data, ground-based reference data is valuable as a comparison point. The NASA-funded GLOBE Observer (GO) program provides volunteer-collected land cover photos tagged with location, date and time, and, in some cases, land cover type. When making a full land cover observation, volunteers take six photos of the site, one facing north, south, east, and west (N-S-E-W), respectively, one pointing straight up to capture canopy and sky, and one pointing down to document ground cover. Together, the photos document a 100-meter square of land. Volunteers may then optionally tag each N-S-E-W photo with the land cover types present. Volunteers collect the data through a smartphone app, also called GLOBE Observer, resulting in consistent data. While land cover data collected through GLOBE Observer is ongoing, this paper presents the results of a data challenge held between June 1 and October 15, 2019. Called “GO on a Trail,” the challenge resulted in more than 3,300 land cover data points from around the world with concentrated data collection in the United States and Australia. GLOBE Observer collections can serve as reference data, complementing satellite imagery for the improvement and verification of broad land cover maps. Continued collection using this protocol will build a database documenting climate-related land cover and land use change into the future.

The potential of citizen science data to complement satellite and airborne lidar tree height measurements: lessons from The GLOBE Program

“…We note that these observations are a result of significant experience with GO data (Dodson et al 2019, Colón Robles et al 2020, Kohl et al 2021, Low et al 2021 and analyses between airborne lidar, ICESat-2, and GO Trees data limited to this study. Additionally, while smart phone GPS measurements are improving with most being at best accurate to within 4 m, an analysis of GO data found an average location accuracy of 14.5 m. Given the 13 m ICESat-2 photon pulse footprint, this means that GO Trees measurements within the footprint may not be resolvable or may be misleading.…”

“…In-app tools for each of the protocols guide volunteers through environmental data collection in which users take geotagged photographs and answer questions to document and classify clouds (Colón Robles et al 2020), eclipse conditions (Dodson et al 2019), mosquito habitats (Low et al 2021), or land cover (Kohl et al 2021). GO Trees is unique among the other tools because tagged photos are not the primary data collected, but rather it uses a smartphone's gyroscope and user input to calculate and estimate tree height.…”

Do Citizen Science Intense Observation Periods Increase Data Usability? A Deep Dive of the NASA GLOBE Clouds Data Set With Satellite Comparisons

“…These IOPs boosted the collection rate of cloud reports considerably above normal, and provide a larger collection of data which is useful for addressing scientific research questions. The success of these challenges has encouraged other GLOBE projects to develop their own IOPs to boost data collection, such as for land cover (Kohl et al., 2021). Such IOPs may become a more important aspect of citizen science efforts in the future.…”

An Insight into the GLOBE Data and its Comparison with Ground-Based Observations

“…Location is recorded in latitude and longitude coordinates determined through the mobile device's location services [cellular, Wi-Fi, Global Positioning System (GPS)]. The accuracy of these coordinates is shown on-screen, providing the user the opportunity to improve the location coordinate accuracy, with a maximum accuracy of 3-meters, or the option to manually adjust the location using a map (Kohl et al, 2021).…”