Luisa Pflumm, Hyeonmin Kang, Andreas Wilting, Jürgen Niedballa

1. Earth observation satellites are collecting vast amounts of data that are both free and openly accessible. These data have immense potential to support environmental, economic, and social fields. However, along with the increasing availability of remotely sensed data, challenges are also increasing in accessing and processing these data. In particular, easy-to-use solutions for accessing and computing cloud-free image composites from often cloudy satellite data are lacking, preventing researchers and practitioners without in-depth training in remote-sensing techniques to use the accessible satellite data.
2. We developed GEE-PICX, a web application with an intuitive user interface in the cloud computing platform Google Earth Engine to overcome these challenges and to create cloud-free and analysis-ready image composites for user-defined areas and time steps based on Sentinel-2 and Landsat 5, 7, 8, and 9 images. Data coverage is global and image composites can be aggregated annually or seasonally. The earliest available data are from 1984 (launch of Landsat 5).
3. The workflow automatically filters all available satellite data according to user input and removes clouds, cloud shadows, and snow. It returns spectral band information, calculates a variety of spectral indices and returns the number of valid scenes per pixel as a quality assessment band.
4. GEE-PICX provides researchers with no or little experience in remote sensing for the first time a customizable tool for creating custom data products from freely accessible satellite data with extensive temporal and global spatial coverage. Server-side data processing ensures the tool is usable without hardware limitations. The simple export of time series of ready-to-use rasters including numerous spectral indices can greatly assist environmental programmes and biodiversity research in a variety of disciplines.