Air quality monitoring is essential for understanding population exposure to pollution, yet many cities—especially in the Global South—do not have complete or continuous Air Quality Monitoring Networks (AQMN). To support scientists, students, journalists, and decision-makers, we developed an interactive web application that allows users to visualize monthly median concentrations of NO₂ and SO₂ anywhere in the world. The application is freely available at
https://cesarivanalvarezmendoza.users.earthengine.app/view/sentinel5pcoordinate. This tool enables anyone to explore air quality conditions by simply clicking on the map or entering geographic coordinates.

The Sentinel-5P Coordinate Explorer is an open-access web application built on the Google Earth Engine (GEE) platform to democratize access to satellite-based atmospheric information. Developed by Dr. César Iván Álvarez (University of Augsburg, Germany), the tool focuses on transforming the Sentinel-5P TROPOMI dataset into an intuitive and fast visualization environment.

- Purpose

The goal of the application is to help researchers, environmental practitioners, students, and the public quickly understand air pollution patterns—especially in cities where no ground stations exist.

- Data and Functionality

The application uses the ESA Sentinel-5P TROPOMI instrument (2018–2025) to compute monthly medians for key atmospheric pollutants:

• Nitrogen dioxide (NO₂) – a major pollutant from traffic and combustion processes
• Sulfur dioxide (SO₂) – typically from industrial activities and power plants

Users can:

- Click on any point on the world map to retrieve pollution values.

- Enter latitude and longitude manually.

- Select year and month to visualize pollution over time.

- Generate dynamic visualizations directly in the browser.

Behind the scenes, the application uses GEE to perform spatial queries, temporal aggregation, and optimized visualization for fast rendering—even at global scale.

The tool promotes:

- Accessibility: runs in any browser, no GIS skills needed

- Reproducibility: based entirely on public Sentinel-5P data

- Transparency: users can inspect the underlying GEE script

- Scalability: designed for global use

Citation: Álvarez, C. I. (2025). Sentinel-5P Coordinate Explorer: A Web Application for Accessing Monthly Median NO₂ and SO₂ Concentrations Using Google Earth Engine. University of Augsburg.

Available online: https://cesarivanalvarezmendoza.users.earthengine.app/view/sentinel5pcoordinate