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NOAA’s CrowdMag is a crowdsourced data collection project that uses a mobile app to collect geomagnetic data from the magnetometers that modern smartphones use as part of their navigation systems. NCEI collects these data from citizen scientists around the world and provides quality control services before making them available through a series of aggregated maps and charts. These data have the potential to provide a high resolution alternative to geomagnetic satellite data, as well as near real-time information about changes in the magnetic field.

Decorative Image

Interactive Map

The CrowdMag Interactive Map shows crowdsourced magnetic data collected in the past 24 hours from the CrowdMag app. Data are updated hourly, and data points are snapped to the nearest grid points (following a roughly 1x1 kilometer grid) to ensure the privacy of data contributors.

Use the “+” sign in the upper right-hand on the map to display older data. The F channel represents Total Magnetic Field Strength, H channel represents the Magnetic Field’s Horizontal Component, and Z channel represents the Magnetic Field’s Vertical Component.

Click to launch CrowdMag Interactive Map

The Geomagnetism Group

The NCEI Geomagnetism Group conducts original research on the Earth’s magnetic field. Our primary goal is to create up-to-date models that accurately track and depict changes to the geomagnetic field. Our magnetic models are integrated into millions of smartphones, car and aircraft navigation systems, and GPS so that users know which way is north.

Frequently Asked Questions

Project Goals

  1. To build, grow, and foster a worldwide community of citizen scientists and enthusiasts collecting magnetic field data and sharing it to further our understanding of Earth’s magnetic field.
  2. To develop magnetic models and maps using the data shared by CrowdMag users in combination with data collected by ships, aircrafts, and satellites to fill in the gaps of professional mapping of Earth’s magnetic field.
  3. To create a community of citizen scientists to support the project. Watch our video to learn more about contributing data using the CrowdMag mobile app. 

Geomagnetic Data Uses

Since ancient times, people have observed and used the geomagnetic field for navigation. Today, magnetic navigation is implemented on most planes, ships, and even smartphones. 

The geomagnetic field changes with both time and location, and it needs to be monitored regularly to assess its impact on magnetic navigation. Scientists use ground-based observatories, data from satellites, and ship/airborne surveys to map the geomagnetic field and its changes, but these observation methods still leave significant coverage gaps. CrowdMag mobile apps are designed to help fill these gaps by using cell phone magnetometers to collect geomagnetic data.

Using CrowdMag Mobile Apps

Contributing data to CrowdMag is incredibly easy. Install the CrowdMag app, and use it to measure magnetic data along your path during walks, runs, or other outdoor activities. Data ("Magtivities") can be used to create a map of the magnetic field in your area. We encourage you to share your data with the NCEI geomagnetism research group, and to take multiple measurements along the same path to improve data quality and resolution.
CrowdMag’s magnetic calculator provides magnetic variation (declination), the magnetic field’s dip angle, the total magnetic field and other magnetic field components (as well as their associated uncertainties) based on the latest World Magnetic Model.

Download from the Appstore

Download from Google Play

Getting a new phone? You can export your data to your computer before switching devices. Once your new phone is ready to go, you can import the backup data and continue using CrowdMag without losing your status for data contributed, areas covered, or magtivities completed.

Flight Mode Tutorial
March 17, 2023

CrowdMag Flight Mode Tutorial

The CrowdMag app now has a flight mode where you can collect magnetic data while you fly. Airplane observations fill in a large gap in magnetic data. Satellites can capture the biggest shapes of the magnetic field, and ground based observations can capture the smallest, but scientists aren’t able to capture observations between those extremes without aircraft. Help contribute to this project the next time you fly!

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CrowdMag Tutorial
November 16, 2021

CrowdMag Tutorial

CrowdMag is a citizen science project that uses your mobile phone’s internal magnetometer to record magnetic data as you move. Anonymous data collected through the application can be used to detect magnetic anomalies caused by objects in the surrounding environment and also helps inform NOAA science.

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CrowdMag Privacy Policy

In addition to the NOAA privacy policy, the CrowdMag app implements the following privacy measure to ensure that CrowdMag data are collected anonymously. We do not collect personally identifiable information, including your name, email address, or your device's unique identification number. If you enable the “send data” option in the CrowdMag app, the following information will be sent to NOAA:

  • Magnetic field data from the phone's magnetic sensor
  • Time of measurement
  • Location of measurement
  • Location accuracy
  • The model of your phone (so that we know which type of sensor was used to collect the magnetic field data)

CrowdMag data are stored in an internal, non-public database at NCEI. Our magnetic field research team will use these data to assess the utility of incorporating crowdsourced magnetic field data for modeling Earth’s magnetic field. Using CrowdMag data, our team will periodically produce scientific products such as maps, graphs and/or mathematical models. In order to further geomagnetic field research, these products may be presented at meetings, be included in publications, or be made available to the public via the Internet.