iSPEX app

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In order to measure tiny atmospheric particles, or atmospheric aerosols, with your iPhone, you will need the iSPEX add-on and the iSPEX app. iSPEX add-on and app currently only suit iPhones 4(s) and 5(s). It includes:

  • fully guided, step-by-step iSPEX measurement procedure
  • a demonstration animation
  • a live map of preliminary iSPEX results
  • background information on iSPEX and its measurement method.

The iPhone app is for free and available in the App Store.

What does the iSPEX app do?

The iSPEX app guides you through the iSPEX measurement procedure. With the add-on in place, in front of the main camera of your iPhone, it instructs you to make a scan of the sky. As you are making the scan the app takes pictures that contain the modulated spectrum and, simultaneously, adds your geographical location and the angles of direction in which you point the add-on. The app guides you through this process twice, as a consistency check for best results, then gathers all pictures –10 to 25 in total– and information in one single package.

Shot of the animated demonstration in the iSPEX app

Shot of the animated demonstration in the iSPEX app

Next, it returns your preliminary measurement result, a color-coded representation of your sky condition based upon your iSPEX measurements. You are then asked to provide your name. This is optional and the name you provide will only be used to be shown along with your preliminary result on the iSPEX live map in the app.

Now, after your agreement to share your iSPEX measurements, they are submitted to the iSPEX database for further post-processing. Sharing your data is important to contribute to the campaign. After the campaign end all iSPEX measurements will be analysed and processed carefully to obtain maps of iSPEX based aerosol information over Europe. This step is required to filter out pictures that contained buildings and to average your measurements with those made by others in close proximity, to obtain the most accurate result. The final maps of iSPEX based aerosol information will be published on this website.

The submission of your iSPEX measurements may take a few minutes depending upon your Internet connection (either 3/4G or Wifi). In case you have not switched on data roaming and there is no Wifi available either, you can still submit your data if you are able to reach a Wifi suited location within 10 minutes after you have taken your measurements. Please keep the app active until you reach this location, otherwise your data will be lost –iSPEX measurements are not stored in the app or elsewhere on your iPhone. After submission, the live map with your preliminary result added to it is shown. You can view the live map also on this website.

More measurements? Yes, please!

Want to take another measurement? You are much welcomed to take more measurements, ideally at least two times a day, once in the morning between 7-11 am, once in late afternoon or early evening 4-8 am –weather permitting, meaning, provided your sky is cloud-free.

To much information here? The app comes along with an animated demonstration to give you a head-start with your first iSPEX measurement!

Check here for details on the latest version of iSPEX app and its known issues (if any).

External links

Snik et al., Mapping atmospheric aerosols with a citizen science network of smartphone spectropolarimeters, scientific paper, Geophysical Research Letters, 2014.