iSPEX 2

iSPEX was originally developed to record light spectra across the sky to determine the absorption and scattering of light by aerosols as an indicator of air pollution.

With iSPEX 2, sensitivity and accuracy are greatly improved to allow spectral measurements of water surfaces as well. Taking the reflectance of water, i.e. the amount of sunlight that is returned from within the water column, we can determine the presence of optical water constituents such as algal pigments.

These types of measurements are already in widespread use using both satellites and ground-based instrumentation. iSPEX 2 brings a low-cost alternative to these procedures.

Currently we do a limited test with research groups. People can reach out to web@ddq.nl for obtaining a kit.

Participants are now invited to inform project leads of their interest to participate. They will then plan how to obtain iSPEX 2 for a specific phone model, which will be mailed to them.

Data collection is to be alongside and synchronous with reference measurements, capturing the same illumination conditions.

Data collection will follow the ‘Mobley protocol’ at 135 degrees azimuth and 40 degrees oblique angle. Obstruction of the downwelling light field is to be prevented, including measurement of the grey card.

Participants will keep a log of their observation windows and provide the nearest-in-time matching reference radiometric measurements (Lt, Ls, Ed or Lr) using a template, so that data can be automatically ingested by post-processing and data analysis scripts.

Access to the project repository will be extended to participants to provide data updates and corrections.