A fourth grade student from Public School 122 (Queens, NY), recently visited NASA Langley for a week. During his visit, he studied the GLOBE Aerosol Protocol. He went outside the Atmospheric Sciences building and collected aerosol data using a Calitoo sun photometer, which measures Aerosol Optical Thickness (AOT) at three wavelengths: 465nm (blue), 540nm (green) and 619nm (red).

After downloading the data measured with the Calitoo to his laptop, the student learned how to access AERONET data. The AERONET (AErosol RObotic NETwork) project is a federation of ground-based remote sensing aerosol networks that provides long-term, continuous and readily accessible public domain aerosol research data.

The student then had AOT values obtained with the Calitoo, plus AOT values obtained from the AERONET instrument located at NASA Langley, and his mission was to compare both sets of values. However, AERONET provides AOT values at wavelengths different to the ones measured by the Calitoo. The question then was: how to compare apples to oranges? The young citizen scientist learned how to use the angstrom exponent and a formula to convert the AOT values measured by AERONET to match the wavelengths measured by the Calitoo sun photometer. The student then was able to plot the values using Excel and Igor Pro.

This comparison can help beginner Calitoo users determine how proficient they are becoming at using the Calitoo, since their values are expected to be comparable to the ones obtained from AERONET; and also, it can help experienced Calitoo users determine whether a specific Calitoo device may need to be recalibrated if the values seems to have considerable discrepancies.

After comparing both sets of values, now the student would like to know how we calibrate Calitoos! Stay tuned for an upcoming post about calibration.

Meanwhile, this fourth grade student is now ready to share his aerosol science adventure with his classmates back in NY!


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