Smartphone-Based Android app for Determining UVA Aerosol Optical Depth and Direct Solar Irradiances.

Area of Science:

• Atmospheric Science
• Environmental Monitoring
• Mobile Sensing Technology

Background:

• Smartphone sensors can detect UVA radiation.
• Calibration allows for measuring direct solar irradiance.
• Previous research established the potential of smartphone sensors for irradiance detection.

Purpose of the Study:

• Develop and evaluate an Android app for solar UVA radiation and aerosol optical depth detection.
• Integrate data collection, calibration, processing, and display onto a smartphone.
• Assess the accuracy and precision of the developed smartphone-based sensor system.

Main Methods:

• Designed and implemented an Android application utilizing the smartphone's image sensor.
• Incorporated external narrow bandpass and neutral density filters.
• Calibrated the app's digital response against a Microtops sun photometer.
• Collected and processed solar irradiance and aerosol optical depth data at 340 and 380 nm.

Main Results:

• Achieved a high coefficient of determination (0.98) after recalibration against a Microtops sun photometer.
• Demonstrated a low mean percentage discrepancy for derived direct solar irradiance (4% at 380 nm, 6% at 340 nm).
• Observed an 8% mean percent difference for aerosol optical depth, with discrepancies decreasing as solar zenith angle decreased.

Conclusions:

• A specifically designed Android app combined with smartphone sensors and external filters can serve as a field sensor.
• The system accurately evaluates direct solar UVA irradiance and low aerosol optical depths.
• This approach offers a cost-effective method for environmental monitoring in areas with low aerosol loads.