A-UVI: GNSS-Assisted UV Index Estimation Method

Overview

Excessive or insufficient UV exposure causes adverse health effects including skin cancer, cataracts, and osteoporosis. Earth observation (EO)-based UV index estimation works well in open-sky environments but lacks accuracy in shaded areas. Conventional personal UV monitoring using mobile/wearable UV sensors faces usability limitations for long-term use.

A-UVI addresses these issues by enhancing the EO-based UV index with raw GNSS (Global Navigation Satellite System) signals. By integrating the EO-based UV index with an attenuation ratio estimated from raw GNSS signals, A-UVI especially improves estimation accuracy in environments affected by obstructions such as buildings and trees.

Approach

• EO-based UV index: Area-level UV index estimation using satellite-derived cloud cover and ozone data
• GNSS signal attenuation: Estimating UV attenuation from raw GNSS signal strength, which reflects the degree of obstruction (shade, foliage, buildings) at the user's location
• Hybrid estimation: Combining EO-based UV index with GNSS-derived attenuation ratio to achieve individual-level precision without additional sensors

Results

• 44.25%+ improvement over existing methods in UV index estimation precision
• 5.53x higher accuracy in forest environments compared to EO-based baseline
• 23% improvement over baseline when using consumer-grade smartphone GNSS receivers
• Validated across different GNSS receivers, mobility scenarios, and observation areas over multiple days

Significance

A-UVI enables passive individual-level UV exposure monitoring without requiring special measurement actions or dedicated UV sensors. This advances UV exposure management beyond simple exposure tracking, enabling adaptive and personalized UV protection strategies using everyday smartphones.