Seasonal and Diurnal Variability of Ultraviolet (UV) Irradiance in Kolhapur, India: Measurements and Implications

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ABSTRACT

Ultraviolet (UV) radiation plays a crucial role in atmospheric processes and human health, with variations influenced by factors such as stratospheric ozone, solar zenith angle (SZA), and local weather conditions. This study investigates the seasonal and diurnal variability of UV irradiance over Atigre village, Kolhapur (16.74°N, 74.37°E, 604 m altitude), using a ground-based Microtops II Ozonometer. The instrument measures solar irradiance at five wavelengths (305.5 nm, 312.5 nm, 320.5 nm, 936 nm, and 1020 nm), with the first three channels dedicated to UV irradiance. Observations from 2017 to 2019 reveal distinct seasonal trends, with maximum UV irradiance in summer (peaking in May) and minimum in winter (lowest in January). The diurnal variation follows a characteristic bell-shaped curve, peaking at noon due to minimal atmospheric path length and higher solar elevation. The highest UV irradiance levels were recorded at 12:30 PM, with values reaching 222.92 mW/m² in summer, compared to 158.07 mW/m² in winter. The study also highlights a 34.9% average increase in monthly mean UV irradiance from 2018 to 2019, with the most significant rise observed in March (67.1% for 305 nm). The findings emphasize the inverse relationship between stratospheric ozone and UV irradiance, with higher UV levels posing potential health risks, particularly for outdoor workers in the region. The study underscores the need for public awareness and protective measures during peak UV exposure periods. These results contribute to understanding regional UV dynamics and their implications for health and environmental monitoring in tropical regions.

Significance of the Study:

This study highlights the critical seasonal and diurnal variations in UV irradiance in Kolhapur, India, emphasizing its implications for public health, particularly for outdoor workers. The findings reveal increasing UV trends, linked to ozone depletion, necessitating protective measures. The research provides essential data for regional UV monitoring, aiding in health risk assessments and policy-making. By understanding UV dynamics, authorities can implement awareness programs to mitigate skin cancer risks, ensuring safer outdoor practices in tropical climates.

Summary of the Study:

The study analyzes UV irradiance in Kolhapur (2017–2019) using a Microtops II Ozonometer, revealing peak UV levels in summer (May) and minima in winter (January). Diurnal patterns show maximum irradiance at noon (222.92 mW/m² in summer). A 34.9% average increase in UV from 2018–2019 was observed, with March showing a 67.1% rise at 305 nm. Findings stress the ozone-UV inverse relationship and health risks, urging protective measures during peak exposure (10 AM–2 PM) for vulnerable populations.