Trends and Variability in Diurnal Temperature Range in Khuzestan Province (1990-2022)

Background:The diurnal temperature range (DTR), representing the difference between daily maximum temperature (Tmax) and minimum temperature (Tmin), is a vital climatic indicator with significant environmental and public health implications.This study examined long-term trends and seasonal patterns of DTR in five cities in Khuzestan Province, Iran (Abadan, Ahvaz, Aghajari, Masjed Soleiman, and Safi Abad) from 1990 to 2022.Materials and Methods: Meteorological data, including Tmax and Tmin, were used to calculate daily DTRs and annual averages.Temporal trends were assessed using linear regression models, while seasonal decomposition analysis identified trend, seasonal, and residual components.Visualization techniques, such as line plots and decomposition graphs, illustrated the findings. Results:The results indicated statistically significant increasing trends in DTR across all cities, with annual increases ranging from 0.0567 to 0.1347 units.Seasonal patterns showed consistent summer peaks and winter troughs, with notable long-term trends and climatic anomalies detected in residual components.These trends mirror global patterns of increasing variability between daytime and nighttime temperatures. Conclusion:The rising DTR, particularly in Abadan and Aghajari, elevates heat stress and public health risks.Ahvaz and Safi Abad also exhibited significant trends, highlighting the need for targeted policy measures.Given the association of high DTR with increased cardiovascular and respiratory diseases, integrating DTR metrics into health action plans is critical, especially for vulnerable populations.In conclusion, DTR serves as a crucial marker of climatic and health risks, reinforcing the urgency of climate adaptation strategies in Khuzestan Province to protect vulnerable groups.