Simulating forest fires in Uttarakhand: Uncovering the role of meteorological variables.

The Himalayas, a critical component of the global water cycle and a hotspot for biodiversity, have been increasingly affected by severe wildfires. These fires disrupt eco-hydrological processes, posing threats to ecosystems, air quality, and human health. Despite their growing prevalence, the dynamics of forest fires in this region, particularly the role of meteorological factors, remain underexplored. Using the Weather Research and Forecasting Model-Fire (WRF-Fire), we simulated forest fires in the Western Himalayas during May 2018 to investigate the relationship between weather conditions and fire behaviour. We conducted four experimental simulations: a control (Fire_ctr), increased temperature by 2 K (Fire_Ti), reduced relative humidity by 15% (Fire_RHd), and a combination of both (Fire_Ti_RHd). Our findings indicate that elevated temperatures (T) alone do not significantly increase fire incidence or extent. However, reduced relative humidity (RH) markedly amplifies fire spread and further raises T and vapour pressure deficit (VPD), highlighting the dominant role of RH over T in fire dynamics. Additionally, smoke dispersion from these fires contributes to atmospheric aerosols, impacting visibility and air quality. This study demonstrates the potential of WRF-Fire to simulate fires in the Himalayas and underscores the critical influence of meteorological factors. Future enhancements could incorporate detailed vegetation and live fuel moisture data, thereby improving early warning systems. Research highlights: Higher temperatures alone don't significantly increase forest fire likelihood. Reduced humidity amplifies fire spread more than elevated temperatures in the Himalayas. Lower relative humidity raises VPD, driving forest fire spread more than heat. Wildfire smoke worsens air quality, reducing visibility and threatening health in the region. [ABSTRACT FROM AUTHOR]