Understanding the influence of land surface conditions on the temporal evolution and spatial propagation of heatwaves in India

Land surface conditions are known to strongly influence the intensity and frequency of heatwaves; however, their role in governing the temporal evolution and spatial propagation of heatwaves remains insufficiently explored. This study investigates the impact of land surface conditions on the temporal evolution and spatial propagation of pre-monsoon heatwaves in northwest and central India. Analysis of surface energy budget components during heatwave events reveals two dominant patterns of land surface flux evolution. In northwest India, the development of heatwaves is typically associated with weak near-surface winds that promote localized heat buildup. This phase is often followed by a strengthening of winds, which enhances sensible heat fluxes and facilitates horizontal heat transport. The resulting advection of warm air from the upwind northwest region plays a crucial role in triggering heatwave conditions over downwind areas of northern and central India. We further find that the downwind propagation of heatwaves is strongly dependent on the initial land surface temperature in the upwind region. Elevated land surface temperatures in northwest India induce anomalously low surface pressures, resulting in intensified wind speeds that enhance heat transport. As a result, heatwaves having high initial land surface conditions propagate more rapidly and are more likely to extend into central India. These results highlight the predictive potential of upwind land surface temperatures for the occurrence of heatwaves in downwind regions.