Roles of forests in moderating the diurnal cycle of land-atmosphere interactions

Forests moderate the microclimate through evapotranspiration and biomass heat flux. However, understanding the contributions of dense forests remains challenging due to observational limitations. Our in-situ observations show that forests regulate the diurnal temperature range by approximately 2 °C compared to open fields. The Community Terrestrial System Model simulation reveal that latent heat and sensible heat fluxes are overestimated by around 10% during the daytime. The nighttime temperatures are underestimated when biomass heat storage (BHS) is excluded. Furthermore, the Single-Column Atmospheric Model indicates that the misestimated daytime heat flux leads to the slight overestimation of boundary layer height. Notably, BHS decreases daytime temperature by adjusting sensible heat flux through land-atmosphere interaction. The warming bias resulting from neglecting BHS reduces vegetation transpiration, further leading to an underestimation of daytime latent heat flux. Facing the threats of climate warming and deforestation, understanding BHS characteristics in models is pivotal for accurately representing land-atmosphere interactions.