Heat wave characterization and its impact on carbon and water vapour fluxes over sugarcane-based agroecosystem

Abstract

Global climate change expected to exacerbate the temperature extremes and intensity of heat waves in recent decades. The terrestrial biosphere plays a crucial role in absorbing carbon from the atmosphere. Therefore, understanding how terrestrial ecosystems respond to extreme temperatures is essential for predicting land-surface feedbacks in a changing climate. In light of this, a study was conducted to assess the effects of 2022 heat wave [March-May (MAM)] on carbon and water vapour fluxes. This study utilized the measurements obtained from the eddy covariance tower mounted within the sugarcane agroecosystem. The study period (MAM) was characterized into three events: Heat wave event 1 (HE1), Heat wave event 2 (HE2), Non heat wave event (NHE). The variation in carbon and water vapour fluxes, along with meteorological variables, during these events in 2020 and 2022 was further analysed. Our findings indicate that the heat wave caused a decrease in net ecosystem exchange (NEE), leading to an increase in atmospheric CO2 concentration during HE1, HE2 compared to NHE. In HE1, maximum NEE in 2020 and 2022 was -19.15 µmol m-2 s-1 and -13.21 µmol m-2 s-1, respectively. Furthermore, the heat wave events led to a decrease in latent heat flux (LE) and sensible heat flux (H), with changes of up to 5% in LE and 57% in H compared to the same period in 2020. These results highlight the significant impact of the heatwave on both carbon and energy fluxes. Overall, the present study provides a valuable reference for further climate change analysis, specifically focusing on both carbon and energy fluxes within sugarcane ecosystem.