Impact of heatwave events on latent and sensible surface heat flux and future perspectives in shallow lakes based on climate change models

Abstract

According to model projections, increases in the frequency and intensity of heatwaves are expected all over the world. This study analyzed, for the first time, the effect of heatwaves events on long-term surface latent (LE) and sensible heat fluxes (H) from two shallow lakes: La Salada lake (LS - 39°27′ S, 62°42′ W) and Sauce Grande lake (SG - 38°57′ S, 61°24′ W). The main drivers of LE and H are wind speed and direction, relative humidity, and the difference between air and water temperature. We found that the daily values of both fluxes were highly fluctuating. Mean daily H values ranged between -309.4 to 200.5 W m-2 and -78.6 to 104.8 W m-2 in LS and SG, respectively. LE oscillated between -152 and 463.9 W m-2 and between -59.2 and 360.1 W m-2 in LS and SG, respectively. Both fluxes decreased with the passage of heatwaves events, presenting a high variation in its amplitude. Changes up to 96% in mean daily LE and 671% in mean daily H for LS and up to 25% in LE and 987% in H for SG were accounted in days with heatwaves respect to regular ones. We analyzed the air temperature increase for both lakes under future global warming scenarios (RCP 4.5 y RCP 8.5), expecting higher amplitudes in heat fluxes. These results contribute to the development of lake models, as well as to water resources management in the future.

Keywords

• sensible heat flux
• latent heat flux
• high-frequency
• heatwave
• shallow lake
• instrumented buoy