Terrestrial evaporation response to modes of climate variability. Issue 1 (December 2018)

• Record Type: Journal Article
• Authors: Martens, Brecht; Waegeman, Willem; Dorigo, Wouter; Verhoest, Niko; Miralles, Diego
• Is Part Of: Npj climate and atmospheric science. Volume 1:Issue 1(2018)
• Page Start: 1
• Page End: 7
• Publication Date: 2018-12
• Subjects: Climatology -- Periodicals; Atmospheric chemistry -- Periodicals; 551.6
• DOI: 10.1038/s41612-018-0053-5
• Languages: English
• ISSNs: 2397-3722

Abstract

Abstract Large-scale modes of climate variability (or teleconnection patterns), such as the El Niño Southern Oscillation and the North Atlantic Oscillation, affect local weather worldwide. However, the response of terrestrial water and energy fluxes to these modes of variability is still poorly understood. Here, we analyse the response of evaporation to 16 teleconnection patterns, using a simple supervised learning framework and global observation-based datasets of evaporation and its key climatic drivers. Our results show that the month-to-month variability in terrestrial evaporation is strongly affected by (coupled) oscillations in sea-surface temperature and air pressure: in specific hotspot regions, up to 40% of the evaporation dynamics can be explained by climate indices describing the fundamental modes of climate variability. While the El Niño Southern Oscillation affects the dynamics in land evaporation worldwide, other phenomena such as the East Pacific–North Pacific teleconnection pattern are more dominant at regional scales. Most modes of climate variability affect terrestrial evaporation by inducing changes in the atmospheric demand for water. However, anomalies in precipitation associated to particular teleconnections are crucial for the evaporation in water-limited regimes, as well as in forested regions where interception loss forms a substantial fraction of total evaporation. Our results highlight the need to consider the concurrent impact of these teleconnections to accurately predict the fate of the terrestrial branch of the hydrological cycle, and provide observational evidence to help improve the representation of surface fluxes in Earth system models. Climate cycles influence patterns of land evaporation Climate cycles cast a far-reaching shadow across evaporation from global land surfaces, but their influence varies across space and time. A team led by Brecht Martens from Ghent University tested the statistical relationship between sixteen climate cycles and land evaporation. They revealed that the El Niño Southern Oscillation (ENSO) has the strongest linkage, or teleconnection, to evaporation. But depending on season and location, other climate cycles influenced evaporation more strongly, in some cases explaining up to 40% of the month-to-month variation in evaporation. Climate cycles influence evaporation by modifying the atmospheric demand for water, rather than altering water supply itself. Yet teleconnections are not universal, and although ENSO may be the most important teleconnection in terms of percentage of land where evaporation is affected, it is not a dominant control of land evaporation. Ultimately, the research highlights the need for a nuanced, multivariate understanding of interactions between climate cycles and land evaporation.