In the context of climate change, ocean moisture is increasingly important in continental precipitation, especially in tropical regions. This is one of the main conclusions of a study carried out by Luis Gimeno, Raquel Nieto and Rogert Sorí, researchers from the Ephyslab CIM-UVigo (Environmental Physics Laboratory) group. The study was recently published in Climate and Atmospheric Science, an online and open access journal published by the Nature group in collaboration with the Center of Excellence for Climate Change Research.
Regarding the relevance of the topic addressed in this article, researchers from the Ourense Campus-Campus da Auga explain how precipitation falling on continents “defines the scope and nature of terrestrial ecosystems and human activity in them”. This precipitation, they recall, is supplied by moisture that comes directly from the ocean or later from the continents themselves and both the processes that control evaporation and the main moisture transport mechanisms differ clearly between the ocean and the continent. Taking these considerations into account, they add, “in the context of a changing climate, the relationship between precipitation of oceanic and terrestrial origin can be expected to vary globally and regionally as well as the influence of these two basic components of total precipitation on global and regional precipitation trends, especially in tropical areas”.
Increase of 0.51% per decade
As the authors of the work explain, “the acceleration of the hydrological cycle with climate change, based on thermodynamic arguments, leads to an intensification of moisture transport from the main sources, that is, generally oceanic regions where evaporation exceeds precipitation, towards the main sinks over continental areas where precipitation exceeds evaporation”. The intensification of this moisture transport, they add, “implies that the oceanic moisture source for continental precipitation will grow in importance compared to terrestrial sources”. Particularly, the members of Ephyslab clarify, “in those regions where precipitation is more linked to moisture transport, such as in tropical regions, precipitation trends must therefore be controlled from their origin in the oceans”.
In the study, the authors explain, they applied an approach based on a Lagrangian technique to estimate precipitation in a target region given the proportions of moisture transported from the two sources (ocean and continent). This method, they comment, allows them to divide the origin of precipitation between moisture from the oceans and moisture of continental origin “to demonstrate that the percentage of precipitation with oceanic origin has already increased in the current climate (1980-2016) at a rate of 0.51% per decade in global terms, with the increase in tropical regions being particularly important, reaching up to 1.15% per decade”.
Their work, they add, “also shows a statistical relationship between precipitation and the percentage of precipitation of oceanic origin in tropical regions, in which both have experienced significant trends.” As a result of their study, they emphasize that “we can conclude that the contribution of oceanic sources to global precipitation is increasing, which is controlling precipitation trends in tropical areas.”
The research activity of Ephyslab has the support of the Xunta de Galicia and the European Union, through the co-financing of the CIM under the FEDER/FSE Galicia 2014-2020 Operational Program.
Source: DUVI
