High-resolution global atmospheric moisture connections from evaporation to precipitation

Abstract

Abstract. A key Earth system process is the circulation of evaporated moisture through the atmosphere. Spatial connections between evaporation and precipitation affect the global and regional climates by redistributing water and latent heat. Through this atmospheric moisture recycling, land cover changes influence regional precipitation patterns, with potentially far-reaching effects on human livelihoods and biome distributions across the globe. However, a globally complete dataset of atmospheric moisture flows from evaporation to precipitation has been lacking so far. Here we present a dataset of global atmospheric moisture recycling on both 0.5∘ and 1.0∘ spatial resolution. We simulated the moisture flows between each pair of cells across all land and oceans for 2008–2017 and present their monthly climatological means. We applied the Lagrangian moisture tracking model UTrack, which is forced with ERA5 reanalysis data on 25 atmospheric layers and hourly wind speeds and directions. Due to the global coverage of the simulations, a complete picture of both the upwind source areas of precipitation and downwind target areas of evaporation can be obtained. We show a number of statistics of global atmospheric moisture flows: land recycling, basin recycling, mean latitudinal and longitudinal flows, absolute latitudinal and longitudinal flows, and basin recycling for the 26 largest river basins. We find that, on average, 70 % of global land evaporation rains down over land, varying between 62 % and 74 % across the year; 51 % of global land precipitation has evaporated from land, varying between 36 % and 57 % across the year. The highest basin recycling occurs in the Amazon and Congo basins, with evaporation and precipitation recycling of 63 % and 36 % for the Amazon basin and 60 % and 47 % for the Congo basin. These statistics are examples of the potential usage of the dataset, which allows users to identify and quantify the moisture flows from and to any area on Earth, from local to global scales. The dataset is available at https://doi.org/10.1594/PANGAEA.912710 (Tuinenburg et al., 2020).

Forests Mitigate Drought in an Agricultural Region of the Brazilian Amazon: Atmospheric Moisture Tracking to Identify Critical Source Areas

“…The Atlantic Ocean contributed slightly less than forests (46.5%), and nonforested areas contributed the least moisture (1.0%-5.6%). The terrestrial recycling percentage in Rondônia, which is the percent of rainfall derived from continental sources (53.5%) is higher than the average for the Amazon basin (24%-35%) (Tuinenburg et al, 2020;Van der Ent et al, 2010;Zemp et al, 2014). PAs in the Brazilian Amazon accounted for 27.0% of Rondônia's precipitation and unprotected forests contributed 20.9%.…”

The global potential of forest restoration for drought mitigation

“…We first integrate the global tree restoration map from Bastin et al [11] with a global hydrological model [15,16] and estimate its evaporation potential (including all sources of evaporation, such as transpiration and bare-soil evaporation). Next, we use a high-resolution atmospheric moisture tracking scheme based on the latest atmospheric reanalysis data [17,18] to determine the precipitation effects of this global tree restoration. Specifically, we use these results to identify where reforestation can best be implemented to counteract regional drying trends as projected for the 21st century under the RCP4.5 climate change scenario.…”

The Effect of Water Vapor Originating from Land on the 2018 Drought Development in Europe

“…The specific dataset we used here [21] provides readily available moisture source-receptor relations globally without the need of running moisture tracking again and has found first applications besides this work [36]. These source-receptor relations were found to be similar compared to another recent dataset [37]. We spatially resampled the data to high resolution around the coast by considering the exact shape of coastline and as such dividing oceanic and land contributions.…”