High-resolution global atmospheric moisture connections from evaporation to precipitation

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).

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High-resolution global atmospheric moisture connections from evaporation to precipitation

10.5194/essd-2020-89 ◽

2020 ◽

Author(s):

Obbe A. Tuinenburg ◽

Jolanda J. E. Theeuwen ◽

Arie Staal

Keyword(s):

Amazon Basin ◽

Reanalysis Data ◽

Congo Basin ◽

Atmospheric Moisture ◽

Moisture Recycling ◽

Wind Speeds ◽

Complete Dataset ◽

Global Land ◽

Land Recycling ◽

Tracking Model

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. 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.pangaea.de/10.1594/PANGAEA.912710 (Tuinenburg et al., 2020).

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Tracking the global flows of atmospheric moisture

10.5194/hess-2019-597 ◽

2019 ◽

Author(s):

Obbe A. Tuinenburg ◽

Arie Staal

Keyword(s):

Vertical Mixing ◽

Three Dimensional ◽

Reanalysis Data ◽

Point Sources ◽

Atmospheric Moisture ◽

Reanalysis Dataset ◽

Considerable Uncertainty ◽

Moisture Recycling ◽

Trade Offs ◽

Spatial Dimensions

Abstract. Many processes in hydrology and Earth system science relate to moisture recycling, the contribution of terrestrial evaporation to precipitation. For example, the effects of land-cover changes on regional rainfall regimes depend on this process. To study moisture recycling, a range of moisture tracking models are in use that are forced with output from atmospheric models, but differ in various ways. They can be Eulerian (grid-based) or Lagrangian (trajectory-based), have two or three spatial dimensions, and rely on a range of other assumptions. Which model is most suitable depends on the purpose of the study, but also on the quality and resolution of the data with which it is forced. Recently, the high-resolution ERA5 reanalysis dataset has become the state-of-the-art, paving the way for a new generation of moisture tracking models. However, it is unclear how the new data can best be used to obtain accurate estimates of atmospheric moisture flows. Here we develop a set of moisture tracking models forced with ERA5 data and systematically test their performance regarding continental evaporation recycling ratio, distances of moisture flows, and footprints of evaporation from seven point sources across the globe. We report simulation times to assess possible trade-offs between accuracy and speed. Three-dimensional Lagrangian models were most accurate and ran faster than Eulerian versions for tracking water from single grid cells. The rate of vertical mixing of moisture in the atmosphere was the greatest source of uncertainty in moisture tracking. We conclude that the recently improved resolution of atmospheric reanalysis data allows for more accurate moisture tracking results in a Lagrangian setting, but that considerable uncertainty regarding turbulent mixing remains. We present an efficient Lagrangian method to track atmospheric moisture flows from any location globally using ERA5 reanalysis data and make the code for this model publicly available.

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Mechanisms Linking Global 5-Day Waves to Tropical Convection

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-17-0101.1 ◽

2017 ◽

Vol 74 (11) ◽

pp. 3679-3702 ◽

Cited By ~ 4

Author(s):

Malcolm J. King ◽

Matthew C. Wheeler ◽

Todd P. Lane

Keyword(s):

Amazon Basin ◽

Tropical Convection ◽

Congo Basin ◽

Gulf Of Guinea ◽

Atmospheric Moisture ◽

Local Climate ◽

Low Level ◽

The Andes ◽

Convergence Zones ◽

Moisture Transports

Abstract Reanalysis data and satellite-derived rainfall measurements are examined to determine possible mechanisms linking the “5 day” Rossby–Haurwitz wave to localized variations of tropical convection. The mechanisms in all regions rely on the modulation of zonal winds near the equator by the wave, but the nature of these mechanisms depends strongly on local topography and local climate. In the upper Amazon basin, the wave modulates the strength of prevailing easterlies and thus the upslope flow and associated convection on the eastern edge of the Andes. Similar modulation of upslope flow is involved off the Panamanian and Colombian Pacific coasts, but the deflection and confluence of low-level wind in the presence of the Andes and moisture transports across the Andes from the Amazon basin are also factors. Similar deflection and confluence of winds around and through the Maritime Continent lead to low-level divergence and convection anomalies over the eastern Indian Ocean. Anomalous moisture transports from the Congo basin to the eastern and northeastern Gulf of Guinea due to the wave affect atmospheric moisture over the Gulf of Guinea and thus convection in the region. Over oceanic convergence zones, modulations of the prevailing winds by the wave affect the overall wind magnitude, changing evaporation from the ocean surface and atmospheric moisture. Most of these mechanisms arise from the nonuniform nature of Earth’s surface and suggest that other external Rossby–Haurwitz waves may have similar interactions with convection.

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Contribution of the Sahel region to precipitation over the African continent

10.5194/egusphere-egu21-15415 ◽

2021 ◽

Author(s):

Sofie te Wierik ◽

Jessica Keune ◽

Diego Miralles ◽

Erik Cammeraat ◽

Yael Artzy-Randrup ◽

...

Keyword(s):

Forest Cover ◽

Reanalysis Data ◽

Congo Basin ◽

Lagrangian Model ◽

African Continent ◽

Tropical Regions ◽

Moisture Recycling ◽

Precipitation Recycling ◽

Interception Loss ◽

Sahel Region

Redistribution of evapotranspiration from land via atmospheric circulation is an important Earth system process. Globally, evapotranspiration contributes significantly to terrestrial rainfall, on both regional and more remote scales. In wet, tropical regions (e.g. the Congo basin), transpiration and interception loss from the dense forest cover are the primary drivers of moisture recycling, which plays a crucial role in preserving regional ecosystem functioning. However, for semi-arid and arid regions, our knowledge on the extent and significance of evapotranspiration for moisture recycling is still very limited, despite the significance this may have for addressing challenges of desertification in times of rapid environmental change. Considering this, we are taking the Sahel region as a case study and investigate its contribution to precipitation in the African continent. In addition, we specifically study what fraction of the precipitation originates from vegetation in the Sahel through transpiration and interception loss. Our study is based on simulated atmospheric moisture trajectories derived from the Lagrangian model FLEXPART with a 1-degree resolution, driven by ECMWF reanalysis data over 1980&#8211;2016. Preliminary results show (1) the temporal variability in the contribution of the region to precipitation in African drylands, and (2) a significant contribution of local precipitation recycling. We conclude that consideration of the naturally and anthropogenically-driven greening of the Sahel, as well as land use and land cover changes in the region, may have both local and far-reaching impacts via the transport of moisture through the atmosphere.

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The ‘global tree restoration potential’: a first estimation of the hydrological effects

10.5194/egusphere-egu21-7697 ◽

2021 ◽

Author(s):

Anne J. Hoek van Dijke ◽

Imme Benedict ◽

Kaniska Mallick ◽

Martin Herold ◽

Miriam Machwitz ◽

...

Keyword(s):

Water Availability ◽

Land Surface ◽

Hydrological Cycle ◽

Local Maximum ◽

Atmospheric Moisture ◽

Moisture Recycling ◽

Restoration Potential ◽

Tracking Model ◽

The Impact ◽

Hydrological Effects

Vegetation plays an important role in the exchange of water between the land surface and the atmosphere through evaporation and redistribution of water. Hence, changes in vegetation cover alter the terrestrial hydrological cycle. Large-scale forest restoration is an effective climate change mitigation strategy through carbon sequestration and is expected to impact the water availability. A better understanding of the impact of reforestation is needed, given the numerous different reforestation missions.Our study aims to provide an estimation of the hydrological effects of 900 million hectares of reforestation, called the &#8216;global tree restoration potential&#8217; (Bastin et al., 2019). We include the effects of forest planting on evaporation and moisture recycling, where evaporation effects local water availability, and moisture recycling effects both local and remote water availability. We used the conventional Budyko&#8217;s moisture index framework to calculate the effects of reforestation on evaporation, and afterwards we used the UTrack dataset to calculate the changes in precipitation. The UTrack dataset presents the monthly climatological mean atmospheric moisture flows from evaporation to precipitation and is created using the Lagrangian moisture tracking model UTrack (Tuinenburg et al., 2020).The results show that reforesting the &#8216;global tree restoration potential&#8217; would effect water availability for most of the Earth&#8217;s surface. The global mean increase in terrestrial evaporation is 8 mm yr-1. The increase in evaporation is highest around the equator (on average 20 mm yr-1), with local maximum changes of up to 200 mm yr-1. This is related to a relatively high restoration potential in low latitude areas, and a generally large evaporation response in high precipitation regions. Enhanced moisture recycling has the potential to partly compensate for this decreased water availability by increasing the downwind precipitation.&#160;Bastin, J.-F., Finegold, Y., Garcia, C., Mollicone, D., Rezende, M., Routh, D., Zohner, C.M., Crowther, T.W. The global tree restoration potential. Science, 365, 76-79, http://doi.org/10.1126/science.aax0848, 2019.Tuinenburg, O. A., Theeuwen, J. J. E., and Staal, A.: High-resolution global atmospheric moisture connections from evaporation to precipitation, Earth Syst. Sci. Data, 12, 3177&#8211;3188, https://doi.org/10.5194/essd-12-3177-2020, 2020.

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Tracking the global flows of atmospheric moisture

10.5194/egusphere-egu2020-7940 ◽

2020 ◽

Author(s):

Obbe Tuinenburg ◽

Arie Staal

Keyword(s):

Vertical Mixing ◽

Three Dimensional ◽

Reanalysis Data ◽

Point Sources ◽

Atmospheric Moisture ◽

Reanalysis Dataset ◽

Considerable Uncertainty ◽

Moisture Recycling ◽

Trade Offs ◽

Spatial Dimensions

Many processes in hydrology and Earth system science relate to moisture recycling, the contribution of terrestrial evaporation to precipitation. For example, the effects of land-cover changes on regional rainfall regimes depend on this process. To study moisture recycling, a range of moisture tracking models are in use that are forced with output from atmospheric models, but differ in various ways. They can be Eulerian (grid-based) or Lagrangian (trajectory-based), have two or three spatial dimensions, and rely on a range of other assumptions. Which model is most suitable depends on the purpose of the study, but also on the quality and resolution of the data with which it is forced. Recently, the high-resolution ERA5 reanalysis dataset has become the state-of-the-art, paving the way for a new generation of moisture tracking models. However, it is unclear how the new data can best be used to obtain accurate estimates of atmospheric moisture flows. Here we develop a set of moisture tracking models forced with ERA5 data and systematically test their performance regarding continental evaporation recycling ratio, distances of moisture flows, and &lt;q&gt;footprints&lt;/q&gt; of evaporation from seven point sources across the globe. We report simulation times to assess possible trade-offs between accuracy and speed. Three-dimensional Lagrangian models were most accurate and ran faster than Eulerian versions for tracking water from single grid cells. The rate of vertical mixing of moisture in the atmosphere was the greatest source of uncertainty in moisture tracking. We conclude that the recently improved resolution of atmospheric reanalysis data allows for more accurate moisture tracking results in a Lagrangian setting, but that considerable uncertainty regarding turbulent mixing remains. We present an efficient Lagrangian method to track atmospheric moisture flows from any location globally using ERA5 reanalysis data and make the code for this model publicly available.

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Length and time scales of atmospheric moisture recycling

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-1853-2011 ◽

2011 ◽

Vol 11 (5) ◽

pp. 1853-1863 ◽

Cited By ~ 97

Author(s):

R. J. van der Ent ◽

H. H. G. Savenije

Keyword(s):

Time Scales ◽

Scaling Laws ◽

Reanalysis Data ◽

Length Scale ◽

Atmospheric Moisture ◽

Climatic Effects ◽

Study Region ◽

Moisture Recycling ◽

Shape Dependence ◽

Novel Approach

Abstract. It is difficult to quantify the degree to which terrestrial evaporation supports the occurrence of precipitation within a certain study region (i.e. regional moisture recycling) due to the scale- and shape-dependence of regional moisture recycling ratios. In this paper we present a novel approach to quantify the spatial and temporal scale of moisture recycling, independent of the size and shape of the region under study. In contrast to previous studies, which essentially used curve fitting, the scaling laws presented by us follow directly from the process equation. thus allowing a fair comparison between regions and seasons. The calculation is based on ERA-Interim reanalysis data for the period 1999 to 2008. It is shown that in the tropics or in mountainous terrain the length scale of recycling can be as low as 500 to 2000 km. In temperate climates the length scale is typically between 3000 to 5000 km whereas it amounts to more than 7000 km in desert areas. The time scale of recycling ranges from 3 to 20 days, with the exception of deserts, where it is much longer. The most distinct seasonal differences can be observed over the Northern Hemisphere: in winter, moisture recycling is insignificant, whereas in summer it plays a major role in the climate. The length and time scales of atmospheric moisture recycling can be useful metrics to quantify local climatic effects of land use change.

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The fate of land evaporation – A global dataset

10.5194/essd-2019-246 ◽

2020 ◽

Author(s):

Andreas Link ◽

Ruud van der Ent ◽

Markus Berger ◽

Stephanie Eisner ◽

Matthias Finkbeiner

Keyword(s):

Land Cover ◽

Hydrological Cycle ◽

Grid Cell ◽

Reanalysis Data ◽

Land Cover Changes ◽

Atmospheric Moisture ◽

Grid Cells ◽

Time Period ◽

Tracking Model ◽

Areas Of Interest

Abstract. Various studies investigated the fate of evaporation and the origin of precipitation. The more recent studies among them were often carried out with the help of numerical moisture tracking. Many research questions could be answered within this context such as dependencies of atmospheric moisture transfers between different regions, impacts of land cover changes on the hydrological cycle, sustainability related questions as well as questions regarding the seasonal and inter-annual variability of precipitation. In order to facilitate future applications, global datasets on the fate of evaporation and the sources of precipitation are needed. Since most studies are on a regional level and focus more on the sources of precipitation, the goal of this study is to provide a readily available global dataset on the fate of evaporation for a fine-meshed grid of source and receptor cells. The dataset was created through a global run of the numerical moisture tracking model WAM-2layers and focused on the fate of land evaporation. The tracking was conducted on a 1.5° × 1.5° grid and was based on reanalysis data from the ERA-Interim database. Climatic input data were incorporated in 3- respectively 6-hourly time steps and represent the time period from 2001 to 2018. Atmospheric moisture was tracked forward in time and the geographical borders of the model were located at +/- 79.5° latitude. As a result of the model run, the annual and monthly average as well as the inter-annual average fate of evaporation was determined for 8684 land grid cells (all land cells except those located within Greenland and Antarctica) and provided via source-receptor matrices. The gained dataset was complemented via an aggregation to country and basin scales in order to highlight possible usages for areas of interest larger than grid cells. This resulted in data for 265 countries and 8223 basins. Finally, five types of source-receptor matrices for average moisture transfers were chosen to build the core of the dataset: land grid cell to grid cell, country to grid cell, basin to grid cell, country to country, basin to basin. The dataset is, to our knowledge, the first ready-to-download dataset providing the overall fate of evaporation for land cells of a global fine-meshed grid in monthly resolution. At the same time, information on the sources of precipitation can be extracted from it. It could be used for investigations into average annual, seasonal and inter-annual sink and source regions of atmospheric moisture from land masses for most of the regions in the world and shows various application possibilities for studying interactions between people and water such as land cover changes or human water consumption patterns. The dataset is accessible under https://doi.pangaea.de/10.1594/PANGAEA.908705 (Link et al., 2019a) and comes along with example scripts for reading and plotting.

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Tracking the global flows of atmospheric moisture and associated uncertainties

Hydrology and Earth System Sciences ◽

10.5194/hess-24-2419-2020 ◽

2020 ◽

Vol 24 (5) ◽

pp. 2419-2435 ◽

Cited By ~ 5

Author(s):

Obbe A. Tuinenburg ◽

Arie Staal

Keyword(s):

Vertical Mixing ◽

Three Dimensional ◽

Reanalysis Data ◽

Point Sources ◽

Atmospheric Moisture ◽

Data Set ◽

Considerable Uncertainty ◽

Moisture Recycling ◽

Trade Offs ◽

Spatial Dimensions

Abstract. Many processes in hydrology and Earth system science relate to continental moisture recycling, the contribution of terrestrial evaporation to precipitation. For example, the effects of land-cover changes on regional rainfall regimes depend on this process. To study moisture recycling, a range of moisture-tracking models are in use that are forced with output from atmospheric models but differ in various ways. They can be Eulerian (grid-based) or Lagrangian (trajectory-based), have two or three spatial dimensions, and rely on a range of other assumptions. Which model is most suitable depends not only on the purpose of the study but also on the quality and resolution of the data with which it is forced. Recently, the high-resolution ERA5 reanalysis data set has become the state of the art, paving the way for a new generation of moisture-tracking models. However, it is unclear how the new data can best be used to obtain accurate estimates of atmospheric moisture flows. Here we develop a set of moisture-tracking models forced with ERA5 data and systematically test their performance regarding continental evaporation recycling ratio, distances of moisture flows, and “footprints” of evaporation from seven point sources across the globe. We report simulation times to assess possible trade-offs between accuracy and speed. Three-dimensional Lagrangian models were most accurate and ran faster than Eulerian versions for tracking water from single grid cells. The rate of vertical mixing of moisture in the atmosphere was the greatest source of uncertainty in moisture tracking. We conclude that the recently improved resolution of atmospheric reanalysis data allows for more accurate moisture tracking results in a Lagrangian setting, but that considerable uncertainty regarding turbulent mixing remains. We present an efficient Lagrangian method to track atmospheric moisture flows from any location globally using ERA5 reanalysis data and make the code for this model, which we call UTrack-atmospheric-moisture, publicly available.

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The fate of land evaporation - A global dataset

10.5194/egusphere-egu2020-3674 ◽

2020 ◽

Author(s):

Andreas Link ◽

Ruud van der Ent ◽

Markus Berger ◽

Stephanie Eisner ◽

Matthias Finkbeiner

Keyword(s):

Land Cover ◽

Hydrological Cycle ◽

Grid Cell ◽

Reanalysis Data ◽

Land Cover Changes ◽

Atmospheric Moisture ◽

Grid Cells ◽

Time Period ◽

Tracking Model ◽

Areas Of Interest

Various studies investigated the fate of evaporation and the origin of precipitation. The more recent studies among them were often carried out with the help of numerical moisture tracking. Many research questions could be answered within this context such as dependencies of atmospheric moisture transfers between different regions, impacts of land cover changes on the hydrological cycle, sustainability related questions as well as questions regarding the seasonal and inter-annual variability of precipitation. In order to facilitate future applications, global datasets on the fate of evaporation and the sources of precipitation are needed. Since most studies are on a regional level and focus more on the sources of precipitation, the goal of this study is to provide a readily available global dataset on the fate of evaporation for a fine-meshed grid of source and receptor cells. The dataset was created through a global run of the numerical moisture tracking model WAM-2layers and focused on the fate of land evaporation. The tracking was conducted on a 1.5&#176; &#215; 1.5&#176; grid and was based on reanalysis data from the ERA-Interim database. Climatic input data were incorporated in 3- respectively 6-hourly time steps and represent the time period from 2001 to 2018. Atmospheric moisture was tracked forward in time and the geographical borders of the model were located at +/- 79.5&#176; latitude. As a result of the model run, the annual and monthly average as well as the inter-annual average fate of evaporation was determined for 8684 land grid cells (all land cells except those located within Greenland and Antarctica) and provided via source-receptor matrices. The gained dataset was complemented via an aggregation to country and basin scales in order to highlight possible usages for areas of interest larger than grid cells. This resulted in data for 265 countries and 8223 basins. Finally, five types of source-receptor matrices for average moisture transfers were chosen to build the core of the dataset: land grid cell to grid cell, country to grid cell, basin to grid cell, country to country, basin to basin. The dataset is, to our knowledge, the first ready-to-download dataset providing the overall fate of evaporation for land cells of a global fine-meshed grid in monthly resolution. At the same time, information on the sources of precipitation can be extracted from it. It could be used for investigations into average annual, seasonal and inter-annual sink and source regions of atmospheric moisture from land masses for most of the regions in the world and shows various application possibilities for studying interactions between people and water such as land cover changes or human water consumption patterns. The dataset is accessible under <a href="https://doi.pangaea.de/10.1594/PANGAEA.908705%20">https://doi.pangaea.de/10.1594/PANGAEA.908705</a> &#160;and comes along with example scripts for reading and plotting. &#160;&#160;

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