scholarly journals Recharge observations indicate strengthened groundwater connection to surface fluxes

2021 ◽  
Author(s):  
Wouter Berghuijs ◽  
Elco Luijendijk ◽  
Christian Moeck ◽  
Ype Van der Velde ◽  
Scott Allen
Keyword(s):  
Water Cycle ◽  
Potential Evapotranspiration ◽  
Surface Fluxes ◽  
Global Water Cycle ◽  
Global Estimates ◽  
Recharge Rates ◽  
Earth System Models ◽  
Climatic Aridity ◽  
Permafrost Regions

Groundwater is an invaluable global resource, but its long-term viability as a resource for consumption, agriculture, and ecosystems depends on precipitation recharging aquifers. How much precipitation recharges groundwaters varies enormously across Earth's surface, but recharge rates are uncertain because field observations are sparse and modeled global estimates remain largely unvalidated. Here we show that recharge is predictable as a simple function of climatic aridity — the ratio of long-term potential evapotranspiration to precipitation — using a global synthesis of measured recharge of 5237 sites across six continents. We use this relationship to estimate long-term recharge globally outside of permafrost regions. Our estimates double previous global estimates and are more consistent with empirical observations. These revised higher estimates of global groundwater recharge imply that much more groundwater must contribute to evapotranspiration and streamflow than previously represented in global water cycle depictions or global hydrological and Earth system models.

Ecological research and large scale land-atmosphere feedbacks: lesson from the Bouchet's complementary relationship

2011 ◽  
Vol 8 (3) ◽  
pp. 6077-6094
Author(s):  
E. Lugato ◽  
G. Alberti ◽  
B. Gioli ◽  
J. O. Kaplan ◽  
A. Peressotti ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Cycle ◽  
Potential Evapotranspiration ◽  
Short Term ◽  
Global Water Cycle ◽  
Long Time ◽  
Large Scale Land ◽  
Global Vegetation ◽  
Term Analysis

Abstract. Acceleration of the global water cycle over recent decades, which is hypothesized by several studies, remains uncertain because of the high inter-annual variability of its components. Observations of pan evaporation (Epan), a proxy of potential evapotranspiration (ETp), may help to identify trends in the water cycle over long time periods. The complementary relation (CR; Bouchet, 1963) states ETp and actual evapotranspiration (ETa) depend on each other in a complementary manner, through land-atmosphere feedbacks in water limited environments. Using a long time series of Epan observations in Australia, we estimated monthly ETa values using the CR and compared our estimates with ETa measured at eddy covariance stations in Fluxnet. Our results confirm that CR can be reliably applied to estimate ETa and produces better results than a global vegetation model run without specific calibration. In addition, our analysis indicated that, on average, ETa did not show any significant trend between 1975 and 2009 in Australia, but short-term analysis including anomaly periods may give the idea of a rapid climate change that is not perceived in a long-term perspective.

scholarly journals Challenges in Quantifying Changes in the Global Water Cycle

2015 ◽  
Vol 96 (7) ◽  
pp. 1097-1115 ◽  
Author(s):  
Gabriele C. Hegerl ◽  
Emily Black ◽  
Richard P. Allan ◽  
William J. Ingram ◽  
Debbie Polson ◽  
...  
Keyword(s):  
Water Cycle ◽  
Internal Variability ◽  
Anthropogenic Aerosols ◽  
Long Term Stability ◽  
Global Water Cycle ◽  
Ocean Salinity ◽  
Long Time ◽  
Global Water

Abstract Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time series over land, but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols and because of the large climate variability presently limits confidence in attribution of observed changes.

scholarly journals Collision dynamics and uptake of water on alcohol-covered ice

2013 ◽  
Vol 13 (4) ◽  
pp. 2223-2233 ◽  
Author(s):  
E. S. Thomson ◽  
X. Kong ◽  
N. Marković ◽  
P. Papagiannakopoulos ◽  
J. B. C. Pettersson
Keyword(s):  
Water Transport ◽  
Water Cycle ◽  
Collision Dynamics ◽  
Molecular Scattering ◽  
Water Ice ◽  
Global Water Cycle ◽  
Ice Surface ◽  
Significant Barrier ◽  
Cloud Evolution

Abstract. Molecular scattering experiments are used to investigate water interactions with methanol and n-butanol covered ice between 155 K and 200 K. The inelastically scattered and desorbed products of an incident molecular beam are measured and analyzed to illuminate molecular scale processes. The residence time and uptake coefficients of water impinging on alcohol-covered ice are calculated. The surfactant molecules are observed to affect water transport to and from the ice surface in a manner that is related to the number of carbon atoms they contain. Butanol films on ice are observed to reduce water uptake by 20%, whereas methanol monolayers pose no significant barrier to water transport. Water colliding with methanol covered ice rapidly permeates the alcohol layer, but on butanol water molecules have mean surface lifetimes of ≲ 0.6 ms, enabling some molecules to thermally desorb before reaching the water ice underlying the butanol. These observations are put into the context of cloud and atmospheric scale processes, where such surfactant layers may affect a range of aerosol processes, and thus have implications for cloud evolution, the global water cycle, and long term climate.

scholarly journals The historical global sea-level budget

2011 ◽  
Vol 52 (59) ◽  
pp. 8-14 ◽  
Author(s):  
J.C. Moore ◽  
S. Jevrejeva ◽  
A. Grinsted
Keyword(s):  
Sea Level ◽  
Water Cycle ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Ice Caps ◽  
Mountain Glaciers ◽  
Global Water Cycle ◽  
Decadal Scale ◽  
Global Sea Level

AbstractWe analyze the global sea-level budget since 1850. Good estimates of sea-level contributions from glaciers and small ice caps, the Greenland ice sheet and thermosteric sea level are available over this period, though considerable scope for controversy remains in all. Attempting to close the sea-level budget by adding the components results in a residual displaying a likely significant trend of ~0.37mma–1 from 1955 to 2005, which can, however, be reasonably closed using estimated melting from unsurveyed high-latitude small glaciers and ice caps. The sea-level budget from 1850 is estimated using modeled thermosteric sea level and inferences from a small number of mountain glaciers. This longer-term budget has a residual component that displays a rising trend likely associated with the end of the Little Ice Age, with much decadal-scale variability that is probably associated with variability in the global water cycle, ENSO and long-term volcanic impacts.

scholarly journals Global water cycle and the coevolution of the Earth’s interior and surface environment

2017 ◽  
Vol 375 (2094) ◽  
pp. 20150393 ◽  
Author(s):  
Jun Korenaga ◽  
Noah J. Planavsky ◽  
David A. D. Evans
Keyword(s):  
Plate Tectonics ◽  
Water Cycle ◽  
Critical Role ◽  
Global Water Cycle ◽  
Water Influx ◽  
The Earth ◽  
Almost All ◽  
Global Water

The bulk Earth composition contains probably less than 0.3% of water, but this trace amount of water can affect the long-term evolution of the Earth in a number of different ways. The foremost issue is the occurrence of plate tectonics, which governs almost all aspects of the Earth system, and the presence of water could either promote or hinder the operation of plate tectonics, depending on where water resides. The global water cycle, which circulates surface water into the deep mantle and back to the surface again, could thus have played a critical role in the Earth’s history. In this contribution, we first review the present-day water cycle and discuss its uncertainty as well as its secular variation. If the continental freeboard has been roughly constant since the Early Proterozoic, model results suggest long-term net water influx from the surface to the mantle, which is estimated to be 3−4.5×10 14  g yr −1 on the billion years time scale. We survey geological and geochemical observations relevant to the emergence of continents above the sea level as well as the nature of Precambrian plate tectonics. The global water cycle is suggested to have been dominated by regassing, and its implications for geochemical cycles and atmospheric evolution are also discussed. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

scholarly journals Collision dynamics and uptake of water on alcohol-covered ice

2012 ◽  
Vol 12 (10) ◽  
pp. 27637-27666
Author(s):  
E. S. Thomson ◽  
X. Kong ◽  
N. Marković ◽  
P. Papagiannakopoulos ◽  
J. B. C. Pettersson
Keyword(s):  
Water Transport ◽  
Water Cycle ◽  
Collision Dynamics ◽  
Molecular Scattering ◽  
Water Ice ◽  
Global Water Cycle ◽  
Ice Surface ◽  
Significant Barrier ◽  
Cloud Evolution

Abstract. Molecular scattering experiments are used to investigate water interactions with methanol and n-butanol covered ice between 155 K and 200 K. The inelastically scattered and desorbed products of an incident molecular beam are measured and analyzed to illuminate molecular scale processes. The residence time and uptake coefficients of water impinging on alcohol-covered ice are calculated. The surfactant molecules are observed to affect water transport to and from the ice surface in a manner that is related to the number of carbon atoms they contain. Butanol films are observed to reduce water uptake by ice by 20%, whereas methanol monolayers pose no significant barrier to water transport. Water colliding with methanol covered ice rapidly permeates the alcohol layer, but on butanol has mean surface lifetimes of ≲0.6 ms, enabling some molecules to thermally desorb before reaching the water ice underlying the butanol. These observations are put into the context of cloud and atmospheric scale processes, where such surfactant layers may affect a range of aerosol processes, and thus have implications for cloud evolution, the global water cycle, and long term climate.

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