A GCM-based assessment of the global moisture budget and the role of land-surface moisture reservoirs in processing precipitation

2002 ◽  
Vol 20 (1) ◽  
pp. 13-29 ◽  
Author(s):  
V. Arora ◽  
G. Boer
2004 ◽  
Vol 35 (4-5) ◽  
pp. 325-334 ◽  
Author(s):  
G.E. Liston ◽  
M. Sturm

In the Arctic, the simplest way to describe the winter surface moisture budget (in the absence of any net horizontal transport) is: snow-water-equivalent depth on the ground (D) equals precipitation (P) minus sublimation (S). D, P and S are the most fundamental components of the winter arctic hydrologic cycle and understanding them is essential to understanding arctic moisture-related processes. Unfortunately, accurate solid-precipitation (P) measurements have proven nearly impossible to achieve in the Arctic, because precipitation generally falls when it is windy. Gauge undercatch can range from 55–75% depending on the gauge type and wind conditions. The state of knowledge for winter sublimation (S) is even more limited. There are few actual measurements and most studies have used physical models to estimate this quantity. Moreover, fundamental questions concerning the boundary-layer physics of arctic winter sublimation remain unanswered. Resolving these is essential to closing local, regional, and pan-Arctic moisture budgets because some studies indicate sublimation may be as much as 50% of the total winter precipitation and 35% of the annual precipitation. This paper summarizes and analyzes the existing literature describing arctic sublimation.


2021 ◽  
Author(s):  
Tyler Harrington ◽  
Christopher Skinner ◽  
Jesse Nusbaumer

<p>Land surface moisture plays a crucial role in precipitation patterns across the globe. Evapotranspiration (the combination of ground evaporation (E), canopy evaporation (I), and transpiration (T)) from the land surface can influence precipitation through local recycling and the propagation of moisture to downwind regions. However, the role of the land surface and of T, E, and I individually in these two processes are not well understood and limit our understanding of the role of the land surface for both drought onset and intensification. Here we use a version of the Community Earth System Model (CESM1.2 with the Community Atmosphere Model CAM5 and the Community Land Model CLM5) with online water tracers to directly track and quantify the movement of T, E and I moisture across North America for the 1985–2015 period. Initial findings suggest that over 50% of summer precipitation for much of central and northern US and Canada comes from the land surface. The tracers also suggest that, with the exception of the US west coast and desert southwest, 40-60% of land precipitation across the continent comes from the T component. The connection between land surface moisture and drought episodes are examined for different regions of North America. The individual roles of T, E, and I in shaping droughts are also examined.</p>


Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.


Science ◽  
2005 ◽  
Vol 310 (5748) ◽  
pp. 657-660 ◽  
Author(s):  
F. S. Chapin

2021 ◽  
Author(s):  
Zhenyu Zhang ◽  
Patrick Laux ◽  
Joël Arnault ◽  
Jianhui Wei ◽  
Jussi Baade ◽  
...  

<p>Land degradation with its direct impact on vegetation, surface soil layers and land surface albedo, has great relevance with the climate system. Assessing the climatic and ecological effects induced by land degradation requires a precise understanding of the interaction between the land surface and atmosphere. In coupled land-atmosphere modeling, the low boundary conditions impact the thermal and hydraulic exchanges at the land surface, therefore regulates the overlying atmosphere by land-atmosphere feedback processes. However, those land-atmosphere interactions are not convincingly represented in coupled land-atmosphere modeling applications. It is partly due to an approximate representation of hydrological processes in land surface modeling. Another source of uncertainties relates to the generalization of soil physical properties in the modeling system. This study focuses on the role of the prescribed physical properties of soil in high-resolution land surface-atmosphere simulations over South Africa. The model used here is the hydrologically-enhanced Weather Research and Forecasting (WRF-Hydro) model. Four commonly used global soil datasets obtained from UN Food and Agriculture Organization (FAO) soil database, Harmonized World Soil Database (HWSD), Global Soil Dataset for Earth System Model (GSDE), and SoilGrids dataset, are incorporated within the WRF-Hydro experiments for investigating the impact of soil information on land-atmosphere interactions. The simulation results of near-surface temperature, skin temperature, and surface energy fluxes are presented and compared to observational-based reference dataset. It is found that simulated soil moisture is largely influenced by soil texture features, which affects its feedback to the atmosphere.</p>


2019 ◽  
Vol 221 ◽  
pp. 210-224 ◽  
Author(s):  
Temesgen Alemayehu Abera ◽  
Janne Heiskanen ◽  
Petri Pellikka ◽  
Miina Rautiainen ◽  
Eduardo Eiji Maeda

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