Large-scale variability of wind erosion mass flux rates at Owens Lake: 2. Role of roughness change, particle limitation, change of threshold friction velocity, and the Owen effect

1997 ◽  
Vol 102 (D22) ◽  
pp. 25989-25998 ◽  
Author(s):  
Dale A. Gillette ◽  
Ellen Hardebeck ◽  
Jim Parker
Keyword(s):  
Mass Flux ◽  
Wind Erosion ◽  
Large Scale ◽  
Friction Velocity ◽  
Threshold Friction Velocity ◽  
Owens Lake ◽  
Roughness Change

Large-scale variability of wind erosion mass flux rates at Owens Lake: 1. Vertical profiles of horizontal mass fluxes of wind-eroded particles with diameter greater than 50 μm

1997 ◽  
Vol 102 (D22) ◽  
pp. 25977-25987 ◽  
Author(s):  
Dale A. Gillette ◽  
D. W. Fryrear ◽  
Jing Bing Xiao ◽  
Paul Stockton ◽  
Duane Ono ◽  
...  
Keyword(s):  
Mass Flux ◽  
Wind Erosion ◽  
Large Scale ◽  
Vertical Profiles ◽  
Owens Lake ◽  
Mass Fluxes

scholarly journals An improved dust emission model – Part 2: Evaluation in the Community Earth System Model, with implications for the use of dust source functions

2014 ◽  
Vol 14 (23) ◽  
pp. 13043-13061 ◽  
Author(s):  
J. F. Kok ◽  
S. Albani ◽  
N. M. Mahowald ◽  
D. S. Ward
Keyword(s):  
Large Scale ◽  
Friction Velocity ◽  
Source Function ◽  
Dust Emission ◽  
Companion Paper ◽  
System Model ◽  
Dust Source ◽  
Threshold Friction Velocity ◽  
Scale Models ◽  
Community Earth System Model

<p><strong>Abstract.</strong> The complex nature of mineral dust aerosol emission makes it a difficult process to represent accurately in weather and climate models. Indeed, results in the companion paper indicate that many large-scale models underestimate the dust flux's sensitivity to the soil's threshold friction velocity for erosion. We hypothesize that this finding explains why many dust cycle simulations are improved by using an empirical dust source function that shifts emissions towards the world's most erodible regions. Here, we both test this hypothesis and evaluate the performance of the new dust emission parameterization presented in the companion paper. We do so by implementing the new emission scheme into the Community Earth System Model (CESM) and comparing the resulting dust cycle simulations against an array of measurements. We find that the new scheme shifts emissions towards the world's most erodible regions in a manner that is strikingly similar to the effect of implementing a widely used source function based on satellite observations of dust source regions. Furthermore, model comparisons against aerosol optical depth measurements show that the new physically based scheme produces a statistically significant improvement in CESM's representation of dust emission, which exceeds the improvement produced by implementing a source function. These results indicate that the need to use an empirical source function is eliminated, at least in CESM, by the additional physics in the new scheme, and in particular by its increased sensitivity to the soil's threshold friction velocity. Since the threshold friction velocity is affected by climate changes, our results further suggest that many large-scale models underestimate the global dust cycle's climate sensitivity.</p>

scholarly journals A simple method to estimate threshold friction velocity of wind erosion in the field

2010 ◽  
Vol 37 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Junran Li ◽  
Gregory S. Okin ◽  
Jeffrey E. Herrick ◽  
Jayne Belnap ◽  
Seth M. Munson ◽  
...  
Keyword(s):  
Wind Erosion ◽  
Friction Velocity ◽  
Simple Method ◽  
Threshold Friction Velocity

scholarly journals Szélerózió okozta talaj-, humusz- és tápanyag-áthalmozás különbségeinek feltárása különböző szerkezeti adottságú csernozjom talajokon terepi szélcsatorna kísérletek alapján

2021 ◽  
Author(s):  
Farsang Andrea ◽  
Barta Károly ◽  
Szatmári József ◽  
Bartus Máté
Keyword(s):  
Wind Erosion ◽  
Friction Velocity ◽  
Humus Content ◽  
Aggregate Size ◽  
List Type ◽  
Chernozem Soil ◽  
Wind Tunnel Experiments ◽  
Threshold Friction Velocity ◽  
Chernozem Soils

Kutatásunk során Magyarország két dél-alföldi réti csernozjom talajú területét vizsgáltuk azon céllal, hogy in situ körülmények között számszerűsítsük a különböző szélesemények által okozott talajveszteség mértékét, az ezzel együtt járó humusz- és tápanyagáthalmozás nagyságrendjét, valamint a két terület defláció érzékenységében tapasztalt különbségek okait.Vizsgálati területeink Békés megyében, Makótól K-re mintegy 10 km-re, Apátfalva külterületén, valamint Csongrád megyében Szegedtől ÉNy-ra 2 km-re helyezkedtek el. Kutatásunk célkitűzései az alábbiak voltak: terepi szélcsatornás mérésekre alapozott laboratóriumi mérések alapján különböző szerkezeti állapotú csernozjom talajokra meghatározni◾az indítósebességet,◾a szélerózióval áthalmozott szedimentben mért makroelem, és humuszanyag feldúsulását,◾valamint az ezekre ható talajtani tényezőket.A hasonló mechanikai összetételű, Szeged és Apátfalva melletti réti csernozjom talajok aggregátum összetételében, valamint a CaCO3 és humusztartalomban megfigyelhető különbségek hatására a Szeged melletti csernozjom mintaterület talaja defláció érzékenyebb. A Szegedtől É-ra eső csernozjomokon 6,5–9,0 m s–1 közötti indítósebesség értékeket mértünk, míg Apátfalván 13,0 m s–1 volt az indítósebesség értéke. Az apátfalvi terület talajának magasabb karbonát- és humusztartalma, valamint aggregátum összetételében mért magasabb morzsa arány az indítósebességérték növelésének irányába hat. A feltalajban a 0,5 mm-nél kisebb aggregátumok magasabb aránya következtében nemcsak kisebb indítósebesség értékeket, hanem nagyobb áthalmozódó talajmennyiséget, valamint ezzel együtt nagyobb mennyiségű humusz- és foszfor elmozdulást mértünk az egységesen 10-10 perces fújatási kísérleteink alkalmával a szegedi mintaterületen. Megállapítható tehát, hogy egyazon talajtípusba eső, s azonos textúrájú (homokos vályog) talajok esetében az aggregátum összetételben, valamint a CaCO3 és humusztartalomban megfigyelhető eltérések hatására jelentős különbségek tapasztalhatók a defláció érzékenység, az indítósebesség, a szediment szállítás módja és a humusz- és elemáthalmozás mértéke között.In our research, two Chernozem soil areas were examined in the southern part of the Great Hungarian Plain in order to quantify the amount of the soil loss, humus and nutrient transport caused by different wind events and in order to show the causes of the differences in the sensitivity of deflation between the two areas.Our study areas were located in Békés County, one of them was near Apátfalva, about 10 km east of Makó, and the other one was 2 km northeast of Szeged in Csongrád County. Our in situ wind tunnel experiments were accomplished on 2–4 June 2011 at Apátfalva and in July 2013 in Szeged. The objectives of our research were the followings:◾determination of the enrichment ratios for humus, macro- and microelements in the wind eroded sediments in the case of Chernozem soils with different structures based on field experiments and laboratory measurements;◾determination the affecting actual soil factors;◾estimation of soil loss and element rearrangement trends on Chernozem arable lands under different wind velocity on plot scale.Because of the differences in the aggregate size distribution, CaCO3 and humus content, Chernozem soil near Szeged is more sensitive to deflation than near Apátfalva. Threshold friction velocity was measured between 6.5 and 9.0 m s–1 near Szeged, while the same parameter was 13.0 m s–1 at Apátfalva. The higher carbonate and humus content and the higher crumb ratio of the soil on the Apátfalva area result increasing threshold friction velocity. Due to the higher proportion of aggregates smaller than 0.5 mm in the topsoil, we have measured not only lower threshold friction velocities, but also a larger quantity of transported soil and a larger humus and phosphorus loss during the uniform 10-10 minute long wind tunnel experiments in the Szeged sample area. It can be concluded that even in spite of the same soil type and same texture there are significant differences between deflation sensitivity, threshold friction velocity, sediment transport mode, humus and nutrient transportation because of the significant differences in aggregate size distribution, CaCO3 and humus content.It means that the agronomic structure of the soils greatly influences the mitigation and aggravation of the soil the stress effects caused by climate change. Extreme weather situations have drawn attention to the fact that improperly applied cultivation methods, tools, and overuse of Chernozem soils can modify the soil structure. One of the most serious affect is the dusting of the surface layer of the soil. During this process the larger macroaggregates disintegrate into microaggregates and the resulting smaller fractions are more exposed to wind erosion.The dust load affecting our settlements is mainly originated from arable lands. The mitigation of this emission is fundamentally based on the regulation of land use, farming practices and deflation. “Best Management Practices” (BMPs) mean a group of selected tools that can reduce or eliminate the transport of pollutants from diffuse sources before, during and/or after agricultural activities. However, these diffuse agricultural loads caused by wind erosion can only be quantified if the magnitude and spatial movement of the dust and pollutants is monitored.

On the effect of moisture bonding forces in air-dry soils on threshold friction velocity of wind erosion

Sedimentology ◽  
2006 ◽  
Vol 53 (3) ◽  
pp. 597-609 ◽  
Author(s):  
SUJITH RAVI ◽  
TED M. ZOBECK ◽  
THOMAS M. OVER ◽  
GREGORY S. OKIN ◽  
PAOLO D'ODORICO
Keyword(s):  
Wind Erosion ◽  
Friction Velocity ◽  
Threshold Friction Velocity ◽  
Effect Of Moisture

Optimal feature selection for prediction of wind erosion threshold friction velocity using a modified evolution algorithm

Geoderma ◽  
2019 ◽  
Vol 354 ◽  
pp. 113873 ◽  
Author(s):  
I. Kouchami-Sardoo ◽  
H. Shirani ◽  
I. Esfandiarpour-Boroujeni ◽  
J. Álvaro-Fuentes ◽  
H. Shekofteh
Keyword(s):  
Feature Selection ◽  
Wind Erosion ◽  
Friction Velocity ◽  
Threshold Friction Velocity ◽  
Erosion Threshold ◽  
Optimal Feature Selection ◽  
Evolution Algorithm ◽  
Selection For ◽  
Optimal Feature

scholarly journals An improved dust emission model – Part 1: Model description and comparison against measurements

2014 ◽  
Vol 14 (23) ◽  
pp. 13023-13041 ◽  
Author(s):  
J. F. Kok ◽  
N. M. Mahowald ◽  
G. Fratini ◽  
J. A. Gillies ◽  
M. Ishizuka ◽  
...  
Keyword(s):  
Large Scale ◽  
Friction Velocity ◽  
Climate Models ◽  
Dust Emission ◽  
Model Description ◽  
Emission Model ◽  
Threshold Friction Velocity ◽  
Dust Flux ◽  
Physically Based ◽  
Flux Measurements

Abstract. Simulations of the dust cycle and its interactions with the changing Earth system are hindered by the empirical nature of dust emission parameterizations in weather and climate models. Here we take a step towards improving dust cycle simulations by using a combination of theory and numerical simulations to derive a physically based dust emission parameterization. Our parameterization is straightforward to implement into large-scale models, as it depends only on the wind friction velocity and the soil's threshold friction velocity. Moreover, it accounts for two processes missing from most existing parameterizations: a soil's increased ability to produce dust under saltation bombardment as it becomes more erodible, and the increased scaling of the dust flux with wind speed as a soil becomes less erodible. Our treatment of both these processes is supported by a compilation of quality-controlled vertical dust flux measurements. Furthermore, our scheme reproduces this measurement compilation with substantially less error than the existing dust flux parameterizations we were able to compare against. A critical insight from both our theory and the measurement compilation is that dust fluxes are substantially more sensitive to the soil's threshold friction velocity than most current schemes account for.

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