A Method for Estimating the Threshold Wind Speed for Dust Emissions as a Function of Soil Moisture

AbstractIn the context of forecasting societally impactful Great Plains low-level jets (GPLLJs), the potential added value of satellite soil moisture (SM) data assimilation (DA) is high. GPLLJs are both sensitive to regional soil moisture gradients and frequent drivers of severe weather, including mesoscale convective systems. An untested hypothesis is that SM DA is more effective in forecasts of weakly synoptically forced, or uncoupled GPLLJs, than in forecasts of cyclone-induced coupled GPLLJs. Using the NASA Unified Weather Research and Forecasting (NU-WRF) Model, 75 GPLLJs are simulated at 9-km resolution both with and without NASA Soil Moisture Active Passive SM DA. Differences in modeled SM, surface sensible (SH) and latent heat (LH) fluxes, 2-m temperature (T2), 2-m humidity (Q2), PBL height (PBLH), and 850-hPa wind speed (W850) are quantified for individual jets and jet-type event subsets over the south-central Great Plains, as well as separately for each GPLLJ sector (entrance, core, and exit). At the GPLLJ core, DA-related changes of up to 5.4 kg m−2 in SM can result in T2, Q2, LH, SH, PBLH, and W850 differences of 0.68°C, 0.71 g kg−2, 59.9 W m−2, 52.4 W m−2, 240 m, and 4 m s−1, respectively. W850 differences focus along the jet axis and tend to increase from south to north. Jet-type differences are most evident at the GPLLJ exit where DA increases and decreases W850 in uncoupled and coupled GPLLJs, respectively. Data assimilation marginally reduces negative wind speed bias for all jets, but the correction is greater for uncoupled GPLLJs, as hypothesized.

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Effects of surface wind speed decline on hydrology in China

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-11293-2013 ◽

2013 ◽

Vol 10 (8) ◽

pp. 11293-11310

Author(s):

X. Liu ◽

X. Zhang ◽

Q. Tang ◽

X. Zhang

Keyword(s):

Soil Moisture ◽

Wind Speed ◽

Surface Wind ◽

Surface Wind Speed ◽

River Basins ◽

Annual Runoff ◽

Infiltration Capacity ◽

Major River ◽

Speed Change ◽

Small Change

Abstract. Surface wind speed decline in China has been widely reported, but its effects on hydrology have not been fully evaluated to date. In this study, the effects of wind speed change on hydrology are investigated using the Variable Infiltration Capacity (VIC) hydrological model for China during 1966–2011. Two model experiments, i.e. VIC simulations with the observed (EXP1) and detrended wind speed (EXP2), are performed over the major river basins in China. The differences between the two experiments are analyzed to assess the effects of wind speed decline on hydrology. Results show that wind speed has decreased by 29% in China. The wind speed decline have resulted in a decrease of evapotranspiration by 1–3% of mean annual evapotranspiration and an increase of runoff by 1–6% of mean annual runoff at most basins in China. The effect of wind speed on runoff and soil moisture is large in the northern basins where small change in hydrological conditions would have significant implications for water management. In addition, Wind speed decline has offset the expansion of the drought area in China. It has contributed to a reduction of drought areas by 8.8% of the mean drought area (i.e. approximate 10.6 × 104 km2 out of 1.2 × 106 km2) over China. The effect of wind speed decline on soil moisture drought is large in most basins in China expect for the Southwest and Pearl River basins.

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Modeling of Mineral Dust Emissions with a Weibull Wind Speed Distribution Including Subgrid-Scale Orography Variance

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-17-0173.1 ◽

2018 ◽

Vol 35 (6) ◽

pp. 1221-1236

Author(s):

Laurent Menut

Keyword(s):

Wind Speed ◽

Mineral Dust ◽

Aerosol Size Distribution ◽

Test Case ◽

Subgrid Scale ◽

Dust Emissions ◽

Speed Distribution ◽

Wind Speed Distribution ◽

Main Driver ◽

Dust Modeling

AbstractThe modeling of mineral dust emissions requires an extensive knowledge of the wind speed close to the surface. In regional and global models, Weibull distributions are often used to better represent the subgrid-scale variability of the wind speed. This distribution mainly depends on a k parameter, itself currently parameterized as a function of the wind speed value. In this study we propose to add the potential impact of the orography variance in the wind speed distribution by changing the k parameter value. Academic test cases are designed to estimate the parameters of the scheme. A realistic test case is performed over a large domain encompassing the northern part of Africa and Europe and for the period 1 January–1 May 2012. The results of the simulations are compared to particulate matter (PM10) surface concentrations and Aerosol Robotic Network (AERONET) aerosol optical depth and aerosol size distribution. We show that with the orography variance, the simulation results are closer to the ones without variance, showing that this additional variability is not the main driver of possible errors in mineral dust modeling.

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Wildfire and Postfire Restoration Action Effects on Microclimate and Seedling Pine Tree Survivorship

Journal of Fish and Wildlife Management ◽

10.3996/072013-jfwm-051 ◽

2014 ◽

Vol 5 (1) ◽

pp. 174-182 ◽

Cited By ~ 6

Author(s):

Donald J. Brown ◽

Ivana Mali ◽

Michael R.J. Forstner

Keyword(s):

Soil Moisture ◽

Wind Speed ◽

Soil Temperature ◽

Air Temperature ◽

Loblolly Pine ◽

Absolute Humidity ◽

Short Term ◽

Burned Areas ◽

High Severity ◽

Postfire Management

Abstract Through modification of structural characteristics, ecological processes such as fire can affect microhabitat parameters, which in turn can influence community composition dynamics. The prevalence of high-severity forest fires is increasing in the southern and western United States, creating the necessity to better understand effects of high-severity fire, and subsequent postfire management actions, on forest ecosystems. In this study we used a recent high-severity wildfire in the Lost Pines ecoregion of Texas to assess effects of the wildfire and postfire clearcutting on six microclimate parameters: air temperature, absolute humidity, mean wind speed, maximum wind speed, soil temperature, and soil moisture. We also assessed differences between burned areas and burned and subsequently clearcut areas for short-term survivorship of loblolly pine Pinus taeda seedling trees. We found that during the summer months approximately 2 y after the wildfire, mean and maximum wind speed differed between unburned and burned areas, as well as burned and burned and subsequently clearcut areas. Our results indicated air temperature, absolute humidity, soil temperature, and soil moisture did not differ between unburned and burned areas, or burned and burned and subsequently clearcut areas, during the study period. We found that short-term survivorship of loblolly pine seedling trees was influenced primarily by soil type, but was also lower in clearcut habitat compared with habitat containing dead standing trees. Ultimately, however, the outcome of the reforestation initiative will likely depend primarily on whether or not the trees can survive drought conditions in the future, and this study indicates there is flexibility in postfire management options prior to reseeding. Further, concerns about negative wildfire effects on microclimate parameters important to the endangered Houston toad Bufo (Anaxyrus) houstonensis were not supported in this study.

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VARIATIONS IN SOIL RADON LEVELS DURING WINTER AND SPRING PERIODS

Radiation Protection Dosimetry ◽

10.1093/rpd/ncaa162 ◽

2020 ◽

Vol 191 (2) ◽

pp. 250-254

Author(s):

Sakhayaan Gavriliev ◽

Tatiana Petrova ◽

Petr Miklyaev ◽

Nikolay Nefedov

Keyword(s):

Lung Cancer ◽

Soil Moisture ◽

Wind Speed ◽

Activity Concentration ◽

Inverse Correlation ◽

Ambient Air ◽

Climatic Conditions ◽

Α Decay ◽

Radon Flux ◽

Significant Health

Abstract Radon poses significant health risk due to inhalation and subsequent α-decay of its progeny and is the second biggest cause of lung cancer worldwide. In Russian Federation, radon flux density (RFD) measurements are performed routinely to assess radon safety of land lots before construction takes place. This study aims to show possible ‘weather’-influenced variations in RFD and radon activity concentration (RAC) that can occur during winter and spring periods in climatic conditions typical for territories with severe snowy winters. Results show that RFD correlates with weather, having a significant correlation with ambient air temperature in winter as well as spring periods and a weak inverse correlation with wind speed. In spring, RFD also responds to an increase in soil moisture, dropping severely because of rainfall. RAC, however, correlates very little with weather but has a weak inverse correlation with RFD.

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Threshold wind speed for dust emission in east Asia and its seasonal variations

Journal of Geophysical Research Atmospheres ◽

10.1029/2006jd007988 ◽

2007 ◽

Vol 112 (D17) ◽

Cited By ~ 65

Author(s):

Y. Kurosaki ◽

M. Mikami

Keyword(s):

Wind Speed ◽

East Asia ◽

Seasonal Variations ◽

Dust Emission ◽

Threshold Wind Speed

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Observed Regional Climate Change in Tibet over the Last Decades

10.1093/acrefore/9780190228620.013.587 ◽

2017 ◽

Cited By ~ 1

Author(s):

Kun Yang

Keyword(s):

Soil Moisture ◽

Wind Speed ◽

Climate Changes ◽

Convective Available Potential Energy ◽

Surface Wind ◽

The Tibetan Plateau ◽

Sudden Increase ◽

Thermal Forcing ◽

Surface Warming ◽

Glacier Melt

The Tibetan Plateau (TP) is subjected to strong interactions among the atmosphere, hydrosphere, cryosphere, and biosphere. The Plateau exerts huge thermal forcing on the mid-troposphere over the mid-latitude of the Northern Hemisphere during spring and summer. This region also contains the headwaters of major rivers in Asia and provides a large portion of the water resources used for economic activities in adjacent regions. Since the beginning of the 1980s, the TP has undergone evident climate changes, with overall surface air warming and moistening, solar dimming, and decrease in wind speed. Surface warming, which depends on elevation and its horizontal pattern (warming in most of the TP but cooling in the westernmost TP), was consistent with glacial changes. Accompanying the warming was air moistening, with a sudden increase in precipitable water in 1998. Both triggered more deep clouds, which resulted in solar dimming. Surface wind speed declined from the 1970s and started to recover in 2002, as a result of atmospheric circulation adjustment caused by the differential surface warming between Asian high latitudes and low latitudes.The climate changes over the TP have changed energy and water cycles and has thus reshaped the local environment. Thermal forcing over the TP has weakened. The warming and decrease in wind speed lowered the Bowen ratio and has led to less surface sensible heating. Atmospheric radiative cooling has been enhanced, mainly through outgoing longwave emission from the warming planetary system and slightly enhanced solar radiation reflection. The trend in both energy terms has contributed to the weakening of thermal forcing over the Plateau. The water cycle has been significantly altered by the climate changes. The monsoon-impacted region (i.e., the southern and eastern regions of the TP) has received less precipitation, more evaporation, less soil moisture and less runoff, which has resulted in the general shrinkage of lakes and pools in this region, although glacier melt has increased. The region dominated by westerlies (i.e., central, northern and western regions of the TP) received more precipitation, more evaporation, more soil moisture and more runoff, which together with more glacier melt resulted in the general expansion of lakes in this region. The overall wetting in the TP is due to both the warmer and moister conditions at the surface, which increased convective available potential energy and may eventually depend on decadal variability of atmospheric circulations such as Atlantic Multi-decadal Oscillation and an intensified Siberian High. The drying process in the southern region is perhaps related to the expansion of Hadley circulation. All these processes have not been well understood.

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