The Experts below are selected from a list of 7917 Experts worldwide ranked by ideXlab platform
Inez Fung - One of the best experts on this subject based on the ideXlab platform.
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the influence on climate forcing of mineral aerosols from Disturbed Soils
Nature, 1996Co-Authors: Ina Tegen, Inez Fung, Andrew A LacisAbstract:AEROSOLS influence the global radiation budget1, and so changes in the atmospheric aerosol load due to either natural causes or human activity will contribute to climate change2. A large fraction of the mass of tropospheric aerosol is wind-blown mineral dust, and its contribution to radiative forcing can be locally significant3,22. Model calculations indicate that 50 ± 20% of the total atmospheric dust mass originates from Disturbed Soils4 (those affected by cultivation, deforestation, erosion, and frequent shifts in vegetation due to droughts and rains). Here, using a radiative transfer model embedded in a general circulation model, we find that dust from Disturbed Soils causes a decrease of the net surface radiation forcing of about lWm-2, accompanied by increased atmospheric heating that may be a significant forcing of atmospheric dynamics. These findings suggest that mineral dust from Disturbed Soils needs to be included among the climate forcing factors that are influenced by human activities.
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contribution to the atmospheric mineral aerosol load from land surface modification
Journal of Geophysical Research, 1995Co-Authors: Ina Tegen, Inez FungAbstract:An estimation of the contribution of mineral dust from Disturbed Soils (i.e., Soils affected by human activity and/or climate variability) to the total atmospheric mineral aerosol load is presented. A three-dimensional atmospheric dust transport model was used to simulate the distribution of dust optical thickness in response to individual dust sources, which include natural Soils known to have been affected by the Saharan/Sahelian boundary shift, cultivation, deforestation, and wind erosion. The distributions extracted from advanced very high resolution radiometer (AVHRR) optical thickness retrievals were used to constrain likely source combinations. The results indicate that observed features like the seasonal shift of maximum optical thickness caused by Saharan dust over the Atlantic ocean are best reproduced if Disturbed sources contribute 30–50% of the total atmospheric dust loading.
Ina Tegen - One of the best experts on this subject based on the ideXlab platform.
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relative importance of climate and land use in determining present and future global soil dust emission
Geophysical Research Letters, 2004Co-Authors: Ina Tegen, Martin Werner, Sandy P Harrison, Karen E KohfeldAbstract:[1] The current consensus is that up to half of the modern atmospheric dust load originates from anthropogenically-Disturbed Soils. Here, we estimate the contribution to the atmospheric dust load from agricultural areas by calibrating a dust-source model with emission indices derived from dust-storm observations. Our results indicate that dust from agricultural areas contributes <10% to the global dust load. Analyses of future changes in dust emissions under several climate and land-use scenarios suggest dust emissions may increase or decrease, but either way the effects of climate change will dominate dust emissions.
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the influence on climate forcing of mineral aerosols from Disturbed Soils
Nature, 1996Co-Authors: Ina Tegen, Inez Fung, Andrew A LacisAbstract:AEROSOLS influence the global radiation budget1, and so changes in the atmospheric aerosol load due to either natural causes or human activity will contribute to climate change2. A large fraction of the mass of tropospheric aerosol is wind-blown mineral dust, and its contribution to radiative forcing can be locally significant3,22. Model calculations indicate that 50 ± 20% of the total atmospheric dust mass originates from Disturbed Soils4 (those affected by cultivation, deforestation, erosion, and frequent shifts in vegetation due to droughts and rains). Here, using a radiative transfer model embedded in a general circulation model, we find that dust from Disturbed Soils causes a decrease of the net surface radiation forcing of about lWm-2, accompanied by increased atmospheric heating that may be a significant forcing of atmospheric dynamics. These findings suggest that mineral dust from Disturbed Soils needs to be included among the climate forcing factors that are influenced by human activities.
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contribution to the atmospheric mineral aerosol load from land surface modification
Journal of Geophysical Research, 1995Co-Authors: Ina Tegen, Inez FungAbstract:An estimation of the contribution of mineral dust from Disturbed Soils (i.e., Soils affected by human activity and/or climate variability) to the total atmospheric mineral aerosol load is presented. A three-dimensional atmospheric dust transport model was used to simulate the distribution of dust optical thickness in response to individual dust sources, which include natural Soils known to have been affected by the Saharan/Sahelian boundary shift, cultivation, deforestation, and wind erosion. The distributions extracted from advanced very high resolution radiometer (AVHRR) optical thickness retrievals were used to constrain likely source combinations. The results indicate that observed features like the seasonal shift of maximum optical thickness caused by Saharan dust over the Atlantic ocean are best reproduced if Disturbed sources contribute 30–50% of the total atmospheric dust loading.
Michael L Winn - One of the best experts on this subject based on the ideXlab platform.
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detection of buried land mines using a dual band lwir lwir qwip focal plane array
Infrared Physics & Technology, 2003Co-Authors: Arnold C Goldberg, Parvez N Uppal, Michael L WinnAbstract:Abstract We report on the development and testing of a new dual-band infrared focal plane array (FPA) specifically designed to detect buried land mines. The detector response spectra were tailored to take advantage of the sharp spectral features associated with Disturbed Soils. The goal was to have a “blue” channel with peak response near 9.2 μm and a “red” channel with maximum response at 10.5 μm. The quantum well infrared photodetector is particularly suited for this application because of the flexibility available in designing the peak wavelength of the detector and the relatively narrow width of the response spectrum. FPAs were produced and tested under the US Army Research Laboratory’s Advanced Sensors Collaborative Research Alliance in co-operation with the Night Vision and Electronic Sensors Directorate. We report on laboratory measurements of the response spectra, the dark current as a function of operating temperature, and the conversion efficiency in both the blue and red channels. Imagery was taken in the field of buried anti-tank mines. The images were analyzed by combining the data from the two channels into single fused images.
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development of a dual band lwir lwir qwip focal plane array for detection of buried land mines
Infrared Detectors and Focal Plane Arrays VII, 2002Co-Authors: Arnold C Goldberg, Parvez N Uppal, Theodore Fischer, Zenon I Derzko, Michael L WinnAbstract:We report on the development and testing of a new dual-band infrared (IR) focal plane array (FPA) specifically designed to detect buried land mines. The detector response spectra were tailored to take advantage of the sharp spectral features associated with Disturbed Soils. The goal was to have a blue channel with peak response near 9.2 micrometers and a red channel with maximum response at 10.5 micrometers . The quantum well infrared photodetector (QWIP) is particularly suited for this application because of the flexibility available in designing the peak wavelength of the detector and the relatively narrow width of the response spectrum. FPAs were produced and tested under the U. S. Army Research Laboratory's Advanced Sensors Collaborative Research Alliance in co-operation with the Night Vision and Electronic Sensors Directorate. We report on laboratory measurements of the response spectra, the dark current as a function of operating temperature, and the conversion efficiency in both the blue and red channels. Imagery was taken in the field of buried anti-tank mines. The images were analyzed by combining the data from the two channels into single fused images.
Alan J Franzluebbers - One of the best experts on this subject based on the ideXlab platform.
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potential c and n mineralization and microbial biomass from intact and increasingly Disturbed Soils of varying texture
Soil Biology & Biochemistry, 1999Co-Authors: Alan J FranzluebbersAbstract:Potential C and N mineralization and soil microbial biomass C were determined following disturbance (i.e. drying and sieving) pretreatments in five Soils varying in texture (30‐350 mg clay g ˇ1 soil) from the southern Piedmont USA. Soil disturbance by drying (i.e. rewetting following drying at 558C for 72 h) of intact soil cores resulted in a flush of C mineralization (70% to 2.5-fold greater) during 0‐3 d of incubation, but was not significantly diAerent during 3‐10 and 10‐24 d periods compared with field-moist-intact soil cores. Soil disturbance by sieving resulted in greater C mineralization earlier than later in the incubation and led to significant immobilization of N of surface soil where respiration was highest. Increasing soil disturbance through smaller sieve openings resulted in a 10‐60% greater flush of C mineralization that may have been due to disruption of macroaggregates, which protected soil organic C. With a conditioning period of 10 d following rewetting of dried soil, soil microbial biomass C was unaAected by drying or extent of sieving. Soil texture (i.e. clay content) did not interact with disturbance eAects. Immobilization of N was predominant in surface Soils (0‐40 mm) of this bermudagrass pasture, where mineralizable C was very high. Carbon mineralization during 0‐3 d was highly related (r 2 =0.9620.04) to C mineralization during 0‐24 d, basal soil respiration and soil microbial biomass C, although increasing soil disturbance (i.e. drying and extent of sieving) altered these relationships in a predictable manner. I conclude that dried and coarsely sieved soil compares favorably to field-moist-intact soil cores for estimating soil microbial biomass and potential activity in landscapes scoured by various degrees of erosion. Published by Elsevier Science Ltd.
Saskia Keesstra - One of the best experts on this subject based on the ideXlab platform.
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the influence of fire history plant species and post fire management on soil water repellency in a mediterranean catchment the mount carmel range israel
Catena, 2017Co-Authors: Saskia Keesstra, Lea Wittenberg, Jerry Maroulis, Francesco Sambalino, Dan Malkinson, Artemio Cerda, Paulo PereiraAbstract:Fire is a key factor impacting soil hydrology in manyMediterranean catchments. Soilwater repellency (SWR) can stimulate land degradation processes by reducing the affinity of soil and water thereby triggering a reduction in soil fertility and increasing soil and water losses. The effects of two consequent fires (1989 and 2005) on SWR were assessed in the Carmel Mountains, Israel. Fire history, plant recovery and post-fire management (14 treatments)were investigated as determining factors in a time dependent system. In total 210 locationswere investigated 9 times fromOctober 2011 to February 2012,which totals 1890water drop penetration tests thatwere performed. During each visit to the field (9 times) a soilmoisture contentwas measured for each treatment. SWR was highest in the N50 years unburnt plots, where soil under Pinus halepensis is most hydrophobic. In the most Disturbed Soils (twice burnt), many sites have a low to absent SWR even if the soil is very dry. The dynamics and fluctuations in SWR differ in magnitude under different plant species. The areas treated with CC (chipping of charred trees) showed a much higher SWR than areas left untreated. From these insights, a conceptual model of the reaction of SWR on multiple fires was developed.
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selection of forest species for the rehabilitation of Disturbed Soils in oil fields in the ecuadorian amazon
Science of The Total Environment, 2016Co-Authors: Saskia Keesstra, Jaime Villacis, Fernando Casanoves, Susana Hang, Cristina ArmasAbstract:Abstract Soils in the Amazon Basin Disturbed by petroleum extraction activities need to be restored to allow for the rehabilitation of these areas and the restoration of the ecosystem services that they can provide. This study explores the performance of saplings of 20 species transplanted to four sites: a paddock and three sites within oil fields that differ in soil substrate contamination and perturbation. In each site we measured sapling survival, possible causes of death, sapling height and diameter at the time of and two years after planting, and the integrated response index. We also analyzed the effects of plants on soil properties. Sapling mortality was limited, with 17 of the 20 species boasting survival rates of over 80%. Saplings in the control site had a higher mortality rate than those in the oil field sites. This was most likely due to competition with and interference of weeds that were more abundant at the control than other sites. Despite the overall low mortality rate, species performance did vary by site, with plants of Flemingia macrophylla, Myrcia aff. fallax, Piptadenia pteroclada, Platymiscium pinnatum, and Zygia longifolia exhibiting the best performance in terms of survival and growth in oil field sites. At the end of the experiment, soil substrates from the oil platform showed increases in pH levels, organic material, Fe, and Zn; whereas substrates contaminated with petroleum showed decreases in hydrocarbon levels ranging from 11 to 22% compared to initial levels before sapling transplanting. Our results shed light on which forest species are most suitable for the rehabilitation of sites Disturbed by activities inherently associated with petroleum extraction in the Ecuadorian Amazon.