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Page C Chamberlain - One of the best experts on this subject based on the ideXlab platform.
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stable isotope records of Hydrologic Change and paleotemperature from smectite in cenozoic western north america
Geochimica et Cosmochimica Acta, 2014Co-Authors: Page C ChamberlainAbstract:Abstract The oxygen and hydrogen isotopic composition of soil water (δ18Ow and δDw hereafter) reflect the history of water through processes such as source evaporation, precipitation and vapor recycling. Temperature, humidity, evaporation, and post-condensation processes can affect δ18Ow and δDw. As such, isotope proxy records are often limited in their ability to constrain paleoclimate, paleoecology or paleoelevation without independently corroborating data. Smectite preserves both the hydrogen and oxygen isotope signature of parent water, and therefore provides critical insight into meteoric water line relationships and paleotemperature. Here, we use in situ pedogenic smectite δ18O and δD records to characterize the evolution of the Hydrologic cycle in Cenozoic western North America. We incorporate 192 samples, 119 of which are previously unpublished, from 11 Cenozoic basins representing a range of environments in the Basin and Range, Rocky Mountains and Great Plains. Our results indicate that the processes controlling smectite isotopic compositions vary both regionally and temporally. In some localities such as Oligocene to Pleistocene western Nebraska, Change in temperature is the primary control on smectite isotopic composition. In other basins such as in Miocene Trapper Creek, ID, isotope values lie along the meteoric water line, suggesting Change in meteoric water composition is responsible for the variation. In most basins, especially those in the Neogene Basin and Range, smectite line slope suggests either evaporation of previously meteoric water or a combination of Change in paleotemperature and meteoric water composition. Smectite geothermometry suggests mineral formation temperatures of 30–40 °C in the Middle Miocene in the Rocky Mountains, Great Plains and Basin and Range, and a decrease of 10–15 °C since the Middle Miocene Climatic Optimum, consistent with clumped isotope and paleofloral temperature estimates.
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grassland expansion as an instrument of Hydrologic Change in neogene western north america
Earth and Planetary Science Letters, 2013Co-Authors: Matthew J Winnick, Andreas Mulch, Page C ChamberlainAbstract:Abstract The evapotranspiration (ET) flux accounts for approximately two thirds of terrestrial precipitation worldwide, and in grassland regions ET is equivalent in magnitude to precipitation. Regional contributions to the terrestrial Hydrologic budget, however, have been far from constant in the past as distribution of vegetation Changed dramatically. The rise of grass-dominated ecosystems is one of the most profound paleoecological Changes in the Cenozoic. Why then, would grassland expansion not feature prominently in the record of Neogene Hydrologic Change? Despite numerous stable isotope paleoenvironmental studies in Neogene North America, the contributions of land cover Change have been largely ignored. We present a compilation of 16 oxygen isotope studies of pedogenic carbonate and smectite from western North America, including 4 new records. Nearly all records from California, the Basin and Range, the Rocky Mountains and the Great Plains show increases in δ O 18 on the order of 2 – 6 ‰ . In order to assess the role of ET in the Hydrologic cycle, we developed an isotopic water vapor transport model wherein we manipulated ET parameters along a specified air mass trajectory. Grasslands lead to δ O 18 of precipitation ( δ O p 18 ) values that are up to 5‰ greater than broadleaf and needleleaf vegetation at inland study sites. These results demonstrate that Changes in vegetation played a critical role in establishing the modern Hydrologic regime in western North America. We suggest that this isotopic increase is due to three primary reasons: 1) Increased evaporation and transpiration fluxes in grassland regions affect water balance, 2) Shallower rooting depths of grasses lead to the transpiration of soil water enriched in O 18 due to evaporation, and 3) Grasslands transpire O 18 -rich waters during a shorter, more punctuated growing season. We argue that the observed isotope signals are indicative of a feedback mechanism wherein grasslands not only respond to regional and global climatic trends, but also act as a driver of Hydrologic Change. By enhancing seasonality and aridity, grasslands transmit Hydrologic disturbances downstream, engineering climatic conditions favorable for their expansion.
Laurence C. Smith - One of the best experts on this subject based on the ideXlab platform.
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Automated Image Registration for Hydrologic Change Detection in the Lake-Rich Arctic
IEEE Geoscience and Remote Sensing Letters, 2008Co-Authors: Yongwei Sheng, Chintan A. Shah, Laurence C. SmithAbstract:Multitemporal remote sensing provides a unique tool to track lake dynamics at the pan-Arctic scale but requires precise registration of thousands of satellite images. This is a challenging task owing to a dearth of stable features to be used as tie points [(TPs), i.e., control points] in the dynamic landscapes. This letter develops an automated method to precisely register images in the lake-rich Arctic. The core premise of the method is that the centers of lakes are generally stable even if their shorelines are not. The proposed procedures first extract lakes in multitemporal satellite images, derive lake centroids and match them between images, and then use the centroids of stable lakes as TPs for image registration. The results show that this approach can achieve subpixel registration accuracy, outcompeting the conventional manual methods in both efficiency and accuracy. The proposed method is fully automated and represents a feasible way to register images for lake Change detection at the pan-Arctic scale.
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Automated Image Registration Based on Pseudoinvariant Metrics of Dynamic Land-Surface Features
IEEE Transactions on Geoscience and Remote Sensing, 2008Co-Authors: Chintan A. Shah, Yongwei Sheng, Laurence C. SmithAbstract:Accurate assessment of land-cover/land-use Change is essential for understanding the impacts of global Change and necessitates the use of satellite data. Satellite Change detection requires large volumes of multitemporal images to be precisely registered. Image registration is particularly difficult in dynamic (i.e., rapidly time varying) landscapes since the Changes themselves interfere with the process of tie-point identification. Despite the existence of sophisticated registration algorithms, it is still problematic to register images acquired over such areas due to a dearth of stable features. Hence, we propose an automated image registration method using tie points derived from pseudoinvariant features (PIFs) and apply the method to register satellite images for Hydrologic Change detection in the Arctic, where abundant shallow lakes dominate the landscape but Change significantly over time. A key to the method is the identification of ldquoshape-stablerdquo lakes as PIFs, which preserve their geometric shape even though the shorelines may migrate significantly. The proposed method automatically identifies PIFs based on scale-invariant shape descriptors and employs their center points for establishing the registration model. Our method thus consists of water-body feature extraction, PIF detection based on feature shape criteria, and image registration using tie points derived from the PIFs. The approach is used to register 1978 and 2000 Landsat images in Alaska, where lakes dominate the landscape and Change significantly over time. The performance of the proposed approach is evaluated quantitatively, and a high subpixel registration accuracy of 0.66 pixel at Enhanced Thematic Mapper Plus resolution (i.e., 19 m) is achieved. A comparative evaluation indicates that the proposed approach outcompetes the conventional manual tie-point selection method and automated image registration techniques based on fast Fourier transform.
Andreas Mulch - One of the best experts on this subject based on the ideXlab platform.
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Grassland expansion as an instrument of Hydrologic Change in Neogene western North America
Earth and Planetary Science Letters, 2020Co-Authors: Matthew J Winnick, Andreas Mulch, C. Page ChamberlainAbstract:The evapotranspiration (ET) flux accounts for approximately two thirds of terrestrial precipitation worldwide, and in grassland regions ET is equivalent in magnitude to precipitation. Regional contributions to the terrestrial Hydrologic budget, however, have been far from constant in the past as distribution of vegetation Changed dramatically. The rise of grass-dominated ecosystems is one of the most profound paleoecological Changes in the Cenozoic. Why then, would grassland expansion not feature prominently in the record of Neogene Hydrologic Change? Despite numerous stable isotope paleoenvironmental studies in Neogene North America, the contributions of land cover Change have been largely ignored. We present a compilation of 16 oxygen isotope studies of pedogenic carbonate and smectite from western North America, including 4 new records. Nearly all records from California, the Basin and Range, the Rocky Mountains and the Great Plains show increases in View the MathML source on the order of 2–6‰. In order to assess the role of ET in the Hydrologic cycle, we developed an isotopic water vapor transport model wherein we manipulated ET parameters along a specified air mass trajectory. Grasslands lead to View the MathML source of precipitation (View the MathML source) values that are up to 5‰ greater than broadleaf and needleleaf vegetation at inland study sites. These results demonstrate that Changes in vegetation played a critical role in establishing the modern Hydrologic regime in western North America. We suggest that this isotopic increase is due to three primary reasons: 1) Increased evaporation and transpiration fluxes in grassland regions affect water balance, 2) Shallower rooting depths of grasses lead to the transpiration of soil water enriched in View the MathML source due to evaporation, and 3) Grasslands transpire View the MathML source-rich waters during a shorter, more punctuated growing season. We argue that the observed isotope signals are indicative of a feedback mechanism wherein grasslands not only respond to regional and global climatic trends, but also act as a driver of Hydrologic Change. By enhancing seasonality and aridity, grasslands transmit Hydrologic disturbances downstream, engineering climatic conditions favorable for their expansion
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grassland expansion as an instrument of Hydrologic Change in neogene western north america
Earth and Planetary Science Letters, 2013Co-Authors: Matthew J Winnick, Andreas Mulch, Page C ChamberlainAbstract:Abstract The evapotranspiration (ET) flux accounts for approximately two thirds of terrestrial precipitation worldwide, and in grassland regions ET is equivalent in magnitude to precipitation. Regional contributions to the terrestrial Hydrologic budget, however, have been far from constant in the past as distribution of vegetation Changed dramatically. The rise of grass-dominated ecosystems is one of the most profound paleoecological Changes in the Cenozoic. Why then, would grassland expansion not feature prominently in the record of Neogene Hydrologic Change? Despite numerous stable isotope paleoenvironmental studies in Neogene North America, the contributions of land cover Change have been largely ignored. We present a compilation of 16 oxygen isotope studies of pedogenic carbonate and smectite from western North America, including 4 new records. Nearly all records from California, the Basin and Range, the Rocky Mountains and the Great Plains show increases in δ O 18 on the order of 2 – 6 ‰ . In order to assess the role of ET in the Hydrologic cycle, we developed an isotopic water vapor transport model wherein we manipulated ET parameters along a specified air mass trajectory. Grasslands lead to δ O 18 of precipitation ( δ O p 18 ) values that are up to 5‰ greater than broadleaf and needleleaf vegetation at inland study sites. These results demonstrate that Changes in vegetation played a critical role in establishing the modern Hydrologic regime in western North America. We suggest that this isotopic increase is due to three primary reasons: 1) Increased evaporation and transpiration fluxes in grassland regions affect water balance, 2) Shallower rooting depths of grasses lead to the transpiration of soil water enriched in O 18 due to evaporation, and 3) Grasslands transpire O 18 -rich waters during a shorter, more punctuated growing season. We argue that the observed isotope signals are indicative of a feedback mechanism wherein grasslands not only respond to regional and global climatic trends, but also act as a driver of Hydrologic Change. By enhancing seasonality and aridity, grasslands transmit Hydrologic disturbances downstream, engineering climatic conditions favorable for their expansion.
Timothy P. Brabets - One of the best experts on this subject based on the ideXlab platform.
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Uranium isotopes (^234U/^238U) in rivers of the Yukon Basin (Alaska and Canada) as an aid in identifying water sources, with implications for monitoring Hydrologic Change in arctic regions
Hydrogeology Journal, 2012Co-Authors: Thomas F. Kraemer, Timothy P. BrabetsAbstract:La capacité à détecter des variations hydrologiques au sein de grands hydrosystèmes arctiques est essentielle pour la compréhension et la prédiction des effets du Changement climatique dans les régions de haute latitude. Le suivi des isotopes de l’uranium (^234U et ^238U) dans l’eau des cours d’eau du bassin versant du Yukon en Alaska et au Nord-Ouest du Canada pour la période 2001–2005 a permis d’accroître la capacité à identifier l’origine des eaux des cours d’eau ainsi que les modifications de flux qui se sont produites au cours des cinq ans de la période d’étude. Les données isotopiques de l’Uranium pour la rivière du Yukon et de ses principaux affluents (Porcupine et Tanana) permettent d’identifier plusieurs sources qui contribuent aux écoulements, incluant : eaux souterraines profondes, eaux souterraines des alluvions dont les cours d’eau sont gelés de manière saisonnière et l’eau de la fonte des glaciers en haute altitude. Le tronçon principal de la rivière du Yukon montre des modalités de variation isotopique en uranium au niveau de plusieurs sites, reflétant des apports de fonte de glace et d’eaux phréatiques au printemps, ainsi que des variabilités pluriannuelles augmentant avec le temps mais aussi en termes de quantité d’eau provenant des zones les plus élevées du bassin versant. Les résultats de cette étude démontrent l’utilité des isotopes de l’uranium pour révéler l’origine des eaux au sein d’un grand hydrosystème et de leur intégration pour le suivi sur le long terme des systèmes hydrologiques arctiques afin d’essayer d’évaluer les effets du Changement climatique. The ability to detect Hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate Change in high-latitude environments. Monitoring uranium isotopes (^234U and ^238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001–2005) has enhanced the ability to identify water sources to rivers, as well as detect flow Changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate Change. 在大规模北极河流系统中监测水文变化的能力对于了解及预测高纬度环境下气候变化的作用很重要。基于对阿拉斯加州及加拿大西北部Yukon流域河水(2001–2005)中铀同位素(^234U/^238U)五年的监测增强了识别河水来源以及监测流场变化的能力。Yukon河及主要支流(Porcupine和 Tanana 河)的铀同位素数据识别出若干个流向河水的水源,包括:深层地下水、季节性结冰河水-山谷冲积地下水以及高地冰川融水。在Yukon河主干的不同位置显示出多种铀同位素变化模式,表现在来自春天冰融化及浅层地下水的补给,以及时间上多年变化模式和从盆地内较高位置补给水的相对份额。研究结果表明利用铀同位素可揭露大规模河流系统的水源,且结合北极河流系统长期观测中的铀同位素分析可尝试进行气候变化效应评价。 A variação hidrológica em grandes sistemas fluviais do Ártico é de grande importância para compreender e prever os efeitos das alterações climáticas em ambientes de latitude elevada. A monitorização dos isótopos de urânio (^234U/^238U) na água da Bacia do Rio Yukon, no Alasca e no noroeste do Canadá (2001–2005), aumentou a capacidade de identificar as fontes de água que alimentam os rios, bem como a possibilidade de detetar alterações de fluxo que têm ocorrido neste período de cinco anos. Os dados de isótopos de urânio do Rio Yukon e dos seus principais afluentes (os Rios Porcupine e Tanana) permitem identificar as diversas fontes que contribuem para o fluxo do rio, incluindo: águas subterrâneas profundas, as que provêm da água subterrânea sazonalmente congelada dos aluviões do rio e águas que provêm do degelo dos glaciares a elevada altitude. O rio principal, oYukon, apresenta padrões de variação isotópica de urânio em diversos locais que refletem a entrada de águas subterrâneas de aquíferos subsuperficiais e do degelo na Primavera, assim como um padrão multianual de variabilidade crescente no tempo e da quantidade relativa de água que provém das partes mais altas da bacia. Os resultados deste estudo demonstram tanto a utilidade de isótopos de urânio em revelar as fontes de água em grandes sistemas fluviais, como a importância da análise de isótopos de urânio incorporando monitorização, a longo prazo, de sistemas fluviais do Ártico, para avaliação dos efeitos das alterações climáticas. La habilidad para detectar variaciones hidrológicas en grandes sistemas de ríos árticos es de fundamental importancia para el entendimiento y la predicción de los efectos del cambio climático en ambientes de altas latitudes. El monitoreo de los isótopos de uranio (^234U y ^238U) en el agua de ríos de la cuenca del río Yukón de Alaska y noroeste de Canadá (2001–2005) ha mejorado la habilidad para identificar las fuentes de agua que alimentan los ríos, así como para detectar cambios de flujo que hayan ocurrido en los cinco años de estudio. Los datos de isótopos de uranio para el Río Yukón y los principales tributarios (los ríos Porcupine y Tanana) identifican varias fuentes que contribuyen al flujo del río, incluyendo agua subterránea profunda, agua subterránea proveniente de agua estacionalmente congelados en ríos de valles aluviales, y agua de derretimiento de glaciares de altas elevaciones. El curso principal del Río Yukón exhibe esquemas de variaciones de isótopos de uranio en varias localidades que reflejan la entrada de agua partir del derretimiento de hielo y del agua subterránea somera en los manantiales, así como un esquema multianual de variabilidad incrementada en el tiempo y en la cantidad relativa de agua proveniente de las más altas elevaciones dentro de la cuenca. Los resultados de este estudio demuestran tanto la utilidad de los isótopos de uranio para las fuentes de agua relevadas en los grandes sistemas de ríos, como la incorporación del análisis de isótopos del uranio en el monitoreo a largo plazo de sistemas de los ríos árticos que intentan evaluar los efectos del cambio climático.
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uranium isotopes 234 u 238 u in rivers of the yukon basin alaska and canada as an aid in identifying water sources with implications for monitoring Hydrologic Change in arctic regions
Hydrogeology Journal, 2012Co-Authors: Thomas F. Kraemer, Timothy P. BrabetsAbstract:The ability to detect Hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate Change in high-latitude environments. Monitoring uranium isotopes (234U and 238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001–2005) has enhanced the ability to identify water sources to rivers, as well as detect flow Changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate Change.
Matthew J Winnick - One of the best experts on this subject based on the ideXlab platform.
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Grassland expansion as an instrument of Hydrologic Change in Neogene western North America
Earth and Planetary Science Letters, 2020Co-Authors: Matthew J Winnick, Andreas Mulch, C. Page ChamberlainAbstract:The evapotranspiration (ET) flux accounts for approximately two thirds of terrestrial precipitation worldwide, and in grassland regions ET is equivalent in magnitude to precipitation. Regional contributions to the terrestrial Hydrologic budget, however, have been far from constant in the past as distribution of vegetation Changed dramatically. The rise of grass-dominated ecosystems is one of the most profound paleoecological Changes in the Cenozoic. Why then, would grassland expansion not feature prominently in the record of Neogene Hydrologic Change? Despite numerous stable isotope paleoenvironmental studies in Neogene North America, the contributions of land cover Change have been largely ignored. We present a compilation of 16 oxygen isotope studies of pedogenic carbonate and smectite from western North America, including 4 new records. Nearly all records from California, the Basin and Range, the Rocky Mountains and the Great Plains show increases in View the MathML source on the order of 2–6‰. In order to assess the role of ET in the Hydrologic cycle, we developed an isotopic water vapor transport model wherein we manipulated ET parameters along a specified air mass trajectory. Grasslands lead to View the MathML source of precipitation (View the MathML source) values that are up to 5‰ greater than broadleaf and needleleaf vegetation at inland study sites. These results demonstrate that Changes in vegetation played a critical role in establishing the modern Hydrologic regime in western North America. We suggest that this isotopic increase is due to three primary reasons: 1) Increased evaporation and transpiration fluxes in grassland regions affect water balance, 2) Shallower rooting depths of grasses lead to the transpiration of soil water enriched in View the MathML source due to evaporation, and 3) Grasslands transpire View the MathML source-rich waters during a shorter, more punctuated growing season. We argue that the observed isotope signals are indicative of a feedback mechanism wherein grasslands not only respond to regional and global climatic trends, but also act as a driver of Hydrologic Change. By enhancing seasonality and aridity, grasslands transmit Hydrologic disturbances downstream, engineering climatic conditions favorable for their expansion
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grassland expansion as an instrument of Hydrologic Change in neogene western north america
Earth and Planetary Science Letters, 2013Co-Authors: Matthew J Winnick, Andreas Mulch, Page C ChamberlainAbstract:Abstract The evapotranspiration (ET) flux accounts for approximately two thirds of terrestrial precipitation worldwide, and in grassland regions ET is equivalent in magnitude to precipitation. Regional contributions to the terrestrial Hydrologic budget, however, have been far from constant in the past as distribution of vegetation Changed dramatically. The rise of grass-dominated ecosystems is one of the most profound paleoecological Changes in the Cenozoic. Why then, would grassland expansion not feature prominently in the record of Neogene Hydrologic Change? Despite numerous stable isotope paleoenvironmental studies in Neogene North America, the contributions of land cover Change have been largely ignored. We present a compilation of 16 oxygen isotope studies of pedogenic carbonate and smectite from western North America, including 4 new records. Nearly all records from California, the Basin and Range, the Rocky Mountains and the Great Plains show increases in δ O 18 on the order of 2 – 6 ‰ . In order to assess the role of ET in the Hydrologic cycle, we developed an isotopic water vapor transport model wherein we manipulated ET parameters along a specified air mass trajectory. Grasslands lead to δ O 18 of precipitation ( δ O p 18 ) values that are up to 5‰ greater than broadleaf and needleleaf vegetation at inland study sites. These results demonstrate that Changes in vegetation played a critical role in establishing the modern Hydrologic regime in western North America. We suggest that this isotopic increase is due to three primary reasons: 1) Increased evaporation and transpiration fluxes in grassland regions affect water balance, 2) Shallower rooting depths of grasses lead to the transpiration of soil water enriched in O 18 due to evaporation, and 3) Grasslands transpire O 18 -rich waters during a shorter, more punctuated growing season. We argue that the observed isotope signals are indicative of a feedback mechanism wherein grasslands not only respond to regional and global climatic trends, but also act as a driver of Hydrologic Change. By enhancing seasonality and aridity, grasslands transmit Hydrologic disturbances downstream, engineering climatic conditions favorable for their expansion.
