Historical Landscape Change in Yellowstone National Park: Demonstrating the Value of Intensive Field Observation and Repeat Photography          下载免费PDF全文

Judith l. Meyer  Yolonda Youngs 《Geographical review》2018,108(3):387-409

Although transportation and outdoor recreation are well‐recognized aspects of national parks, few studies have explored these aspects from the perspective of human geography as a means of analyzing historical landscape change. This paper offers an innovative synthesis of methods for studying cultural landscape change over time through a case study of the historical geography of transportation, tourism, and outdoor recreation along the Howard Eaton Trail (HET) in Yellowstone National Park. We conducted research through a field course that combined repeat photography, archival research, Geographic Information Systems (GIS), and traditional field methods. Results indicate that a combination of repeat photography and other methods can create an effective means of evaluating cultural landscape change; even short field courses provide opportunities for students and faculty to conduct collaborative research that provides powerful, multidimensional, situated‐learning experiences; and repeat photography creates datasets that may benefit future research and teaching.  相似文献   

Evaporation from boreal reservoirs: A comparison between eddy covariance observations and estimates relying on limited data     

Judith Fournier  Antoine Thiboult  Daniel F. Nadeau  Nikki Vercauteren  François Anctil  Annie-Claude Parent  Ian B. Strachan  Alain Tremblay 《水文研究》2021,35(8):e14335

Hydrological models used for reservoir management typically lack an accurate representation of open-water evaporation and must be run in a scarce data context. This study aims to identify an accurate means to estimate reservoir evaporation with simple meteorological inputs during the open-water season, using long-term eddy covariance observations from two boreal hydropower reservoirs with contrasting morphometry as reference. Unlike the temperate water bodies on which the majority of other studies have focused, northern reservoirs are governed by three distinct periods: ice cover in the cold season, warming in the summer and energy release in the fall. The reservoirs of interest are Eastmain-1 (52°N, mean depth of 11 m) and Romaine-2 (51°N, mean depth of 42 m), both located in eastern Canada. Four approaches are analysed herein: a combination approach, a radiation-based approach, a mass-transfer approach, and empirical methods. Of all the approaches, the bulk transfer equation with a constant Dalton number of 1.2 x 10⁻³ gave the most accurate estimation of evaporation at hourly time steps, compared with the eddy covariance observations (RMSE of 0.06 mm h⁻¹ at Eastmain-1 and RMSE of 0.04 mm h⁻¹ at Romaine-2). The daily series also showed good accuracy (RMSE of 1.38 mm day⁻¹ at Eastmain-1 and RMSE of 0.62 mm day⁻¹ at Romaine-2) both in the warming and energy release phases of the open-water season. The bulk transfer equation, on the other hand, was incapable of reproducing condensation episodes that occurred soon after ice breakup. Basic and variance-based sensitivity analyses were conducted, in particular to measure the variation in performance when the bulk transfer equation was applied with meteorological observations collected at a certain distance (~10–30 km) from the reservoir. This exercise illustrated that accurate estimates of open water evaporation require representative measurements of wind speed and water surface temperature.  相似文献   

Chemical Characteristics of Carbonaceous Aerosols During Dust Storms over Xi'an in China   总被引：1，自引：0，他引：1  

LI Xuxiang  CAO Junji  Judith CHOW  HAN Yongming  Shuncheng LEE  John WATSON 《大气科学进展》2008,25(5):847-855

Characterization of carbonaceous aerosols including CC （carbonate carbon）, OC （organic carbon）, and EC （elemental carbon） were investigated at Xi＇an, China, near Asian dust source regions in spring 2002. OC varied between 8.2 and 63.7μgm^- 3, while EC ranged between 2.4 and 17.2 μ m^-3 during the observation period. OC variations followed a similar pattern to EC and the correlation coefficient between OC and EC is 0.89 （n=31）. The average percentage of total carbon （TC, sum of CC, OC, and EC） in PM2.5 during dust storm （DS） events was 13.6%, which is lower than that during non-dust storm （NDS） periods （22.7%）. CC, OC, and EC accounted for 12.9%, 70.7%, and 16.4% of TC during DS events, respectively. The average ratio of OC/EC was 5.0 in DS events and 3.3 in NDS periods. The OC-EC correlation （R^2=0.76, n=6） was good in DS events, while it was stronger （R^2=0.90, n=25） in NDS periods. The percentage of watersoluble OC （WSOC） in TC accounted for 15.7%, and varied between 13.3% and 22.3% during DS events. The distribution of eight carbon fractions indicated that local emissions such as motor vehicle exhaust were the dominant contributors to carbonaceous particles. During DS events, soil dust dominated the chemical composition, contributing 69% to the PM2.5 mass, followed by organic matter （12.8%）, sulfate （4%）, EC （2.2%）, and chloride （1.6%）. Consequently, CC was mainly entrained by Asian dust. However, even in the atmosphere near Asian dust source regions, OC and EC in atmospheric dust were controlled by local emission rather titan the transport of Asian dust.  相似文献   

南京蒋庙岩体的年代学、地球化学及其地质意义   总被引：1，自引：1，他引：0  

洪文涛  徐夕生  贺振宇  闫峻 《岩石学报》2010,26(5):1577-1588

南京蒋庙侵入岩体的主体为辉长岩-闪长岩,并伴有少量的二长岩。LA-ICP-MS锆石U-Pb定年表明,其形成于118±1.1Ma,为长江中下游地区中生代最晚的一次岩浆活动。岩石地球化学资料表明,在岩浆上升及结晶过程中无明显的地壳物质混染。蒋庙岩体的εNd(t)值为-0.49～-2.29,介于DMM及EMII之间。简单二单元混合计算表明,其源区中有较高比例的软流圈物质加入。综合其它年龄资料,长江中下游地区中生代岩浆活动可分为3期:早期为151～133Ma,中期为131～126Ma,晚期为125～118Ma。中生代时期该区总体处于板内伸展的构造环境,经历了岩石圈拉张、软流圈持续上涌的地幔过程。  相似文献   

Simulated impacts of artificial groundwater recharge and discharge on the source area and source volume of an Atlantic Coastal Plain stream, Delaware, USA     

Joshua W. Kasper  Judith M. Denver  Thomas E. McKenna  William J. Ullman 《Hydrogeology Journal》2010,18(8):1855-1866

A numerical groundwater-flow model was used to characterize the source area and volume of Phillips Branch, a baseflow-dominated stream incising a highly permeable unconfined aquifer on the low relief Delmarva Peninsula, USA. Particle-tracking analyses indicate that the source area (5.51 km²) is ～20% smaller than the topographically defined watershed (6.85 km²), and recharge entering ～37% of the surface watershed does not discharge to Phillips Branch. Groundwater residence time within the source volume ranges from a few days to almost 100 years, with 95% of the volume “flushing” within 50 years. Artificial discharge from groundwater pumping alters the shape of the source area and reduces baseflow due to the interception of stream flow paths, but has limited impacts on the residence time of groundwater discharged as baseflow. In contrast, artificial recharge from land-based wastewater disposal substantially reduces the source area, lowers the range in residence time due to the elimination of older flow paths to the stream, and leads to increased discharge to adjacent surface-water bodies. This research suggests that, in this and similar hydrogeologic settings, the “watershed” approach to water-resource management may be limited, particularly where anthropogenic stresses alter the transport of soluble contaminants through highly permeable unconfined aquifers.  相似文献   

3D model of fracture zones at Soultz-sous-Forêts based on geological data,image logs,induced microseismicity and vertical seismic profiles     

Judith Sausse  Chrystel Dezayes  Louis Dorbath  Albert Genter  Joachim Place 《Comptes Rendus Geoscience》2010,342(7-8):531-545

This study presents a new deterministic 3D model of the fracture zones observed in the granitic reservoir of the Soultz European geothermal project. The major fracture zones encountered around 6 wells (4550, EPS1, GPK1, GPK2, GPK3 and GPK4) consist in 53 main structures that are located and characterized in terms of size and orientation: 39 fracture zones, 8 microseismic structures and 6 structures derived from vertical seismic profiles are represented in the 3D model using Discrete Fracture Network tools of the gOcad modelling platform (Paradigm?, Earth Decision?). This work illustrates the complexity of 3D fracture zone correlation and interpretation in crystalline rock masses characterized at meter scale (borehole) and at the reservoir scale (kilometer) thanks to geophysical imaging techniques.  相似文献   

Modelling the mean and turbulent structure of the summertime Arctic cloudy boundary layer     

Kathleen L. Mcinnes  Judith A. Curry 《Boundary-Layer Meteorology》1995,73(1-2):125-143

This paper addresses the problem of modelling the summertime Arctic cloudy boundary layer. Specifically we consider the problem of multi-layered clouds in the boundary layer that includes the decoupling of the turbulence between upper and lower clouds. A high-resolution one-dimensional model with second-order turbulence closure and spectral radiative transfer is used to simulate a case study that was obtained during the 1980 Arctic Stratus Experiment. The effects of radiation, large-scale vertical motion and drizzle are investigated in sensitivity studies. Results of this study show that radiative transfer is important to the maintenance of the multiple cloud layers, and suggest that weak rising vertical motion is the most favorable situation to maintain two separate cloud layers.  相似文献   

Field measurements of snow-drift threshold and mass fluxes,and related model simulations   总被引：2，自引：2，他引：0  

Judith?J.?JDoorschot  Michael?LehningEmail author  Anouck?Vrouwe 《Boundary-Layer Meteorology》2004,113(3):347-368

Field measurements were carried out to calculate the threshold friction velocity for snow saltation, and mass fluxes during snow drift. The wind was measured in three components by an ultrasonic anemometer, and the mass fluxes were determined using an optical sensor (snow particle counter), acoustic sensors (Flowcapt) and mechanical traps. The threshold friction velocity was found to be correlated to the grain size (R²=0.75). The mass flux measurements were compared with numerical simulations of snow drift, and it was demonstrated that the maximum snow transport takes place at shear stress values of roughly two times the average shear stress over 20 min. By implementing a probability distribution for the shear stress the mass flux was simulated with only the mean measured value of the shear stress as input. This procedure enables the future use of the numerical model for operational applications.  相似文献   

Assessing the Goodness-of-Fit of Statistical Distributions When Data Are Grouped     

Judith K. Haschenburger  John J. Spinelli 《Mathematical Geology》2005,37(3):261-276

Modeling statistical distributions of phenomena can be compromised by the choice of goodness-of-fit statistics. The Pearson chi-square test is the most commonly used test in the geosciences, but the lesser known empirical distribution function (EDF) statistics should be preferred in many test situations. Using a data set from geomorphology, the Anderson–Darling test for grouped exponential distributions is employed to illustrate ease of use and statistical advantages of this EDF test. Attention to the issues discussed will result in more informed statistic selection and increased rigor in the identification of distribution functions that describe random variables.  相似文献   

Mapping Curvilinear Structures with Local Anisotropy Kriging     

Chris B. M. te Stroet  Judith J. J. C. Snepvangers 《Mathematical Geology》2005,37(6):635-649

Interpolating geo-data with curvilinear structures using geostatistics is often disappointing. Channels, for example, become disconnected sets of lakes when interpolated from point data. In order to improve the interpolation of geological structures (e.g., curvilinear structures), we present a new form of kriging, local anisotropy kriging (LAK). Local anisotropy kriging combines a gradient algorithm from image analysis with kriging in an iterative way. After an initial standard kriging interpolation, the gradient algorithm determines the local anisotropy for each cell in the grid using a search area around the cell. Subsequently, kriging is carried out with the spatially varying anisotropy. The anisotropy calculation and subsequent kriging steps will then succeed until the result is satisfactory in the way of reproducing the curvilinear structures. Depending on the size of the search area more or less detail in the geological structures can be reproduced with LAK. Using test examples we show that LAK interpolates data with curvilinear structures more realistically than standard kriging. In a real world case, using bathymetric data of the Oosterschelde estuary, LAK also proves to be quantitatively superior to standard kriging. Absolute interpolation errors are decreased by 23%. Local anisotropy kriging only uses information from point data, which makes the method very objective, it only presents “what the data can tell.”  相似文献