The paleoclimatic and geochronologic utility of coring red beds and evaporites: a case study from the RKB core (Permian,Kansas, USA)     

Gerilyn S. Soreghan  Kathleen C. Benison  Tyler M. Foster  Jay Zambito  Michael J. Soreghan 《International Journal of Earth Sciences》2015,104(6):1589-1603

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Temporal and Spatial Variabilities of Chemical and Physical Parameters on the Heron Island Coral Reef Platform     

Kekuewa  Samuel A. H.  Courtney  Travis A.  Cyronak  Tyler  Kindeberg  Theodor  Eyre  Bradley D.  Stoltenberg  Laura  Andersson  Andreas J. 《Aquatic Geochemistry》2021,27(4):241-268

Globally, coral reefs are threatened by ocean warming and acidification. The degree to which acidification will impact reefs is dependent on the local hydrodynamics, benthic community composition, and biogeochemical processes, all of which vary on different temporal and spatial scales. Characterizing the natural spatiotemporal variability of seawater carbonate chemistry across different reefs is critical for elucidating future impacts on coral reefs. To date, most studies have focused on select habitats, whereas fewer studies have focused on reef scale variability. Here, we investigate the temporal and spatial seawater physicochemical variability across the entire Heron Island coral reef platform, Great Barrier Reef, Australia, for a limited duration of six days. Autonomous sensor measurements at three sites across the platform were complemented by reef-wide boat surveys and discrete sampling of seawater carbonate chemistry during the morning and evening. Variability in both temporal and spatial physicochemical properties were predominantly driven by solar irradiance (and its effect on biological activity) and the semidiurnal tidal cycles but were influenced by the local geomorphology resulting in isolation of the platform during low tide and rapid flooding during rising tides. As a result, seawater from previous tidal cycles was sometimes trapped in different parts of the reef leading to unexpected biogeochemical trends in space and time. This study illustrates the differences and limitations of data obtained from high-frequency measurements in a few locations compared to low-frequency measurements at high spatial resolution and coverage, showing the need for a combined approach to develop predictive capability of seawater physicochemical properties on coral reefs.

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Evaporation from three water bodies of different sizes and climates: Measurements and scaling analysis   总被引：3，自引：0，他引：3  

S. Assouline  S.W. Tyler  J. Tanny  S. Cohen  E. Bou-Zeid  M.B. Parlange  G.G. Katul 《Advances in water resources》2008

Evaporation from small reservoirs, wetlands, and lakes continues to be a theoretical and practical problem in surface hydrology and micrometeorology because atmospheric flows above such systems can rarely be approximated as stationary and planar-homogeneous with no mean subsidence (hereafter referred to as idealized flow state). Here, the turbulence statistics of temperature (T) and water vapor (q) most pertinent to lake evaporation measurements over three water bodies differing in climate, thermal inertia and degree of advective conditions are explored. The three systems included Lac Léman in Switzerland (high thermal inertia, near homogeneous conditions with no appreciable advection due to long upwind fetch), Eshkol reservoir in Israel (intermediate thermal inertia, frequent strong advective conditions) and Tilopozo wetland in Chile (low thermal inertia, frequent but moderate advection). The data analysis focused on how similarity constants for the flux-variance approach, C_T/C_q, and relative transport efficiencies R_wT/R_wq, are perturbed from unity with increased advection or the active role of temperature. When advection is small and thermal inertia is large, C_T/C_q < 1 (or R_wT/R_wq > 1) primarily due to the active role of temperature, which is consistent with a large number of studies conducted over bare soil and vegetated surfaces. However, when advection is significantly large, then C_T/C_q > 1 (orR_wT/R_wq < 1). When advection is moderate and thermal inertia is low, then C_T/C_q ∼ 1. This latter equality, while consistent with Monin–Obukhov similarity theory (MOST), is due to the fact that advection tends to increase C_T/C_q above unity while the active role of temperature tends to decrease C_T/C_q below unity. A simplified scaling analysis derived from the scalar variance budget equation, explained qualitatively how advection could perturb MOST scaling (assumed to represent the idealized flow state).  相似文献   

Secondary Hydrogeologic Regions of the Conterminous United States     

Kenneth Belitz  Elise Watson  Tyler D. Johnson  Jennifer Sharpe 《Ground water》2019,57(3):367-377

The U.S. Geological Survey (USGS) previously identified and mapped 62 Principal Aquifers (PAs) in the U.S., with 57 located in the conterminous states. Areas outside of PAs, which account for about 40% of the conterminous U.S., were collectively identified as “other rocks.” This paper, for the first time, subdivides this large area into internally-consistent features, defined here as Secondary Hydrogeologic Regions (SHRs). SHRs are areas of other rock within which the rocks or deposits are of comparable age, lithology, geologic or physiographic setting, and relationship to the presence or absence of underling PAs or overlying glacial deposits. A total of 69 SHRs were identified. The number and size of SHRs identified in this paper are comparable to the number and size of PAs previously identified by the USGS. From a two-dimensional perspective, SHRs are complementary to PAs, mapped only where the PAs were not identified on the USGS PA map and not mapped where the PAs were identified. SHRs generally consist of low permeability rocks or deposits, but can include locally productive aquifers. The two maps, taken together, provide a comprehensive, national-scale hydrogeologic framework for assessing and understanding groundwater systems.  相似文献   

Normal modes and resonance in Ontario Lacus: a hydrocarbon lake of Titan     

Vincent  David  Lambrechts  Jonathan  Karatekin  Özgür  Van Hoolst  Tim  Tyler  Robert H.  Dehant  Véronique  Deleersnijder  Eric 《Ocean Dynamics》2019,69(10):1121-1132

Ocean Dynamics - The natural modes of Ontario Lacus surface oscillations, the largest lake in Titan’s southern hemisphere, are simulated and analyzed as they are potentially of broad interest...  相似文献   

A microbial perspective on the life‐history evolution of marine invertebrate larvae: If,where and when to feed          下载免费PDF全文

Tyler J. Carrier  Jason Macrander  Adam M. Reitzel 《Marine Ecology》2018,39(1)

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Mid-infrared imaging and spectroscopy of the southern HII region RCW 38     

Craig H. Smith  Tyler L. Bourke  Christopher M. Wright  Henrik W. W. Spoon Spoon  David K. Aitken  Garry Robinson  John W. V. Storey  Takuya Fujiyoshi  Patrick F. Roche  Thomas Lehmann 《Monthly notices of the Royal Astronomical Society》1999,303(2):367-379

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R-band light curve of Comet 9P/Tempel 1 during the Deep Impact event     

Tyler R. Mitchell  William F. Welsh  Robert J. Barber  Tom S. Stallard 《Icarus》2010,205(2):619-626

We present high-speed CCD photometry of Comet 9P/Tempel 1 during the Deep Impact event on 2005 July 4 UT. Approximately 2 h and 50 min of R-band data were acquired at Mount Laguna Observatory with a temporal resolution of 5.5 s. The flux increased by 9% in the first minute after impact. This was followed by a more gradual two-part linear rise, with a change in slope at 9.2 min post-impact, at which time the rate of brightening increased from ∼ to ∼. An analysis of the light curve obtained with the guide camera on the United Kingdom Infrared Telescope and yields very similar results. These findings are mildly in disagreement with the 3-part linear rise found by Fernández et al. (2007) in that we do not find any evidence for a change at 4 min post-impact. We interpret the linear rise phase as due to solar illumination of the edge of an expanding optically thick dust ejecta plume. After approximately 20 min, the light curves begin to flatten out, perhaps coincident with the start of the transition to becoming optically thin. In the large apertures (>10^″) the light curve continues to gradually rise until the end of the observations. In smaller apertures, the light curves reach a peak at approximately 50 min, then decrease back towards the pre-impact flux level. The drop in flux in the smaller apertures may be caused by the ejecta expanding beyond the edge of the photometric aperture, and if so, we can use this timescale to infer an expansion velocity of ∼, consistent with previous published estimates.  相似文献   

Polymictic pool behaviour in a montane meadow,Sierra Nevada,CA          下载免费PDF全文

Ryan G. Lucas  Francisco Suárez  Scott W. Tyler  Jean E. Moran  Martha H. Conklin 《水文研究》2016,30(18):3274-3288

We observed polymictic behaviour in stream pools in Long Meadow, Sequoia National Park, California—part of the Southern Sierra Critical Zone Observatory. Stream pools stratified thermally during the day time and were isothermal at night—this pattern persists from the middle of summer into the fall. We found that four characteristics typical of a mountain meadow environment—low stream flow, open sky, cold groundwater discharge, and elevated organic carbon concentrations—are particularly conducive to pool stratification. Incoming shortwave radiation was the dominant energy input to heat pool water while nighttime emitted longwave radiation was the major cooling mechanism. Relatively cold groundwater discharge into the pool bottom increased density stratification within the pool. Elevated DOC concentrations increased the capacity of the pool to absorb photosynthetically active radiation and also promoted stratification. Stream velocities in the meadow were generally insufficient to meet threshold Richardson numbers and mix the pools during the daytime; smaller stream cross sectional areas would have potential for destabilizing pools in the daytime. We propose a conceptual model for describing polymictic stream pools and assessing the potential for polymictic pools to occur. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Landscape‐scale controls on the spatial distribution of caesium 137: A study based on an airborne geophysical survey across Northern Ireland     

B. G. Rawlins  C. Scheib  D. Beamish  R. Webster  A. N. Tyler  M. E. Young 《地球表面变化过程与地形》2011,36(2):158-169

The spatial distribution of ¹³⁷Cs across the landscape and the processes controlling its redistribution are of interest because (i) ¹³⁷Cs has been widely used to quantify the movement of soil and sediments and (ii) substantial fallout of ¹³⁷Cs after the Chernobyl accident has led to contamination of foodstuffs in some places. A high‐resolution airborne geophysical radiometric survey of Northern Ireland has provided an opportunity to study the distribution and possible redistribution of ¹³⁷Cs. The ¹³⁷Cs activity (recorded at 1·2 million points) is distributed in a series of bands oriented approximately 160° and 115° clockwise from north. Geostatistical analysis of the data shows a strong, short‐range structure (correlation ranges between 0·6 and 8 km) in ¹³⁷Cs activity across the vast majority of the region; the spatial distribution shows association with a published, coarse‐scale depositional pattern of ¹³⁷Cs from Chernobyl. Two indices of land form derived from a digital elevation model, namely compound topographic index and the length–slope factor of the Revised Universal Soil Loss Equation, account for only 3% of the variance in ¹³⁷Cs activity. In contrast, soil type and land cover in combination (including their interaction) account for 20% of the variance. In areas that received moderate fallout from Chernobyl, soil type alone accounts for a substantial proportion of the spatially correlated ¹³⁷Cs activity. We attribute this to each soil type having a fairly uniform radiocaesium interception potential that differs from those of other soil types and that this potential controls the vertical migration of ¹³⁷Cs. Over the granitic Mourne Mountains there is a strong spatial cross‐correlation between ¹³⁷Cs activity and airborne estimates of soil potassium, suggesting that the latter provides a measure of the soil's radiocaesium interception potential; this is probably dominated by the quantity of the mineral illite. Copyright © 2010 John Wiley & Sons, Ltd. and British Geological Survey  相似文献