Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)     

R. Wachter  J. Schou  M. C. Rabello-Soares  J. W. Miles  T. L. Duvall Jr.  R. I. Bush 《Solar physics》2012,275(1-2):261-284

We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light, image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.  相似文献   

Design and Ground Calibration of the Helioseismic and Magnetic Imager (HMI) Instrument on the Solar Dynamics Observatory (SDO)     

J. Schou  P. H. Scherrer  R. I. Bush  R. Wachter  S. Couvidat  M. C. Rabello-Soares  R. S. Bogart  J. T. Hoeksema  Y. Liu  T. L. Duvall Jr.  D. J. Akin  B. A. Allard  J. W. Miles  R. Rairden  R. A. Shine  T. D. Tarbell  A. M. Title  C. J. Wolfson  D. F. Elmore  A. A. Norton  S. Tomczyk 《Solar physics》2012,275(1-2):229-259

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Divergent trends in ecosystem services under different climate-management futures in a fire-prone forest landscape     

Joshua S. Halofsky  Jessica E. Halofsky  Miles A. Hemstrom  Anita T. Morzillo  Xiaoping Zhou  Daniel C. Donato 《Climatic change》2017,142(1-2):83-95

While ecosystem services and climate change are often examined independently, quantitative assessments integrating these fields are needed to inform future land management decisions. Using climate-informed state-and-transition simulations, we examined projected trends and tradeoffs for a suite of ecosystem services under four climate change scenarios and two management scenarios (active management emphasizing fuel treatments and no management other than fire suppression) in a fire-prone landscape of dry and moist mixed-conifer forests in central Oregon, USA. Focal ecosystem services included fire potential (regulating service), timber volume (provisioning service), and potential wildlife habitat (supporting service). Projections without climate change suggested active management in dry mixed-conifer forests would create more open forest structures, reduce crown fire potential, and maintain timber stocks, while in moist mixed-conifer forests, active management would reduce crown fire potential but at the expense of timber stocks. When climate change was considered, however, trends in most ecosystem services changed substantially, with large increases in wildfire area predominating broad-scale trends in outputs, regardless of management approach (e.g., strong declines in timber stocks and habitat for closed-forest wildlife species). Active management still had an influence under a changing climate, but as a moderator of the strong climate-driven trends rather than being a principal driver of ecosystem service outputs. These results suggest projections of future ecosystem services that do not consider climate change may result in unrealistic expectations of benefits.  相似文献   

A modified normalized model for predicting effective soil thermal conductivity     

Hailong He  Ying Zhao  Miles F. Dyck  Bingcheng Si  Huijun Jin  Jialong Lv  Jinxin Wang 《Acta Geotechnica》2017,12(6):1281-1300

Effective soil thermal conductivity (λ _eff) describes the ability of a multiphase soil to transmit heat by conduction under unit temperature gradient. It is a critical parameter for environmental science, earth and planetary science, and engineering applications. Numerous models are available in the literature, but their applicability is generally restricted to certain soil types or water contents (θ). The objective of this study was to develop a new model in the similar form of the Johansen 1975 model to simulate the λ _eff(θ) relationship of soils of various soil textures and water contents. An exponential type model with two parameters is developed and a new function for calculating dry soil thermal conductivity is presented. Performance of the new model and six other normalized models were evaluated with published datasets. The results show that the new model is able to well mimic λ _eff(θ) relationship of soils from sand to silt loam and from oven dry to full saturation. In addition, it has the best performance among the seven models under test (with root-mean-square error of 0.059 W m^?1 °C^?1, average deviations of 0.0009 W m^?1 °C^?1, and Nash–Sutcliffe efficiency of 0.994). The new model has potential to improve the reliability of soil thermal conductivity estimation and be incorporated into numerical modeling for environmental, earth and engineering studies.  相似文献   

Cytochrome P4501A biomarker indication of the timeline of chronic exposure of Barrow's goldeneyes to residual Exxon Valdez oil     

Esler D  Ballachey BE  Trust KA  Iverson SA  Reed JA  Miles AK  Henderson JD  Woodin BR  Stegeman JJ  McAdie M  Mulcahy DM  Wilson BW 《Marine pollution bulletin》2011,62(3):609-614

We examined hepatic EROD activity, as an indicator of CYP1A induction, in Barrow’s goldeneyes captured in areas oiled during the 1989 Exxon Valdez spill and those from nearby unoiled areas. We found that average EROD activity differed between areas during 2005, although the magnitude of the difference was reduced relative to a previous study from 1996/1997, and we found that areas did not differ by 2009. Similarly, we found that the proportion of individuals captured from oiled areas with elevated EROD activity (?2 times unoiled average) declined from 41% in winter 1996/1997 to 10% in 2005 and 15% in 2009. This work adds to a body of literature describing the timelines over which vertebrates were exposed to residual Exxon Valdez oil and indicates that, for Barrow’s goldeneyes in Prince William Sound, exposure persisted for many years with evidence of substantially reduced exposure by 2 decades after the spill.  相似文献   

On topographic coupling of surface and internal tides     

Peter G. Baines  John W. Miles 《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(12):124

The problem of the generation of internal tides through the interaction of surface tides with oceanic bottom topography is re-examined, taking into account the horizontal components of the Earth's rotation. It is shown that previous models that have omitted these terms may be readily extended to include them, and changes in the magnitude and character of the barotropic to baroclinic conversion are estimated. For semi-diurnal tides the energy conversion is increased, but only by about 2%. However, the character of the waves differs at high latitudes, where the phase and location of the wave energy may change by as much as 14%. Accordingly, inclusion of these terms is recommended in future studies with these models.  相似文献   

Compartmentalisation and groundwater–surface water interactions in a prospective shale gas basin: Assessment using variance analysis and multivariate statistics on water quality data     

Miles P. Wilson  Fred Worrall  Sarah A. Clancy  Chris J. Ottley  Alwyn Hart  Richard J. Davies 《水文研究》2020,34(15):3271-3294

An environmental concern with hydraulic fracturing for shale gas is the risk of groundwater and surface water contamination. Assessing this risk partly involves the identification and understanding of groundwater–surface water interactions because potentially contaminating fluids could move from one water body to the other along hydraulic pathways. In this study, we use water quality data from a prospective shale gas basin to determine: if surface water sampling could identify groundwater compartmentalisation by low-permeability faults; and if surface waters interact with groundwater in underlying bedrock formations, thereby indicating hydraulic pathways. Variance analysis showed that bedrock geology was a significant factor influencing surface water quality, indicating regional-scale groundwater–surface water interactions despite the presence of an overlying region-wide layer of superficial deposits averaging 30–40 m thickness. We propose that surface waters interact with a weathered bedrock layer through the complex distribution of glaciofluvial sands and gravels. Principal component analysis showed that surface water compositions were constrained within groundwater end-member compositions. Surface water quality data showed no relationship with groundwater compartmentalisation known to be caused by a major basin fault. Therefore, there was no chemical evidence to suggest that deeper groundwater in this particular area of the prospective basin was reaching the surface in response to compartmentalisation. Consequently, in this case compartmentalisation does not appear to increase the risk of fracking-related contaminants reaching surface waters, although this may differ under different hydrogeological scenarios.  相似文献   

时域反射仪（TDR）测定土壤含水量标定曲线评价与方案推荐     

徐玲玲  高彩虹  王佳铭  金会军  吴青柏  DYCK Miles  何海龙 《冰川冻土》2020,42(1):265-275

时域反射仪（Time Domain Reflectometry）可用于室内和田间快速、 准确、 自动测定土壤含水量, 是目前应用最广泛的土壤含水量测定方法之一。适宜的土壤含水量标定曲线（即土壤表观介电常数和土壤含水量之间的关系）是TDR准确测定土壤含水量的关键。目前文献中存在大量的土壤含水量标定曲线, 但尚未有研究对这些标定曲线进行系统的验证和分析评价。因此, 它们的准确性和适用范围尚不明晰, 严重影响到与土壤含水量测定相关的研究。通过查阅大量国内外文献, 收集整理了一系列土壤含水量标定曲线的经验公式（19个）和半经验半物理模型（5个）, 并利用大量的文献实测数据对其进行综合评价。同时运用均方根差（RMSE）, 平均误差（AD）, 纳什效率系数（NSE）等三个指标对比分析和评价这些标定曲线的准确性和可靠性。研究结果表明： 经验公式中Topp、 Roth（1992）2、 Jacobosen、 Yoshikawa2、 Alharathi模型和半经验模型中Malicki1公式及其修订模型综合性能较好。研究成果可为利用TDR准确测定土壤含水量及土壤含水量标定曲线的选择提供参考和指导。  相似文献   

On viscoelastic eddy viscosity for flow over a wavy surface     

John Miles 《Boundary-Layer Meteorology》1996,79(1-2):177-179

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The Cretaceous-Tertiary fireball layer,ejecta layer and coal seam: Platinum-group element content and mineralogy of size fractions     

Noreen Joyce Evans  D. Conrad Gregoire  Wayne D. Goodfellow  Norman Miles  Jn Veizer 《Meteoritics & planetary science》1994,29(2):223-235

Abstract— Grain size separates of the Cretaceous-Tertiary (K-T) fireball layer at marine sites and the entire K-T boundary interval at nonmarine sites (fireball layer, ejecta layer, coal seam) were analysed for platinum-group elements (PGE: Ru, Ir, Ft, Pd, Rh) and Au using inductively coupled plasma mass-spectrometry. X-ray diffractometry and scanning electron microscopy were performed on each fraction to establish the mineralogy. It was determined that the most abundant minerals in the finest fraction were a smectite-group mineral at marine K-T sites and illite-smectite mixed layer clay at nonmarine K-T sites. Positive correlation of PGE content and mineralogy indicates that the PGE are presently associated with these clay minerals which were likely formed by alteration of a condensed mafic phase (e.g., olivine or pyroxene). The correlation of clay mineral abundance with PGE content is imperfect because not all of the clay minerals in the fireball layer are derived by alteration of the original condensed ejecta. In addition, undetected PGE host(s), present in trace amounts, are likely also present.  相似文献