Near surface properties derived from Phobos transits with HP RAD³ on InSight, Mars

Computing evapotranspiration (ET) with satellite-based energy balance models such as METRIC (Mapping EvapoTranspiration at high Resolution with Internalized Calibration) requires internal calibration of sensible heat flux using anchor pixels (“hot” and “cold” pixels). Despite the development of automated anchor pixel selection methods that classify a pool of candidate pixels using the amount of vegetation (normalized difference vegetation index, NDVI) and surface temperature (Ts), final pixel selection still relies heavily on operator experience. Yet, differences in final ET estimates resulting from subjectivity in selecting the final “hot” and “cold” pixel pair (from within the candidate pixel pool) have not yet been investigated. This is likely because surface properties of these candidate pixels, as quantified by NDVI and surface temperature, are generally assumed to have low variability that can be attributed to random noise. In this study, we test the assumption of low variability by first applying an automated calibration pixel selection process to 42 nearly cloud-free Landsat images of the San Joaquin area in California taken between 2013 and 2015. We then compute Ts (vertical near-surface temperature differences) vs. Ts relationships at all pixels that could potentially be used for model calibration in order to explore ET variance between the results from multiple calibration schemes where NDVI and Ts variability is intrinsically negligible. Our results show significant variability in ET (ranging from 5% to 20%) and a high—and statistically consistent—variability in dT values, indicating that there are additional surface properties affecting the calibration process not captured when using only NDVI and Ts. Our findings further highlight the potential for calibration improvements by showing that the dT vs. Ts calibration relationship between the cold anchor pixel (with lowest dT) and the hot anchor pixel (with highest dT) consistently provides the best daily ET estimates. This approach of quantifying ET variability based on candidate pixel selection and the accompanying results illustrate an approach to quantify the biases inadvertently introduced by user subjectivity and can be used to inform improvements on model usability and performance.

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Shale Caprock/Acidic Brine Interaction in Underground CO2 Storage

Journal of Energy Resources Technology ◽

10.1115/1.4027567 ◽

2014 ◽

Vol 136 (4) ◽

Cited By ~ 14

Author(s):

Abiola Olabode ◽

Mileva Radonjic

Keyword(s):

Surface Properties ◽

Co2 Storage ◽

Analytical Techniques ◽

Elevated Pressure ◽

Time Frame ◽

Carbon Accounting ◽

Pore Geometry ◽

Fractional Flow ◽

Near Surface ◽

Carbon Dioxide Co2

Shale caprock integrity is critical in ensuring that subsurface injection and storage of anthropogenic carbon dioxide (CO2) is permanent. The interaction of clay-rich rock with aqueous CO2 under dynamic conditions requires characterization at the nanoscale level due to the low-reactivity of clay minerals. Geochemical mineral–fluid interaction can impact properties of shale rocks primarily through changes in pore geometry/connectivity. The experimental work reported in this paper applied specific analytical techniques in investigating changes in surface/near-surface properties of crushed shale rocks after exposure (by flooding) to CO2–brine for a time frame ranging between 30 days and 92 days at elevated pressure and fractional flow rate. The intrinsically low permeability in shale may be altered by changes in surface properties as the effective permeability of any porous medium is largely a function of its global pore geometry. Diffusive transport of CO2 as well as carbon accounting could be significantly affected over the long term. The estimation of permeability ratio indicated that petrophysical properties of shale caprock can be doubled.

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A study on the Surface Properties of Nitrogen Implanted H13 Steel by Plasma Immersion Ion Implantation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.118.275 ◽

2006 ◽

Vol 118 ◽

pp. 275-280

Author(s):

Y.Z. You ◽

D.I. Kim ◽

H.G. Chun

Keyword(s):

Surface Roughness ◽

Ion Implantation ◽

Surface Properties ◽

Photoelectron Spectroscopy ◽

Surface Hardness ◽

Wear Loss ◽

Wear Property ◽

H13 Steel ◽

Near Surface ◽

Plasma Immersion Ion Implantation

The near surface of the H13 steel was implanted by using Plasma immersion ion implantation (PIII) system at constant bias voltage of −20 kV with varying nitrogen (N+ ) ion dose (3, 6, 9, 12, 15×1017 ions/cm2 ). The surface properties of the N+ ion implanted steel were investigated by measuring the microhardness, wear loss and friction coefficient. As increasing N+ ion dose (12×1017 ions/cm2), both wear property and surface hardness were increased. However, these properties were decreased as the incident ion dose increased over 12×1017 ions/cm2. The elemental depth profile and surface roughness were obtained with X-ray photoelectron spectroscopy (XPS) and surface roughness tester, respectively.

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