scholarly journals ABSOLUTE STANDARDS FOR CLIMATE MEASUREMENTS

2016 ◽  
Vol XLI-B8 ◽  
pp. 1407-1408
Author(s):  
J. Leckey
Keyword(s):  
Climate Change ◽  
Melting Point ◽  
Phase Change ◽  
Time Scale ◽  
Physical Constant ◽  
Sufficient Accuracy ◽  
Climate Variables ◽  
Political Uncertainty ◽  
Decadal Time Scale ◽  
The Status

In a world of changing climate, political uncertainty, and ever-changing budgets, the benefit of measurements traceable to SI standards increases by the day. To truly resolve climate change trends on a decadal time scale, on-orbit measurements need to be referenced to something that is both absolute and unchanging. One such mission is the Climate Absolute Radiance and Refractivity Observatory (CLARREO) that will measure a variety of climate variables with an unprecedented accuracy to definitively quantify climate change. In the CLARREO mission, we will utilize phase change cells in which a material is melted to calibrate the temperature of a blackbody that can then be observed by a spectrometer. A material’s melting point is an unchanging physical constant that, through a series of transfers, can ultimately calibrate a spectrometer on an absolute scale. CLARREO consists of two primary instruments: an infrared (IR) spectrometer and a reflected solar (RS) spectrometer. The mission will contain orbiting radiometers with sufficient accuracy to calibrate other space-based instrumentation and thus transferring the absolute traceability. The status of various mission options will be presented.

scholarly journals Climate Absolute Radiance and Refractivity Observatory (CLARREO)

2015 ◽  
Vol XL-7/W3 ◽  
pp. 213-217 ◽  
Author(s):  
J. Leckey
Keyword(s):  
Climate Change ◽  
Fourier Transform ◽  
Phase Change ◽  
Radio Occultation ◽  
Wavelength Region ◽  
Sufficient Accuracy ◽  
Fourier Transform Spectrometer ◽  
Climate Variables ◽  
The Status ◽  
Order Of Magnitude

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a mission, led and developed by NASA, that will measure a variety of climate variables with an unprecedented accuracy to quantify and attribute climate change. CLARREO consists of three separate instruments: an infrared (IR) spectrometer, a reflected solar (RS) spectrometer, and a radio occultation (RO) instrument. The mission will contain orbiting radiometers with sufficient accuracy, including on orbit verification, to calibrate other space-based instrumentation, increasing their respective accuracy by as much as an order of magnitude. The IR spectrometer is a Fourier Transform spectrometer (FTS) working in the 5 to 50 μm wavelength region with a goal of 0.1 K (<i>k</i> = 3) accuracy. The FTS will achieve this accuracy using phase change cells to verify thermistor accuracy and heated halos to verify blackbody emissivity, both on orbit. The RS spectrometer will measure the reflectance of the atmosphere in the 0.32 to 2.3 μm wavelength region with an accuracy of 0.3% (<i>k</i> = 2). The status of the instrumentation packages and potential mission options will be presented.

North Atlantic decadal variability in a coupled global model and relevance to observations

2020 ◽  
Author(s):  
Yochanan Kushnir ◽  
Dog Run (Donna) Lee ◽  
Mingfang Ting
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Time Scale ◽  
Decadal Variability ◽  
North Atlantic Ocean ◽  
Heat Content ◽  
Decadal Climate Variability ◽  
North Atlantic Current ◽  
Decadal Time Scale ◽  
The North

&lt;p&gt;This study focuses on the decadal time scale variability of the North Atlantic Ocean-Atmosphere system. This time scale is relevant to preparedness and adaptation as society becomes increasingly threatened by the adverse impact of anthropogenic climate change. North Atlantic decadal climate variability has been related to interaction between the subpolar and subtropical gyre and manifested in persistent multi-year SST and heat content anomalies and shifts in the latitude of the Gulf Stream/North Atlantic Current (GS/NAC). We apply a space-time analysis to annual, North Atlantic, upper ocean heat content (OHC) anomalies from the National Center for Atmospheric Research (NCAR), Community Earth System Model (CESM) long pre-industrial control run. The analysis reveals decadal anomalies associated with two patterns: a dipole centered on the GS/NAC, in the western side of the Basin that oscillates quasi-regularly, reversing its sign every of 6 to 7 years. The second pattern is centered in the eastern side of the basin and lags the first by about 5 years, implying that heat is transported between the subtropical and subpolar gyres. Analysis of surface windstress anomalies connected with these OHC fluctuations implies that the latter are forced by stochastic atmospheric variability. Further analysis compares the model patterns with observations to determine their relevance and predictability and assesses their response to climate change.&lt;/p&gt;

scholarly journals Lyell, the Geikies and Croll's observations on terrestrial glacial sediments and landforms

2021 ◽  
pp. 1-14
Author(s):  
James ROSE
Keyword(s):  
Climate Change ◽  
High Quality ◽  
Glacial Sediments ◽  
Direct Observations ◽  
The Social ◽  
The Status ◽  
Social And Physical Environment ◽  
Glacial Landforms

ABSTRACT Within the context of the work and achievements of James Croll, this paper reviews the records of direct observations of glacial landforms and sediments made by Charles Lyell, Archibald and James Geikie and James Croll himself, in order to evaluate their contributions to the sciences of glacial geology and Quaternary environmental change. The paper outlines the social and physical environment of Croll's youth and contrasts this with the status and experiences of Lyell and the Geikies. It also outlines the character and role of the ‘Glasgow School’ of geologists, who stimulated Croll's interest into the causes of climate change and directed his focus to the glacial and ‘interglacial’ deposits of central Scotland. Contributions are outlined in chronological order, drawing attention to: (i) Lyell's high-quality observations and interpretations of glacial features in Glen Clova and Strathmore and his subsequent rejection of the glacial theory in favour of processes attributed to floating icebergs; (ii) the significant impact of Archibald Geikie's 1863 paper on the ‘glacial drift of Scotland’, which firmly established the land-ice theory; (iii) the fact that, despite James Croll's inherent dislike of geology and fieldwork, he provided high-quality descriptions and interpretations of the landforms and sediments of central Scotland in order to test his theory of climate change; and (iv) the great communication skills of James Geikie, enhanced by contacts and evidence from around the world. It is concluded that whilst direct observations of glacial landforms and sediments were critical to the long-term development of the study of glaciation, the acceptance of this theory was dependent also upon the skills, personality and status of the Geikies and Croll, who developed and promoted the concepts. Sadly, the subsequent rejection of the land-ice concept by Lyell resulted in the same factors challenging the acceptance of the glacial theory.

scholarly journals Enhanced Performance and Diffusion Robustness of Phase-Change Metasurfaces via a Hybrid Dielectric/Plasmonic Approach

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 525
Author(s):  
Joe Shields ◽  
Carlota Ruiz de Galarreta ◽  
Jacopo Bertolotti ◽  
C. David Wright
Keyword(s):  
Melting Point ◽  
Phase Change ◽  
Noble Metals ◽  
Phase Change Materials ◽  
High Efficiency ◽  
The Body ◽  
Design Stage ◽  
High Melting ◽  
Optical Performance ◽  
Electrical Conductors

Materials of which the refractive indices can be thermally tuned or switched, such as in chalcogenide phase-change alloys, offer a promising path towards the development of active optical metasurfaces for the control of the amplitude, phase, and polarization of light. However, for phase-change metasurfaces to be able to provide viable technology for active light control, in situ electrical switching via resistive heaters integral to or embedded in the metasurface itself is highly desirable. In this context, good electrical conductors (metals) with high melting points (i.e., significantly above the melting point of commonly used phase-change alloys) are required. In addition, such metals should ideally have low plasmonic losses, so as to not degrade metasurface optical performance. This essentially limits the choice to a few noble metals, namely, gold and silver, but these tend to diffuse quite readily into phase-change materials (particularly the archetypal Ge2Sb2Te5 alloy used here), and into dielectric resonators such as Si or Ge. In this work, we introduce a novel hybrid dielectric/plasmonic metasurface architecture, where we incorporated a thin Ge2Sb2Te5 layer into the body of a cubic silicon nanoresonator lying on metallic planes that simultaneously acted as high-efficiency reflectors and resistive heaters. Through systematic studies based on changing the configuration of the bottom metal plane between high-melting-point diffusive and low-melting-point nondiffusive metals (Au and Al, respectively), we explicitly show how thermally activated diffusion can catastrophically and irreversibly degrade the optical performance of chalcogenide phase-change metasurface devices, and how such degradation can be successfully overcome at the design stage via the incorporation of ultrathin Si3N4 barrier layers between the gold plane and the hybrid Si/Ge2Sb2Te5 resonators. Our work clarifies the importance of diffusion of noble metals in thermally tunable metasurfaces and how to overcome it, thus helping phase-change-based metasurface technology move a step closer towards the realization of real-world applications.

Vegetation ecology with anthropic drivers and consequences

2021 ◽  
pp. 030913332199937
Author(s):  
George P Malanson ◽  
Michelle L Talal ◽  
Elizabeth R Pansing ◽  
Scott B Franklin
Keyword(s):  
Climate Change ◽  
Invasive Species ◽  
Plant Communities ◽  
Fire Ecology ◽  
Progress Report ◽  
Processes Of Change ◽  
Community Classification ◽  
The Status ◽  
Plant Community Classification ◽  
Anthropogenic Drivers

Current research on vegetation makes a difference in people’s lives. Plant community classification is a backbone of land management, plant communities are changing in response to anthropogenic drivers, and the processes of change have impacts on ecosystem services. In the following progress report, we summarize the status of classification and recent research on vegetation responses to pollution, especially nitrogen deposition, invasive species, climate change, and land use and direct exploitation. Two areas with human feedbacks are underscored: fire ecology and urban ecology. Prominent questions at the current research frontier are highlighted with attention to new perspectives.

Screening of high melting point phase change materials (PCM) in solar thermal concentrating technology based on CLFR

Solar Energy ◽  
2005 ◽  
Vol 79 (3) ◽  
pp. 332-339 ◽  
Author(s):  
Akira Hoshi ◽  
David R. Mills ◽  
Antoine Bittar ◽  
Takeo S. Saitoh
Keyword(s):  
Melting Point ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solar Thermal ◽  
High Melting ◽  
High Melting Point

scholarly journals Spatiotemporal climate and vegetation greenness changes and their nexus for Dhidhessa River Basin, Ethiopia

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Gizachew Kabite Wedajo ◽  
Misgana K. Muleta ◽  
Berhan Gessesse ◽  
Sifan A. Koriche
Keyword(s):  
Climate Change ◽  
Trend Analysis ◽  
River Basin ◽  
Climate Change Adaptation ◽  
Spatial Relationship ◽  
Local Scale ◽  
Climate Variables ◽  
Climatic Zones ◽  
Vegetation Greenness ◽  
Climate Change Adaptation Strategies

Abstract Background Understanding spatiotemporal climate and vegetation changes and their nexus is key for designing climate change adaptation strategies at a local scale. However, such a study is lacking in many basins of Ethiopia. The objectives of this study were (i) to analyze temperature, rainfall and vegetation greenness trends and (ii) determine the spatial relationship of climate variables and vegetation greenness, characterized using Normalized Difference in Vegetation Index (NDVI), for the Dhidhessa River Basin (DRB). Quality checked high spatial resolution satellite datasets were used for the study. Mann–Kendall test and Sen’s slope method were used for the trend analysis. The spatial relationship between climate change and NDVI was analyzed using geographically weighted regression (GWR) technique. Results According to the study, past and future climate trend analysis generally showed wetting and warming for the DRB where the degree of trends varies for the different time and spatial scales. A seasonal shift in rainfall was also observed for the basin. These findings informed that there will be a negative impact on rain-fed agriculture and water availability in the basin. Besides, NDVI trends analysis generally showed greening for most climatic zones for the annual and main rainy season timescales. However, no NDVI trends were observed in all timescales for cool sub-humid, tepid humid and warm humid climatic zones. The increasing NDVI trends could be attributed to agroforestry practices but do not necessarily indicate improved forest coverage for the basin. The change in NDVI was positively correlated to rainfall (r2 = 0.62) and negatively correlated to the minimum (r2 = 0.58) and maximum (r2 = 0.45) temperature. The study revealed a strong interaction between the climate variables and vegetation greenness for the basin that further influences the biophysical processes of the land surface like the hydrologic responses of a basin. Conclusion The study concluded that the trend in climate and vegetation greenness varies spatiotemporally for the DRB. Besides, the climate change and its strong relationship with vegetation greenness observed in this study will further affect the biophysical and environmental processes in the study area; mostly negatively on agricultural and water resource sectors. Thus, this study provides helpful information to device climate change adaptation strategies at a local scale.

scholarly journals On the characterization of glacier response by a single time-scale

2001 ◽  
Vol 47 (159) ◽  
pp. 659-664 ◽  
Author(s):  
W. D. Harrison ◽  
D. H. Elsberg ◽  
K. A. Echelmeyer ◽  
R. M. Krimmel
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
Time Constant ◽  
Time Scale ◽  
Response Models ◽  
Single Time ◽  
Glacier Changes ◽  
Major Increase ◽  
Effect Of Surface

AbstractGlacier response to climate can be characterized by a single time-scale when the glacier changes sufficiently slowly. Then the derivative of volume with respect to area defines a thickness scale similar to that of Jóhannesson and others, and the time-scale follows from it. Our version of the time-scale is different from theirs because it explicitly includes the effect of surface elevation on mass-balance rate, which can cause a major increase in the time-scale or even lead to unstable response. The time constant has a dual role, controlling both the rate and magnitude of response to a given climate change. Data from South Cascade Glacier, Washington, U.S.A., illustrate the ideas, some of the difficulty in obtaining accurate values for the thickness and time-scales, and the susceptibility of all response models to potentially large errors.

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