Evaluation of Near-Surface Air Temperature from Reanalysis over the United States and Ukraine: Application to Winter Wheat Yield Forecasting

In this work we evaluate the near-surface air temperature datasets from the ERA-Interim, JRA55, MERRA2, NCEP1, and NCEP2 reanalysis projects. Reanalysis data were first compared to observations from weather stations located on wheat areas of the United States and Ukraine, and then evaluated in the context of a winter wheat yield forecast model. Results from the comparison with weather station data showed that all datasets performed well (r2>0.95) and that more modern reanalysis such as ERAI had lower errors (RMSD ~ 0.9) than the older, lower resolution datasets like NCEP1 (RMSD ~ 2.4). We also analyze the impact of using surface air temperature data from different reanalysis products on the estimations made by a winter wheat yield forecast model. The forecast model uses information of the accumulated Growing Degree Day (GDD) during the growing season to estimate the peak NDVI signal. When the temperature data from the different reanalysis projects were used in the yield model to compute the accumulated GDD and forecast the winter wheat yield, the results showed smaller variations between obtained values, with differences in yield forecast error of around 2% in the most extreme case. These results suggest that the impact of temperature discrepancies between datasets in the yield forecast model get diminished as the values are accumulated through the growing season

The surface temperatures of Earth: steps towards integrated understanding of variability and change

Surface temperature is a key aspect of weather and climate, but the term may refer to different quantities that play interconnected roles and are observed by different means. In a community-based activity in June 2012, the EarthTemp Network brought together 55 researchers from five continents to improve the interaction between scientific communities who focus on surface temperature in particular domains, to exploit the strengths of different observing systems and to better meet the needs of different communities. The workshop identified key needs for progress towards meeting scientific and societal requirements for surface temperature understanding and information, which are presented in this community paper. A "whole-Earth" perspective is required with more integrated, collaborative approaches to observing and understanding Earth's various surface temperatures. It is necessary to build understanding of the relationships between different surface temperatures, where presently inadequate, and undertake large-scale systematic intercomparisons. Datasets need to be easier to obtain and exploit for a wide constituency of users, with the differences and complementarities communicated in readily understood terms, and realistic and consistent uncertainty information provided. Steps were also recommended to curate and make available data that are presently inaccessible, develop new observing systems and build capacities to accelerate progress in the accuracy and usability of surface temperature datasets

Challenges with Assessing the Impact of NFS Advances on the Security of Pairing-based Cryptography

In the past two years there have been several advances in Number Field Sieve (NFS) algorithms for computing discrete logarithms in finite fields $\mathbb{F}_{p^n}$ where $p$ is prime and $n > 1$ is a small integer. This article presents a concise overview of these algorithms and discusses some of the challenges with assessing their impact on keylengths for pairing-based cryptosystems

A first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core

A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05) and its model extension (GICC05modelext) from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the electrical conductivity measurement (ECM) and dielectrical profiling (DEP) records. Tephra horizons found in both the NEEM and NGRIP ice cores are used to test the matching based on ECM and DEP and provide five additional horizons used for the timescale transfer. A thinning function reflecting the accumulated strain along the core has been determined using a Dansgaard–Johnsen flow model and an isotope-dependent accumulation rate parameterization. Flow parameters are determined from Monte Carlo analysis constrained by the observed depth-age horizons. In order to construct a chronology for the gas phase, the ice age–gas age difference (Δage) has been reconstructed using a coupled firn densification-heat diffusion model. Temperature and accumulation inputs to the Δage model, initially derived from the water isotope proxies, have been adjusted to optimize the fit to timing constraints from δ¹⁵N of nitrogen and high-resolution methane data during the abrupt onset of Greenland interstadials. The ice and gas chronologies and the corresponding thinning function represent the first chronology for the NEEM core, named GICC05modelext-NEEM-1. Based on both the flow and firn modelling results, the accumulation history for the NEEM site has been reconstructed. Together, the timescale and accumulation reconstruction provide the necessary basis for further analysis of the records from NEEM.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.clim-past.net/volumes_and_issues.html

Quantifying Vegetation Biophysical Variables from Imaging Spectroscopy Data: A Review on Retrieval Methods

An unprecedented spectroscopic data stream will soon become available with forthcoming Earth-observing satellite missions equipped with imaging spectroradiometers. This data stream will open up a vast array of opportunities to quantify a diversity of biochemical and structural vegetation properties. The processing requirements for such large data streams require reliable retrieval techniques enabling the spatiotemporally explicit quantification of biophysical variables. With the aim of preparing for this new era of Earth observation, this review summarizes the state-of-the-art retrieval methods that have been applied in experimental imaging spectroscopy studies inferring all kinds of vegetation biophysical variables. Identified retrieval methods are categorized into: (1) parametric regression, including vegetation indices, shape indices and spectral transformations; (2) nonparametric regression, including linear and nonlinear machine learning regression algorithms; (3) physically based, including inversion of radiative transfer models (RTMs) using numerical optimization and look-up table approaches; and (4) hybrid regression methods, which combine RTM simulations with machine learning regression methods. For each of these categories, an overview of widely applied methods with application to mapping vegetation properties is given. In view of processing imaging spectroscopy data, a critical aspect involves the challenge of dealing with spectral multicollinearity. The ability to provide robust estimates, retrieval uncertainties and acceptable retrieval processing speed are other important aspects in view of operational processing. Recommendations towards new-generation spectroscopy-based processing chains for operational production of biophysical variables are given

A combustion setup to precisely reference d13C and d2H isotope ratios of pure CH4 to produce isotope reference gases of d13C-CH4 in synthetic air

info:eu-repo/semantics/publishe

A combustion setup to precisely reference δ¹³C and δ²H isotope ratios of pure CH₄ to produce isotope reference gases of δ¹³C-CH₄ in synthetic air

Isotope records of atmospheric CH₄ can be used to infer changes in the biogeochemistry of CH₄. One factor currently limiting the quantitative interpretation of such changes are uncertainties in the isotope measurements stemming from the lack of a unique isotope reference gas, certified for δ¹³C-CH₄ or δ²H-CH₄. We present a method to produce isotope reference gases for CH₄ in synthetic air that are precisely anchored to the VPDB and VSMOW scales and have δ¹³C-CH₄ values typical for the modern and glacial atmosphere. We quantitatively combusted two pure CH₄ gases from fossil and biogenic sources and determined the δ¹³C and δ²H values of the produced CO₂ and H₂O relative to the VPDB and VSMOW scales within a very small analytical uncertainty of 0.04‰ and 0.7‰, respectively. We found isotope ratios of −39.56‰ and −56.37‰ for δ¹³C and −170.1‰ and −317.4‰ for δ²H in the fossil and biogenic CH₄, respectively. We used both CH₄ types as parental gases from which we mixed two filial CH₄ gases. Their δ¹³C was determined to be −42.21‰ and −47.25‰ representing glacial and present atmospheric δ¹³C-CH₄. The δ²H isotope ratios of the filial CH₄ gases were found to be −193.1‰ and −237.1‰, respectively. Next, we mixed aliquots of the filial CH₄ gases with ultrapure N₂/O₂ (CH₄ ≤ 2 ppb) producing two isotope reference gases of synthetic air with CH₄ mixing ratios near atmospheric values. We show that our method is reproducible and does not introduce isotopic fractionation for δ¹³C within the uncertainties of our detection limit (we cannot conclude this for δ²H because our system is currently not prepared for δ²H-CH₄ measurements in air samples). The general principle of our method can be applied to produce synthetic isotope reference gases targeting δ²H-CH₄ or other gas species

La mise en œuvre d'une démarche éthique peut-elle influencer la souffrance des soignants?

Pour un soignant, la question éthique fondamentale est celle de l’attention à l’autre, en tant que sujet singulier et non pas en tant qu’objet de soins. Dans la pratique, sa mise en œuvre ne permet pas — et c’est heureux — de dispenser le soignant d’un questionnement quant à sa propre manière d’être sujet et de s’engager dans le soin. Cet article relate l’expérience d’un atelier d’aide à la décision éthique, en montrant qu’une démarche éthique peut aider les soignants à trouver un juste milieu dans leur engagement, évitant à la fois l’épuisement et l’indifférence, tous deux signes de souffrance. Les réponses à une enquête menée auprès des soignants qui participent régulièrement à cet atelier mettent en évidence différents éléments qui influencent favorablement leur bien-être et la qualité de leur présence, en faisant de l’écoute de soi un préalable à l’écoute de l’autre. Une seconde expérience, celle de la création et de l’utilisation d’un outil d’apprentissage du raisonnement éthique, confirme cette influence positive. La conscience apportée à la dimension éthique de notre travail nous aide ainsi à comprendre la nécessité de poser, seconde après seconde, des choix conscients et de les incarner dans les moindres de nos gestes. Elle montre que le sens de nos actions est à chercher, non pas seulement dans le contenu des décisions à prendre, mais également dans la manière dont nous les prenons et les mettons en œuvre. En cela, elle nous permet d’éprouver quotidiennement qu’en construisant les meilleures décisions possibles pour les patients, nous nous construisons en tant que soignants. C’est toute une philosophie de la transmission qui est alors à l’œuvre.[Can the implementation of ethical processes have an influence on medical persons' suffering?] The fundamental ethical question for medical staff is that of the attention to the other as a singular subject and not as the object of care. In practice, its implementation does not allow — fortunately — to exempt the medical staff from questioning their own way of being a subject and of becoming involved in care. The article relates the experience of an “assistance to ethical decision-making” workshop, showing that ethical processes can help medical staff find a middle way in their commitment, avoiding exhaustion as well as indifference, which are both signs of suffering. Answers to a survey among medical staff who regularly take part in the workshop clearly emphasize several elements that favourably influence their well-being and the quality of their presence, making self-attention a preliminary to attention to the other. A second experience, the creation and use of a learning tool for ethical reasoning, confirms that positive influence. Being conscious of the ethical dimension of our work helps us understand, second after second, the need of making conscious choices and making them come true in every single gesture. It shows that the meaning of our actions is not only to be sought in the content of our decisions but also in the way we take and implement them. As such, it allows us daily to feel that building the best possible decisions for the patients enables us to build ourselves as medical persons. It is a whole philosophy of transmission which is then at work

A first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core

A stratigraphy-based chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core has been derived by transferring the annual layer counted Greenland Ice Core Chronology 2005 (GICC05) and its model extension (GICC05modelext) from the NGRIP core to the NEEM core using 787 match points of mainly volcanic origin identified in the electrical conductivity measurement (ECM) and dielectrical profiling (DEP) records. Tephra horizons found in both the NEEM and NGRIP ice cores are used to test the matching based on ECM and DEP and provide five additional horizons used for the timescale transfer. \ud A thinning function reflecting the accumulated strain along the core has been determined using a Dansgaard–Johnsen flow model and an isotope-dependent accumulation rate parameterization. Flow parameters are determined from Monte Carlo analysis constrained by the observed depth-age horizons. In order to construct a chronology for the gas phase, the ice age–gas age difference (Δage) has been reconstructed using a coupled firn densification-heat diffusion model. Temperature and accumulation inputs to the Δage model, initially derived from the water isotope proxies, have been adjusted to optimize the fit to timing constraints from δ15N of nitrogen and high-resolution methane data during the abrupt onset of Greenland interstadials. The ice and gas chronologies and the corresponding thinning function represent the first chronology for the NEEM core, named GICC05modelext-NEEM-1. Based on both the flow and firn modelling results, the accumulation history for the NEEM site has been reconstructed. Together, the timescale and accumulation reconstruction provide the necessary basis for further analysis of the records from NEEM