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Vegetation Functional Properties Determine Uncertainty of Simulated Ecosystem Productivity: A Traceability Analysis in the East Asian Monsoon Region
Get PDFGlobal and regional projections of climate change by Earth system models are limited by their uncertain estimates of terrestrial ecosystem productivity. At the middle to low latitudes, the East Asian monsoon region has higher productivity than forests in Europe-Africa and North America, but its estimate by current generation of terrestrial biosphere models (TBMs) has seldom been systematically evaluated. Here, we developed a traceability framework to evaluate the simulated gross primary productivity (GPP) by 15 TBMs in the East Asian monsoon region. The framework links GPP to net primary productivity, biomass, leaf area and back to GPP via incorporating multiple vegetation functional properties of carbon-use efficiency (CUE), vegetation C turnover time (tau(veg)), leaf C fraction (F-leaf), specific leaf area (SLA), and leaf area index (LAI)-level photosynthesis (P-LAI), respectively. We then applied a relative importance algorithm to attribute intermodel variation at each node. The results showed that large intermodel variation in GPP over 1901-2010 were mainly propagated from their different representation of vegetation functional properties. For example, SLA explained 77% of the intermodel difference in leaf area, which contributed 90% to the simulated GPP differences. In addition, the models simulated higher CUE (18.1 21.3%), tau(veg) (18.2 26.9%), and SLA (27.436.5%) than observations, leading to the overestimation of simulated GPP across the East Asian monsoon region. These results suggest the large uncertainty of current TBMs in simulating GPP is largely propagated from their poor representation of the vegetation functional properties and call for a better understanding of the covariations between plant functional properties in terrestrial ecosystems.PublishedYe
Cluster perturbation theory. III. Perturbation series for coupled cluster singles and doubles excitation energies
Get PDFThe cluster perturbation series, CPS(D), for coupled cluster singles and doubles excitation energies is considered. It is demonstrated that the second-order model CPS(D-2) is identical to the configuration interaction singles with perturbative doubles, CIS(D) model. The third-order model, CPS(D-3), provides excitation energies of coupled cluster singles and doubles (CCSD) quality in the sense that the difference between CPS(D-3) and CCSD excitation energies is of the same size or smaller than the effect of adding triples corrections to CCSD excitation energies. We further show that the third-order corrections can be efficiently implemented, in particular, when the resolution of the identity approximation is used for integrals. We also show that the CPS(D-3) excitation energies can be determined for system sizes that are far beyond what can be considered in conventional CCSD excitation energy calculations. Published under license by AIP Publishing.Publishe
Beating the Heat: nest characteristics of anoles across suburban and forest habitats in South Miami
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Structural analysis of asteroid Ryugu
No full textThis document describes the input files of ANSYS structural analyses for Ryugu rotating at spin periods of 3.5 hr and 3.75 hr
Cluster perturbation theory. V. Theoretical foundation for cluster linear target states
Get PDFCluster perturbation (CP) theory was developed in Paper I [F. Pawlowski et al., J. Chem. Phys. 150, 134108 (2019)] for a coupled cluster (CC) target state and is extended in this paper to comprehend a cluster linear (CL) target state, for which the embedding of a CC parent state in the target excitation space is described using a linear parametrization. The theory is developed for determining the energy and molecular properties for a CL state. When CP theory is applied to a CL target state, a series of corrections is determined in orders of the CC parent-state similarity-transformed fluctuation potential, where the zeroth-order term is the energy or molecular property of the CC parent state and where the series formally converges to the energy or molecular property of the CL target state. The determination of energies and molecular properties is simpler for a CL state than for a CC state because the CL state is linearly parametrized. The amplitude equations are quadratic for a CL target state, while quartic for a CC target state, and molecular property expressions for a CL target state have the same simple structure as for a configuration interaction state. The linear parametrization introduces non-size-extensive contributions in the energy and molecular property expressions. However, since the linear parametrization describes the embedding of the CC parent state in the target excitation space, the energy and molecular properties for a CL state are weakly size-extensive. For the energy, weak size-extensivity means that non-size-extensive contributions enter in sixth and higher orders in the CP energy series, whereas for molecular properties, weak size-extensivity means that non-size-extensive contributions enter in second and higher orders. Weak size-extensivity therefore has a little or vanishing effect on calculated energies or molecular properties. The determination of the CP energy and molecular property corrections does not require that amplitude or response equations are solved explicitly for the target state and it becomes computationally tractable to use low-order corrections from these series to obtain energies and molecular properties of CL target state quality. For three simple molecules, HF, N-2, and CH2, the accuracy of the CL approach for ground-state energies is tested using a parent state including single and double excitations (i.e., the CC singles-and-doubles state, CCSD) and a target state that includes triple excitations. It is found that the size-extensive fifth-order CL energies deviate by less than 0.0001 hartree from the energies of a target CC that includes triple excitations (i.e., the CC singles-doubles-and-triples state, CCSDT). CP theory with a CL target state therefore becomes a very attractive replacement of standard CC theory for high-accuracy energy and molecular property calculations, in which triple and higher excitation levels are considered. Published under license by AIP Publishing.Publishe
Platinum, gold, and silver standards of intermolecular interaction energy calculations
Get PDFHigh-accuracy noncovalent interaction energies are indispensable as data points for potential energy surfaces and as benchmark values for improving and testing more approximate approaches. The preferred algorithm (the gold standard) for computing these energies has been the coupled-cluster method with singles, doubles, and perturbative triples [CCSD(T)] converged to the complete basis set (CBS) limit. However, gold-standard calculations are expensive as correlated interaction energies converge slowly with the basis set size, and establishing the CBS limit to better than 0.05 kcal/mol typically requires a CCSD(T) calculation in a basis set of at least triple-zeta quality. If an even higher accuracy is required (for example, for the assignment of complicated high-resolution spectra), establishing a superior platinum standard requires both a precisely converged CCSD(T)/CBS limit and the corrections for the core correlation, relativistic effects, and higher-order coupled-cluster terms at least through the perturbative quadruple excitations. On the other hand, if a triple-zeta CCSD(T) calculation is not feasible but a double-zeta one is, it is worthwhile to look for a silver standard that provides the most accurate and consistent approximation to the gold standard at a reduced computational cost. We review the recent developments aimed at (i) increasing the breadth and diversity of the available collection of gold-standard benchmark interaction energies, (ii) evaluating the best computational strategies for platinum-standard calculations and producing beyond-CCSD(T) potential energy surfaces for spectroscopic and scattering applications of the highest precision, and (iii) improving the accuracy of the silver-standard, double-zeta-level CCSD(T)/CBS estimates through the use of explicit correlation and midbond basis functions. We also outline the remaining challenges in the accurate ab initio calculations of noncovalent interaction energies.PublishedYe
Unlocking Your Courier Potential in the 21st Century with Tableau
Get PDFThe courier data collected by the circulation department at Auburn University Libraries had not been closely examined prior to the arrival of the current Business and Economics subject specialist librarian. What started as an exercise in using the software Tableau to practice visualizing local data became much more useful as the courier team began to derive applicable insights from the data.N
LOCKSS Networks: Community-Based Digital Preservation
Get PDFTen years ago, the landscape of working digital preservation (DP) solutions and/or networks was sparsely populated. Today, there is an increasing variety of DP approaches and solutions to choose from. Institutions can outsource the preservation of their digital content to private companies that are active in the library, archives, and museum (LAM) market space. They can take advantage of cloud services such as DuraCloud, Amazon Glacier, or Google Nearline. Additionally, academic institutions may join membership networks such as the Digital Preservation Network (DPN) or Academic Preservation Trust (APTrust). Or they can form other types of associations based on geographic proximity, institution type, or some other shared characteristic or concern. One approach that has proven successful over time is the Community LOCKSS Network, or CLN. Originally developed at Stanford University in the late 1990s to preserve e-publisher content, LOCKSS has continually demonstrated its ability to be a stable and reliable preservation solution for locally produced digital content as well. Starting with the first Community LOCKSS Network—the MetaArchive Cooperative, in 2004—CLNs have spread throughout the United States, Canada, Latin America, and Europe. There are currently at least 15 CLNs around the world, including networks in Brazil, Belgium, Germany, and the UK. The authors examine five geographically and administratively diverse CLNs: the MetaArchive Cooperative, an international PLN with members in the United States, Brazil, and Spain; the Alabama Digital Preservation Network (ADPNet), a statewide PLN serving a diverse set of institutions in an economically challenged state; the Council of Prairie and Pacific University Libraries (COPPUL) WestVault CLN, a network serving academic libraries in western Canada; the Public Knowledge Project Preservation Network (PKP-PN), a network for preserving content from Open Journal Systems (OJS) journals; and the Indiana Digital Preservation (InDiPres) CLN, a new statewide collaborative within the MetaArchive Cooperative.PublishedYe