bluuebunny/crossref_metadata_2025_split huggingface dataset:
The NAO, the AO, and Global Warming: How Closely Related?
Authors: Cohen Judah , Barlow Mathew 
Published: November 2005

Abstract
The North Atlantic Oscillation (NAO) and the closely related Arctic Oscillation (AO) strongly affect Northern Hemisphere (NH) surface temperatures with patterns reported similar to the global warming trend. The NAO and AO were in a positive trend for much of the 1970s and 1980s with historic highs in the early 1990s, and it has been suggested that they contributed significantly to the global warming signal. The trends in standard indices of the AO, NAO, and NH average surface temperature for December–February, 1950–2004, and the associated patterns in surface temperature anomalies are examined. Also analyzed are factors previously identified as relating to the NAO, AO, and their positive trend: North Atlantic sea surface temperatures (SSTs), Indo–Pacific warm pool SSTs, stratospheric circulation, and Eurasian snow cover.
Recently, the NAO and AO indices have been decreasing; when these data are included, the overall trends for the past 30 years are weak to nonexistent and are strongly dependent on the choice of start and end date. In clear distinction, the wintertime hemispheric warming trend has been vigorous and consistent throughout the entire period. When considered for the whole hemisphere, the NAO/AO patterns can also be distinguished from the trend pattern. Thus the December–February warming trend may be distinguished from the AO and NAO in terms of the strength, consistency, and pattern of the trend. These results are insensitive to choice of index or dataset. While the NAO and AO may contribute to hemispheric and regional warming for multiyear periods, these differences suggest that the large-scale features of the global warming trend over the last 30 years are unrelated to the AO and NAO. The related factors may also be clearly distinguished, with warm pool SSTs linked to the warming trend, while the others are linked to the NAO and AO.
Near-Annual SST Variability in the Equatorial Pacific in a Coupled General Circulation Model
Authors: Wu Renguang , Kirtman Ben P. 
Published: November 2005

Abstract
Equatorial Pacific sea surface temperature (SST) anomalies in the Center for Ocean–Land–Atmosphere Studies (COLA) interactive ensemble coupled general circulation model show near-annual variability as well as biennial El Niño–Southern Oscillation (ENSO) variability. There are two types of near-annual modes: a westward propagating mode and a stationary mode. For the westward propagating near-annual mode, warm SST anomalies are generated in the eastern equatorial Pacific in boreal spring and propagate westward in boreal summer. Consistent westward propagation is seen in precipitation, surface wind, and ocean current. For the stationary near-annual mode, warm SST anomalies develop near the date line in boreal winter and decay locally in boreal spring. Westward propagation of warm SST anomalies also appears in the developing year of the biennial ENSO mode. However, warm SST anomalies for the westward propagating near-annual mode occur about two months earlier than those for the biennial ENSO mode and are quickly replaced by cold SST anomalies, whereas warm SST anomalies for the biennial ENSO mode only experience moderate weakening.
Anomalous zonal advection contributes to the generation and westward propagation of warm SST anomalies for both the westward propagating near-annual mode and the biennial ENSO mode. However, the role of mean upwelling is markedly different. The mean upwelling term contributes to the generation of warm SST anomalies for the biennial ENSO mode, but is mainly a damping term for the westward propagating near-annual mode. The development of warm SST anomalies for the stationary near-annual mode is partially due to anomalous zonal advection and upwelling, similar to the amplification of warm SST anomalies in the equatorial central Pacific for the biennial ENSO mode. The mean upwelling term is negative in the eastern equatorial Pacific for the stationary near-annual mode, which is opposite to the ENSO mode.
The development of cold SST anomalies in the aftermath of warm SST anomalies for the westward propagating near-annual mode is coupled to large easterly wind anomalies, which occur between the warm and cold SST anomalies. The easterly anomalies contribute to the cold SST anomalies through anomalous zonal, meridional, and vertical advection and surface evaporation. The cold SST anomalies, in turn, enhance the easterly anomalies through a Rossby-wave-type response. The above processes are most effective during boreal spring when the mean near-surface-layer ocean temperature gradient is the largest. It is suggested that the westward propagating near-annual mode is related to air–sea interaction processes that are limited to the near-surface layers.
Effects of Temperature and Precipitation Variability on Snowpack Trends in the Western United States*
Authors: Hamlet Alan F. , Mote Philip W. , Clark Martyn P. , Lettenmaier Dennis P. 
Published: November 2005

Abstract
Recent studies have shown substantial declines in snow water equivalent (SWE) over much of the western United States in the last half century, as well as trends toward earlier spring snowmelt and peak spring streamflows. These trends are influenced both by interannual and decadal-scale climate variability, and also by temperature trends at longer time scales that are generally consistent with observations of global warming over the twentieth century. In this study, the linear trends in 1 April SWE over the western United States are examined, as simulated by the Variable Infiltration Capacity hydrologic model implemented at 1/8° latitude–longitude spatial resolution, and driven by a carefully quality controlled gridded daily precipitation and temperature dataset for the period 1915–2003. The long simulations of snowpack are used as surrogates for observations and are the basis for an analysis of regional trends in snowpack over the western United States and southern British Columbia, Canada. By isolating the trends due to temperature and precipitation in separate simulations, the influence of temperature and precipitation variability on the overall trends in SWE is evaluated. Downward trends in 1 April SWE over the western United States from 1916 to 2003 and 1947 to 2003, and for a time series constructed using two warm Pacific decadal oscillation (PDO) epochs concatenated together, are shown to be primarily due to widespread warming. These temperature-related trends are not well explained by decadal climate variability associated with the PDO. Trends in SWE associated with precipitation trends, however, are very different in different time periods and are apparently largely controlled by decadal variability rather than longer-term trends in climate.
Paramount Impact of the Indian Ocean Dipole on the East African Short Rains: A CGCM Study
Authors: Behera Swadhin K. , Luo Jing-Jia , Masson Sebastien , Delecluse Pascale , Gualdi Silvio , Navarra Antonio , Yamagata Toshio 
Published: November 2005

Abstract
The variability in the East African short rains is investigated using 41-yr data from the observation and 200-yr data from a coupled general circulation model known as the Scale Interaction Experiment-Frontier Research Center for Global Change, version 1 (SINTEX-F1). The model-simulated data provide a scope to understand the climate variability in the region with a better statistical confidence. Most of the variability in the model short rains is linked to the basinwide large-scale coupled mode, that is, the Indian Ocean dipole (IOD) in the tropical Indian Ocean. The analysis of observed data and model results reveals that the influence of the IOD on short rains is overwhelming as compared to that of the El Niño–Southern Oscillation (ENSO); the correlation between ENSO and short rains is insignificant when the IOD influence is excluded. The IOD–short rains relationship does not change significantly in a model experiment in which the ENSO influence is removed by decoupling the ocean and atmosphere in the tropical Pacific. The partial correlation analysis of the model data demonstrates that a secondary influence comes from a regional mode located near the African coast.
Inconsistent with the observational findings, the model results show a steady evolution of IOD prior to extreme events of short rains. Dynamically consistent evolution of correlations is found in anomalies of the surface winds, currents, sea surface height, and sea surface temperature. Anomalous changes of the Walker circulation provide a necessary driving mechanism for anomalous moisture transport and convection over the coastal East Africa. The model results nicely augment the observational findings and provide us with a physical basis to consider IOD as a predictor for variations of the short rains. This is demonstrated in detail using the statistical analysis method. The prediction skill of the dipole mode SST index in July and August is 92% for the observation, which scales slightly higher for the model index (96%) in August. As observed in data, the model results show decadal weakening in the relationship between IOD and short rains owing to weakening in the IOD activity.
Multilevel Regression Modeling of Nonlinear Processes: Derivation and Applications to Climatic Variability
Authors: Kravtsov S. , Kondrashov D. , Ghil M. 
Published: November 2005

AbstractPredictive models are constructed to best describe an observed field’s statistics within a given class of nonlinear dynamics driven by a spatially coherent noise that is white in time. For linear dynamics, such inverse stochastic models are obtained by multiple linear regression (MLR). Nonlinear dynamics, when more appropriate, is accommodated by applying multiple polynomial regression (MPR) instead; the resulting model uses polynomial predictors, but the dependence on the regression parameters is linear in both MPR and MLR.The basic concepts are illustrated using the Lorenz convection model, the classical double-well problem, and a three-well problem in two space dimensions. Given a data sample that is long enough, MPR successfully reconstructs the model coefficients in the former two cases, while the resulting inverse model captures the three-regime structure of the system’s probability density function (PDF) in the latter case.A novel multilevel generalization of the classic regression procedure is introduced next. In this generalization, the residual stochastic forcing at a given level is subsequently modeled as a function of variables at this level and all the preceding ones. The number of levels is determined so that the lag-0 covariance of the residual forcing converges to a constant matrix, while its lag-1 covariance vanishes.This method has been applied to the output of a three-layer, quasigeostrophic model and to the analysis of Northern Hemisphere wintertime geopotential height anomalies. In both cases, the inverse model simulations reproduce well the multiregime structure of the PDF constructed in the subspace spanned by the dataset’s leading empirical orthogonal functions, as well as the detailed spectrum of the dataset’s temporal evolution. These encouraging results are interpreted in terms of the modeled low-frequency flow’s feedback on the statistics of the subgrid-scale processes.
Remote Connection of the Northeast Asian Summer Rainfall Variation Revealed by a Newly Defined Monsoon Index
Authors: Lee Eun-Jeong , Jhun Jong-Ghap , Park Chung-Kyu 
Published: November 2005

Abstract
A new northeast Asian summer monsoon index is introduced to investigate the characteristics of the northeast Asian summer rainfall variation, including Korea, Japan, and northeast China, and its possible connection to the tropical and midlatitude circulations. The summer precipitation over northeast Asia is separated into two components associated with tropical forcing and midlatitude dynamics using this monsoon index. The connection between the northeast Asian summer rainfall and ENSO is clearly identified by separating the Tropics-related component from the northeast Asian summer rainfall. That is, the Tropics-related precipitation over northeast Asia tends to be enhanced after the mature phase of El Niño. On the other hand, it is revealed that the extratropics-related component of summer precipitation is connected to the Eurasian wave pattern with no significant lag correlation.
The intensity of the western North Pacific anticyclone modulated by ENSO is a key factor in the variation of the northeast Asian summer precipitation. It is found that the warm SST over the tropical eastern Pacific plays an important role in establishing the western North Pacific anticyclone during the preceding winter of strong northeast Asian summer monsoon years, whereas convective activities over the Bay of Bengal are contributed to the modulation of the anticyclonic circulation in the summer. The warming over the Indian Ocean in the summer of strong monsoon years induces the development of the anticyclone over the western North Pacific and the suppressed convection over the western Pacific tends to enhance the northeast Asian summer rainfall through the Pacific–Japan or East Asia–Pacific teleconnections.
Simulation of Storm Occurrences Using Simulated Annealing
Authors: Lokupitiya Ravindra S. , Borgman Leon E. , Anderson-Sprecher Richard 
Published: November 2005

AbstractModeling storm occurrences has become a vital part of hurricane prediction. In this paper, a method for simulating event occurrences using a simulated annealing algorithm is described. The method is illustrated using annual counts of hurricanes and of tropical storms in the Atlantic Ocean and Gulf of Mexico. Simulations closely match distributional properties, including possible correlations, in the historical data. For hurricanes, traditionally used Poisson and negative binomial processes also predict univariate properties well, but for tropical storms parametric methods are less successful. The authors determined that simulated annealing replicates properties of both series. Simulated annealing can be designed so that simulations mimic historical distributional properties to whatever degree is desired, including occurrence of extreme events and temporal patterning.
The 1935–2003 Air Temperature Record from the Summit of Mount Washington, New Hampshire
Authors: Grant Andrea N. , Pszenny Alexander A. P. , Fischer Emily V. 
Published: November 2005

Abstract
Meteorological observations have been taken continuously at the summit of Mount Washington since 1932. Results of an analysis of the air temperature record over the 1935–2003 period show a statistically significant increase in mean temperature of ∼0.3°C, while the diurnal temperature range has decreased by ∼0.15°C. The decadal structure evident in the record reveals that, in contrast to North American trends, the summit experienced relatively cool temperatures in the 1940s. The late 1980s and early 1990s were relatively warm on the summit, in agreement with North American decadal trends. The times of daily maximum and minimum temperatures show that the summit climate is dominantly influenced by boundary layer processes 30% of the time and free air circulation 50% of the time. No evidence of a “weekend effect” was found.
Detection of Regional Surface Temperature Trends
Authors: Karoly David J. , Wu Qigang 
Published: November 2005

Abstract
Trends in surface temperature over the last 100, 50, and 30 yr at individual grid boxes in a 5° latitude–longitude grid are compared with model estimates of the natural internal variability of these trends and with the model response to increasing greenhouse gases and sulfate aerosols. Three different climate models are used to provide estimates of the internal variability of trends, one of which appears to overestimate the observed variability of surface temperature at interannual and 5-yr time scales. Significant warming trends are found at a large fraction of the individual grid boxes over the globe, a much larger fraction than can be explained by internal climate variations. The observed warming trends over the last 50 and 30 yr are consistent with the modeled response to increasing greenhouse gases and sulfate aerosols in most of the models. However, in some regions, the observed century-scale trends are significantly larger than the modeled response to increasing greenhouse gases and sulfate aerosols in the atmosphere. Warming trends consistent with the response to anthropogenic forcing are detected at scales on the order of 500 km in many regions of the globe.
A Hierarchy of Data-Based ENSO Models
Authors: Kondrashov D. , Kravtsov S. , Robertson A. W. , Ghil M. 
Published: November 2005

AbstractGlobal sea surface temperature (SST) evolution is analyzed by constructing predictive models that best describe the dataset’s statistics. These inverse models assume that the system’s variability is driven by spatially coherent, additive noise that is white in time and are constructed in the phase space of the dataset’s leading empirical orthogonal functions. Multiple linear regression has been widely used to obtain inverse stochastic models; it is generalized here in two ways. First, the dynamics is allowed to be nonlinear by using polynomial regression. Second, a multilevel extension of classic regression allows the additive noise to be correlated in time; to do so, the residual stochastic forcing at a given level is modeled as a function of variables at this level and the preceding ones. The number of variables, as well as the order of nonlinearity, is determined by optimizing model performance.The two-level linear and quadratic models have a better El Niño–Southern Oscillation (ENSO) hindcast skill than their one-level counterparts. Estimates of skewness and kurtosis of the models’ simulated Niño-3 index reveal that the quadratic model reproduces better the observed asymmetry between the positive El Niño and negative La Niña events. The benefits of the quadratic model are less clear in terms of its overall, cross-validated hindcast skill; this model outperforms, however, the linear one in predicting the magnitude of extreme SST anomalies.Seasonal ENSO dependence is captured by incorporating additive, as well as multiplicative forcing with a 12-month period into the first level of each model. The quasi-quadrennial ENSO oscillatory mode is robustly simulated by all models. The “spring barrier” of ENSO forecast skill is explained by Floquet and singular vector analysis, which show that the leading ENSO mode becomes strongly damped in summer, while nonnormal optimum growth has a strong peak in December.
Reduced Flavin: NMR investigation of N(5)-H exchange mechanism, estimation of ionisation constants and assessment of properties as biological catalyst
Authors: Macheroux Peter , Ghisla Sandro , Sanner Christoph , Rüterjans Heinz , Müller Franz 
Published: November 2005

Abstract

Background
The flavin in its FMN and FAD forms is a versatile cofactor that is involved in catalysis of most disparate types of biological reactions. These include redox reactions such as dehydrogenations, activation of dioxygen, electron transfer, bioluminescence, blue light reception, photobiochemistry (as in photolyases), redox signaling etc. Recently, hitherto unrecognized types of biological reactions have been uncovered that do not involve redox shuffles, and might involve the reduced form of the flavin as a catalyst. The present work addresses properties of reduced flavin relevant in this context.

Results
N(5)-H exchange reactions of the flavin reduced form and its pH dependence were studied using the 15N-NMR-signals of 15N-enriched, reduced flavin in the pH range from 5 to 12. The chemical shifts of the N(3) and N(5) resonances are not affected to a relevant extent in this pH range. This contrasts with the multiplicity of the N(5)-resonance, which strongly depends on pH. It is a doublet between pH 8.45 and 10.25 that coalesces into a singlet at lower and higher pH values. From the line width of the 15N(5) signal the pH-dependent rate of hydrogen exchange was deduced. The multiplicity of the 15N(5) signal and the proton exchange rates are little dependent on the buffer system used.

Conclusion
The exchange rates allow an estimation of the pKa value of N(5)-H deprotonation in reduced flavin to be ≥ 20. This value imposes specific constraints for mechanisms of flavoprotein catalysis based on this process. On the other hand the pK ≈ 4 for N(5)-H protonation (to form N(5)+-H2) would be consistent with a role of N(5)-H as a base.
Suppression of AC railway power-line interference in ECG signals recorded by public access defibrillators
Authors: Dotsinsky Ivan 
Published: November 2005

Abstract

Background
Public access defibrillators (PADs) are now available for more efficient and rapid treatment of out-of-hospital sudden cardiac arrest. PADs are used normally by untrained people on the streets and in sports centers, airports, and other public areas. Therefore, automated detection of ventricular fibrillation, or its exclusion, is of high importance. A special case exists at railway stations, where electric power-line frequency interference is significant. Many countries, especially in Europe, use 16.7 Hz AC power, which introduces high level frequency-varying interference that may compromise fibrillation detection.

Method
Moving signal averaging is often used for 50/60 Hz interference suppression if its effect on the ECG spectrum has little importance (no morphological analysis is performed). This approach may be also applied to the railway situation, if the interference frequency is continuously detected so as to synchronize the analog-to-digital conversion (ADC) for introducing variable inter-sample intervals. A better solution consists of rated ADC, software frequency measuring, internal irregular re-sampling according to the interference frequency, and a moving average over a constant sample number, followed by regular back re-sampling.

Results
The proposed method leads to a total railway interference cancellation, together with suppression of inherent noise, while the peak amplitudes of some sharp complexes are reduced. This reduction has negligible effect on accurate fibrillation detection.

Conclusion
The method is developed in the MATLAB environment and represents a useful tool for real time railway interference suppression.