bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser desorption‐atmospheric pressure chemical ionization: a novel ion source for the direct coupling of polyacrylamide gel electrophoresis to mass spectrometry
Authors: Coon Joshua J. , Steele Heather A. , Laipis Philip J. , Harrison W. W. 
Published: November 2002

AbstractLaser desorption‐atmospheric pressure chemical ionization‐mass spectrometry (LD‐APCI‐MS) is presented for the atmospheric pressure (AP) sampling of tryptic peptides directly from a polyacrylamide gel. In contrast to other gel sampling mass spectrometric approaches, this technique does not require the addition of any exogenous matrices to the gel to assist with ionization. In this arrangement, a CO2 laser at 10.6 µm is used to desorb intact neutral peptide molecules from the gel, followed by ionization in the gas‐phase with APCI. The ions are then sampled via a heated capillary inlet and transferred to a quadrupole ion trap mass spectrometer for mass analysis. Preliminary results suggest the polyacrylamide gel electrophoresis–LD‐APCI‐MS technique provides several advantages that could translate into a more convenient, robust methodology for the rapid identification and characterization of proteins. Finally, strategies regarding the further development of the method are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Cool‐season precipitation in the southwestern USA sinceAD1000: comparison of linear and nonlinear techniques for reconstruction
Authors: Ni Fenbiao , Cavazos Tereza , Hughes Malcolm K. , Comrie Andrew C. , Funkhouser Gary 
Published: November 2002

AbstractA 1000 year reconstruction of cool‐season (November–April) precipitation was developed for each climate division in Arizona and New Mexico from a network of 19 tree‐ring chronologies in the southwestern USA. Linear regression (LR) and artificial neural network (NN) models were used to identify the cool‐season precipitation signal in tree rings. Using 1931–88 records, the stepwise LR model was cross‐validated with a leave‐one‐out procedure and the NN was validated with a bootstrap technique. The final models were also independently validated using the 1896–1930 precipitation data. In most of the climate divisions, both techniques can successfully reconstruct dry and normal years, and the NN seems to capture large precipitation events and more variability better than the LR. In the 1000 year reconstructions the NN also produces more distinctive wet events and more variability, whereas the LR produces more distinctive dry events. The 1000 year reconstructed precipitation from the two models shows several sustained dry and wet periods comparable to the 1950s drought (e.g. 16th century mega drought) and to the post‐1976 wet period (e.g. 1330s, 1610s). The impact of extreme periods on the environment may be stronger during sudden reversals from dry to wet, which were not uncommon throughout the millennium, such as the 1610s wet interval that followed the 16th century mega drought. The instrumental records suggest that strong dry to wet precipitation reversals in the past 1000 years might be linked to strong shifts from cold to warm El Niño‐southern oscillation events and from a negative to positive Pacific decadal oscillation. Copyright © 2002 Royal Meteorological Society.
Links between circulation and changes in the characteristics of Iberian rainfall
Authors: Goodess C. M. , Jones P. D. 
Published: November 2002

AbstractInvestigation of the links between atmospheric circulation patterns and rainfall is important for the understanding of climatic variability and for the development of empirical circulation‐based downscaling methods. Here, spatial and temporal variations in circulation‐rainfall relationships over the Iberian Peninsula during the period 1958–97 are explored using an automated circulation classification scheme and daily rainfall totals for 18 stations. Links between the circulation classification scheme and the North Atlantic oscillation (NAO) are also considered, as are the direct links between rainfall and the NAO. Trends in rainfall and circulation‐type frequency are explored. A general tendency towards decreasing mean seasonal rainfall over the peninsula, with the exception of the southeastern Mediterranean coast, hides larger changes in wet day amount and rainfall probability. There is a tendency towards more, less‐intensive rain days across much of Iberia, with a tendency towards more, more‐intensive rain days along the southeastern Mediterranean coast, both of which are reflected in changes in rainfall amount quantiles. A preliminary analysis indicates that these changes may have occurred systematically across all circulation types. Comparison of the trends in rainfall and in circulation‐type frequency suggests possible links. These links are supported by linear regression analyses using circulation‐type frequencies as predictor variables and rainfall totals for winter months as the predictands. The selected predictor variables reflect the main circulation features influencing winter rainfall across the peninsula, i.e. the strong influence of Atlantic westerly and southwesterly airmasses over much of the peninsula, of northerly and northwesterly surface flow over northern/northwestern Spain and northern Portugal and the stronger effect of Mediterranean rather than Atlantic influences in southeastern Spain. The observed rainfall changes cannot, however, be explained by changes in circulation alone. Copyright © 2002 Royal Meteorological Society.
A graphical sensitivity analysis for statistical climate models: application to Indian monsoon rainfall prediction by artificial neural networks and multiple linear regression models
Authors: Cannon Alex J. , McKendry Ian G. 
Published: November 2002

AbstractA form of sensitivity analysis is described that illustrates the effects that inputs have on outputs of statistical models. The strength and sign of relationships, the types of nonlinearity, and the presence of interactions between inputs can be diagnosed using this technique. Intended for interpreting flexible nonlinear models, the graphical sensitivity analysis is applied to artificial neural networks (ANNs) in this study. As ANNs are increasingly being used for climate prediction, the discussion focuses on specific problems associated with their use in this context. The technique is illustrated using a real‐world, long‐range climate prediction example. Principal components (PCs) of circulation fields prior to the Indian summer monsoon are related to rainfall during monsoon months for the 1958–98 period. The skill of multiple linear regression and ensemble ANNs are compared using a resampling procedure. Interpretation of the models is then conducted using traditional diagnostic tools and graphical sensitivity analysis. This provides an improved investigation of precursor circulation field–summer monsoon rainfall relationships identified in a previous modelling study. The relatively stable, linear relationship identified between the May 200 hPa geopotential height field and summer monsoon rainfall is confirmed. Correlations previously identified between 850 hPa geopotential heights during January and rainfall by ANNs are shown to be the result of a weakly nonlinear, interactive relationship involving the first and second PCs of this field. An analysis of out‐of‐sample model predictions suggests that this relationship does not persist over the entire study period. This may result from a modulation of the strength of the circulation–rainfall relationship by El Niño–southern oscillation. Stratification of the results also reveals a relatively strong, nearly linear relationship with monsoon strength during years exhibiting positive scores of the second PC. On extending the analysis to longer lead‐times, the surface pressure and 850 hPa geopotential height fields during November show relatively strong, persistent precursor relationships with summer monsoon rainfall. Sensitivity analyses suggest a mildly nonlinear relationship that is common to both fields. Copyright © 2002 Environment Canada. Published by John Wiley & Sons, Ltd.
Recent variations in seasonality of temperature and precipitation in Canada, 1976–95
Authors: Whitfield Paul H. , Bodtker Karin , Cannon Alex J. 
Published: November 2002

AbstractA previously reported analysis of rehabilitated monthly temperature and precipitation time series for several hundred stations across Canada showed generally spatially coherent patterns of variation between two decades (1976–85 and 1986–95). The present work expands that analysis to finer time scales and a greater number of stations. We demonstrate how the finer temporal resolution, at 5 day or 11 day intervals, increases the separation between clusters of recent variations in seasonal patterns of temperature and precipitation. We also expand the analysis by increasing the number of stations from only rehabilitated monthly data sets to rehabilitated daily sets, then to approximately 1500 daily observation stations. This increases the spatial density of data and allows a finer spatial resolution of patterns between the two decades. We also examine the success of clustering partial records, i.e. sites where the data record is incomplete. The intent of this study was to be consistent with previous work and explore how greater temporal and spatial detail in the climate data affects the resolution of patterns of recent climate variations. The variations we report for temperature and precipitation are taking place at different temporal and spatial scales. Further, the spatial patterns are much broader than local climate regions and ecozones, indicating that the differences observed may be the result of variations in atmospheric circulation. Copyright © 2002 Environment Canada. Published by John Wiley & Sons, Ltd.
Interannual rainfall variability in the Amazon basin and sea‐surface temperatures in the equatorial Pacific and the tropical Atlantic Oceans
Authors: Ronchail Josyane , Cochonneau Gérard , Molinier Michel , Guyot Jean‐Loup , De Miranda Chaves Adriana Goretti , Guimarães Valdemar , de Oliveira Eurides 
Published: November 2002

AbstractRainfall variability in the Amazon basin is studied in relation to sea‐surface temperatures (SSTs) in the equatorial Pacific and the northern and southern tropical Atlantic during the 1977–99 period, using the HiBAm original rainfall data set and complementary cluster and composite analyses.The northeastern part of the basin, north of 5 °S and east of 60 °W, is significantly related with tropical SSTs: a rainier wet season is observed when the equatorial Pacific and the northern (southern) tropical Atlantic are anomalously cold (warm). A shorter and drier wet season is observed during El Niño events and negative rainfall anomalies are also significantly associated with a warm northern Atlantic in the austral autumn and a cold southern Atlantic in the spring. The northeastern Amazon rainfall anomalies are closely related with El Niño–southern oscillation during the whole year, whereas the relationships with the tropical Atlantic SST anomalies are mainly observed during the autumn. A time–space continuity is observed between El Niño‐related rainfall anomalies in the northeastern Amazon, those in the northern Amazon and south‐eastern Amazon, and those in northern South America and in the Nordeste of Brazil.A reinforcement of certain rainfall anomalies is observed when specific oceanic events combine. For instance, when El Niño and cold SSTs in the southern Atlantic are associated, very strong negative anomalies are observed in the whole northern Amazon basin. Nonetheless, the comparison of the cluster and the composite analyses results shows that the rainfall anomalies in the northeastern Amazon are not always associated with tropical SST anomalies.In the southern and western Amazon, significant tropical SST‐related rainfall anomalies are very few and spatially variable. The precipitation origins differ from those of the northeastern Amazon: land temperature variability, extratropical perturbations and moisture advection are important rainfall factors, as well as SSTs. This could partially explain why: (a) the above‐mentioned signals weaken or disappear, with the exception of the relative dryness that is observed at the peak of an El Niño event and during the dry season when northern Atlantic SSTs are warmer than usual; (b) rainfall anomalies tend to resemble those of southeastern South America, noticeably at the beginning and the end of El Niño and La Niña events; (c) some strong excesses of rain are not associated with any SST anomalies and merit further investigation. Copyright © 2002 Royal Meteorological Society.
Atmospheric mechanisms governing the spatial and temporal variability of phenological phases in central Europe
Authors: Scheifinger Helfried , Menzel Annette , Koch Elisabeth , Peter Christian , Ahas Rein 
Published: November 2002

AbstractA data set of 17 phenological phases from Germany, Austria, Switzerland and Slovenia spanning the time period from 1951 to 1998 has been made available for analysis together with a gridded temperature data set (1° × 1° grid) and the North Atlantic Oscillation (NAO) index time series. The disturbances of the westerlies constitute the main atmospheric source for the temporal variability of phenological events in Europe. The trend, the standard deviation and the discontinuity of the phenological time series at the end of the 1980s can, to a great extent, be explained by the NAO. A number of factors modulate the influence of the NAO in time and space. The seasonal northward shift of the westerlies overlaps with the sequence of phenological spring phases, thereby gradually reducing its influence on the temporal variability of phenological events with progression of spring (temporal loss of influence). This temporal process is reflected by a pronounced decrease in trend and standard deviation values and common variability with the NAO with increasing year‐day. The reduced influence of the NAO with increasing distance from the Atlantic coast is not only apparent in studies based on the data set of the International Phenological Gardens, but also in the data set of this study with a smaller spatial extent (large‐scale loss of influence). The common variance between phenological and NAO time series displays a discontinuous drop from the European Atlantic coast towards the Alps. On a local and regional scale, mountainous terrain reduces the influence of the large‐scale atmospheric flow from the Atlantic via a proposed ‘decoupling mechanism’. Valleys in mountainous terrain have the inclination to harbour temperature inversions over extended periods of time during the cold season, which isolate the valley climate from the large‐scale atmospheric flow at higher altitudes. Most phenological stations reside at valley bottoms and are thus largely decoupled in their temporal variability from the influence of the westerly flow regime (local‐scale loss of influence). This study corroborates an increasing number of similar investigations that find that vegetation does react in a sensitive way to variations of its atmospheric environment across various temporal and spatial scales. Copyright © 2002 Royal Meteorological Society.
Changes in European spring phenology
Authors: Ahas R. , Aasa A. , Menzel A. , Fedotova V. G. , Scheifinger H. 
Published: November 2002

AbstractThe European phyto‐phenological database of the EU 5th Framework project ‘POSITIVE’ facilitated an examination of the rate and spatial pattern of changes in spring phenology across Europe. This database was collected, evaluated and composed from different national databases of Eastern and Western Europe covering the time period 1951–1998. Results show that spring phases have advanced four weeks in Western and Central Europe, and have been delayed up to two weeks in Eastern Europe. Western European spring starts earlier because of the intensive flow of warmer Atlantic air masses; the Eastern part of Europe has a different phenological rhythm and trends, that can be explained by the influence of the Siberian high. The highest rate of significant (p< 0.05) phenological change (−0.3 to −0.4 days per year) occurs in the Western Europe and Baltic Sea regions for early spring phases of hazel and colts‐foot. Spring phases of birch, apple and lilac, and summer phases, such as the flowering of linden, tend to occur earlier with an average rate of −0.1 to 0.3 days per year. Copyright © 2002 Royal Meteorological Society.
Assessing satellite‐derived start‐of‐season measures in the conterminous USA
Authors: Schwartz Mark D. , Reed Bradley C. , White Michael A. 
Published: November 2002

AbstractNational Oceanic and Atmospheric Administration (NOAA)‐series satellites, carrying advanced very high‐resolution radiometer (AVHRR) sensors, have allowed moderate resolution (1 km) measurements of the normalized difference vegetation index (NDVI) to be collected from the Earth's land surfaces for over 20 years. Across the conterminous USA, a readily accessible and decade‐long data set is now available to study many aspects of vegetation activity in this region. One feature, the onset of deciduous plant growth at the start of the spring season (SOS) is of special interest, as it appears to be crucial for accurate computation of several important biospheric processes, and a sensitive measure of the impacts of global change.In this study, satellite‐derived SOS dates produced by the delayed moving average (DMA) and seasonal midpoint NDVI (SMN) methods, and modelled surface phenology (spring indices, SI) were compared at widespread deciduous forest and mixed woodland sites during 1990–93 and 1995–99, and these three measures were also matched to native species bud‐break data collected at the Harvard Forest (Massachusetts) over the same time period. The results show that both SOS methods are doing a modestly accurate job of tracking the general pattern of surface phenology, but highlight the temporal limitations of biweekly satellite data. Specifically, at deciduous forest sites: (1) SMN SOS dates are close in time to SI first bloom dates (average bias of +0.74 days), whereas DMA SOS dates are considerably earlier (average bias of −41.24 days) and also systematically earlier in late spring than in early spring; (2) SMN SOS tracks overall yearly trends in deciduous forests somewhat better than DMA SOS, but with larger average error (MAEs 8.64 days and 7.37 days respectively); and (3) error in both SOS techniques varies considerably by year. Copyright © 2002 Royal Meteorological Society.
The influence of temperature and climate change on the timing of pollen release in the Netherlands
Authors: van Vliet Arnold J. H. , Overeem Aart , De Groot Rudolf S. , Jacobs Adrie F. G. , Spieksma Frits T. M. 
Published: November 2002

AbstractIn the last decade it has become clear that the timing of many phenological processes, like the start of flowering and leaf unfolding in spring, have changed. The increase in temperature is believed to be the main cause. The earlier start of flowering will have consequences for the start of the pollen season, and thus for the start of the hay fever season. Millions of people world‐wide will therefore experience the impact of climate change in their daily lives during spring and summer. In this paper we analyse the relation between climate parameters, especially temperature, and the start of the pollen season in the western part of the Netherlands based on daily pollen counts of the Leiden University Medical Centre and temperature measurements from 1969 till 2000 by the Royal Netherlands Meteorological Institute in De Bilt. The results indicate that there is a strong correlation between temperature and start of the pollen season. An advance of the start of the pollen season of 3 to 22 days has been observed. The potential future changes in the start of the pollen season under climate change scenarios are also discussed. Copyright © 2002 Royal Meteorological Society.
Observed changes in seasons: an overview
Authors: Sparks T. H. , Menzel A. 
Published: November 2002

AbstractWithin the last decade the study of phenology has taken on a new legitimacy in the area of climate change research. A growing literature reveals that a change in the timing of natural events is occurring in a wide range of locations and affecting a wide range of species. Changes in spring have been those most commonly reported, with the emphasis on an advance in spring linked to an increase in temperature. Detection of change in autumn is hampered by a smaller pool of available data, events that are harder to define (such as leaf coloration), and various influencing environmental factors triggering autumnal phases. Despite this, the general pattern may be towards a delay in autumn. Plant, animal and abiotic responses, especially in spring, are quite similar. Thus, it would appear that winter is being squeezed at both ends, and this effect, of increasing the growing season, should become more pronounced in the face of predicted global warming. Copyright © 2002 Royal Meteorological Society.
Phenological studies in Australia: potential application in historical and future climate analysis
Authors: Keatley Marie R. , Fletcher Tim D. , Hudson Irene L. , Ades Peter K. 
Published: November 2002

AbstractPhenological observations of eucalypts (Myrtaceae) were undertaken in four Australian states (New South Wales, Queensland, Victoria, and Western Australia) from the late 1920s until the early 1980s, by the respective State Forest Commissions. Unfortunately, few records have survived. For Victoria, surviving records encompass 42 forest districts, covering from less than 2 years to 42 years, and approximately 50 species.This paper concentrates on the flowering of four competing species (Eucalyptus leucoxylon, E. microcarpa, E. polyanthemos, and E. tricarpa) over 23 years (1940–62) from Maryborough, Victoria, recorded on a monthly basis by one observer over the period. This study represents one of the first attempts to utilize Australian phenological data to detect responses to climate change.There were no significant trends (P = 0.05) over time in the mean flowering commencement date. Forward stepwise regression found a significant relationship between temperature and flowering commencement in two species (E. leucoxylon: R2 = 0.42, P < 0.01; E. polyanthemos: R2 = 0.47, P = 0.02). Rainfall also had a significant influence on flowering commencement in E. tricarpa (R2 = 0.60, P < 0.01), E. leucoxylon (R2 = 0.43, P = 0.02) and E. polyanthemos (R2 = 0.24, P < 0.01). The combination of temperature and rainfall (with temperature exerting the greatest influence), however, was significant for all species and had the most explanatory power (ranging from R2 = 0.74 to 0.85, P < 0.01).Overall, in response to predicted increases in temperature and summer rainfall, E. leucoxylon and E. tricarpa would commence flowering later. In E. polyanthemos and E. microcarpa, increased temperature and rainfall will result in an earlier onset of flowering. Copyright © 2002 Royal Meteorological Society.