pinecone/core-2020-05-10-deduplication huggingface dataset:
Annual and seasonal mapping of peak intensity, magnitude and duration of extreme precipitation events across a climatic gradient, northeast Spain

50 Pag., 5 Tabl., 11 Fig.  The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-0088Assessing the characteristics of extreme precipitation over large regions has a great interest, mainly due to its applications in hazard analysis. However, most of the analyses are reduced to daily rainfall intensity due to the fact that most long precipitation records were collected on a daily basis. Hazardous situations related to extreme precipitation events, however, can be originated either by very intense rainfall, or by large accumulated precipitation due to the persistence of the rainy conditions over a long period of time. In this paper, we show the use of a methodology based on the extreme-value theory to obtain continuous maps of quantiles of precipitation event parameters—peak intensity, magnitude and duration—for a large region with contrasted climatic characteristics in the northeastern Iberian Peninsula. Spatial models of the probability distributions parameters were calculated, which allowed constructing the regional probability models. The analysis was based on time series of precipitation events, which were obtained from the original daily series. In addition to the usual annual-based analysis, seasonal analyses were also performed. This allowed assessing the differences in the spatial distribution of the probability of extreme events at different times of the year.Funded by\ud
Spanish Commission of Science and Technology and FEDER. Grant Number: CGL2005-04508/BOS\ud
Aragón Government. Grant Number: PIP176/2005\ud
Programa de grupos de investigación consolidados. Grant Number: BOA 48 of 20-04-2005\ud
Ramón y Cajal Research\ud
Spanish Ministry of Science and EducationPeer reviewe
An analysis of present and future ECHAM5 pressure fields using a classification of circulation patterns

Several both subjective and objective methods for the classification of circulation patterns into categories have been developed over the past century. In this study, we used the automated Lamb weather type (WT) classification method, based on Mean Sea Level Pressure (MSLP) to examine present and future circulation patterns above Western and Central Europe. First, the European Center for Medium-Range Weather Forecast 40-year reanalysis data (ECMWF – ERA40) is used to evaluate the occurring WTs within the newly developed ECHAM5-MPI/OM model for the period 1961-2000. Our analysis shows that the ECHAM5 model is capable of reproducing circulation patterns for the October to April season. For the remaining part of the year, there are some significant differences in eastern and western directional circulation types. Therefore, in the second part of this study, past, present and future ECHAM5 pressure fields are investigated for the autumn and winter season only. Finally, long-term trends of MSLP fields of the A1B scenario simulation using ECHAM5-MPI/OM for the period 1860-2100 show a significant increase in western circulation and anticyclonic weather types over Western and Central Europe, accompanied by a decrease in eastern circulation and cyclonic weather types.status: publishe
A complete daily precipitation database for northeast Spain: reconstruction, quality control, and homogeneity

49 Pag., 16 Fig.\ud
\ud
The definitive version is available at:\ud
www.interscience.wiley.comThis paper reports the procedure used in creating a homogeneous database of daily precipitation in northeast\ud
Spain. The source database comprised 3106 daily precipitation observatories, with data ranging from 1901 to 2002. Firstly,\ud
a reconstruction of the series was performed. Data from adjacent observatories were combined to provide long temporal\ud
coverage. Data gaps were filled using values from the nearest neighbour observatories. A distance threshold was set to\ud
avoid the introduction of spurious information in the series. Secondly, the reconstructed series were subjected to a quality\ud
control process. Empirical percentiles corresponding to each precipitation observation were compared to the percentiles\ud
corresponding to the closest neighbour observatory, and a threshold difference was set to identify questionable extremes.\ud
After careful inspection of each case, 0.1% of the data was rejected and replaced with information from the nearest\ud
neighbour. Thirdly, the homogeneity of the series was checked using the standard normal homogeneity test. This allowed\ud
detection of inconsistencies present in the original database or introduced by the reconstruction process. Four parameters\ud
were assessed at a monthly level: amount of precipitation, number of rainy days, daily maxima, and number of days above\ud
the 99th percentile. A total of 43% of the series had some periods of inhomogeneity and were discarded. The final database\ud
comprised 828 series with varying time coverages. The greatest number of stations existed during the 1990s, but more than\ud
300 series contained information from the 1960s, and 34 series contained a complete record since 1920. Comparisons of\ud
the spatial variability of several parameters describing the daily precipitation characteristics were made. The results showed\ud
that the final database had improved spatial coherence. The process described here is proposed as a model for developing a\ud
standard procedure for the construction of databases of daily climate data.This work has been supported\ud
by the following projects: CGL2005-04508/BOS\ud
(financed by the Spanish Commission of Science and Technology and FEDER), PIP176/2005 (financed by the Aragon Government), and ‘Programa de grupos de investigacion consolidados’ (BOA 48 of 20-04-2005), also financed by the Aragon Government.Peer reviewe
Recent trends of thunderstorm and hailstorm frequency and their relationship to atmospheric characteristics in southwest Germany

In the context of climate change, it is of particular interest whether extreme events connected to severe thunderstorms have been increasing in number or intensity over the past few decades. Due to their small horizontal extent, such events are not entirely and uniquely captured by current observation systems. To obtain comprehensive information about the convective activity in the state of Baden-WÃ�Â¼rttemberg (southwest Germany), we analysed different datasets for the period 1974Ã¢Â�Â�2003. They comprise thunderstorm days detected at synoptic stations, hail damage data from a building insurance company, large-scale circulation and weather patterns, and convective indices derived from radiosonde observations at 12:00 UTC.\ud
\ud
While the annual number of thunderstorm days remained almost unchanged in the mean, hail damage and hail days significantly increased in the last three decades. Both damage and additional radar data indicate that the majority of hail days can be attributed to three specific circulation patterns. Two of the three patterns associated with the preferable occurrence of hail show a significant increase.\ud
\ud
Most of the commonly used convective indices that depend upon surface temperature and moisture reveal a positive trend regarding both the annual extreme values and the number of days above/below specific thresholds. A relationship was established between the indices and the annual number of hail damage days, yielding correlation coefficients between 0.65 and 0.80. In contrast to this, indices derived from temperature and moisture at higher levels exhibit either a negative or no significant trend. It is shown that the trend directions of the indices may be attributed to differential temperature and moisture stratification in the various atmospheric layers. The significant positive trends of both surface temperature and water vapour can be concisely expressed by an increase in wet-bulb potential temperature. This indicates the presence of warmer parcels throughout the whole troposphere during convection
Effect of the climate shift around mid 1970s on the relationship between wintertime Ural blocking circulation\ud
and East Asian climate

Blocking variability over the Ural Mountain region in the boreal winter and its relationship with the East Asian winter climate is investigated. The climate shift around mid 1970s has been shown to exert a significant influence on the blocking pattern. In contrast with the years before 1976/1977, the Ural blocking signal after 1976/1977 is found to propagate less into the stratosphere and more eastward in the troposphere to East Asia, which therefore exerts more influence on the East Asian winter climate. This enhanced Ural blocking-East Asian climate relationship amplifies the impact of Ural blocking on East Asia and, with the background of decreasing Ural blocking, contributes to the higher frequency of warm winters in this region. Further analyses suggest that the NAM-related stratospheric polar vortex strength and its modulation on the propagation of atmospheric stationary waves can account for this change, with the key area being located in the North Atlantic region
Seasonal prediction of lake inflows and rainfall in a hydro-electricity catchment, Waitaki river, New Zealand

The Waitaki River is located in the centre of the South Island of New Zealand, and hydro-electricity generated on the river accounts for 35-40% of New Zealand's electricity. Low inflows in 1992 and 2001 resulted in the threat of power blackouts. Improved seasonal rainfall and inflow forecasts will result in the better management of the water used in hydro-generation on a seasonal basis.
Researchers have stated that two key directions in the fields of seasonal rainfall and streamflow forecasting are to a) decrease the spatial scale of forecast products, and b) tailor forecast products to end-user needs, so as to provide more relevant and targeted forecasts.
Several season-ahead lake inflow and rainfall forecast models were calibrated for the Waitaki river catchment using statistical techniques to quantify relationships between land-ocean-atmosphere state variables and seasonally lagged inflows and rainfall. Techniques included principal components analysis and multiple linear regression, with cross-validation techniques applied to estimate model error and randomization techniques used to establish the significance of the skill of the models.
Many of the models calibrated predict rainfall and inflows better than random chance and better than the long-term mean as a predictor. When compared to the range of all probable inflow seasonal totals (based on the 80-year recorded history in the catchment), 95% confidence limits around most model predictions offer significant skill. These models explain up to 19% of the variance in season-ahead rainfall and inflows in this catchment.
Seasonal rainfall and inflow forecasting on a single catchment scale and focussed to end-user needs is possible with some skill in the South Island of New Zealand
Comparison of regression techniques for mapping fog frequency: application to the Aragón region (northeast Spain)

28 páginas,, 4 tablas, 7 figuras.\ud
\ud
The definitive version is available at:\ud
http://www3.interscience.wiley.com/journal/4735/homeWe compare different spatial interpolation techniques in mapping the monthly frequency of fogs in the Aragón region (northeast Spain). The local and spatially complex nature of the fogs makes them more difficult to map than other climatic variables such as precipitation and temperature. We found clear seasonal differences in the quality of the obtained maps. The localized nature of spring and summer fogs, mainly restricted to valley bottoms in mountainous areas, gives rise to several limitations. The modelling of fog frequency is more complex than that of other climate variables; to improve the model predictions, it is necessary to consider topographic variables that simulate the terrain structure. Moreover, the highly complex nature of the relationship between fog frequency and terrain means that simple linear models perform poorly in accounting for the role of geographic and topographic variables in determining the spatial distribution of fog frequency. The inclusion of non-linear relationships between fog frequency and terrain variables in the models following a general additive model (GAM) procedure leads to an improvement in model performance because the flexibility of GAMs enables the inclusion of non-linear relationships and the generation of response-curve shapes that detail the exact relationship between the dependent variable and predictors throughout the entire range of the variable.This work has been supported by the following research projects: CGL2005-04508/BOS (financed by the Spanish Commission of Science and Technology and FEDER), PIP176/2005 (financed by the Aragón Government), and “Programa de grupos de investigación consolidados” (BOA 48 of 20-04-2005), also financed by the Aragón Government.Peer reviewe
Trends in daily precipitation on the northeastern Iberian Peninsula, 1955–2006

38 Pag., 5 Tabl., 6 Fig.\ud
\ud
The definitive version is available at:\ud
http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-0088The temporal evolution of nine daily precipitation indices over the northeastern Iberian Peninsula was analysed for the period 1955–2006, using data from 217 observatories. Cross-tabulation analysis enabled detection of statistically significant overlap among spatial distributions of trends in the study area. There was a general decrease in annual precipitation at most observatories, a decrease in the number of rainy days and precipitation intensity and an increase in the duration of dry spells. The frequency and contribution to annual precipitation of moderate and heavy rainfall events did not change at most observatories, or showed a decreasing trend in these events. There was very large spatial and seasonal variability, with implications for water management and risk assessment in the region. The decrease in precipitation was very marked in headwaters during winter and spring, potentially affecting reservoir management in the region. Heavy rainfall events generally decreased in the west of the region in winter, and in the east of the region in autumn, when these areas are more exposed to hazards related to extreme rainfall. Large differences in the sign and magnitude of trends occurred over very short distances, suggesting the need for dense networks of observatories to ensure reliable and robust detection of regional trends.This study was supported by the PROBASE projects CGL2006-11619 and CGL2008-01189/BTE, both financed by the Spanish Commission of Science and Technology (Ministry of Education and Science) and FEDER, and the FP7 EU project ACQWA (Assessing Climatic Change and Impact on the Quantity and Quality of Water).Peer reviewe
Seasonal precipitation interpolation at the Valencia region with multivariate methods using geographic and topographic information

The spatial pattern of precipitation is a complex variable that strongly depends on other geographic and topographic factors. As precipitation is usually known only at certain locations, interpolation procedures are needed in order to predict this variable in other regions. The use of multivariate interpolation methods is usually preferred, as secondary variables generally derived using GIS tools correlated with precipitation can be included. In this paper, a comparative study on different univariate and multivariate interpolation methodologies is presented. Our study area is centred in the region of Valencia, located to the eastern Spanish Mediterranean coast. The followed methodology can be divided in three steps. First, secondary variables having significant correlations with the precipitation were derived, where the hillsides were used as influence areas of certain variables. Secondly, precipitation was interpolated with different methodologies. Finally, the derived models were compared in terms of predicted errors. Models were achieved for seasonal scales, considering a total of 179 raingauges; data of another 45 raingauges were also used to predict errors. Results prove that there is no ideal method for all the cases but it will depend on one hand, on the number of geographical factors that influence the rainfall and, on the other hand, on the major or minor spatial correlation within the rainfall
Spatial–temporal dynamics of precipitation extremes in southern Portugal: a geostatistical assessment study

12 páginas, 10 figuras, 5 tablas.-- et al.Most of the recent studies and projections of precipitation patterns, based on records observed in the past and climate change scenarios for the Mediterranean basin, suggest a relatively slow decrease in rainfall amounts over the years but an increase in the frequency of extreme precipitation events. These are key factors in desertification processes and these will cause social and environmental impacts in the short term, mainly because changes in heavy rainfall events may have severe implications and impacts on soil erosion, resulting in increased risk of soil degradation.\ud
\ud
The main objective of the present work is to evaluate the spatial–temporal dynamics of extreme precipitation events in southern Portugal, using a direct sequential simulation algorithm (DSS models) in order to assess the relationships between spatial and temporal extreme rainfall patterns. Local probability density functions (pdfs) and spatial uncertainty are evaluated by a set of equiprobable simulated images of the chosen extreme precipitation indices.\ud
\ud
The used dataset in this work comprises a set of 105 station records of observed daily precipitation within the period 1961–2000. Two indices of extreme precipitation were selected: one representing the frequency of extremely heavy precipitation events (R30) and another characterizing the occurrence of dry events (RL10), both obtained from observed daily precipitation series.\ud
\ud
Results show that the spatial continuity of extreme precipitation events has increased in the last 40 years in southern Portugal. It also demonstrates a decrease in spatial variability, implying that extreme precipitation events tend to be more spatially homogeneous, which may have a severe impact on water resources, agriculture and soil erosion, particularly when associated with desertification risks.This paper was developed in the framework of the\ud
following projects: BioAridRisk – Space-Time Evaluation\ud
of the Risks of Climate Change Based on an\ud
Aridity Index (POCI/CLI/56371/2004FCT/MCTES),\ud
CIDmeg – Construction of a Desertification Susceptibility\ud
Index for the Left Margin of Guadiana\ud
(POCI/CLI/58865/2004 FCT/MCTES) and SADMO –\ud
Système d’Évaluation et Contrôle de la Désertification\ud
dans la Méditerranée Occidentale (Programme\ud
Interreg IIIB, MEDDOC, CONVENTION\ud
n. 2005-05-4.4-P-105).Peer reviewe
A 50-year high-resolution atmospheric reanalysis over France with the Safran system

Publié en ligne dans Wiley InterScience (www.interscience.wiley.com). Version auteur dans fichier pdf attaché.International audienceThe assessment of regional climate change requires the development of reference long-term retrospective meteorological datasets. This article presents an 8-km-resolution atmospheric reanalysis over France performed with the the Safran-gauge-based analysis system for the period 1958–2008. Climatological features of the Safran 50-year analysis – long-term mean values, inter-annual and seasonal variability – are first presented for all computed variables: rainfall, snowfall, mean air temperature, specific humidity, wind speed and solar and infrared radiation. The spatial patterns of precipitation, minimum and maximum temperature are compared with another spatialization method, and the temporal consistency of the reanalysis is assessed through various validation experiments with both dependent and independent data. These experiments demonstrate the overall robustness of the Safran reanalysis and the improvement of its quality with time, in connection with the sharp increase in the observation network density that occurred in the 1990s. They also show the differentiated sensitivity of variables to the number of available ground observations, with precipitation and air temperature being the more robust ones. The comparison of trends from the reanalysis with those from homogenized series finally shows that if spatial patterns are globally consistent with both approaches, care must be taken when using literal values from the reanalysis and corresponding statistical significance in climate change detection studies. The Safran 50-year atmospheric reanalysis constitutes a long-term forcing datasets for land surface schemes and thus enables the simulation of the past 50 years of water resources over France. Copyright © 2009 Royal Meteorological Societ
Snow trends in Northern Spain: analysis and simulation with statistical downscaling methods

12 páginas, 11 figuras, 2 tablas.In this study we analyze and simulate (with statistical downscaling techniques) the snow trends observed in the Northern Iberian Peninsula using daily snow occurrence (DSO) data from a network of 33 stations ranging from 60 to 1350 m. We first analyze the annual snow frequency measured as the annual number of snow days (NSD), obtaining a significant decreasing trend since the mid-seventies with a NSD reduction of about 50%; moreover, this magnitude is similar for low and high stations and for winter and spring separately. Then, we analyze the existing correlations with mean temperature and precipitation occurrence obtaining different relationships depending on the season and elevation. Finally, we simulate the observed trends using the connection of DSO with large-scale fields simulated by a General Circulation Model; for this purpose we apply an analog-based statistical downscaling method to obtain an estimation of DSO, working in perfect prognosis conditions using reanalysis data. On the one hand, the downscaling method is able to estimate/predict the DSO with typical values of hit and false alarm rates around 60% and 2%, respectively. On the other hand, the annual frequency obtained by averaging the DSO estimations reproduces very well both the observed trends and the high inter-annual variability. These promising results open the possibility to future research in seasonal or climate change projections of snow frequency.The authors are also grateful to the University of Cantabria, CSIC and the Comisión Interministerial de Ciencia y Tecnología\ud
(CICYT, CGL-2007-64387/CLI and CGL2005-06966-\ud
C07-02/CLI) for partial support of this work.Peer reviewe