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Precipitation Series (precipitation + series)
Selected AbstractsRegional Climate Change: Trend Analysis of Temperature and Precipitation Series at Selected Canadian SitesCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 1 2000J. Stephen Clark Global climate change does not necessarily imply that temperature or precipitation is increasing at specific locations. The hypothesis of increasing temperature and precipitation trends associated with global climate change is tested using actual annual temperature and precipitation data for nine selected weather stations, spatially distributed across Canada. Vogelsang's (1998) partial sum and Woodward et al's (1997) bootstrap methods are used for testing for trend. Both methods suggest no warming in the Canadian temperature series except for Toronto, Ontario, which had significant increase over time, along with Moncton, New Brunswick, and Indian Head, Saskatchewan, which had marginal increases. There is no evidence of increasing trend in precipitation except for Moncton, New Brunswick, which had a significantly increasing trend. Thus, public policies designed to address the regional effects of climate change need to be adapted for a particular ecological zone, based on knowledge of the climate trends for that region, rather than on general global climate change patterns. Les changements climatiques à l'échelle planétaire ne signifient pas nécessairement que la température et les précipitations sont en augmentation dans des emplacements donnés. Nous avons testé I'hypothèse d'une assoviation de la tendance à la hausse de la température et des précipitations avec les changements climatiques planétaires à partir des données réelles de température et de précipitations obtenues à 9 stations d'observation climatique réparties dans les diverses régions du Canada. Nous utilisons, pour cefaire, la méthode des sommes partielles de Vogelsang (1998) et celle de rééchantillonnage bootstrap de Woodward et al (1997). Les deux méthodes ne révèlent aucun réchauffement de la température dans les séries chronologiques, sauf pour Toronto, en Ontario, où l'on constate une hausse significative en fonction du temps, ainsi que pour Moncton au Nouveau-Brunswick et Indian Head en Saskatchewan qui marquent de très légères augmentations. Rien n'indique une tendance à la hausse des précipitations, sauf à Moncton où se dessine une tendance significative dans ce sens. Les programmes publics destinés à faire face aux effets régionaux du changement climatique doivent donc être adaptés à chaque zone écologique particulière, à partir d"observations faites dans la région même, plutôt que de la configuration du changement climatique à l'échelle planétaire. [source] New Evidence for The Role of The North Sea , Caspian Pattern on The Temperature and Precipitation Regimes in Continental Central TurkeyGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2005H. Kutiel Abstract Monthly mean temperatures and monthly precipitation totals at six stations from theCappadocian sub-region in the continental Central Anatolia region of Turkey were analysed in order to detect the response of the variability in the Cappadocian climate to the variability of the North Sea - Caspian Pattern Index (NCPI). Most of this region is classified as semi-arid according to various climate classifications. Time series of the NCPI for the period 1958,1998, enabled each month from October toApril to be classified as belonging to the negative phase NCP(,), positive phase NCP(+) or neutral conditions. Monthly temperature and precipitation series for each station were analysed separately for both phases. Temperatures during NCP(,) were found to be considerably higher than during NCP(+). These results confirm previous results regarding the role of the NCP in controlling the temperature regime in that region. No significant differences were found in precipitation totals between the two phases, but major differences were identified in their spatial structure. [source] Homogeneity analysis of Turkish meteorological data setHYDROLOGICAL PROCESSES, Issue 8 2010Sinan Sahin Abstract The missing value interpolation and homogeneity analysis were performed on the meteorological data of Turkey. The data set has the observations of six variables: the maximum air temperature, the minimum air temperature, the mean air temperature, the total precipitation, the relative humidity and the local pressure of 232 stations for the period 1974,2002. The missing values on the monthly data set were estimated using two methods: the linear regression (LR) and the expectation maximization (EM) algorithm. Because of higher correlations between test and reference series, EM algorithm results were preferred. The homogeneity analysis was performed on the annual data using a relative test and four absolute homogeneity tests were used for the stations where non-testable series were found due to the low correlation coefficients between the test and the reference series. A comparison was accomplished by the graphics where relative and absolute tests provided different outcomes. Absolute tests failed to detect the inhomogeneities in the precipitation series at the significance level 1%. Interestingly, most of the inhomogeneities detected on the temperature variables existed in the Aegean region of Turkey. It is considered that theseinhomogeneities were mostly caused by non-natural effects such as relocation. Because of changes at topography at short distance in this region intensify non-random characteristics of the temperature series when relocation occurs even in small distances. The marine effect, which causes artifical cooling effect due to sea breezes has important impact on temperature series and the orograhpy allows this impact go through the inner parts in this region. Copyright © 2010 John Wiley & Sons, Ltd. [source] A new instrumental precipitation dataset for the greater alpine region for the period 1800,2002INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2005Ingeborg Auer Abstract The paper describes the development of a dataset of 192 monthly precipitation series covering the greater alpine region (GAR, 4,18°E by 43,49°N). A few of the time series extend back to 1800. A description is provided of the sometimes laborious processes that were involved in this work: from locating the original sources of the data to homogenizing the records and eliminating as many of the outliers as possible. Locating the records required exhaustive searches of archives currently held in yearbooks and other sources of the states, countries and smaller regional authorities that existed at various times during the last 200 years. Homogeneity of each record was assessed by comparison with neighbouring series, although this becomes difficult when the density of stations reduces in the earliest years. An additional 47 series were used, but the density of the sites in Austria and Switzerland was reduced to maintain an even coverage in space across the whole of the GAR. We are confident of the series back to 1840, but the quality of data before this date must be considered poorer. Of all of the issues involved in homogenizing these data, perhaps the most serious problem is associated with the differences in the height above ground of the precipitation gauges, in particular the general lowering of gauge heights in the late 19th century for all countries, with the exception of Italy. The standard gauge height in the early-to-mid 19th century was 15,30 m above the ground, with gauges being generally sited on rooftops. Adjustments to some series of the order of 30,50% are necessary for compatibility with the near-ground location of gauges during much of the 20th century. Adjustments are sometimes larger in the winter, when catching snowfall presents serious problems. Data from mountain-top observatories have not been included in this compilation (because of the problem of measuring snowfall), so the highest gauge sites are at elevations of 1600,1900 m in high alpine valley locations. Two subsequent papers will analyse the dataset. The first will compare the series with other large-scale precipitation datasets for this region, and the second will describe the major modes of temporal variability of precipitation totals in different seasons and determine coherent regions of spatial variability. Copyright © 2005 Royal Meteorological Society [source] A statistical downscaling method for monthly total precipitation over TurkeyINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2004Hasan Tatli Abstract Researchers are aware of certain types of problems that arise when modelling interconnections between general circulation and regional processes, such as prediction of regional, local-scale climate variables from large-scale processes, e.g. by means of general circulation model (GCM) outputs. The problem solution is called downscaling. In this paper, a statistical downscaling approach to monthly total precipitation over Turkey, which is an integral part of system identification for analysis of local-scale climate variables, is investigated. Based on perfect prognosis, a new computationally effective working method is introduced by the proper predictors selected from the National Centers for Environmental Prediction,National Center for Atmospheric Research reanalysis data sets, which are simulated as perfectly as possible by GCMs during the period of 1961,98. The Sampson correlation ratio is used to determine the relationships between the monthly total precipitation series and the set of large-scale processes (namely 500 hPa geopotential heights, 700 hPa geopotential heights, sea-level pressures, 500 hPa vertical pressure velocities and 500,1000 hPa geopotential thicknesses). In the study, statistical preprocessing is implemented by independent component analysis rather than principal component analysis or principal factor analysis. The proposed downscaling method originates from a recurrent neural network model of Jordan that uses not only large-scale predictors, but also the previous states of the relevant local-scale variables. Finally, some possible improvements and suggestions for further study are mentioned. Copyright © 2004 Royal Meteorological Society [source] Daily dataset of 20th-century surface air temperature and precipitation series for the European Climate AssessmentINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2002A. M. G. Klein Tank Abstract We present a dataset of daily resolution climatic time series that has been compiled for the European Climate Assessment (ECA). As of December 2001, this ECA dataset comprises 199 series of minimum, maximum and/or daily mean temperature and 195 series of daily precipitation amount observed at meteorological stations in Europe and the Middle East. Almost all series cover the standard normal period 1961,90, and about 50% extends back to at least 1925. Part of the dataset (90%) is made available for climate research on CDROM and through the Internet (at http://www.knmi.nl/samenw/eca). A comparison of the ECA dataset with existing gridded datasets, having monthly resolution, shows that correlation coefficients between ECA stations and nearest land grid boxes between 1946 and 1999 are higher than 0.8 for 93% of the temperature series and for 51% of the precipitation series. The overall trends in the ECA dataset are of comparable magnitude to those in the gridded datasets. The potential of the ECA dataset for climate studies is demonstrated in two examples. In the first example, it is shown that the winter (October,March) warming in Europe in the 1976,99 period is accompanied by a positive trend in the number of warm-spell days at most stations, but not by a negative trend in the number of cold-spell days. Instead, the number of cold-spell days increases over Europe. In the second example, it is shown for winter precipitation between 1946 and 1999 that positive trends in the mean amount per wet day prevail in areas that are getting drier and wetter. Because of its daily resolution, the ECA dataset enables a variety of empirical climate studies, including detailed analyses of changes in the occurrence of extremes in relation to changes in mean temperature and total precipitation. Copyright © 2002 Royal Meteorological Society. [source] Droughts and extreme events in regional daily Italian precipitation seriesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2002Michele Brunetti Abstract This paper proposes a methodology to study daily precipitation series that include a significant proportion of missing data, without resorting to completion methods based on randomly generated numbers. It is applied to a data set consisting of 75 station records (1951,2000) covering the Italian territory. They are clustered by principal component analysis into six regions: the north-west, the northern part of the north-east, the southern part of the north-east, the centre, the south and the islands (i.e. Sicily and Sardinia). Complete annual and seasonal regional average series are obtained from the incomplete station records, and analysed for droughts and extreme precipitation events. Droughts are identified by means of two indicators: the longest dry period and the proportion of dry days. The most remarkable result is a systematic increase in winter droughts over all of Italy, especially in the north, due mainly to the very dry 1987,93 period. Extreme events are analysed considering 5 day regional totals. In this case, however, an attempt to search for a statistically significant trend is not successful because of the scarcity of events in such a short period. The reliability of the regional series is checked by computing some basic statistics concerning total precipitation, rainy days and precipitation intensity and comparing them with the same statistics computed for regional series obtained by station records completed with methods based on random number generators. Copyright © 2002 Royal Meteorological Society. [source] Trends and abrupt changes of precipitation maxima in the Pearl River basin, ChinaATMOSPHERIC SCIENCE LETTERS, Issue 2 2009Q. Zhang Abstract We applied the Mann-Kendall (MK) test and Bayesian model to systematically explore trends and abrupt changes of the precipitation series in the Pearl River basin. The results showed that no significant trends were detected for annual precipitation and summer or winter precipitation totals. Significant negative trends were identified for the number of rainy days across the Pearl River basin; significant positive trends were observed regarding precipitation intensity (PI). In particular, the precipitation totals and frequencies of extremely high precipitation events are subject to significant positive trends. In addition, the number of extremely low precipitation events was also increasing significantly. Factors affecting the changes in precipitation patterns are the weakening Asian monsoon and consequently increasing moisture transport to Southern China and the Pearl River basin. In summary, the main findings of this study are: (1) increased precipitation variability and high-intensity rainfall was observed though rainy days and low-intensity rainfall have decreased, and (2) the amount of rainfall has changed little but its variability has increased over the time interval divided by change points. These finds indicate potentially increased risk for both agriculture and in locations subject to flooding, both urban and rural, across the Pearl River basin. Copyright © 2009 Royal Meteorological Society [source] | ||||||||||