Η παρούσα εργασία διαπραγματεύεται την επεξεργασία ετήσιων και εποχικών χρονοσειρών βροχόπτωσης από 12 σταθμούς της Δυτικής Ελλάδας για την περίοδο 1975-2004. Επιπλέον για τους 8 από τους συνολικά 12 σταθμούς όπου υπήρχε η δυνατότητα, η επεξεργασία αφορά μια περίοδο 50 ετών (1956-2005). Χρησιμοποιώντας ως κλιματικό δείκτη το ετήσιο βροχομετρικό ύψος προκύπτει ότι το σύνολο των 12 σταθμών χαρακτηρίζεται εν γένει από έναν συνδυασμό ημίυγρου ή υγρού κλιματικού τύπου. Χρησιμοποιώντας τον μη-παραμετρικό έλεγχο των Mann-Kendall για την εξακρίβωση παρουσίας τάσεων σε βάθος χρόνου, για την περίοδο 1975-2004 δεν διαφαίνεται η ύπαρξη κάποιας σημαντικής τάσης εκτός από τις ετήσιες βροχοπτώσεις του Πύργου που εμφανίζουν μία σημαντικά αρνητική τάση. Την περίοδο από το 1956-2005 προκύπτουν σημαντικά αρνητικές τάσεις τόσο σε εποχική βάση (κυρίως την άνοιξη) όσο και σε ετήσια για τους μισούς από τους οκτώ σταθμούς που εξετάστηκαν. Η Γάμμα κατανομή είναι εκείνη που περιγράφει καλύτερα το φυσικό μέγεθος ύψος βροχόπτωσης και στην περίπτωση μας προσδιορίζονται ανά σταθμό και για την περίοδο 1975-2004 (σε εποχική και ετήσια βάση), οι παράμετροι της με την βοήθεια της μεθόδου μέγιστης πιθανοφάνειας. Στα πλαίσια της φασματικής ανάλυσης, για να εξακριβωθεί η ύπαρξη ή οχι περιοδικότητας στην τιμή της διασποράς των εποχικών και ετήσιων τιμών βροχόπτωσης χρησιμοποιούνται οι 7 σταθμοί για τους οποίους υπάρχει επάρκεια μετρήσεων με εξεταζόμενη περίοδο την πεντηκονταετία 1955-2004 και κάνοντας χρήση της μεθόδου Blackman-Tukey. Προκύπτει με την εν λόγω μέθοδο ότι κατά την διάρκεια του φθινοπώρου και της άνοιξης δεν διαφαίνονται κάποια σαφή στοιχεία περιοδικότητας στην διασπορά των υψών υετού των 7 σταθμών. Αυτό δεν ισχύει όμως για τον χειμώνα αλλά και σε ετήσια βάση, όπου στα φάσματα των τιμών υετού των σταθμών αποκαλύπτονται τρεις περιοχές συχνοτήτων περιοδικότητας που μοιάζουν αρκετά μεταξύ τους. Αυτό αντανακλά το γεγονός ότι σε γενικές γραμμές οι σταθμοί της Δυτικής Ελλάδας επηρεάζονται από τα ίδια περιπου βαρομετρικά συστήματα και άρα είναι φυσιολογικό να εμφανίζουν παρόμοιες συνιστώσες περιοδικότητας στις διασπορές των τιμών υετού τους. / This work deals with the processing of annual and seasonal precipitation series from 12 stations of West Greece for a 30-year study period (1975-2004). Moreover for 8 out for τηε 12 stations where possible, the processing uses a 50-year study period (1956-2005). By using the annual precipitation height as an climatic index it follows that the total of the twelve stations is characterized generally by a combination of semi-wet and wet climatic type. Making use of nonparametric Mann-Kendall test for ascertaining the existence of trend, it doesn't follow any significant trend for the 30-year period (1975-2004), with the exception of the annual precipitation heights of Pirgos that show a significant negative trend. During the 50-year period (1956-2005) significant negative trends occur in seasonal (mainly during spring) and annual basis as well, for half of the eight stations which have been examined. Gamma distribution is tha type of statistical distribution that describes more effectively the physical quantity precipitation height, and in our case its parameters per station are being computed for the period 1975-2004, by using the maximum likelihood method. Under the framework of a Spectral analysis of the precipitation series (for the verification of periodicity in the variances of precipitation rates) , 7 stations are used for a 50-year study period (1955-2004) by using the Blackman-Tukey method. It follows after this method has been used, that precipitation series don't appear any periodicity during autumn and spring seasons. This is in contrast with the winter season and the annual rainfall values as well, where three parts of periodicity in the spectra of the stations appear that bear a common resemblance. This depicts the fact that genarally the total of West Greece stations are influenced by almost the same barometric pressure systems which leads to the variances of precipitation rates to appear common periodicity components.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-05-14T19:52:45Z No. of bitstreams: 1 VIRGÍNIA DE FÁTIMA BEZERRA NOGUEIRA – TESE (PPGMET) 2015.pdf: 2294664 bytes, checksum: 660de8adf5292855bb29d8690566ac6b (MD5) / Made available in DSpace on 2018-05-14T19:52:45Z (GMT). No. of bitstreams: 1 VIRGÍNIA DE FÁTIMA BEZERRA NOGUEIRA – TESE (PPGMET) 2015.pdf: 2294664 bytes, checksum: 660de8adf5292855bb29d8690566ac6b (MD5) Previous issue date: 2015-02-27 / A avaliação das conexões entre degradação ambiental no bioma Cerrado e mudanças climáticas constitui o foco central desta pesquisa. Nos últimos anos a intervenção humana em biomas ricos em biodiversidade, que é de grande importância para o país, aumentou consideravelmente provocando alterações significativas no ciclo hidrológico. O impacto dessas intervenções exige a realização de pesquisas com abordagens mais específicas, que permitam aprimorar o conhecimento sobre os impactos de influências antrópicas no clima regional e evidenciar a urgência de medidas mitigadoras. Os procedimentos de análise se basearam na caracterização ambiental da área através de informações de satélite (sensoriamento remoto), e detecção de mudanças no padrão de comportamento de variáveis atmosféricas resultantes da transformação da vegetação nativa em áreas agrícolas (monocultura da soja) na região de Chapadinha-MA. Técnicas estatísticas, incluindo análise multivariada (análise fatorial em análise de componentes principais) e testes paramétricos (teste – t, teste F / análise de variância) e não paramétricos (teste Sequencial de Mann-Kendall / teste de Pettitt), foram usadas como principais ferramentas de investigação. Os resultados indicam que o processo de degradação da vegetação nativa (Cerrado) na região de Chapadinha teve início antes da entrada da soja; no entanto, a sojicultora foi determinante para tornar significativa este impacto no clima. Evidências de impacto de mudanças antrópicas foram detectadas nas temperaturas máxima e mínima. O aumento significativo nos valores das temperaturas extremas é um indício importante de que a degradação no Cerrado pode contribuir no processo de desertificação na região analisada. / The evaluation of the connections between environmental degradation in the Cerrado biome and climate change is the central focus of this research. In recent years human intervention in biomes rich in biodiversity, which is of great importance for the country has risen sharply causing significant changes in the hydrological cycle. The impact of these interventions requires conducting research with more specific approaches, which allow improve knowledge about the impacts of anthropogenic influences on regional climate and highlight the urgent need for mitigation measures. Screening procedures were based on environmental characterization of the area through satellite information (remote sensing), and detection of changes in the pattern of behavior of atmospheric variables resulting from the processing of native vegetation in agricultural areas (Soy monoculture) in the Chapadinha region -MA. Statistical techniques, including multivariate analysis (factor analysis in principal component analysis) and parametric tests (t - test, test F / ANOVA) and nonparametric (Sequential Mann-Kendall / Pettitt test) were used as main research tools. The results indicate that the native vegetation degradation process (cerrado) in the region Chapadinha started before soybean input; however, the sojicultora was crucial to make this significant impact on the climate. Impact evidence of anthropogenic changes were detected in maximum and minimum temperatures. The significant increase in extremes of temperature values is an important indication that the degradation in the Cerrado can contribute to the process of desertification in the region analyzed.

Šlapių žemių sausinimo įtaka nuotėkiui Lietuvoje vertinama nevienareikšmiškai. Darbe analizuojama Mūšos upės ties Ustukiais hidrologinės charakteristikos ir žemių sausinimo šioje baseino dalyje įtaka upės nuotėkiui. Darbui atlikti panaudoti 1960 – 2006 metų paros nuotėkio, metinio kritulių kiekio, vidutinės paros oro temperatūros duomenys ir nusausintų plotų apimtys. Sudarytas kritulių įtakos debitui grafikas, kuris parodo, kad šie rodikliai glaudžiai susiję. Nagrinėjami du laikotarpiai 1960-1981 metai iki patvenkiant Mūšos upę, ir 1983-2006 metai po Dvariukų tvenkinio įrengimo. Naudojant DHRAM programinę įrangą, išskirtos ir analizuotos 33 debito charakteristikos. Naudojant Mano–Kendalio testą nustatyti 33-jų hidrologinių charakteristikų kaitos trendai. Tyrimas parodė, kad žemių sausinimas didelės įtakos Mūšos upės nuotėkio pokyčiams nepadarė. Sausinimo poveikis pasireiškia maksimalių debitų sumažėjimu ir paros debitų pokyčiais. / Wet soil drainage on the runoff Lithuania controversial. The paper analyzes the beating of the river at Ustukiai hydrological characteristics and soil drainage in the basin of the river runoff influence. Used to carry out the 1960 - 2006 years of daily runoff, rainfall, average daily air temperature data and the volume of drained areas. Made in rainfall affect the flow graph, which shows that these indicators are closely related. Study of two periods of 1960-1981 years before damming Mūša river, and the 1983-2006 year Dvariukų pond construction. Using DHRAM software identified and analyzed the 33 characteristics of flow. Using Mann-Kendall test to determine their 33-hydrological characteristics of the change in trend. The study showed that the draining of lands affected by high river runoff beating did not change. The drainage effect of maximal decrease in discharges and daily discharges change.

The objective of this Bachelor thesis is to analyze moving patterns in Norrköping’s municipality. The main aim is to analyze the migration to, from, and within the municipality of Norrköping, not only for the population as a whole but also for groups of special interest. Another aim is to compare migration patterns in Norrköping with those of other municipalities in Sweden.Several data sets have been used, each of them extracted from population statistics carried out by Statistics Sweden (SCB).Data mining using association analysis is used for finding the migration pattern within Norrköping’s municipality and several questions are examined using descriptive statistics. Mann-Kendall tests are used to determine interesting trends in the population changes.The results show that pre-school children do not remain longer in the city centre than they did previously; people moving to Norrköping from within Sweden move mostly to the city centre, though immigrants from abroad mainly favour Hageby and Åby tätort. Furthermore, the results show that people generally move to areas that are geographically similar to where they were or have been before. There is a decrease in migration of people with a Humanities or Arts background, as there is for those with a pedagogy and teacher training background. Areas with a decrease in migration are the suburbs as well as built-up areas at the fringe of the municipality. Norrköping has both lower immigration and emigration than other comparable Swedish municipalities. / Syftet med denna kandidatuppsats är att analysera flyttmönster i Norrköpings kommun. Målet är att analysera både flyttningar till, från, och inom Norrköpings kommun för dels hela populationen och dels speciellt intressanta grupper. Ett annat mål är att jämföra flyttmönster i Norrköping med några andra kommuner i Sverige.För att kunna genomföra dessa analyser har flera datamaterial använts. Gemensamt för datamaterialen är att de allihop baseras på Statistiska Centralbyråns (SCB:s) befolkningsstatistik.För att hitta mönster för hur människor flyttar inom Norrköpings kommun används associationsanalys. Med hjälp av deskriptiv analys undersöks olika särskilt intressanta områden av omflyttningarna i kommunen. Vidare används Mann-Kendalltester för att se om det finns några särskilt intressanta trender i befolkningsutvecklingen.Resultatet visar att ingen förändring har skett när det gäller ifall barn i förskoleåldern bor kvar i stadskärnan i större utsträckning än tidigare. Inflyttare från Sverige flyttar i stor utsträckning till stadskärnan, medan Hageby och Åby tätort är vanliga att flytta till om man flyttar från utlandet. Vidare visar resultatet att människor oftast flyttar till geografiskt nära områden samt områden som har ungefär samma bostadsform som det man tidigare bott i. Flyttningsnettot är negativt för de med utbildning inom Humaniora och konst samt Pedagogik och lärarutbildning. De områden som har negativ befolkningsutveckling ligger i utkanten av centralorten eller är tätorter i utkanten av kommunen. Norrköpings kommun har lägre inflyttning och utflyttning än de flesta andra jämförbara kommuner.

The aim of this study was to analyze the presence of the trend of long-term time series of concentrations and losses of nutrients and their descriptions. The concentrations of nitrogen and phosphorus compounds were evaluated. The analysis was performed on selected catchment of large, medium and small areas. All observed catchment are located in the basin of dam Švihov. Trends were tested using non parametric methods - Mann-Kendall test, Seasonal Mann-Kendall test and Kendall's correlation coefficient . In this study there are generally described monitored cycles of nutrients, nitrogen and phosphorous. There are also characterized the factors, which effect leaching of these nutrients to water (from the catchment). The paper also outlines the progression of water quality in the Czech Republic, which was influenced by political and economic changes in Europe in the second half of the 20th century.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-06-23T22:05:00Z No. of bitstreams: 1 LayaraCampeloDosReis_DISSERT.pdf: 2271838 bytes, checksum: c4d28430acbd6f35763abf08b3d4b899 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-29T18:30:11Z (GMT) No. of bitstreams: 1 LayaraCampeloDosReis_DISSERT.pdf: 2271838 bytes, checksum: c4d28430acbd6f35763abf08b3d4b899 (MD5) / Made available in DSpace on 2016-06-29T18:30:11Z (GMT). No. of bitstreams: 1 LayaraCampeloDosReis_DISSERT.pdf: 2271838 bytes, checksum: c4d28430acbd6f35763abf08b3d4b899 (MD5) Previous issue date: 2015-11-13 / Nos ?ltimos anos o munic?pio de Bom Jesus (PI) passou a figurar como uma regi?o de grande potencial para produ??o de soja (Glycine max (L.) Merrill) em larga escala. Esta cultura agr?cola ganha espa?o nos cerrados bonjesuenses apresentando, no decorrer dos anos, crescimento exponencial de ?reas cultivadas. Entretanto, a produtividade n?o acompanha esse mesmo ritmo de crescimento, passando por per?odos de oscila??es, ainda que exista dispon?vel um grande suporte de tecnologias, materiais gen?ticos de maior potencial produtivo, uso de t?cnicas de manejo e corre??o do solo e da crescente qualifica??o dos produtores rurais. Portanto, no presente estudo, considerou-se que as condi??es clim?ticas exercem uma a??o limitante ?s m?ximas produtividades de soja neste munic?pio. Diante desse contexto, a pesquisa visa analisar poss?veis tend?ncias em vari?veis meteorol?gicas que possam influenciar na produtividade da soja no munic?pio de Bom Jesus. Para tanto utilizaram-se diferentes conjuntos de dados meteorol?gicos: i) dados di?rios de dois per?odos (1984-2014) e (1974-2014), ambos obtidos a partir do banco de dados do Instituto Nacional de Meteorologia (INMET); ii) Normais Climatol?gicas do Brasil de 1961-1990 do INMET; iii) dados de produ??o agr?cola municipal da cultura da soja dos anos/safras de 1997/1998 a 2012/2013 obtidos no banco de dados de Produ??o Agr?cola Municipal (PAM) do Instituto Brasileiro de Geografia e Estat?stica (IBGE). Nas an?lises foram realizados c?lculos para o c?mputo das Normais Climatol?gicas (1984-2014) e aplica??es estat?sticas. Dentre os m?todos estat?sticos foram realizados: i) o teste de Wilcoxon - pareado para avaliar as diferen?as entre as climatologias dos per?odos de 1961-90 e 1984-14; ii) o teste de tend?ncia (Mann-Kendall), no intuito de analisar a tend?ncia de varia??o dos dados agrometeorol?gicos (precipita??o, temperatura m?xima, temperatura m?nima e amplitude diurna da temperatura - DTR); iii) an?lise multivariada (an?lise de Cluster) pelo m?todo de Ward e o teste de correla??o de Spearman (rs), para identificar a rela??o entre os dados agrometeorol?gicos e dados de variabilidade anual da produtividade da soja. Para a aplica??o dos testes o estudo adotou n?vel de signific?ncia estat?stica de 5%. Os resultados apresentados indicam que a sazonalidade da climatologia de 1984-2014 apresentou mudan?as com rela??o ? climatologia passada em todas as vari?veis analisadas, exceto na insola??o e na precipita??o. Quanto ? variabilidade dos elementos agrometeorol?gicos, observaram-se tend?ncia negativa significativa para a precipita??o no m?s de outubro e positiva significativa no m?s de dezembro, as quais constatam altera??es nos padr?es do clima local, demonstrado pelo atraso da retomada do per?odo chuvoso, que poder? ser considerado na condu??o de medidas de planejamento para a defini??o da ?poca de semeadura do cultivo da soja. Foi poss?vel identificar tamb?m tend?ncias positivas com signific?ncias estat?sticas, na temperatura m?xima, para todos os meses que fazem parte do ciclo da soja (novembro - abril), que por sua vez tender? a provocar efeitos adversos sobre a fisiologia da cultura, e consequentemente impactos no rendimento final. Notou-se uma correla??o positiva significativa entre a produtividade de soja e a precipita??o no m?s de mar?o, apontando que per?odos de estiagens neste m?s s?o prejudiciais para o desenvolvimento da cultura da soja. Quanto ? correla??o entre as vari?veis (temperatura m?xima, m?nima e DTR) e a variabilidade anual da produtividade da soja, o resultado do teste n?o mostrou correla??o com signific?ncia estat?stica para o per?odo analisado, visto que considerando a faixa recomendada para o desenvolvimento do cultivo, estas vari?veis clim?ticas n?o s?o fatores limitantes na produtividade final da soja no munic?pio de Bom Jesus (PI). Assim, espera-se que este estudo possa contribuir para a proposi??o de medidas estrat?gias de planejamento, que levam em conta o papel da variabilidade clim?tica sobre a produtividade final da cultura da soja. / The climate is still main responsible for the variations soybean productivity (Glycine max (L.) Merrill), exerting a limiting action on these agricultural systems. The bomjesuense cerrado, this culture has proved, over the years, an increase of cultivated areas, however, productivity does not keep the same pace, going through periods of oscillations. Thus, although the crop is added to high technology, culture has great vulnerability to climatic adversities. Thus, the present study aims to analyze possible trends in meteorological variables, which can influence the soybean yield in Bom Jesus. For this purpose, different datasets were used, as follows: i) two periods of daily data (1984-2014 and 1974-2014), both obtained from the National Meteorological Institute (INMET); ii) climate normals from 1961-1990 as defined by INMET; iii) local agricultural production data of soybean-year (1997/1998 to 2012/2013) obtained from the Municipal Agricultural Production (PAM) dataset, which is management by Brazilian Institute of Geography and Statistics (IBGE). The analysis procedures included calculations of climate normals for 1984 to 2014 period and some statistical applications, as follows: i) the Wilcoxon test, used to evaluate differences between climate normals (1961 to 1990 and 1984 to 2014); ii) the Mann-Kendall nonparametric test, in order to analyze the linear trend of agrometeorological variables (rainfall, maximum temperature, minimum temperature and diurnal range of temperature; iii) cluster analysis by Ward method and the Spearman correlation test (rs) to identify the relationship between agrometeorological variable and soybean annual productivity. We adopted a statistical significance level of 5%. The results indicate changes in seasonality of the 1984-2014 climatology with respect to past climatology for all variables analyzed, except for insolation and precipitation. However, the monthly analysis of precipitation indicate negative trend during October and positive trend in December, causing a delay in start of rainy season. If this trend is persistent this result must be considered in futures definitions of the soybean crop sowing date over the region studied. With Mann-Kendall test was possible to identify positive trends with statistical significance in maximum temperature for all month forming part of soybean cycle (from November to April), which in turn tends to cause adverse effects on crop physiology, and consequently impacts on the final yield. Was identified a significant positive correlation between soybean yield and precipitation observed in March, thus precipitation deficit in this month is harmful to the soybean crop development. No statistically significant correlation was identified among maximum temperature, minimum temperature, and DTR with annual soybean productivity due these range of meteorological variables are not limiting factors in the final soybean yield in Bom Jesus (PI). It is expected that this study will contribute to propose planning strategies considering the role of climate variability on soybean crop final yield.

CHANGES OF RAINFALL-RUNOFF REGIME IN THE ŠUMAVA / BOHEMIAN FOREST REGION Abstract: The goal of this thesis is the evaluation of changes in rainfall-runoff regime in the Šumava region from time and spacial point of view. The thesis includes research and applied part. The research part is dedicated to the methods of evaluation of runoff changes and their possible causes in the Šumava region. In the applied part there is an analysis of precipitaion - runoff regime for long-term time series of average annual and monthly discharges and also annual and monthly precipitations for selected gauging stations in Czech, German and Austrian part of Šumava using absolute and relative homogenity tests and Mann - Kendall test for long-term trend. One of the main aims of this thesis is the identification of possible orographical effect or the difference between windward and leeward part of Šumava. In conclusion the achieved results are evaluated, discussed and compared with subject publications. Key words: absolute homogenity, Mann - Kendall test, runoff, discharge, relative homogenity, precipitation, trend, Šumava, changes

The precipitation falling as rain or snow has different impact on regional water resources and their annual distribution. Shift from solid to liquid form of precipitation following the increase of the surface air temperatures could be important because such change could influence the timing of spring runoff and cause water scarcity in summer. In this study, the spatial and temporal variations of ratio of snowfall to total precipitation (Sf), mean air temperature, day of year of melt-out and winter and spring runoff is analysed. Data were examined for 11 meteorological and 6 hydrological stations in the mountains catchment in Czechia for November-April 1965-2014. Data were analyzed using the Mann-Kendall trend test. Major results show that Sf has been decreasing strongly throughout the whole examined area, with the strongest decrease in the foothill area of the northern mountains of Czechia. Stronger decrease is observed in lower elevations, at the stations with meant air temperature close to melt temperature. Strongest decrease was observed in March and the weakest decrease was observed in December and April, The significant decreases in Sf are associated with large increase in mean winter air temperatures. Due to the increasing mean air temperature in the cold season, the total rainfall is...

This thesis develops an optimal interpolation method that takes daily precipitation values collected from weather stations and produces precipitation estimates on a grid. The method, called Hybrid 2.0, combines EOF-based linear interpolation with the nearest-station method. Gridded monthly precipitation is first obtained via EOF, then distributed among days via nearest station. Hybrid 2.0 builds on an earlier method, called Hybrid 1.0, that applies an inverse-distance weighting method to obtain gridded monthly values. Hybrid 2.0 uses these monthly Hybrid 1.0 values as inputs when constructing EOF functions. The data used in this thesis were obtained from the Meteorological Service of Canada. Few weather stations were located in the northern and mountain regions of Alberta prior to 1950. As a result, the Hybrid 1.0 gridded results underestimate precipitation in these regions for that period. The main contribution of Hybrid 2.0 is a substantial reduction in this bias, obtained by implicitly taking topographic elevation into account. Bias reduction is achieved by extracting EOFs from Hybrid 1.0 output for 1951-2002, when many more stations were present in the northern and mountain regions. Hybrid 2.0 is shown to be more accurate in interpolating both monthly and daily precipitation in Alberta, when compared with Hybrid 1.0 and other methods. The thesis also provides detailed analyses of precipitation trends and droughts using the gridded Hybrid 2.0 daily values. Optimality of the selected EOF modes and sensitivity to data error in the EOF-based linear reconstruction are also discussed in this thesis. Agricultural uses of historical climate data have become extremely important. Applications include: enabling prompt, optimal decisions on market prices and disaster aid, designing future agricultural practices such as adaptation to climate and technology changes, and managing risks for agricultural producers and governments in areas such as drought monitoring. Many applications require a reliable interpolation technique to accurately reconstruct daily climate estimates onto grids of various resolutions. The gridded Hybrid 2.0 daily precipitation values produced by this thesis satisfy this requirement and can be used as inputs for many agricultural applications. / Applied Mathematics

Les travaux présentés portent sur les retombées atmosphériques en zone rurale et s'inscrivent dans le cadre du programme français de Mesure des Retombées Atmosphériques (MERA). Les polluants mesurés dans les stations du dispositif sont en rapport avec les problèmes des pluies acides et de la pollution photochimique. Deux tests statistiques pour détecter et estimer les tendances au sein de séries chronologiques ont été utilisés. La procédure est basée sur le test non paramétrique de Mann-Kendall pour déterminer la tendance et sur la méthode de Sen pour en estimer la magnitude. Ces tests ont été appliqués aux 5.000.000 de données MERA, annuelles, saisonnières et mensuelles sur la période 1990-2003, puis, aux émissions nationales et européennes des principaux polluants précurseurs. L'acidité moyenne des pluies, après avoir baissée au début des années 90, augmente légèrement depuis 1996 alors que les émissions de composés acidifiants diminuent. Cette observation semble être corrélée à la diminution en cations basiques, NH4+ et aux aérosols acides. Les concentrations en composés soufrés (gaz et aérosols) ont fortement diminué depuis le début des années 90 associées aux fortes réductions d'émission. Pour l'O3, une augmentation des teneurs est observée entre 1995 et 2003, associée à une diminution des émissions de précurseurs. Plusieurs facteurs peuvent expliquer cette augmentation : les changements des émissions de précurseurs, les échanges strato-troposphériques, le transport intercontinental, les changements climatiques, le rapport COV/NOx, les émissions des composés bio-géogéniques. Prochainement, des prévisions subjectives par extrapolations linéaires pourront être effectuées avec un intervalle de confiance à 99%.