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Global climate changes significantly contribute to increased frequency of hydrologic extremes. This significantly underestimates the hydrologic design parameters, bringing of hydro systems to increased failure risk. In order to address this concern, the current practice of development of hydrologic frequency tools need to be updated accounting for non-stationarity. This study first considered a diverse set of statistical tests to examine the trend, change points, non-stationarity and randomness of streamflow, rainfall and temperature time series of scales ranging from daily to annual. The annual maxima time series indicated non stationarity against the stationary behaviour of daily series of hydro-meteorological datasets of the basin. Subsequently, this study developed the Temperature Duration Frequency (TDF), Rainfall Intensity Duration Frequency (IDF) and Flood Frequency (FF) curves of Greater Pamba river basin in Kerala India, the part of which was most severely affected by the near century return period flood event of 2018. The analysis was performed for a multitude of combinations of variations in distribution parameters with time and climatic drivers as physical covariates in the extreme value formulations. The study proposed a novel wavelet coherence (WC) based driver selection of most dominant combination of climatic precursors in developing FF and IDF relations of three locations of Kalloopara, Malakkara and Thumpamon and TDF curve of Kuttanad region in the basin, considering data of 1985–2015 period. The proposed WC framework considers bi-multi-and partial effects of climatic oscillations (COs) like El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO) in identifying potential drivers. The different WC formulations captured in-phase relationships of streamflows and rainfall with COs at intra-annual, annual and inter annual scales up to 4 years. The methods showed that addition of climatic precursors improved the NS estimates of flood and rainfall quantiles by more accurately capturing the magnitudes of extreme streamflows and rainfalls of 2018, 2021 than the time covariate formulations. However, the role of COs on extreme temperature is not found to be influential in developing TDF relationships, which needs further investigation. [ABSTRACT FROM AUTHOR]

The Indian Ocean Dipole (IOD) signature in European summertime surface air temperature (SAT) and sea level pressure (SLP) fields were investigated in this study. The SAT and SLP anomalies of the surface fields over the European region associated with the IOD variability are described based on the results of experiments with atmospheric general circulation model and re-analysis data. It is shown that the prevalent positive significant SAT/SLP anomaly tends to form over Central/Eastern Europe in the negative phase of the IOD events. That accompanied by weak and insignificant negative SAT/SLP anomalies in July-August over Western Europe. The opposite anomalies in sign have appeared in the positive IOD phase. The ensemble simulation gave evidence that the European summertime atmospheric response carries the nonlinear effect on stepping up the values of SST IOD anomalies in the Indian Ocean. The composite difference between the negative and positive phases of the IOD, constructed based on the re-analysis of 20CR data, generally confirms the described simulation results of the ensemble climate model for the SAT/SLP fields. However, it can be only noted a slight shift toward the east of the European region in 20CR reanalysis data compared with the simulation. In addition, the amplitude of the obtained pattern based on 20CR re-analysis has 2-3 times high values than in the simulations. It might have resulted from the low 20CR re-analysis cases with pure IOD years in the last century, when the other oscillations (North Atlantic oscillation, El Nino-Southern oscillation and others) are in the neutral phase. [ABSTRACT FROM AUTHOR]

The article analyses the air temperature characteristics of the winter season in northwestern Poland (Fig. 1) between 1951 and 2015.The aim of this work is to analyses the changeability of thermal conditions in the winter, taking into consideration the speed of changes determined by a coefficient of linear trend, and to investigate the relations between North Atlantic Oscillation and the air temperature. In this study, the Jones' index, whose values were determined in 1825 and regularly published on National Weather Service website since then, has been used. The monthly measuring data are the basis on which the air temperatures in north-western Poland can be worked out. In this study only winter from all the seasons has been chosen, to be from now on called the winter season. This stems from the fact that it is a turning season of December of one year as well as January and February of the next year. This division of the seasons of the year varies from the traditional one in a sense that it is the December of the same calendar year that is taken into account, not the previous year. The authors of this study were particularly interested in presenting the influence of NAO on the thermal characteristics of winter seasons as being shaped by changeable heat reserves stored in the waters of the North Atlantic in the warm season, which in turn shape the atmospheric oscillation and the course of air temperature change in the winter season being analysed. [ABSTRACT FROM AUTHOR]

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In this study, we investigated characteristics of cyclones over the Arctic Ocean during the summer season (June-August). An automatic cyclone Tracking Algorithm (Hodges, 1994; Hodges, 1996.) developed in the University of Reading (TA_UR) was applied on the basis of the ERAInterim Reanalysis of the European Centre for Medium-Range Weather Forecasts 1979-2012. Cyclone climatology characteristics, such as the total cyclone numbers, regional counts, tracks, densities, intensities, as well as deepening rates, were investigated. The results suggest that the total number of cyclones in summer season is less than in other seasons. About 50% of cyclones in Arctic summer were generated south of 70°N. The total number of cyclones has no overall tendency in the period 1979-2012, but a large inter-annual variability. The time series of cyclone counts have no significant trends in the five regions of CHU (Chukchi and East Siberian Sea), CRU (Central Russia), GNB (Greenland, Norwegian and Barents Seas), GRL Greenland) and HNA (High-latitude North American). The correlation and composite analysis show that cyclone activities are closely associated with atmospheric circulation, such as AO (Arctic Oscillation), NAO (North Atlantic Oscillation) and PNA (Pacific-North American Pattern). [ABSTRACT FROM AUTHOR]

The article discusses the climate of Ireland and how its proximity to the Atlantic Ocean creates an environment where oscillations from the ocean impact the climate. Research has found that vegetation in Ireland is greener and the net ecosystem production is higher when the climate is warmer than during cooler years. The possibility that greenhouse gas, comprised largely of carbon dioxide, is altering the Earth's atmosphere is considered. The future climate of Ireland in 2070 is considered, particularly what a warmer climate could mean.