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In this paper, we quantify the changes in precipitation distribution in south-western Poland between the periods 1891-1930 and 1981-2010. The average monthly precipitation totals available for 368 and 245 stations, respectively, are spatially interpolated and processed to calculate maps of differences and pluvial continentality indices for both periods. The maps are analysed against changes in atmospheric circulation and take into account the potential role of the mountain barrier of the Sudetes. The main findings are (1) winter totals generally increased in conjunction with a higher frequency of zonal circulation; it is more pronounced in the upper parts of the Sudetes due to orographic effects; (2) a decreased frequency of zonal circulation together with an increased frequency of southern flows has likely led to the reduction of precipitation in spring and autumn. These changes have led to a significant modification of the region's pluvial regime, mostly by decreasing continentality features (especially in the Sudetes and the western lowlands). In addition, the strong sheltering influence of the mountain barrier is observed, driving the preservation or even the enhancement of the continental pluvial characteristics in the north-eastern to eastern foregrounds of the Sudetes. This leads to the conclusion that in areas where long-term observed trends or future projections of precipitation are ambiguous, there may occur significant modifications in regional characteristics, especially as a result of changes in atmospheric circulation modified by local orography. [ABSTRACT FROM AUTHOR]

Meteorological and oceanographic data from ships of opportunity are the largest contributor to the world’s ocean surface database and thus are extensively used to estimate the change in climatic properties over the world’s oceans during the previous 150 years. The importance of these data for climate change studies underscores the need to fully understand the error associated with averages of these data. The sampling error problem is especially acute for ship data due to the fact that ships are moving platforms and, thus, report observations from constantly varying locations with time. This paper develops a theoretical framework for assessing the averaged sampling error associated with monthly, 1°×1° latitude-longitude box averaged ship data. It should be noted that the time-space distribution of ships within the averaging domain strongly affects the sampling error. This is shown in our derivation. The framework developed here can be used to improve upon existing methods for estimating the sampling error associated with three-dimensional box averages of meteorological and oceanographic data obtained from ship records. The framework is complimentary to existing methods of assessing biases and random error due to instrumentation, recording, etc. It is demonstrated mathematically that the uncertainty due to incomplete sampling is primarily a trade off between of the number of observations and their relative locations within the box as well as the inherent time-space correlation structure of the variable of interest. This work differs from other studies in that the three-dimensional interdependence of data is taken into account in deriving an expression for the sampling error. [ABSTRACT FROM AUTHOR]

Significant changes in the climatic system have been observed, which may be attributed to human-enhanced greenhouse effect. Even stronger changes are projected for the future, impacting in an increasing way on human activity sectors. The present contribution, prepared in the framework of the MICE (Modelling the Impact of Climate Extremes) Project of the European Union, reviews how climate change may impact on winter tourism in the Alpine region, intense precipitation and flood potential in central Europe, forest damage in Scandinavia and beach holidays in the Mediterranean coast. Impacts are likely to be serious and largely adverse. Due to a lack of adequate information and lack of broadly accepted and reliable mathematical models describing the impact of changes in climate extremes on these activity sectors, it has been found useful to use expert judgement based impact assessment. Accordingly, regional mini-workshops were organized serving as platforms for communication between scientists and stakeholders, vehicles for dissemination of the state-of-the-art of the scientific understanding and for learning stakeholders’ view on extreme events, their impacts and the preparedness system. Stakeholders had the opportunity to react to the scientific results and to reflect on their perception of the likely impacts of projected changes in extremes on relevant activity sectors and the potential to adapt and avert adverse consequences. The results reported in this paper present the stakeholders’ suggestions for essential information on different extreme event impacts and their needs from science. [ABSTRACT FROM AUTHOR]

Changes in precipitation exert an enormous impact on human life, and it is of vital importance to study regular patterns of meteorological and hydrological events. In order to explore the changing spatial and temporal patterns of precipitation amounts, precipitation extremes and precipitation concentration in Jiangxi province in southeast China between 1960 and 2008, several precipitation indices series were analysed using the Mann-Kendall test in this study. Our results indicate remarkable differences among the stations with negative and positive precipitation trends at the annual, seasonal and monthly scales, significant increasing trends are mainly found during January, August, winter and summer, while significant decreasing trends mostly are observed during October and autumn. For precipitation extremes, most precipitation indices suggest that both the intensity and the days of extreme precipitation are increasing; the mean precipitation amount, especially, on a wet day shows a significant positive trend. When it comes to precipitation concentration, the monthly rainfall heterogeneity shows an insignificant downward trend, while the contribution of the days with greatest rainfall displays an insignificant upward trend. Furthermore, the long-range persistence is detected for changing process of precipitation amount, extreme precipitation and precipitation concentration using the Rescaled Range Analysis. [ABSTRACT FROM AUTHOR]

Water scarcity has a destructive impact on the social and economic development around the world. The present study investigated the variations of drought conditions during 1961–2016 in the Zoige Wetland of Southwest China by adapting the Mann–Kendall (MK) analysis, the Theil–Sen slope estimator, continuous wavelet transforms (CWT), and the inverse distance weighting (IDW) algorithm. The partial correlation coefficient (PC) was also used to understand the causes of Standardized Precipitation Evapotranspiration Index (SPEI) characteristics from different climate factors. The results showed that the majority of the wetland had a drying trend with a − 0.142/(10 years) rate of SPEI on annual scale, while a 2–8-year significant period was observed on both annual and seasonal scales. In spring, the wetland presented dryness and had a tendency of mitigation except for the northeastern area. In summer, the wetland mainly presented humidity, but it had a drying trend except for the southern area. In autumn, the overall wetland was humid with an abrupt change towards dryness occurring around 1983 and the whole wetland showed a manifest drying trend. In winter, most areas showed drought while the Jiuzhi County and part of the southern wetland had an alleviating trend of drought. The decrease of annual SPEI was primarily due to the decrease in precipitation, the mean temperature increase, and relative humidity decrease that offset the reversed impact of wind speed decrease and sunshine duration decrease. The change of SPEI on a seasonal scale was the consequence of the significant change in precipitation only in winter. The results of this study would be of use for understanding the characteristics of climate variation and water resources management across the Zoige Wetland in a changing environment. [ABSTRACT FROM AUTHOR]

Over the past decades, drought has become a major concern in Morocco due to the importance of agriculture in the economy of the country. In the present work, the standardized precipitation index (SPI) is used to monitor the evolution, frequency, and severity of droughts in the High Atlas basins (N'Fis, Ourika, Rhéraya, Zat, and R'dat), located south of Marrakech city. The spatiotemporal characterization of drought in these basins is performed by computing the SPI with precipitation spatially interpolated over the catchments. The Haouz plain, located downstream of these basins, is strongly dependent on water provided by the mountain ranges, as shown by the positive correlations between the normalized difference vegetation index (NDVI) in the plain and the 3, 6, and 12-month SPI in the High Atlas catchments. On the opposite, no significant correlations are found with piezometric levels of the Haouz groundwater due to intensified pumping for irrigation in the recent decades. A relative SPI index was computed to evaluate the climate change impacts on drought occurrence, based on the projected precipitation (2006-2100) from five high-resolution CORDEX regional climate simulations, under two emission scenarios (RCP 4.5 and RCP 8.5). These models show a decrease in precipitation towards the future up to − 65% compared to the historical period. In terms of drought events, the future projections indicate a strong increase in the frequency of SPI events below − 2, considered as severe drought condition. [ABSTRACT FROM AUTHOR]

Daily precipitation data from 595 stations are analyzed based on regionalization to investigate changing properties of precipitation regimes across the entire China. The results indicate that the northwestern China is characterized by increasing monthly precipitation. The abrupt increase of precipitation is after early 1980s and early 1990s in the western arid zone and Qinghai-Tibet plateau, respectively. Other climate zones are dominated by decreasing precipitation regimes in autumn and increasing precipitation regimes in winter, and it is particularly true in the southwestern, southern and central China, showing seasonal shifts of precipitation changes. Besides, weak precipitation regimes are decreasing and strong precipitation regimes are increasing, and it is particularly the case in the southwestern, southern and central China, implying intensifying hydrological cycle reflected by precipitation changes in these regions. This study steps further into different hydrological responses within different regions of China to climate changes and will be relevant in regional management of agriculture development and water resources. [ABSTRACT FROM AUTHOR]

(1) The main objectives of this study are the spatial and temporal analysis of annual 24-hour extreme precipitation amounts for different return periods, and (2) the interannual variability of the frequency of month-to-month maximum rainfall using harmonic analysis. Long time series data from 110 well-scattered rain gauges are analysed using extreme values theory and harmonic analysis techniques. The results indicate that the Jenkinson solution is more appropriate than the linear Gumbel solution for the extreme value law. The maximum expected values of 180–200 mm are observed along the southern coasts of the Greek peninsula and in the islands close to the Turkish coast, as well as in the north–west parts of the country. The harmonic analysis showed that the highest percentage of variance for rainfall extremes explained by the first harmonic (PVR(1)) appears over the southern and south-eastern parts of Greece in association with the greatest values of the amplitude of this harmonic, therefore explaining more than 90% of the variation of the frequency of maximum annual 24-hour rainfall amounts. In contrast, for regions north of 38° N and especially mountainous regions, more harmonics (3–5) are necessary to describe the parameter under investigation. [ABSTRACT FROM AUTHOR]

Precipitation division and climate shift in China were analysed using daily precipitation data from 486 stations for the period 1960–2000. A modified hierarchical clustering method was used to divide China into sub-regions that have a coherent annual cycle, interannual evolutions and long-term trends. A division with 20 grouping areas can well describe the anomalous regional features seasonally, and a division with 40 grouping areas can reach a relatively stable level, theoretically for the annual and summer precipitation in mainland China. Rapid changes or interdecadal transition points of the regional precipitation series are detected by a multiple timescale t-test method. For mean annual precipitation, the interdecadal shift from a low to a high level is found to occur around 1987 in the Xinjiang region and around 1983 in Northeast China. The transition points of increasing summer rainfall in the eastern Tibetan Plateau and the lower Yangtze River are centred closely about 1979. Changes in the double-decadal precipitation are also detected for the two periods of 1961–1980 and 1981–2000. An increasing trend in annual precipitation is mainly found in the lower Yangtze River valley, the Xinjiang region, and Northeast China. Decreasing annual precipitation is mainly situated from the middle Yangtze River to the Yellow River. In summer and winter, the spatial pattern of precipitation anomalies shows two pairs of contrasting shifts with negative departures in North China and southern coastal China, while positive departures are found in the middle and lower Yangtze River valley and Northeast China. This pattern of regional precipitation shift in China is associated with southerly monsoon flow in eastern China and westerly flow in northwestern China. [ABSTRACT FROM AUTHOR]