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Abstract: This paper presents a climatological validation of atmospheric circulation type catalogues included in the COST 733 dataset (COST733CAT). The circulation type classifications ability to describe patterns of the Norwegian precipitation climate is analysed. For all 73 classifications included in the COST733CAT several statistical measures are calculated for each individual circulation type. These statistics include both frequencies of precipitation occurrence and statistical moments used to fit γ-distributions for each circulation type at precipitation stations. In this paper results from four stations in different precipitation regions and classifications with ∼9 types are emphasized. The circulation types employed represent the COST 733 domain 02 (57–72°N, 6°W–25°E). Precipitation occurrence frequency statistics and probability density functions are used to analyse if the types within the circulation type classifications can describe different precipitation conditions. Simple measures are developed in order to compare classifications. The similarity of probability density functions of type specific precipitation within classifications are analysed applying Kolmogorov–Smirnov tests. The type-specific distribution functions are also compared with the probability function of all precipitation events. The results reveal that some classifications, particularly those associated with the neural network methods does not discriminate precipitation distributions very well. On the other side many classifications performs well and get high scores. Evaluating all 73 catalogues the results indicate best results for classifications with 27–30 types. [Copyright &y& Elsevier]

Abstract: Precipitation is one of the most important elements of the hydrological cycle, and extreme events associated with precipitation are considered a key factor in several types of human activities, including agriculture, for instance. Therefore, the main objective of this paper is to evaluate extreme precipitation indices for the past century, and to analyse the possible tendency of future precipitation conditions for this century for the Carpathian Basin. Several climate extreme indices have been analysed according to the guidelines suggested by the joint WMO-CCl/CLIVAR Working Group (formed at the end of the 1990s) on climate change detection. These precipitation indices include the number of wet days using several threshold values, e.g., 20mm (RR20), 10mm (RR10), 5mm (RR5), 1mm (RR1), 0.1mm (RR0.1), the upper quartile and the 95th percentile of daily precipitation in the base-period 1961–1990 (R75 and R95); the maximum number of consecutive dry days (CDD); the highest 1-day precipitation amount (Rx1); the greatest 5-day rainfall total (Rx5); the annual fraction due to extreme precipitation events (R95T); simple daily intensity index (SDII), etc. Our results suggest that regional intensity and frequency of extreme precipitation increased in the Carpathian Basin during the second half of the 20th century, while the total precipitation decreased and the mean climate became slightly drier during the whole 20th century. In the second part of this paper, several IPCC emission scenarios have been compared and GCM outputs have been analysed in order to project precipitation conditions in the Carpathian Basin for the 21st century. These climate simulations suggest that climate of this region may become drier in summer and wetter in winter, which highlight the importance of hydrological and agricultural planning in Hungary. [Copyright &y& Elsevier]

Abstract: Human activity is known to have an important impact both in the radiation budget and the hydrological cycle. One particular aspect is the increase of anthropogenic aerosols due to changes in land use and industrial activity. However the relation between aerosols and precipitation is still far from being fully understood due to the complexity of the mechanisms involved and the lack of sound data. A multi-sensor approach, combining instruments meant to study aerosols and others meant at the study of precipitation, is required to get a better insight on this phenomenon. The International Research Centre for Telecommunications and Radar (IRCTR) has developed a meteorological radar called IDRA (IRCTR Drizzle Radar) aimed at obtaining high resolution temporal and spatial measurements of all sorts of precipitation including those non-detectable by standard meteorological radar like drizzle. The measurements obtained by the system, coupled with data obtained by other sensors placed in the Cabauw Experimental Site for Atmospheric Research (CESAR) observatory (Cabauw, The Netherlands), are expected to provide crucial information for a better characterization of these mechanisms. The information obtained can be used for a better spatial planning in order to reduce the impact of human activity in the climate. This paper describes the relevant characteristics of the system, its signal processing and the products obtained. [Copyright &y& Elsevier]