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19 Pags.- 5 Figs.- 2 Tabls. © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license, Drought monitoring is essential to determine, at short time intervals, the main characteristics of drought events, such as their duration, severity, and spatial distribution. To ensure that drought monitoring represents a useful tool for governmental plans aimed at preventing or minimizing drought impacts, up-to-date information must be instantaneously accessible and it must provide high spatial and temporal resolution. This study presents a system that allows the automatic tracking of meteorological droughts in the Spanish territory, based on an open and easy-to-use online platform (https://monitordesequia.csic.es/monitor). This drought monitoring system provides two drought synthetic indices: the Standardised Precipitation Index (SPI) and the Standardised Precipitation Evapotranspiration Index (SPEI). Information is provided on a quasi-weekly basis, in a grid format, with a spatial resolution of 1.1*1.1 km, and with data from 1961 to the present time. This drought monitor is updated based on the real-time information gathered from automatic stations, which in turn requires historic information to identify and track drought events. The drought indices are obtained from data processing (quality control, temporal series reconstruction, homogenisation, interpolation, and validation) using climatic variables (maximum and minimum temperatures, solar radiation, rainfall, dew point, and wind speed) which are provided by the Spanish Meteorology Agency and the Ministry of Agriculture of the Spanish Government. We performed a validation of the drought indices for the whole historical period (1961–2020). This allowed us to observe a strong spatial agreement between the indices obtained with the historical dataset and the indices from the monitoring dataset, especially for mainland Spain and the Balearic Islands (Pearson's r, SPI and SPEI >0.99). The presented real-time drought monitoring system represents a relevant and useful tool that allows for quick and effective actions to prevent and mitigate the effects of drought on society and ecosystems., This work was supported by projects PCI2019-103631 financed by the Spanish Ministry of Science and Technology and FEDER and CROSSDRO project funded by AXIS (Assessment of Cross (X) - sectoral climate Impacts and pathways for Sustainable transformation), JPI-Climate co-funded call of the European Commission.

11 Pags., There is a strong scientific debate on how drought will evolve under future climate change. Climate model outputs project an increase in drought frequency and severity by the end of the 21st century. However, there is a large uncertainty related to the extent of the global land area that will be impacted by enhanced climatological and hydrological droughts. Although climate metrics suggest a likely strong increase in future drought severity, hydrologic metrics do not show a similar signal. In the literature, numerous attempts have been made to explain these differences using several physical mechanisms. This study provides evidence that characterization of drought from different statistical perspectives can lead to unreliable detection of climatological/hydrological droughts in model projections and accordingly give a “false alarm” of the impacts of future climate change. In particular, this study analyses future projections based on different drought metrics and stresses that detecting trends in drought behavior in future projections must consider the extreme character of drought events by comparing the percentage change in drought magnitude relative to a reference climatological period and rely on the frequency of events in the tail of the distribution. In addition, the autoregressive character of drought indices makes necessary the use of the same temporal scale when comparing different drought metrics in order to maintain comparability. Taking into consideration all these factors, our study demonstrates that climatological and hydrological drought trends are likely to undergo similar temporal evolution during the 21st century, with almost 30% of the global land areas experiencing water deficit under future greenhouse gas emissions scenarios. As such, a proper characterization of drought using comparable metrics can introduce lower differences and more consistent outputs for future climatic and hydrologic droughts., Ministerio de Ciencia e Innovación, Grant/Award Number: CGL2017‐82216‐R; European Union, Grant/Award Number: 690462; European Commission

35 Pags.- 8 Figs.- 6 Tabls. The definitive version is available at: http://rmets.onlinelibrary.wiley.com/hub/journal/10.1002/(ISSN)1097-0088, This study analyses variability and trends of atmospheric evaporative demand (AED) across Uruguay in the past four decades. Changes were assessed using pan evaporation measurements from 10 meteorological stations and compared to PenPan model calculations, which is a physically based model that employs meteorological data as input. Results demonstrate a high agreement between the observed AED and those estimated from the PenPan model. Both observations and model estimations agree on a high interannual variability in AED, though being statistically insignificant (p > 0.05) at seasonal and annual scales. Given that AED shows high sensitivity to changes in relative humidity and sunshine duration, as a surrogate of solar radiation, the lack of significant trends in the AED observations and estimations over Uruguay can be linked to the insignificant trend found for these climate variables for the period from 1973 to 2014. This is the first study that reports Pan evaporation trends for this part of the world, helping to infill gaps for mid-latitude Southern Hemisphere areas, which are poorly represented in Pan evaporation trends., This work was supported by the by the EPhysLab (UVIGO-CSIC Associated Unit) and research projects I-Link1001 financed by CSIC, PCIN-2015-220, CGL2014-52135-C03-01, Red de variabilidad y cambio climático RECLIM (CGL2014-517221-REDT) financed by the Spanish Commission of Science and Technology and FEDER, and IMDROFLOOD financed by the Water Works 2014 co-funded call of the European Commission.

In this study we analyze the observed trends for the period 1950-2006 in a number of climate indices related to the occurrence of winter warm events in the Ebro basin, northeast Iberian Peninsula. Climatic simulations using 12 regional climate models (RCMs) from the ENSEMBLES database enable calculation of the multi-model means for the projected evolution of these climatic indices for the time periods 2021-2050 and 2051-2080. The results based on observations indicate a significant increase in occurrence of warm and very warm days and nights, melting events at 2000m a.s.l. and the duration of warm spells across most of the study area. The number of warm spells comprising at least five consecutive warm days or nights also tends to increase, although the trend is not statistically significant for many of the observatories involved in the study. The RCMs project that the trends observed during the observation period will continue, and that the occurrence of warm day and night events and spells are very likely to increase during this century. In some cases the occurrence of warm events is projected to double during the period 2021-2050, and continue increasing for the period 2051-2080. For both the observed and projected periods, most of the indices show a greater increase in the occurrence of these events in the mountain areas of the basin (the Pyrenees and the Iberian mountains). © 2013 Royal Meteorological Society., We thank the Agencia Estatal de Meteorología for providing the temperature data used in this study. This work was supported by the research projects CGL2011-27574-CO2-02 and CGL2011-27536, financed by the Spanish Commission of Science and Technology and FEDER; and ACQWA (FP7-ENV-2007-1-212250), financed by the VII Framework Programme of the European Commission; Efecto de los escenarios de cambio climatico sobre la hidrología superficial y la gestión de embalses del PirineoAragonés, financed by Obra Social La Caixa and the Aragón Government and Influencia del cambioclimático en el turismo de nieve CTTP01/10, financed by the Comunidad de Trabajo de los Pirineos.

[ES] En este estudio se analizaron las tendencias observadas en una serie de índices climáticos relacionados con la ocurrencia de eventos cálidos invernales en la cuenca del río Ebro, noreste de la Península Ibérica, durante el período 1950-2006. Las simulaciones de los mismos índices para el futuro se han estudiado utilizando las proyecciones de 12 modelos climáticos regionales (RCMs) para los periodos 2021-2050 y 2051-2080. Los resultados indicaron un aumento significativo en el número de días y noches cálidos y muy cálidos en la mayor parte del área de estudio. El aumento en la ocurrencia de eventos cálidos se relaciona con un aumento en los días de fusión de nieve por encima de 2000 m s.n.m. Los modelos climáticos regionales proyectan que las tendencias observadas durante el período observado continuarán, siendo muy probable un incremento en la ocurrencia de eventos cálidos invernales en las próximas décadas. En algunos casos, la ocurrencia de eventos cálidos se prevé que se duplique durante el período de 2021-2050. La mayoría de los índices mostraron un mayor incremento en las zonas montañosas de la cuenca (los Pirineos y el Sistema Ibérico) tanto para el periodo observado como para las proyecciones para las próximas décadas. [EN] In this study we analyzed the observed trends for the period 1950–2006 in a number of climate indices related to the occurrence of winter warm events in the Ebro basin, northeast Iberian Peninsula. Climatic simulations using12 regional climate models (RCMs) from the ENSEMBLES database enabled calculation of the inter-model means for the projected evolution of these climatic indices for the time periods2021–2050 and 2051–2080.The results indicated a significant increase in the future occurrence of warm and very warm day and night events across the majority of the study area. The increase in the occurrence and duration of warm events was statistically correlated with the occurrence of melt events in areas at altitudes higher than 2000 m a.s.l. The RCMs predicted that the trends observed during the observation period will continue, and that the occurrence of warm day and night events and spells are very likely to increase progressively during this century. In some cases the occurrence of warm events was predicted to double during the period 2021–2050. For both the observed and projected periods, most of the indices showed a greater increase in the occurrence of these events in mountain areas of the basin (the Pyrenees and the Iberian mountains)., Agradecemos a la Agencia Estatal de Meteorología el suministro de datos utilizados en este estudio. Este trabajo ha sido financiado por los proyectos cicyt CGL2011-27574-CO2-02 and CGL2011-27536, el proyecto europeo ACQWA (FP7-ENV-2007-1- 212250), el proyecto DGA-La Caixa: “Efecto de los escenarios de cambio sobre la hidrología superficial y la gestión de embalses del Pirineo Aragonés, y el proyecto financiado por la Comunidad de Trabajo de los Pirineos (CTTP01/10): “La Influencia del cambio climático en el turismo de nieve”.

38 Pag., 5 Tabl., 6 Fig. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-0088, The temporal evolution of nine daily precipitation indices over the northeastern Iberian Peninsula was analysed for the period 1955–2006, using data from 217 observatories. Cross-tabulation analysis enabled detection of statistically significant overlap among spatial distributions of trends in the study area. There was a general decrease in annual precipitation at most observatories, a decrease in the number of rainy days and precipitation intensity and an increase in the duration of dry spells. The frequency and contribution to annual precipitation of moderate and heavy rainfall events did not change at most observatories, or showed a decreasing trend in these events. There was very large spatial and seasonal variability, with implications for water management and risk assessment in the region. The decrease in precipitation was very marked in headwaters during winter and spring, potentially affecting reservoir management in the region. Heavy rainfall events generally decreased in the west of the region in winter, and in the east of the region in autumn, when these areas are more exposed to hazards related to extreme rainfall. Large differences in the sign and magnitude of trends occurred over very short distances, suggesting the need for dense networks of observatories to ensure reliable and robust detection of regional trends., This study was supported by the PROBASE projects CGL2006-11619 and CGL2008-01189/BTE, both financed by the Spanish Commission of Science and Technology (Ministry of Education and Science) and FEDER, and the FP7 EU project ACQWA (Assessing Climatic Change and Impact on the Quantity and Quality of Water).

120 páginas., The objective of this study was to examine how semi-variograms can be used to model the spatial variability of water quality in Lake Manzala, Egypt. The lake has potential economic value not only to the local community but also to the national economy. The lake wetland habitats are rich in wildlife species. More recently, the lake has been subje... more »cted to abrupt changes in its water quality giving the most alarming example amongst the northern Egyptian lakes as a result of economic development, urbanization and population growth,urban agglomeration and land reclamation schemes. Spherical models were found to be a more successful estimator of water quality condition and were of support to traditional methods as an adequate tool to provide valuable spatial and temporal detailed information about water quality in the Lake. Ordinary Kriging provided good estimations of water quality parameters points in the lake where field sampling was limited and which can be of importance in future sampling schemes. The modeled distribution of water quality was presented in the form of digital maps based on both traditional sample data and variogram models.

22 Pag., 17 Fig., The SPEIbase is a global SPEI dataset at time scales from 1 to 48 months with a spatial resolution of 0.5° for the period 1901-2006. It is based on the CRU TS3 dataset, the most complete and up-to-date source of gridded temperature and precipitation data for the entire World. It is also based on the same grid and time structure. Monthly temperature data was used to compute the ET0 based on the approximation of Thornthwaite (1948). Overview of the talk: 1. The SPEI: motivation, advantages 2. The SPEIbase: methodology, data sources, distribution 3. Examples of use 4. Data distribution