scholarly journals European drought trends

2015 ◽  
Vol 369 ◽  
pp. 75-79 ◽  
Author(s):  
L. Gudmundsson ◽  
S. I. Seneviratne
Keyword(s):  
Time Scales ◽  
Multiple Testing ◽  
Standardized Precipitation Index ◽  
Multiple Time Scales ◽  
Climate Projections ◽  
Multiple Time ◽  
Drought Frequency ◽  
The Past ◽  
The North ◽  
Recent Climate

Abstract. Recent climate projections suggest pronounced changes in European drought frequency. In the north, increased precipitation volumes are likely to reduce drought occurrence, whereas more frequent droughts are expected for southern Europe. To assess whether this pattern of changes in drought frequency can already be identified for the past decades, we analyse trends in a recently developed pan-European drought climatology that is based on the Standardized Precipitation Index (SPI). The index is derived on multiple time scales, ranging from 1 to 36 months, which allows the assessment of trends in both short term and multi-year droughts. Trends are quantified using the Theil-Sen trend estimator combined with an extension of the Mann–Kendal test (p < 0.05) that accounts for serial correlation. Field significance is assessed on the basis of techniques that control the false discovery rate in a multiple testing setting. The trend analysis indicates that changes in drought frequency are more pronounced on time scales of one year and longer. The analysis also reveals that there has been a tendency for decreased drought frequency in northern Europe in the past decades, whereas droughts have likely become more frequent in selected southern regions.

scholarly journals The Evaporative Demand Drought Index. Part II: CONUS-Wide Assessment against Common Drought Indicators

2016 ◽  
Vol 17 (6) ◽  
pp. 1763-1779 ◽  
Author(s):  
Daniel J. McEvoy ◽  
Justin L. Huntington ◽  
Michael T. Hobbins ◽  
Andrew Wood ◽  
Charles Morton ◽  
...  
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Time Scales ◽  
Drought Index ◽  
Standardized Precipitation Index ◽  
Stress Index ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Evaporative Demand ◽  
Hydrologic Drought

Abstract Precipitation, soil moisture, and air temperature are the most commonly used climate variables to monitor drought; however, other climatic factors such as solar radiation, wind speed, and humidity can be important drivers in the depletion of soil moisture and evolution and persistence of drought. This work assesses the Evaporative Demand Drought Index (EDDI) at multiple time scales for several hydroclimates as the second part of a two-part study. EDDI and individual evaporative demand components were examined as they relate to the dynamic evolution of flash drought over the central United States, characterization of hydrologic drought over the western United States, and comparison to commonly used drought metrics of the U.S. Drought Monitor (USDM), Standardized Precipitation Index (SPI), Standardized Soil Moisture Index (SSI), and the evaporative stress index (ESI). Two main advantages of EDDI over other drought indices are that it is independent of precipitation (similar to ESI) and it can be decomposed to identify the role individual evaporative drivers have on drought onset and persistence. At short time scales, spatial distributions and time series results illustrate that EDDI often indicates drought onset well in advance of the USDM, SPI, and SSI. Results illustrate the benefits of physically based evaporative demand estimates and demonstrate EDDI’s utility and effectiveness in an easy-to-implement agricultural early warning and long-term hydrologic drought–monitoring tool with potential applications in seasonal forecasting and fire-weather monitoring.

scholarly journals Assessment of the influence of bias correction on meteorological drought projections for Poland

2015 ◽  
Vol 12 (10) ◽  
pp. 10331-10377 ◽  
Author(s):  
M. Osuch ◽  
R. J. Romanowicz ◽  
D. Lawrence ◽  
W. K. Wong
Keyword(s):  
Time Scales ◽  
Bias Correction ◽  
Climate Model ◽  
Precipitation Index ◽  
Future Climate Change ◽  
Multiple Time Scales ◽  
Climate Projections ◽  
Multiple Time ◽  
Monthly Precipitation ◽  
Standard Precipitation Index

Abstract. Possible future climate change effects on drought severity in Poland are estimated for six ENSEMBLE climate projections using the Standard Precipitation Index (SPI). The time series of precipitation represent six different RCM/GCM run under the A1B SRES scenario for the period 1971–2099. Monthly precipitation values were used to estimate the Standard Precipitation Index (SPI) for multiple time scales (1, 3, 6, 12 and 24 months) for a spatial resolution of 25 km × 25 km for the whole country. Trends in SPI were analysed using a Mann–Kendall test with Sen's slope estimator for each 25 km × 25 km grid cell for each RCM/GCM projection and timescale, and results obtained for uncorrected precipitation and bias corrected precipitation were compared. Bias correction was achieved using a distribution-based quantile mapping (QM) method in which the climate model precipitation series were adjusted relative to gridded E-OBS precipitation data for Poland. The results show that the spatial pattern of the trend depends on the climate model, the time scale considered and on the bias correction. The effect of change on the projected trend due to bias correction is small compared to the variability among climate models. We also summarise the mechanisms underlying the influence of bias correction on trends using a simple example of a linear bias correction procedure. In the case of precipitation the bias correction by QM does not change the direction of changes but can change the slope of trend. We also have noticed that the results for the same GCM, with differing RCMs, are characterized by similar pattern of changes, although this behaviour is not seen at all time scales and seasons.

scholarly journals Classificação de Eventos Extremos de Precipitação em Múltiplas Escalas de Tempo em Belém-PA: Utilizando o Índice de Precipitação Normalizada (Classification of Extreme Precipitation Events in Multiple Time Scales in Belém, PA: Using the Standardized ...)

2014 ◽  
Vol 7 (4) ◽  
pp. 628
Author(s):  
Sérgio Rodrigo Quadros dos Santos ◽  
Celia Campos Braga ◽  
Ana Paula Paes dos Santos ◽  
Thamiris Luiza De Oliveira Brandão Campos ◽  
José Ivaldo Barbosa de Brito
Keyword(s):  
Time Scales ◽  
Extreme Event ◽  
Standardized Precipitation Index ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Monthly Precipitation ◽  
Extreme Precipitation Events ◽  
The Standardized Precipitation Index ◽  
The City

O Índice de Precipitação Normalizada (SPI) é utilizado para quantificar o déficit e/ou excesso de precipitação nas múltiplas escalas de tempo. Ele tem se mostrado bastante útil no monitoramento da precipitação, principalmente pela sua flexibilidade, simplicidade de cálculo e interpretação. Desta forma este estudo tem como objetivo quantificar os eventos extremos secos e chuvosos na cidade de Belém-PA nas escalas de tempo de 3, 6 e 12 meses por meio do SPI. Para isto, utilizaram-se dados mensais de precipitação provenientes da estação meteorológicas de superfície do INMET no período de 1980-2011. Os resultados mostraram que a escala de tempo do SPI é inversamente proporcional à frequência dos eventos de chuva e seca. Os SPIs 3,6 e 12 mostraram mais eventos secos do que chuvosos para a cidade e a maioria dos eventos de chuva e seca estavam associados, principalmente, ao fenômeno ENOS. ABSTRACT The Standardized Precipitation Index (SPI) is used to quantify the deficit/ excess rainfall at multiple time scales. It has been very useful in monitoring of precipitation, mainly because of its flexibility, ease of calculation and interpretation. Thus this study aims to quantify the extreme wet and dry events in the city of Belém-PA in time scales of 3, 6 and 12 months by SPI. For this, we used monthly precipitation data from meteorological station at the INMET in the period 1980-2011. The results show that the timescale of the SPI is inversely proportional to the frequency of rain and dry events. The SPIs 3.6 and 12 showed driest events that rainy events to the city and most of the rainfall and drought events were associated, mainly, with the ENSO phenomenon. Key Words: Belem; SPI; Extreme Event.   

scholarly journals Climate change effects on drought severity

2008 ◽  
Vol 17 ◽  
pp. 23-29 ◽  
Author(s):  
A. Loukas ◽  
L. Vasiliades ◽  
J. Tzabiras
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Standardized Precipitation Index ◽  
Precipitation Index ◽  
Geographical Information ◽  
Multiple Time Scales ◽  
Drought Severity ◽  
Multiple Time ◽  
Monthly Precipitation ◽  
Climate Change Effects

Abstract. This paper evaluates climate change effects on drought severity in the region of Thessaly, Greece. The Standardized Precipitation Index (SPI) has been used for estimation of drought severity. A geographical information system is applied for the division of Thessaly region to twelve hydrological homogeneous areas based on their geomorphology. Mean monthly precipitation values from 50 precipitation stations of Thessaly for the hydrological period October 1960–September 1990 were used for the estimation of mean areal precipitation. These precipitation timeseries have been used for the estimation of Standardized Precipitation Index (SPI) for multiple time scales (1-, 3-, 6-, 9-, and 12-months) for each sub-basin or area. The outputs of Global Circulation Model CGCM2 were applied for two socioeconomic scenarios, namely, SRES A2 and SRES B2 for the assessment of climate change impact on droughts. The GCM outputs were downscaled to the region of Thessaly using a statistical methodology to estimate precipitation time series for two future periods 2020–2050 and 2070–2100. A method has been proposed for the estimation of annual cumulative drought severity-time scale-frequency curves. These curves integrate the drought severity and frequency for various types of drought. The SPI timeseries and annual weighted cumulative drought severity were estimated and compared with the respective timeseries and values of the historical period 1960–1990. The results showed that the annual drought severity is increased for all hydrological areas and SPI time scales, with the socioeconomic scenario SRES A2 being the most extreme.

scholarly journals Unraveling the spatial diversity of Indian precipitation teleconnections via nonlinear multi-scale approach

2019 ◽  
Author(s):  
Jürgen Kurths ◽  
Ankit Agarwal ◽  
Norbert Marwan ◽  
Maheswaran Rathinasamy ◽  
Levke Caesar ◽  
...  
Keyword(s):  
Time Scales ◽  
Southern Oscillation ◽  
Indian Subcontinent ◽  
Spatial Diversity ◽  
Wavelet Coherence ◽  
Multiple Time Scales ◽  
Multiscale Approach ◽  
Multiple Time ◽  
The North ◽  
Wavelet Coherence Analysis

Abstract. A better understanding of precipitation dynamics in the Indian subcontinent is required since India’s society depends heavily on reliable monsoon forecasts. We introduce a nonlinear, multiscale approach, based on wavelets and event synchronization, for unraveling teleconnection influences on precipitation. We consider those climate patterns with highest relevance for Indian precipitation. Our results suggest significant influences which are not well captured by only the wavelet coherence analysis, the state-of-the-art method in understanding linkages at multiple time scales. We find substantial variation across India and across time scales. In particular, El Niño/Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) mainly influence precipitation in the southeast at interannual and decadal scales, respectively, whereas the North Atlantic Oscillation (NAO) has a strong connection to precipitation particularly in the northern regions. The effect of PDO stretches across the whole country, whereas AMO influences precipitation particularly in the central arid and semi-arid regions. The proposed method provides a powerful approach for capturing the dynamics of precipitation and, hence, helps improving precipitation forecasting.

SOME REMARKS ON THE MULTIPLE TIME SCALES OF DIFFUSION IN MINERALS AND MELTS

2018 ◽  
Author(s):  
Yan Liang ◽  
◽  
Daniele J. Cherniak ◽  
Chenguang Sun
Keyword(s):  
Time Scales ◽  
Multiple Time Scales ◽  
Multiple Time
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