Transitions between dry and wet periods in Europe during 1950–2019

2021 ◽  
Author(s):  
Zuzana Bestakova ◽  
Petr Maca ◽  
Jan Kysely ◽  
Ujjwal Singh ◽  
Yannis Markonis ◽  
...  
Keyword(s):  
Potential Evapotranspiration ◽  
Aridity Index ◽  
Research Unit ◽  
Climatic Research Unit ◽  
Energy Availability ◽  
East Anglia ◽  
Weather Forecasts ◽  
Humid Environment ◽  
Medium Range ◽  
Dry Conditions

<p>The study deals with probabilities of transitions from arid to humid environment and vice versa in<br>Europe. Aridity index, defined as a ratio of potential evapotranspiration and precipitation and<br>representing the ratio between energy availability and water availability, is used to characterize humid<br>(wet) and arid (dry) regions and allows us to study transitions between individual periods (wet-wet,<br>wet-dry, dry-dry, dry-wet). Three gridded datasets – CRU (UEA, 2020), E-OBS (ECAD, 2020) and ERA5<br>(ECMWF, 2020) – are used for this purpose. The aim of the study is to compare the three datasets as<br>to transitions between wet and dry conditions, which are determined according to the aridity index,<br>and evaluate the variability in Europe over 1950–2019. The changes in the aridity index since 1950 are<br>found to be most pronounced in Northern and Central Europe.</p><p><br>references:<br>ECAD, 2020: E-OBS gridded dataset, available from<br><https://www.ecad.eu/download/ensembles/download.php>.<br>UEA, 2020: University of East Anglia – Climatic Research Unit, available from<br><https://lr1.uea.ac.uk/cru/data>.<br>ECMWF, 2020: European Centre for Medium-Range Weather Forecasts – ERA5, available from<br><https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5>.</p>

Economical exposition to drought events (1980-2001)

2017 ◽  
Author(s):  
Chloé Meyer
Keyword(s):  
World Bank ◽  
Standardized Precipitation Index ◽  
Research Unit ◽  
Precipitation Index ◽  
Climatic Research Unit ◽  
Columbia University ◽  
East Anglia ◽  
Gis Modeling ◽  
The World Bank ◽  
Year 2000

Estimation of the annual economical exposition to drought based on Standardized Precipitation Index. It is based on three sources: 1) A global monthly gridded precipitation dataset obtained from the Climatic Research Unit (University of East Anglia). 2) A GIS modeling of global Standardized Precipitation Index based on Brad Lyon (IRI, Columbia University) methodology. 3) A Global Domestic Product grid for the year 2010, provided by the World Bank. Unit is expected average annual GDP (2007 as the year of reference) exposed in (US $, year 2000 equivalent). For more information, visit: http://preview.grid.unep.ch/ Cost Drought Exposure Risk

scholarly journals Streamflow projections for the Brazilian hydropower sector from RCP scenarios

2016 ◽  
Vol 8 (1) ◽  
pp. 114-126 ◽  
Author(s):  
Cleiton da Silva Silveira ◽  
Francisco de Assis de Souza Filho ◽  
Francisco das Chagas Vasconcelos Júnior
Keyword(s):  
Potential Evapotranspiration ◽  
Research Unit ◽  
Climatic Research Unit ◽  
Monthly Precipitation ◽  
Intergovernmental Panel ◽  
Rcp Scenarios ◽  
Soil Moisture Accounting ◽  
Northern Regions ◽  
The Impact ◽  
Observational Record

Streamflow projections were estimated for river basins of relevance to the Brazilian hydroelectric sector from monthly precipitation projections from global models of the fifth report of the Intergovernmental Panel on Climate Change – IPCC-AR5 from 2010 to 2098 for RCP4.5 and RCP8.5 scenarios. Streamflow were computed using the Soil Moisture Accounting Procedure (SMAP) hydrological model, which was forced by bias-corrected precipitation from the monthly rain data of the Climatic Research Unit and by the estimation of potential evapotranspiration according to the Penman–Monteith method. The impacts on average annual streamflow were analyzed for the periods 2010–2039, 2040–2069 and 2070–2098 in comparison with the observational record (historical experiment) from 1950 to 1999. Most IPCC-AR5 models agree in terms of the impact on the electrical sector in the southeastern/midwestern and northern regions, showing that streamflow may be reduced up to 15% in each 30-year period on Furnas basin and approximately 30% by the end of the century in Tucuruí basin under RCP8.5 scenario. In the northeastern sector, the divergence of the models suggests great uncertainty, emphasized in the Xingó basin. In the southern sector, results show increasing streamflow over southernmost Brazil and decreasing over intersection between southern and southeastern regions.

scholarly journals Spatiotemporal Trends and Attribution of Drought across China from 1901–2100

2020 ◽  
Vol 12 (2) ◽  
pp. 477
Author(s):  
Yongxia Ding ◽  
Shouzhang Peng
Keyword(s):  
Adverse Effects ◽  
General Circulation ◽  
Potential Evapotranspiration ◽  
Northern China ◽  
General Circulation Models ◽  
Research Unit ◽  
Mitigation Strategies ◽  
Climatic Research Unit ◽  
The Past ◽  
Spatiotemporal Trends

Investigating long-term drought trends is of great importance in coping with the adverse effects of global warming. However, little attention has been focused on studying the detailed spatial variability and attribution of drought variation in China. In this study, we first generated a 1 km resolution monthly climate dataset for the period 1901–2100 across China using the delta spatial downscaling method to assess the variability of the Standardized Precipitation Evaporation Index (SPEI). We then developed a simple approach to quantifying the contributions of water supply (precipitation) and demand (potential evapotranspiration, PET) on SPEI variability, according to the meaning of the differentiating SPEI equation. The results indicated that the delta framework could accurately downscale and correct low-spatial-resolution monthly temperatures and precipitation from the Climatic Research Unit and general circulation models (GCMs). Of the 27 GCMs analyzed, the BNU-ESM, CESM1-CAM5, and GFDL-ESM2M were found to be the most accurate in modeling future temperatures and precipitation. We also found that, compared with the past (1901–2017), the climate in the future (2018–2100) will tend toward significant droughts, although both periods showed a high spatial heterogeneity across China. Moreover, the proportion of areas with significantly decreasing SPEI trends was far greater than the proportion of those with increasing trends in most cases, especially for northwestern and northern China. Finally, the proposed approach to quantifying precipitation and PET contributions performed well according to logical evaluations. The percentage contributions of precipitation and PET on SPEI variability varied with study periods, representative concentration pathway scenarios, trend directions, and geographic spaces. In the past, PET contributions for significant downward trends and precipitation contributions for significantly upward trends accounted for 95% and 72%, while their future contributions were 57 ± 22%–149 ± 20% and 95 ± 27%–190 ± 58%, respectively. Overall, our results provide detailed insights for planning flexible adaptation and mitigation strategies to cope with the adverse effects of climate drought across China.

scholarly journals Projeção da suscetibilidade a desertificação em Pernambuco utilizando o modelo HADGEM-ES (Projection of susceptibility to desertification in Pernambuco using the HADGEM-ES model)

2017 ◽  
Vol 10 (4) ◽  
pp. 1170
Author(s):  
Thalyta Soares dos Santos
Keyword(s):  
Coupled Model ◽  
Aridity Index ◽  
Research Unit ◽  
Climatic Research Unit ◽  
Model Intercomparison ◽  
Intergovernmental Panel ◽  
Desertification Process ◽  
Rcp 8.5 ◽  
Intercomparison Project ◽  
Brazilian Northeast

A suscetibilidade da região Nordeste do Brasil ao processo de desertificação está associada à variabilidade do clima e a fatores antropogênicos. Nesse contexto, extremos climáticos intensos associados à degradação do solo podem levar à aceleração do processo de desertificação no semiárido. O objetivo do trabalho é avaliar processo de desertificação no estado de Pernambuco e suas projeções para o século XXI. O estudo foi realizado com dados mensais de simulações de precipitação e temperatura do Climatic Research Unit (CRU) e projeções do modelo HADGEM2-ES derivado do Coupled Model Intercomparison Project Phase 5 (CMIP5, utilizados no quinto relatório do Intergovernmental Panel on Climate Change - IPCC-AR5) no cenário RCP 8.5. Para analise, a evapotranspiração potencial foi calculada pelo método de Thornthwaite, que serviu para o cálculo do índice de aridez. O índice de aridez é bastante utilizado nos estudos para a determinação de áreas secas e principalmente nos estudos do processo de desertificação. Os resultados indicaram que, considerando a variabilidade do climática atual e futura no Nordeste do Brasil, associada a ações antrópicas, o estado de Pernambuco tem uma alta suscetibilidade a desertificação.  A B S T R A C TThe Brazilian Northeast region susceptibility to desertification process is associated with climate variability and anthropogenic factors. Intense climatic extremes associated with soil degradation may accelerate the desertification process in the semiarid region. The main objective of this study is to evaluate the desertification process in Pernambuco state and its projections for the 21st century. The study was carried out with monthly precipitation and temperature datasets from Climatic Research Unit (CRU) and HADGEM2-ES projections, derived from the Coupled Model Intercomparison Project Phase 5 (CMIP5, used in the fifth report of the Intergovernmental Panel on Climate Change - IPCC -AR5) in the RCP 8.5 scenario. The potential evapotranspiration was calculated by the Thornthwaite method, which was used to calculate the aridity index. The aridity index is widely used in to determine dry areas, especially in desertification process studies. The results shows that, considering the current and future climate variability in Brazilian Northeast, associated with anthropic actions, Pernambuco has a high susceptibility to desertification.Keywords: CMIP5; Aridity Index; Semi-arid. 

scholarly journals Rankings of extreme and widespread dry and wet events in the Iberian Peninsula between 1901–2016

2020 ◽  
Author(s):  
Margarida L. R. Liberato ◽  
Irene Montero ◽  
Célia Gouveia ◽  
Ana Russo ◽  
Alexandre M. Ramos ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Time Scales ◽  
Extreme Events ◽  
Potential Evapotranspiration ◽  
Grid Point ◽  
Research Unit ◽  
Climatic Research Unit ◽  
The Impact ◽  
Monteith Equation

Abstract. Extensive, longstanding dry and wet episodes are one of the most frequent climatic extreme events in the Iberian Peninsula. Here, we present a method for ranking regional extremes of persistent, widespread drought and wet events, considering different time scales. The method is based on the multiscalar Standardized Precipitation Evapotranspiration Index (SPEI) gridded dataset for the Iberian Peninsula. SPEI was computed using the Climatic Research Unit (CRU) between 1901 and 2016 using a log-logistic probability distribution function. The Potential Evapotranspiration (PET) was computed through the Penmann-Monteith equation. The ranking classification method is based on the evaluation of the magnitude of an event, which is obtained after considering both the area affected respectively by the dryness or wetness – defined by SPEI values over a certain threshold – and its intensity in each grid point. A sensitivity analysis on the impact of different thresholds to define dry and wet events is performed. A comprehensive dataset of rankings of the most extreme, prolonged, widespread dry and wet periods in the Iberian Peninsula is presented, for aggregated time scales of 6, 12, 18 and 24 months. Results show that in the Iberian Peninsula there is not a region more prone to the occurrence of any of these long-term (dry and/or wet) most extreme events.

scholarly journals Climatic Variability and Estimation of Supplementary Irrigation Water Needs of Selected Food Crops in the Sokoto-Rima River Basin, Nigeria

2019 ◽  
Vol 3 (1) ◽  
pp. 86-104 ◽  
Author(s):  
C. N. Emeribe ◽  
E. T. Ogbomida ◽  
J. O. Enoma-Calus
Keyword(s):  
River Basin ◽  
Irrigation Water ◽  
Potential Evapotranspiration ◽  
Climatic Variability ◽  
Research Unit ◽  
Climatic Research Unit ◽  
Food Crops ◽  
Water Requirements ◽  
Irrigation Project ◽  
Supplementary Irrigation

The study investigated the effects of rainfall and temperature variability on crop water requirements of selected food crops in the Sokoto-Rima River Basin, Northwest of Nigeria. Rainfall and temperature datasets were obtained from the Climatic Research Unit (CRU) TS 3.21 of the University of East Anglia, Norwich, for a period of 70 years (1943-2012). The suitability of CRU datasets were verified by correlating the datasets with measured rainfall data of Yelwa synoptic station, from the Nigerian Meteorological Agency. Selected food crops were used for estimating supplementary irrigation water needs in the River basin. Results of Mann-Kendal, Spearman’s Rho and linear regression tests showed strong evidence of increasing annual temperature and potential evapotranspiration with corresponding decrease in rainfall amounts, especially in the northern parts of the basin which houses big irrigation projects and dams such as the Goronyo Irrigation and the Bakolori Dam and Bakolori Irrigation Project. This will impact on the water availability within the basin, through reduction in surface and ground water supply for ongoing irrigation and other water resources projects. Water requirements for selected crops were modeled to ascertain crop sensitivity to climatic variability which will aid in the design of supplementary irrigation water needs models. Results showed that even in the rainfall months, supplementary irrigation of varying quantity is required to complement rainfall, most especially, in the northeast of the basin. Surprisingly, the month of May which marks commencement of rainfall, recorded the highest water need and this has implication for agriculture yields in the region.

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