scholarly journals Climate change projections of boreal summer precipitation over tropical America by using statistical downscaling from CMIP5 models

2017 ◽  
Vol 12 (12) ◽  
pp. 124011 ◽  
Author(s):  
Reiner Palomino-Lemus ◽  
Samir Córdoba-Machado ◽  
Sonia Raquel Gámiz-Fortis ◽  
Yolanda Castro-Díez ◽  
María Jesús Esteban-Parra
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Summer Precipitation ◽  
Cmip5 Models ◽  
Boreal Summer ◽  
Climate Change Projections ◽  
Tropical America

Representation of the Angolan low and Southern African Summer Precipitation in the CORDEX and CMIP5 models. 

2021 ◽  
Author(s):  
Sabina Abba-Omar ◽  
Francesca Raffaele ◽  
Erika Coppola ◽  
Daniela Jacob ◽  
Claas Teichmann ◽  
...  
Keyword(s):  
Climate Change ◽  
Regression Analysis ◽  
Southern Africa ◽  
Summer Precipitation ◽  
Precipitation Variability ◽  
Cmip5 Models ◽  
Impact Of Climate Change ◽  
The Future ◽  
Rainfall Patterns ◽  
The Impact

<p>The impact of climate change on precipitation over Southern Africa is of particular interest due to its possible devastating societal impacts. To add to this, simulating precipitation is challenging and models tend to show strong biases over this region, especially during the Austral Summer (DJF) months. One of the reasons for this is the mis-representation of the Angolan Low (AL) and its influence on Southern Africa’s Summer precipitation in the models. Therefore, this study aims to explore and compare different models’ ability to capture the AL and its link to precipitation variability as well as consider the impact climate change may have on this link. We also explore how the interaction between ENSO, another important mode of variability for precipitation, and the Angolan Low, impact precipitation, how the models simulate this and whether this could change in the future under climate change. </p><p>We computed the position and strength of the AL in reanalysis data and compared these results to three different model ensembles with varying resolutions. Namely, the CORDEX-CORE ensemble (CCORE), a new phase of CORDEX simulations with higher resolutions (0.22 degrees), the lower resolution (0.44 degrees) CORDEX-phase 1 ensemble (C44) and the CMIP5 models that drive the two RCM ensembles. We also used Self Organizing Maps to group DJF yearly anomaly patterns and identify which combination of ENSO and AL strength scenarios are responsible for particularly wet or dry conditions. Regression analysis was performed to analyze the relationships between precipitation and the AL and ENSO. This analysis was repeated for near (2041-2060) and far (2080-2099) future climate and compared with the present to understand how the strength of the AL, and its connection to precipitation variability and ENSO, changes in the future. </p><p>We found that, in line with previous studies, models with stronger AL tend to produce more rainfall. CCORE tends to simulate a stronger AL than C44 and therefore, higher precipitation biases. However, the regression analysis shows us that CCORE is able to capture the relationship between precipitation and the AL strength variability as well as ENSO better than the other ensembles. We found that generally dry rainfall patterns over Southern Africa are associated with a weak AL and El Nino event whereas wet rainfall patterns occur during a strong AL and La Nina year. While the models are able to capture this, they also tend to show more neutral ENSO conditions associated with these wet and dry patterns which possibly indicates less of a connection between AL strength and ENSO than seen in the observed results. Analysis of the future results indicates that the AL weakens, this is shown across all the ensembles and could be a contributing factor to some of the drying seen. These results have applications in understanding and improving model representation of precipitation over Southern Africa as well as providing some insight into the impact of climate change on precipitation and some of its associated dynamics over this region.</p>

scholarly journals Climate change assessment for Mediterranean agricultural areas by statistical downscaling

2010 ◽  
Vol 10 (7) ◽  
pp. 1647-1661 ◽  
Author(s):  
L. Palatella ◽  
M. M. Miglietta ◽  
P. Paradisi ◽  
P. Lionello
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Statistical Downscaling ◽  
Principal Component ◽  
Summer Precipitation ◽  
Ebro River ◽  
Po Valley ◽  
Apulia Region ◽  
Climate Change Assessment ◽  
Agricultural Areas

Abstract. In this paper we produce projections of seasonal precipitation for four Mediterranean areas: Apulia region (Italy), Ebro river basin (Spain), Po valley (Italy) and Antalya province (Turkey). We performed the statistical downscaling using Canonical Correlation Analysis (CCA) in two versions: in one case Principal Component Analysis (PCA) filter is applied only to predictor and in the other to both predictor and predictand. After performing a validation test, CCA after PCA filter on both predictor and predictand has been chosen. Sea level pressure (SLP) is used as predictor. Downscaling has been carried out for the scenarios A2 and B2 on the basis of three GCM's: the CCCma-GCM2, the Csiro-MK2 and HadCM3. Three consecutive 30-year periods have been considered. For Summer precipitation in Apulia region we also use the 500 hPa temperature (T500) as predictor, obtaining comparable results. Results show different climate change signals in the four areas and confirm the need of an analysis that is capable of resolving internal differences within the Mediterranean region. The most robust signal is the reduction of Summer precipitation in the Ebro river basin. Other significative results are the increase of precipitation over Apulia in Summer, the reduction over the Po-valley in Spring and Autumn and the increase over the Antalya province in Summer and Autumn.

scholarly journals Oxygen minimum zones in the tropical Pacific across CMIP5 models: mean state differences and climate change trends

2015 ◽  
Vol 12 (8) ◽  
pp. 6525-6587 ◽  
Author(s):  
A. Cabré ◽  
I. Marinov ◽  
R. Bernardello ◽  
D. Bianchi
Keyword(s):  
Climate Change ◽  
Tropical Pacific ◽  
Cmip5 Models ◽  
Upper Ocean ◽  
Intermediate Water ◽  
Climate Change Projections ◽  
Oxygen Minimum Zones ◽  
Mean State ◽  
Oxygen Minimum ◽  
The Tropical Pacific

Abstract. We analyze simulations of the Pacific Ocean oxygen minimum zones (OMZs) from 11 Earth System model contributions to the Coupled Model Intercomparison Project Phase 5, focusing on the mean state and climate change projections. The simulations tend to overestimate the volume of the OMZs, especially in the tropics and Southern Hemisphere. Compared to observations, five models introduce incorrect meridional asymmetries in the distribution of oxygen including larger southern OMZ and weaker northern OMZ, due to interhemispheric biases in intermediate water mass ventilation. Seven models show too deep an extent of the tropical hypoxia compared to observations, stemming from a deficient equatorial ventilation in the upper ocean combined with a too large biologically-driven downward flux of particulate organic carbon at depth, caused by too high particle export from the euphotic layer and too weak remineralization in the upper ocean. At interannual timescales, the dynamics of oxygen in the eastern tropical Pacific OMZ is dominated by biological consumption and linked to natural variability in the Walker circulation. However, under the climate change scenario RCP8.5, all simulations yield small and discrepant changes in oxygen concentration at mid depths in the tropical Pacific by the end of the 21st century due to an almost perfect compensation between warming-related decrease in oxygen saturation and decrease in biological oxygen utilization. Climate change projections are at odds with recent observations that show decreasing oxygen levels at mid depths in the tropical Pacific. Out of the OMZs, all the CMIP5 models predict a decrease of oxygen over most of the surface, deep and high latitudes ocean due to an overall slow-down of ventilation and increased temperature.

scholarly journals Climate change projections of temperature and precipitation in Chile based on statistical downscaling

2020 ◽  
Vol 54 (9-10) ◽  
pp. 4309-4330 ◽  
Author(s):  
Daniela Araya-Osses ◽  
Ana Casanueva ◽  
Celián Román-Figueroa ◽  
Juan Manuel Uribe ◽  
Manuel Paneque
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Climate Change Projections ◽  
Temperature And Precipitation

scholarly journals Evaluation of statistical downscaling methods for climate change projections over Spain: present conditions with perfect predictors

2021 ◽  
Author(s):  
Alfonso Hernanz ◽  
Juan Andrés García‐Valero ◽  
Marta Domínguez ◽  
Petra Ramos‐Calzado ◽  
María A. Pastor‐Saavedra ◽  
...  
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Climate Change Projections

scholarly journals Oxygen minimum zones in the tropical Pacific across CMIP5 models: mean state differences and climate change trends

2015 ◽  
Vol 12 (18) ◽  
pp. 5429-5454 ◽  
Author(s):  
A. Cabré ◽  
I. Marinov ◽  
R. Bernardello ◽  
D. Bianchi
Keyword(s):  
Climate Change ◽  
Tropical Pacific ◽  
Cmip5 Models ◽  
Upper Ocean ◽  
Intermediate Water ◽  
Climate Change Projections ◽  
Oxygen Minimum Zones ◽  
Mean State ◽  
Oxygen Minimum ◽  
The Tropical Pacific

Abstract. We analyse simulations of the Pacific Ocean oxygen minimum zones (OMZs) from 11 Earth system model contributions to the Coupled Model Intercomparison Project Phase 5, focusing on the mean state and climate change projections. The simulations tend to overestimate the volume of the OMZs, especially in the tropics and Southern Hemisphere. Compared to observations, five models introduce incorrect meridional asymmetries in the distribution of oxygen including larger southern OMZ and weaker northern OMZ, due to interhemispheric biases in intermediate water mass ventilation. Seven models show too deep an extent of the tropical hypoxia compared to observations, stemming from a deficient equatorial ventilation in the upper ocean, combined with too large a biologically driven downward flux of particulate organic carbon at depth, caused by particle export from the euphotic layer that is too high and remineralization in the upper ocean that is too weak. At interannual timescales, the dynamics of oxygen in the eastern tropical Pacific OMZ is dominated by biological consumption and linked to natural variability in the Walker circulation. However, under the climate change scenario RCP8.5, all simulations yield small and discrepant changes in oxygen concentration at mid depths in the tropical Pacific by the end of the 21st century due to an almost perfect compensation between warming-related decrease in oxygen saturation and decrease in biological oxygen utilization. Climate change projections are at odds with recent observations that show decreasing oxygen levels at mid depths in the tropical Pacific. Out of the OMZs, all the CMIP5 models predict a decrease of oxygen over most of the surface and deep ocean at low latitudes and over all depths at high latitudes due to an overall slow-down of ventilation and increased temperature.

scholarly journals Incorporation of Long Term Climate Changes in Hydrological Modelling

2019 ◽  
Vol 8 (10) ◽  
pp. 4521-4526
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
General Circulation ◽  
Global Climate ◽  
Circulation Model ◽  
Cmip5 Models ◽  
Future Climate Change ◽  
Statistical Downscaling Model ◽  
Intergovernmental Panel ◽  
Statistical Relationships

One of climate change's most important concerns at the moment is its impact on hydrology as it has direct links with agriculture, vegetation, and livelihood. This study tries to analyze potential future climate change in the Kumaradhara river basin. This study involved three steps: (1) acquiring and using general circulation model (GCM) to project future global climate scenarios; (2) establishing statistical relationships between GCM data and observed data using Statistical Downscaling Model (SDSM); (3) downscaling the second generation Canadian Earth system Model (CanESM2)GCM output based on the established statistical relationship. The statistical downscaling is carried out for three scenarios used in the fifth evaluation report of the recent Intergovernmental Panel on Climate Change (IPCC) viz., Representative Concentration Pathways (RCPs) 2.6, 4.5 and 8.5. The statistical downscaling Model (SDSM) results showed that the mean annual daily precipitation is altered in the basin under all the scenarios but it will be different in different time periods depending on scenarios and the basin will experience the reduced precipitation levels in summer. Also the precipitation will marginally rise in all the time slices with reference to baseline data. We can conclude from the results that this region's climate will affect future farming as the availability of water is bound to change. This study should, however, be followed up by a larger study incorporating multiple CMIP5 models such that changes in hydrological-regimes can be examined appropriately.

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