scholarly journals Projected Changes in the Annual Cycle of High-Intensity Precipitation Events over West Africa for the Late Twenty-First Century*

2015 ◽  
Vol 28 (16) ◽  
pp. 6475-6488 ◽  
Author(s):  
Mouhamadou Bamba Sylla ◽  
Filippo Giorgi ◽  
Jeremy S. Pal ◽  
Peter Gibba ◽  
Ibourahima Kebe ◽  
...  
Keyword(s):  
West Africa ◽  
Annual Cycle ◽  
High Intensity ◽  
Daily Precipitation ◽  
Monsoon Season ◽  
First Century ◽  
Increased Risk ◽  
Twenty First Century ◽  
Projected Changes ◽  
Precipitation Events

Abstract In this study, the response of the annual cycle of high-intensity daily precipitation events over West Africa to anthropogenic greenhouse gas for the late twenty-first century is investigated using an ensemble of high-resolution regional climate model experiments. For the present day, the RCM ensemble substantially improves the simulation of the annual cycle for various precipitation statistics compared to the driving Earth system models. The late-twenty-first-century projected changes in mean precipitation exhibit a delay of the monsoon season, consistent with previous studies. In addition, these projections indicate a prevailing decrease in frequency but increase in intensity of very wet events, particularly in the premonsoon and early mature monsoon stages, more pronounced over the Sahel and in RCP8.5 than the Gulf of Guinea and in RCP4.5. This is due to the presence of stronger moisture convergence in the boundary layer that sustains intense precipitation once convection is initiated. The premonsoon season experiences the largest changes in daily precipitation statistics, particularly toward an increased risk of drought associated with a decrease in mean precipitation and frequency of wet days and an increased risk of flood associated with very wet events. Both of these features can produce significant stresses on important sectors such as agriculture and water resources at a time of the year (e.g., the monsoon onset) where such stresses can have stronger impacts. The results thus point toward the importance of analyzing changes of precipitation characteristics as a function of the regional seasonal and subseasonal cycles of rainfall.

Projected changes of summer monsoon extremes and hydroclimatic regimes over West Africa for the twenty-first century

2016 ◽  
Vol 47 (12) ◽  
pp. 3931-3954 ◽  
Author(s):  
Ismaïla Diallo ◽  
Filippo Giorgi ◽  
Abdoulaye Deme ◽  
Moustapha Tall ◽  
Laura Mariotti ◽  
...  
Keyword(s):  
West Africa ◽  
Summer Monsoon ◽  
First Century ◽  
Twenty First Century ◽  
Projected Changes

scholarly journals Projected Changes in Climate Extremes Using CMIP6 Simulations Over SREX Regions

2021 ◽  
Vol 5 (3) ◽  
pp. 481-497
Author(s):  
Mansour Almazroui ◽  
Fahad Saeed ◽  
Sajjad Saeed ◽  
Muhammad Ismail ◽  
Muhammad Azhar Ehsan ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Extreme Events ◽  
First Century ◽  
Maximum Temperature ◽  
Annual Maximum ◽  
Temperature And Precipitation ◽  
Projected Change ◽  
Twenty First Century ◽  
Projected Changes ◽  
The Tropics

AbstractThis paper presents projected changes in extreme temperature and precipitation events by using Coupled Model Intercomparison Project phase 6 (CMIP6) data for mid-century (2036–2065) and end-century (2070–2099) periods with respect to the reference period (1985–2014). Four indices namely, Annual maximum of maximum temperature (TXx), Extreme heat wave days frequency (HWFI), Annual maximum consecutive 5-day precipitation (RX5day), and Consecutive Dry Days (CDD) were investigated under four socioeconomic scenarios (SSP1-2.6; SSP2-4.5; SSP3-7.0; SSP5-8.5) over the entire globe and its 26 Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) regions. The projections show an increase in intensity and frequency of hot temperature and precipitation extremes over land. The intensity of the hottest days (as measured by TXx) is projected to increase more in extratropical regions than in the tropics, while the frequency of extremely hot days (as measured by HWFI) is projected to increase more in the tropics. Drought frequency (as measured by CDD) is projected to increase more over Brazil, the Mediterranean, South Africa, and Australia. Meanwhile, the Asian monsoon regions (i.e., South Asia, East Asia, and Southeast Asia) become more prone to extreme flash flooding events later in the twenty-first century as shown by the higher RX5day index projections. The projected changes in extremes reveal large spatial variability within each SREX region. The spatial variability of the studied extreme events increases with increasing greenhouse gas concentration (GHG) and is higher at the end of the twenty-first century. The projected change in the extremes and the pattern of their spatial variability is minimum under the low-emission scenario SSP1-2.6. Our results indicate that an increased concentration of GHG leads to substantial increases in the extremes and their intensities. Hence, limiting CO2 emissions could substantially limit the risks associated with increases in extreme events in the twenty-first century.

How Often Will It Rain?

2007 ◽  
Vol 20 (19) ◽  
pp. 4801-4818 ◽  
Author(s):  
Ying Sun ◽  
Susan Solomon ◽  
Aiguo Dai ◽  
Robert W. Portmann
Keyword(s):  
Climate Change ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Precipitation Intensity ◽  
First Century ◽  
Simultaneous Increase ◽  
Percentage Increase ◽  
Precipitation Frequency ◽  
Twenty First Century

Abstract Daily precipitation data from climate change simulations using the latest generation of coupled climate system models are analyzed for potential future changes in precipitation characteristics. For the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) B1 (a low projection), A1B (a medium projection), and A2 (a high projection) during the twenty-first century, all the models consistently show a shift toward more intense and extreme precipitation for the globe as a whole and over various regions. For both SRES B1 and A2, most models show decreased daily precipitation frequency and all the models show increased daily precipitation intensity. The multimodel averaged percentage increase in the precipitation intensity (2.0% K−1) is larger than the magnitude of the precipitation frequency decrease (−0.7% K−1). However, the shift in precipitation frequency distribution toward extremes results in large increases in very heavy precipitation events (>50 mm day−1), so that for very heavy precipitation, the percentage increase in frequency is much larger than the increase in intensity (31.2% versus 2.4%). The climate model projected increases in daily precipitation intensity are, however, smaller than that based on simple thermodynamics (∼7% K−1). Multimodel ensemble means show that precipitation amount increases during the twenty-first century over high latitudes, as well as over currently wet regions in low- and midlatitudes more than other regions. This increase mostly results from a combination of increased frequency and intensity. Over the dry regions in the subtropics, the precipitation amount generally declines because of decreases in both frequency and intensity. This indicates that wet regions may get wetter and dry regions may become drier mostly because of a simultaneous increase (decrease) of precipitation frequency and intensity.

scholarly journals Late Twenty-First-Century Changes in the Midlatitude Atmospheric Circulation in the CESM Large Ensemble

2017 ◽  
Vol 30 (15) ◽  
pp. 5943-5960 ◽  
Author(s):  
Y. Peings ◽  
J. Cattiaux ◽  
S. Vavrus ◽  
Gudrun Magnusdottir
Keyword(s):  
Atmospheric Circulation ◽  
Extreme Temperature ◽  
Internal Variability ◽  
First Century ◽  
The Arctic ◽  
Arctic Amplification ◽  
Large Ensemble ◽  
Longitudinal Sector ◽  
Twenty First Century ◽  
Projected Changes

Projected changes in the midlatitude atmospheric circulation at the end of the twenty-first century are investigated using coupled ocean–atmosphere simulations from the Community Earth System Model Large Ensemble (CESM-LENS). Different metrics are used to describe the response of the midlatitude atmospheric dynamics in 40 ensemble members covering the 1920–2100 period. Contrasted responses are identified depending on the season and longitudinal sector that are considered. In winter, a slowdown of the zonal flow and an increase in waviness is found over North America, while the European sector exhibits a reinforced westerly flow and decreased waviness. Extreme temperature events in midlatitudes are more sensitive to thermodynamical than dynamical changes, and a general decrease in the intensity of wintertime cold spells is found. Analyses of individual ensemble members reveal a large spread in circulation changes due to internal variability. Causes for this spread are found to be tied to the Arctic amplification in the Pacific–North American sector and to the polar stratosphere in the North Atlantic. A competition mechanism is also discussed between the midlatitude response to polar versus tropical changes. While the upper-tropospheric tropical warming pushes the jet stream poleward, in winter, Arctic amplification and the weaker polar vortex exert an opposite effect. This competition results in a narrowing of the jet path in the midlatitudes, leading to decreased/unchanged waviness/blockings. This interpretation somewhat reconciles conflicting results between the hypothesized effect of Arctic amplification and projected changes in midlatitude flow characteristics. This study also illustrates that further understanding of regional processes is critical for anticipating changes in the midlatitude dynamics.

scholarly journals Trends in Storm-Triggered Landslides over Southern California

2014 ◽  
Vol 53 (2) ◽  
pp. 217-233 ◽  
Author(s):  
Diandong Ren ◽  
Lance M. Leslie ◽  
Mervyn J. Lynch
Keyword(s):  
Extreme Precipitation ◽  
Southern California ◽  
Extreme Rainfall ◽  
First Century ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Intergovernmental Panel ◽  
Extreme Precipitation Events ◽  
Landslide Frequency ◽  
Twenty First Century ◽  
Precipitation Events

AbstractChanges in storm-triggered landslide activity for Southern California in a future warming climate are estimated using an advanced, fully three-dimensional, process-based landslide model, the Scalable and Extensible Geofluid Modeling System for landslides (SEGMENT-Landslide). SEGMENT-Landslide is driven by extreme rainfall projections from the Geophysical Fluid Dynamics Laboratory High Resolution Atmospheric Model (GFDL-HIRAM). Landslide changes are derived from GFDL-HIRAM forcing for two periods: 1) the twentieth century (CNTRL) and 2) the twenty-first century under the moderate Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios A1B enhanced greenhouse gas emissions scenario (EGHG). Here, differences are calculated in landslide frequency and magnitude between the CNTRL and EGHG projections; kernel density estimation (KDE) is used to determine differences in projected landslide locations. This study also reveals that extreme precipitation events in Southern California are strongly correlated with several climate drivers and that GFDL-HIRAM simulates well the southern (relative to Aleutian synoptic systems) storm tracks in El Niño years and the rare (~27-yr recurrence period) hurricane-landfalling events. GFDL-HIRAM therefore can provide satisfactory projections of the geographical distribution, seasonal cycle, and interannual variability of future extreme precipitation events (>50 mm) that have possible landslide consequences for Southern California. Although relatively infrequent, extreme precipitation events contribute most of the annual total precipitation in Southern California. Two findings of this study have major implications for Southern California. First is a possible increase in landslide frequency and areal distribution during the twenty-first century. Second, the KDE reveals three clusters in both the CNTRL and EGHG model mean scarp positions, with a future eastward (inland) shift of ~0.5° and a northward shift of ~1°. These findings suggest that previously stable areas might become susceptible to storm-triggered landslides in the twenty-first century.

scholarly journals Twenty-First Century Projected Changes in Extreme Temperature over Côte d’Ivoire (West Africa)

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Assi L. M. Yapo ◽  
Adama Diawara ◽  
Fidèle Yoroba ◽  
Benjamin K. Kouassi ◽  
Mouhamadou B. Sylla ◽  
...  
Keyword(s):  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Extreme Temperature ◽  
First Century ◽  
Cote D’Ivoire ◽  
Côte D'ivoire ◽  
Frequency Index ◽  
The Future ◽  
Twenty First Century ◽  
Projected Changes

The projection of the future climate changes is of paramount importance inasmuch as it contributes to provide useful information for adaptation planning worldwide to local scales. This study investigated the future changes using four temperature related indices based on an ensemble of 14 CORDEX-Africa simulations at 0.44° × 0.44° of resolution under the RCP4.5 and RCP8.5 scenarios. These indices indicate moderate extremes over Côte d’Ivoire. The results show an increase in the warm extreme indices such as the warm spell days index (HWFI), very warm days frequency index (TX90P), and the warm nights frequency index (TN90P) over the entire country under both emission scenarios. The increase in these indices was higher under RCP8.5 and reached 85, 72, and 90% for HWFI, TX90P, and TN90P respectively. In addition, the magnitude of the changes is relevant along the coastal areas in the 2031–2060 and 2071–2100 periods. Moreover, the intra period extreme temperature range (ETR) shows future decrease following a south-north gradient with values in the range [−0.5; 1.5°C] over the country during January–March (JFM) and October–December (OND) seasons whereas an increase (~0.5°C) is projected for April–June (AMJ) and July–September (JAS) seasons, particularly in the central and northern parts. The minimum temperature increases faster than the maximum, except in AMJ and JAS in the central and northern regions. On the other hand, the changes in the indices based on the mean values of the reference period (1976–2005) are in concordance to the expected warming at the end of the twenty-first century with important trends. The projected changes are, however, subject to uncertainties, which are higher under RCP8.5 than under RCP4.5 scenarios. Overall, these changes are meaningful as all the 14 CORDEX-Africa simulations agree to an increase of warm extreme temperature.

Projected changes in extreme precipitation events over Iran in the 21st century based on CMIP5 models

2020 ◽  
Vol 82 ◽  
pp. 75-95
Author(s):  
M Darand
Keyword(s):  
21St Century ◽  
Extreme Precipitation ◽  
Model Simulation ◽  
Climate Extremes ◽  
Cmip5 Models ◽  
Trend Test ◽  
Extreme Precipitation Events ◽  
Increased Risk ◽  
Projected Changes ◽  
Precipitation Events

Climate extremes have large impacts on human societies and natural ecosystems. Projection of changes in climate extremes is very important for long-term planning. The current study investigated future changes in extreme precipitation events over Iran based on 18 CMIP5 models for the period 2006-2100. National gridded data from the Asfazari database were used to evaluate climate model simulation. Results indicate that models with higher spatial resolution (CCSM4 and MRI-CGCM3) perform better than those with lower resolution in capturing the spatial features of extreme precipitation events. Bias correction was applied to the models and the projected changes were assessed with the nonparametric modified Mann-Kendal trend test and Sen slope estimator at a 95% confidence level. Annual total precipitation (PRPCTOT) and rainy days (RD) were projected to decrease but the intensity and frequency of precipitation extremes were predicted to increase significantly. The projected decreases were larger in northwestern parts than other regions, with PRPCTOT decreasing by 18 to 22 mm decade-1 and RD by 4 to 4.8 d decade-1. Although there were discrepancies in rates between the models, extreme precipitation events over Iran were generally projected to increase. An increase in consecutive dry days (CDD) was predicted for most regions by the end of the 21st century under RCP8.5, with the largest increase of 5 to 6.8 d decade-1 found for northwestern Iran. In eastern areas of Iran, where precipitation occurs extremely rarely, the number of days with daily precipitation exceeding 10 mm (R10) or even 20 mm (R20) were projected to increase significantly. In conclusion, these changes suggest an increased risk of flash floods in Iran from increased extreme precipitation under the RCP8.5 emission scenario.

Bridging the Archival-Ethnographic Divide: Gender, Kinship, and Seniority in the Study of Yoruba Masquerade

2016 ◽  
Vol 44 ◽  
pp. 63-100 ◽  
Author(s):  
John Thabiti Willis
Keyword(s):  
Nineteenth Century ◽  
West Africa ◽  
First Century ◽  
Sex And Gender ◽  
Gendered Identities ◽  
Twenty First Century ◽  
And Gender ◽  
Fluid Interpretation

Abstract:This study juxtaposes the observations and interpretations of a twenty-first-century ethnographer with those of nineteenth-century Christian missionaries to rethink interpretations of the practice of gender in precolonial West Africa. The article uses the evolving relationship between an ethnographic researcher and a group of contemporary female ancestral masquerade chiefs to reflect on the ways in which generations of missionaries and scholars have interpreted the gendered construction of power. It critiques previous writers for assuming sex and gender in Yoruba culture to be fixed, and argues for a more fluid interpretation of the gendered identities of the observer and subject being observed.

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