Spatial and temporal variability of summer rainfall over Ethiopia from observations and a regional climate model experiment

2012 ◽  
Vol 111 (3-4) ◽  
pp. 665-681 ◽  
Author(s):  
T. Zeleke ◽  
F. Giorgi ◽  
G. Mengistu Tsidu ◽  
G. T. Diro
Keyword(s):  
Regional Climate Model ◽  
Temporal Variability ◽  
Model Experiment ◽  
Climate Model ◽  
Regional Climate ◽  
Summer Rainfall ◽  
Spatial And Temporal Variability ◽  
Climate Model Experiment

scholarly journals Representation of spatial and temporal variability of daily wind speed and of intense wind events over the Mediterranean Sea using dynamical downscaling: impact of the regional climate model configuration

2011 ◽  
Vol 11 (7) ◽  
pp. 1983-2001 ◽  
Author(s):  
M. Herrmann ◽  
S. Somot ◽  
S. Calmanti ◽  
C. Dubois ◽  
F. Sevault
Keyword(s):  
Wind Speed ◽  
Spatial Variability ◽  
Regional Climate Model ◽  
Mediterranean Sea ◽  
Temporal Variability ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Spatial And Temporal Variability ◽  
Wind Events

Abstract. Atmospheric datasets coming from long term reanalyzes of low spatial resolution are used for different purposes. Wind over the sea is, for example, a major ingredient of oceanic simulations. However, the shortcomings of those datasets prevent them from being used without an adequate corrective preliminary treatment. Using a regional climate model (RCM) to perform a dynamical downscaling of those large scale reanalyzes is one of the methods used in order to produce fields that realistically reproduce atmospheric chronology and where those shortcomings are corrected. Here we assess the influence of the configuration of the RCM used in this framework on the representation of wind speed spatial and temporal variability and intense wind events on a daily timescale. Our RCM is ALADIN-Climate, the reanalysis is ERA-40, and the studied area is the Mediterranean Sea. First, the dynamical downscaling significantly reduces the underestimation of daily wind speed, in average by 9 % over the whole Mediterranean. This underestimation has been corrected both globally and locally, and for the whole wind speed spectrum. The correction is the strongest for periods and regions of strong winds. The representation of spatial variability has also been significantly improved. On the other hand, the temporal correlation between the downscaled field and the observations decreases all the more that one moves eastwards, i.e. further from the atmospheric flux entry. Nonetheless, it remains ~0.7, the downscaled dataset reproduces therefore satisfactorily the real chronology. Second, the influence of the choice of the RCM configuration has an influence one order of magnitude smaller than the improvement induced by the initial downscaling. The use of spectral nudging or of a smaller domain helps to improve the realism of the temporal chronology. Increasing the resolution very locally (both spatially and temporally) improves the representation of spatial variability, in particular in regions strongly influenced by the complex surrounding orography. The impact of the interactive air-sea coupling is negligible for the temporal scales examined here. Using two different forcing datasets induces differences on the downscaled fields that are directly related to the differences between those datasets. Our results also show that improving the physics of our RCM is still necessary to increase the realism of our simulations. Finally, the choice of the optimal configuration depends on the scientific objectives of the study for which those wind datasets are used.

Influence of Lake Malawi on regional climate from a double-nested regional climate model experiment

2017 ◽  
Vol 50 (9-10) ◽  
pp. 3397-3411 ◽  
Author(s):  
Ismaïla Diallo ◽  
Filippo Giorgi ◽  
Frode Stordal
Keyword(s):  
Regional Climate Model ◽  
Model Experiment ◽  
Climate Model ◽  
Regional Climate ◽  
Lake Malawi ◽  
Climate Model Experiment

Large-Scale Atmospheric Drivers of Snowfall on Thwaites Glacier

2020 ◽  
Author(s):  
Michelle Maclennan ◽  
Jan Lenaerts
Keyword(s):  
Temporal Variability ◽  
Large Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Regional Climate ◽  
Southern Annular Mode ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Amundsen Sea ◽  
Weather Patterns

<p>High snowfall events on Thwaites Glacier are a key influencer of its ice mass change. In this study, we diagnose the mechanisms for orographic precipitation on Thwaites Glacier by analyzing the atmospheric conditions that lead to high snowfall events. A high-resolution regional climate model, RACMO2, is used in conjunction with MERRA-2 and ERA5 reanalysis to map snowfall and associated atmospheric conditions over the Amundsen Sea Embayment. We examine these conditions during high snowfall events over Thwaites Glacier to characterize the drivers of the precipitation and their spatial and temporal variability. Then we examine the seasonal differences in the associated weather patterns and their correlations with El Nino Southern Oscillation and the Southern Annular Mode. Understanding the large-scale atmospheric drivers of snowfall events allows us to recognize how these atmospheric drivers and consequent snowfall climatology will change in the future, which will ultimately improve predictions of accumulation on Thwaites Glacier.</p>

scholarly journals Projections of a Wetter Sahel in the Twenty-First Century from Global and Regional Models

2013 ◽  
Vol 26 (13) ◽  
pp. 4664-4687 ◽  
Author(s):  
Edward K. Vizy ◽  
Kerry H. Cook ◽  
Julien Crétat ◽  
Naresh Neupane
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Scale ◽  
Summer Rainfall ◽  
West African ◽  
First Century ◽  
Wet Season ◽  
Surface Moisture ◽  
Twenty First Century

Abstract Confident regional-scale climate change predictions for the Sahel are needed to support adaptation planning. State-of-the-art regional climate model (RCM) simulations at 90- and 30-km resolutions are run and analyzed along with output from five coupled atmosphere–ocean GCMs (AOGCMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5) to predict how the Sahel summer surface temperature, precipitation, and surface moisture are likely to change at the mid- and late-twenty-first century due to increased atmospheric CO2 concentrations under the representative concentration pathway 8.5 (RCP8.5) emission scenario and evaluate confidence in such projections. Future lateral boundary conditions are derived from CMIP5 AOGCMs. It is shown that the regional climate model can realistically simulate the current summer evolution of the West African monsoon climate including the onset and demise of the Sahel wet season, a necessary but not sufficient condition for confident prediction. RCM and AOGCM projections indicate the likelihood for increased surface air temperatures over this century, with Sahara and Sahel temperature increases of 2–3.5 K by midcentury, and 3–6 K by late century. Summer rainfall and surface moisture are also projected to increase over most of the Sahel. This is primarily associated with an increase in rainfall intensity and not a lengthening of the wet season. Pinpointing exactly when the rainfall and surface moisture increase will first commence and by exactly what magnitude is less certain as these predictions appear to be model dependent. Models that simulate stronger warming over the Sahara are associated with larger and earlier rainfall increases over the Sahel due to an intensification of the low-level West African westerly jet, and vice versa.

East China Summer Rainfall during ENSO Decaying Years Simulated by a Regional Climate Model

2011 ◽  
Vol 4 (2) ◽  
pp. 91-97 ◽  
Author(s):  
Zeng Xian-Feng ◽  
Li Bo ◽  
Feng Lei ◽  
Liu Xiao-Juan ◽  
Zhou Tian-Jun
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Summer Rainfall ◽  
East China

An original way to evaluate daily rainfall variability simulated by a regional climate model: the case of South African austral summer rainfall

2014 ◽  
Vol 35 (9) ◽  
pp. 2485-2502 ◽  
Author(s):  
Julien Crétat ◽  
Benjamin Pohl ◽  
Carmela Chateau Smith ◽  
Nicolas Vigaud ◽  
Yves Richard
Keyword(s):  
Regional Climate Model ◽  
South African ◽  
Climate Model ◽  
Rainfall Variability ◽  
Regional Climate ◽  
Austral Summer ◽  
Daily Rainfall ◽  
Summer Rainfall
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