scholarly journals Discrepancies in the Climatology and Trends of Cloud Cover in Global and Regional Climate Models for the Mediterranean Region

2017 ◽  
Vol 122 (21) ◽  
pp. 11,664-11,677 ◽  
Author(s):  
Aaron Enriquez-Alonso ◽  
Josep Calbó ◽  
Arturo Sanchez-Lorenzo ◽  
Elcin Tan
Keyword(s):  
Mediterranean Region ◽  
Cloud Cover ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
The Mediterranean

scholarly journals Regional climate models' performance in representing precipitation and temperature over selected Mediterranean areas

2013 ◽  
Vol 17 (12) ◽  
pp. 5041-5059 ◽  
Author(s):  
R. Deidda ◽  
M. Marrocu ◽  
G. Caroletti ◽  
G. Pusceddu ◽  
A. Langousis ◽  
...  
Keyword(s):  
Climate Change ◽  
Mediterranean Region ◽  
Climate Models ◽  
Hydrological Modeling ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Data Set ◽  
The Mediterranean ◽  
Ensembles Project ◽  
The Eu

Abstract. This paper discusses the relative performance of several climate models in providing reliable forcing for hydrological modeling in six representative catchments in the Mediterranean region. We consider 14 Regional Climate Models (RCMs), from the EU-FP6 ENSEMBLES project, run for the A1B emission scenario on a common 0.22° (about 24 km) rotated grid over Europe and the Mediterranean region. In the validation period (1951 to 2010) we consider daily precipitation and surface temperatures from the observed data fields (E-OBS) data set, available from the ENSEMBLES project and the data providers in the ECA&D project. Our primary objective is to rank the 14 RCMs for each catchment and select the four best-performing ones to use as common forcing for hydrological models in the six Mediterranean basins considered in the EU-FP7 CLIMB project. Using a common suite of four RCMs for all studied catchments reduces the (epistemic) uncertainty when evaluating trends and climate change impacts in the 21st century. We present and discuss the validation setting, as well as the obtained results and, in some detail, the difficulties we experienced when processing the data. In doing so we also provide useful information and advice for researchers not directly involved in climate modeling, but interested in the use of climate model outputs for hydrological modeling and, more generally, climate change impact studies in the Mediterranean region.

scholarly journals Global Radiative Flux and Cloudiness Variability for the Period 1959–2010 in Belgium: A Comparison between Reanalyses and the Regional Climate Model MAR

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 262 ◽  
Author(s):  
Coraline Wyard ◽  
Sébastien Doutreloup ◽  
Alexandre Belleflamme ◽  
Martin Wild ◽  
Xavier Fettweis
Keyword(s):  
Cloud Cover ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Horizontal Resolution ◽  
Radiative Flux ◽  
Added Value ◽  
Historical Trends ◽  
The Mean

The use of regional climate models (RCMs) can partly reduce the biases in global radiative flux (Eg↓) that are found in reanalysis products and global models, as they allow for a finer spatial resolution and a finer parametrisation of surface and atmospheric processes. In this study, we assess the ability of the MAR («Modèle Atmosphérique Régional») RCM to reproduce observed changes in Eg↓, and we investigate the added value of MAR with respect to reanalyses. Simulations were performed at a horizontal resolution of 5 km for the period 1959–2010 by forcing MAR with different reanalysis products: ERA40/ERA-interim, NCEP/NCAR-v1, ERA-20C, and 20CRV2C. Measurements of Eg↓ from the Global Energy Balance Archive (GEBA) and from the Royal Meteorological Institute of Belgium (RMIB), as well as cloud cover observations from Belgocontrol and RMIB, were used for the evaluation of the MAR model and the forcing reanalyses. Results show that MAR enables largely reducing the mean biases that are present in the reanalyses. The trend analysis shows that only MAR forced by ERA40/ERA-interim shows historical trends, which is probably because the ERA40/ERA-interim has a better horizontal resolution and assimilates more observations than the other reanalyses that are used in this study. The results suggest that the solar brightening observed since the 1980s in Belgium has mainly been due to decreasing cloud cover.

scholarly journals Effect of Model Resolution on Intense and Extreme Precipitationinthe Mediterranean Region

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 699
Author(s):  
Dario Conte ◽  
Silvio Gualdi ◽  
Piero Lionello
Keyword(s):  
Climate Change ◽  
Mediterranean Region ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Global Climate Models ◽  
Total Precipitation ◽  
Model Resolution

This study explores the role of model resolution on the simulation of precipitation and on the estimate of its future change in the Mediterranean region. It compares the results of two regional climate models (RCMs, with two different horizontal grid resolutions, 0.44 and 0.11 degs, covering the whole Mediterranean region) and of the global climate model (GCM, 0.75 degs) that has provided the boundary conditions for them. The regional climate models include an interactive oceanic component with a resolution of 1/16 degs. The period 1960–2100 and the representative concentration pathways RCP4.5 and RCP8.5 are considered. The results show that, in the present climate, increasing resolution increases total precipitation and its extremes over steep orography, while it has the opposite effect over flat areas and the sea. Considering climate change, in all simulations, total precipitation will decrease over most of the considered domain except at the northern boundary, where it will increase. Extreme precipitation will increase over most of the northern Mediterranean region and decrease over the sea and some southern areas. Further, the overall probability of precipitation (frequency of wet days) significantly decreases over most of the region, but wet days will be characterized with precipitation intensity higher than the present. Our analysis shows that: (1) these projected changes are robust with respect to the considered range of model resolution; (2) increasing the resolution (within the considered resolution range) decreases the magnitude of these climate change effects. However, it is likely that resolution plays a less important role than other factors, such as the different physics of regional and global climate models. It remains to be investigated whether further increasing the resolution (and reaching the scale explicitly permitting convection) would change this conclusion.

Evolution of extreme hot temperatures over Euro-Mediterranean main airports 

2021 ◽  
Author(s):  
Victoria Gallardo ◽  
Emilia Sanchez-Gomez ◽  
Eleonore Riber
Keyword(s):  
Global Warming ◽  
Mediterranean Region ◽  
Climate Models ◽  
Regional Climate ◽  
Temporal Trends ◽  
Regional Climate Models ◽  
Health Impact ◽  
Pollutant Emissions ◽  
Weight Restrictions ◽  
Hot Temperature

<p><span><span>As a result of global warming, the magnitude and the frequency of extreme hot temperature events have increased remarkably in the recent decades. </span><span>In the absence of policies, global warming is expected to continue during the next years, and certain regions which are already characterized by warm and hot temperatures, such as the Euro-Mediterranean region, may be notably impacted in numerous and diverse fields. The aeronautical sector is among these vulnerable fields, as aircraft takeoff performances also depend on air temperature. For instance, a</span><span>n increase in ground temperature results in a decrease in air density, and consequently in the available thrust for takeoff. This may lead to flight delays, weight restrictions or even flight cancellations. Concerning the aircraft engines, an increase in temperature may negatively impact the performance and may also lead to an increase of pollutant emissions into the atmosphere. All of these effects would have a social, economic and health impact.</span></span></p><p><span><span>In this study we analyze the evolution of extreme hot temperatures on aircraft performance over the main airports in the Southern Euro-Mediterranean region, using simulations performed by regional climate models (RCMs) from the Euro-CORDEX international exercise. To this end, we first evaluate RCMs in terms of their representation of extreme hot temperatures and their trends in the present period by comparing to different observational datasets and also to the driving GCMs. The results of this comparison show that RCMs don't </span><span>represent better the amplitude nor the temporal trends of hot temperature events in summer</span><span>, despide their higher spatial resolution. We assess the changes in the hot temperature extremes from the Euro-CORDEX future projections and we evaluate the risk of weight restriction in the next decades.</span></span></p>

scholarly journals Future Changes in Euro-Mediterranean Daytime Severe Thunderstorm Environments Based on an RCP8.5 Med-CORDEX Simulation

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 822
Author(s):  
Abdullah Kahraman ◽  
Deniz Ural ◽  
Barış Önol
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Warm Season ◽  
Regional Climate Models ◽  
Severe Thunderstorm ◽  
Convective Scale ◽  
Thermodynamic Conditions ◽  
The Mediterranean ◽  
Climate Model Simulations

Convective scale processes and, therefore, thunderstorm-related hazards cannot be simulated using regional climate models with horizontal grid spacing in the order of 10 km. However, larger-scale environmental conditions of these local high-impact phenomena can be diagnosed to assess their frequency in current and future climates. In this study, we present a daytime climatology of severe thunderstorm environments and its evolution for a wide Euro-Mediterranean domain through the 21st century, using regional climate model simulations forced by Representative Concentration Pathway (RCP) 8.5 scenario. Currently, severe convective weather is more frequently favored around Central Europe and the Mediterranean Sea. Our results suggest that with a steady progress until the end of the century, Mediterranean coasts are projected to experience a significantly higher frequency of severe thunderstorm environments, while a slight decrease over parts of continental Europe is evaluated. The increase across the Mediterranean is mostly owed to the warming sea surface, which strengthens thermodynamic conditions in the wintertime, while local factors arguably keep the shear frequency relatively higher than the entire region. On the other hand, future northward extension of the subtropical belt over Europe in the warm season reduces the number of days with severe thunderstorm environments.

scholarly journals Evaluation and Bias Correction of Regional Climate Model Results Using Model Evaluation Measures

2012 ◽  
Vol 51 (9) ◽  
pp. 1670-1684 ◽  
Author(s):  
Robert Schoetter ◽  
Peter Hoffmann ◽  
Diana Rechid ◽  
K. Heinke Schlünzen
Keyword(s):  
Wind Speed ◽  
Bias Correction ◽  
Model Evaluation ◽  
Cloud Cover ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Total Cloud Cover ◽  
Evaluation Measures

AbstractFor the assessment of regional climate change the reliability of the regional climate models needs to be known. The main goal of this paper is to evaluate the quality of climate model data that are used for impact research. Temperature, precipitation, total cloud cover, relative humidity, and wind speed simulated by the regional climate models Climate Local Model (CLM) and Regional Model (REMO) are evaluated for the metropolitan region of Hamburg in northern Germany for the period 1961–2000. The same evaluation is performed for the global climate model ECHAM5 that is used to force the regional climate models. The evaluation is based on comparison of the simulated and observed climatological annual cycles and probability density functions of daily averages. Several model evaluation measures are calculated to assure an objective model evaluation. As a very selective model evaluation measure, the hit rate of the percentiles is introduced for the evaluation of daily averages. The influence of interannual climate variability is considered by determining confidence intervals for the model evaluation measures by bootstrap resampling. Evaluation shows that, with some exceptions, temperature and wind speed are well simulated by the climate models; whereas considerable biases are found for relative humidity, total cloud cover, and precipitation, although not for all models in all seasons. It is shown that model evaluation measures can be used to decide for which meteorological parameters a bias correction is reasonable.

scholarly journals Regional climate change projections for the Barents region

2016 ◽  
Author(s):  
Andreas Dobler ◽  
Jan Erik Haugen ◽  
Rasmus Emil Benestad
Keyword(s):  
Sea Ice ◽  
Regional Climate Model ◽  
Cloud Cover ◽  
Climate Models ◽  
Climate Model ◽  
Barents Sea ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Barents Region ◽  
The Barents Sea

Abstract. Regional climate models can provide estimates for quantities that are difficult to study in empirical studies, such as cloud cover, wind, sea-ice or dependencies between variables. In this study, the regional climate model COSMO-CLM was used to simulate local climate conditions over the Barents region and provide projections for the three emission scenarios RCP2.6, RCP4.5 and RCP8.5. The results indicate that the most pronounced local warming can be expected in winter in the high Arctic near the present sea-ice border. The changes reach up to 20K, resulting in future temperatures close to melting. Similar spatial patterns are seen for changes in precipitation and wind in all scenarios, but with different amplitudes. Precipitation sensitivities, however, show the highest values along the west coast of Norway and in the Arctic during summer. For clouds, the projections show a decrease in winter mean cloud cover over sea and an increase over land, dominated by changes in low layer clouds. Over the Barents sea, convective cloud fraction is projected to increase, together with an increases in convective and total precipitation. In contrast to the COSMO-CLM and two other regional climate models taken into account, the ensemble mean of the driving global models shows an increasing trend in total cloud cover over the Barents sea. An analysis of the opposing trends reveals that there is an added value in the regional climate model projections for the Barents region.

scholarly journals Simulation of regional climate models of total cloud fraction in Morocco for the period of 2020-2050

2018 ◽  
pp. 21-27
Author(s):  
El Hadri Youssef ◽  
V. M. Khokhlov
Keyword(s):  
Renewable Energy ◽  
Solar Radiation ◽  
Cloud Cover ◽  
Climate Models ◽  
Sunshine Duration ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Cloud Fraction ◽  
Green Energy ◽  
The Future

The Moroccan energy system is highly dependent on external energy markets. The use of solar energy is one of the most promising ways in the development of renewable energy sources. At the moment, there are several scenarios for the development of renewable energy in Morocco diverging only in quantitative assessments. All of them are aimed at increasing the generation of green energy, from the complete satisfaction of all needs of Moroccan consumers to the opportunity of exporting some of its environmentally friendly electricity to Europe. Estimation of energy efficiency of solar installations is usually carried out on the basis of calculations of solar radiation arrival in the presence of cloudless sky. Clouds significantly reduce amount of solar radiation and sunshine duration. This study is aimed at determination of possible quantitative parameters of the total cloud cover and the areas in which the cloud cover would have the least impact on the amount of incoming solar radiation in Morocco in 2020-2050. The article presents the results of simulation of total cloud fraction using 11 regional climate models of CORDEX project for the period of 2020-2050 in Morocco. For the period of 2020-2050 the average values of total cloud fraction on the territory of Morocco will have the smallest values within the plains located near the border with Algeria on the territory of the prefecture of Sous-Massa lying at the foot of the southern slopes of the Anti-Atlas. The analysis of the annual regime of total cloud fraction showed that in the future it will be of a different nature in different parts of the country due to various factors affecting its formation. The area with the smallest volumes of monthly total cloud fraction will lie within the territory the southern part of prefecture Draa-Tafilalet and prefectures Sous-Massa, Guelmim-Oued Noun, Laayoune-Sakia El Hamra, Dakhla-Oued Ed-Dahab excluding their coastal parts of the Atlantic Ocean. In the future most of the territory of Morocco will be characterized by a low amount of total cloud fraction, which, in its turn, will have an insignificant effect on the amount of solar radiation entering to the underlying surface of these areas. In terms of solar power, the best conditions will exist at the southern parts of Morocco, excluding the coast where the total cloud fraction will have the least impact on the amount of solar radiation reaching the earth’s surface and on sunshine duration.

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