Seasonal assessments of future precipitation extremes in the Mediterranean area considering nonstationarities in predictor-predictand relationships

2020 ◽  
Vol 80 (1) ◽  
pp. 19-42
Author(s):  
C Merkenschlager ◽  
E Hertig

Within the context of analyzing daily heavy precipitation events in the Mediterranean under enhanced greenhouse gas forcing in the 21st century, a new method considering non-stationarities in the relationships of large-scale circulation predictors and regional precipitation extremes was applied. The Mediterranean area was split into up to 22 precipitation regions, and analyses were performed separately for 3 different seasons (autumn, winter and spring) and 3 different quantiles (90th, 95th and 99th). Estimations are based on a three-step censored quantile regression. Future estimations are performed by means of 3 model runs of the Max Planck Institute Earth System Model with Low Resolution (MPI-ESM-LR) for representative concentration pathways (RCPs) 4.5 and 8.5. Overall, the Mediterranean is mainly characterized by decreasing quantile values. Especially in the regions in the southeast, declines are significant, with up to 71.7% (-1.65 mm) in the Levante region (autumn) and over 16 mm (-38.2%) on Crete (winter). Increased precipitation quantiles were only assessed for a more or less extended region in the northern parts of the Central Mediterranean (winter and spring), for the northeastern coast of the Iberian Peninsula (autumn) and for northern Spain (spring). Overall, analyses showed that non-stationarities seriously affect precipitation behavior in most parts of the Mediterranean. Results indicated that 2 different regimes (western and eastern) inducing non-stationarities are predominant in the Mediterranean area. In autumn (winter), the western (eastern) regime is limited to the Iberian Peninsula (Levante), whereas in spring, the area of influence of both regimes is of equal size.

2021 ◽  
Author(s):  
Alba de la Vara ◽  
William Cabos ◽  
Dmitry V. Sein ◽  
Claas Teichmann ◽  
Daniela Jacob

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.


2017 ◽  
Vol 30 (24) ◽  
pp. 9827-9845 ◽  
Author(s):  
Xin Zhou ◽  
Marat F. Khairoutdinov

Subdaily temperature and precipitation extremes in response to warmer SSTs are investigated on a global scale using the superparameterized (SP) Community Atmosphere Model (CAM), in which a cloud-resolving model is embedded in each CAM grid column to simulate convection explicitly. Two 10-yr simulations have been performed using present climatological sea surface temperature (SST) and perturbed SST climatology derived from the representative concentration pathway 8.5 (RCP8.5) scenario. Compared with the conventional CAM, SP-CAM simulates colder temperatures and more realistic intensity distribution of precipitation, especially for heavy precipitation. The temperature and precipitation extremes have been defined by the 99th percentile of the 3-hourly data. For temperature, the changes in the warm and cold extremes are generally consistent between CAM and SP-CAM, with larger changes in warm extremes at low latitudes and larger changes in cold extremes at mid-to-high latitudes. For precipitation, CAM predicts a uniform increase of frequency of precipitation extremes regardless of the rain rate, while SP-CAM predicts a monotonic increase of frequency with increasing rain rate and larger change of intensity for heavier precipitation. The changes in 3-hourly and daily temperature extremes are found to be similar; however, the 3-hourly precipitation extremes have a significantly larger change than daily extremes. The Clausius–Clapeyron scaling is found to be a relatively good predictor of zonally averaged changes in precipitation extremes over midlatitudes but not as good over the tropics and subtropics. The changes in precipitable water and large-scale vertical velocity are equally important to explain the changes in precipitation extremes.


2012 ◽  
Vol 12 (10) ◽  
pp. 28195-28235 ◽  
Author(s):  
J. Pey ◽  
X. Querol ◽  
A. Alastuey ◽  
F. Forastiere ◽  
M. Stafoggia

Abstract. The occurrence of African dust outbreaks over the whole Mediterranean Basin has been identified on an 11-yr period (2001–2011). In order to evaluate the impact of such mineral dust outbreaks on ambient concentrations of particulate matter, PM10 data from regional and suburban background sites across the Mediterranean area were compiled. After identifying the daily influence of African dust, a methodology for estimating natural dust contributions on daily PM10 concentrations was applied. Our results reveal that African dust outbreaks occur with much higher frequency in southern areas of the Mediterranean, from 30 to 37% of the annual days, whereas they take place less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to equivalent areas in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10 is patent across the Mediterranean. Our study demonstrates that this gradient may be mainly explained by the latitudinal position. A longitudinal increasing trend of African dust contribution to PM10 is also observed from 25° E eastwards, and is due to the annual occurrence of intense dust episodes. Thus, the slightly higher frequency of African dust episodes over the lower part of Central Mediterranean is compensated by its moderately lower intensity. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 μg m−3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn-spring in the eastern side, with yearly occurrence of various severe episodes. Overall, African dust emerges as the largest PM10 source in regional background southern areas of the Mediterranean (35–50% of PM10), with seasonal peak contributions to PM10 up to 80% of the total mass. The multi-year study of African dust episodes and their contributions to PM10 concentrations allowed us to identify a consistent decreasing trend in the period 2006/2007 to 2011 in 4 of the 17 studied regions, all of them located in the NW of the Mediterranean. The observed trend is almost parallel to the NAO (North Atlantic Oscillation) index for the summer period, progressively more negative since 2006 onwards. As a consequence, a sharp change in the atmospheric circulation over the last 5 yr (a similar negative NAO period occurred in the 1950 decade) have affected the number of African dust episodes and their mean contribution to PM10 in the NW part of the Mediterranean. The investigation of summer temperatures at 850 hPa suggest that warm air accomplishing African dust air masses moved anomalously through the central Mediterranean in the 2007–2008 period, whereas it was displaced atypically to the NW African coast and the Canary Islands in the 2009–2011 period.


1997 ◽  
Vol 40 (4) ◽  
Author(s):  
M. Viti ◽  
D. Albarello ◽  
E. Mantovani

Seismological investigations have provided an estimate of the gross structnral features of the crust/upper mantle system in the Mediterranean area. However, this information is only representative of the short-term me- chanical behaviour of rocks and cannot help us to understand slow deformations and related tectonic processes on the geological time scale. In this work strength envelopes for several major structural provinces of the Mediterranean area have been tentatively derived from seismological stratification and heat flow data, on the assumption of constant and uniforrn strain rate (10-16 S-1), wet rocks and conductive geotherm. It is also shown how the uncertainties in the reconstruction of thermal profiles can influence the main rheological prop- erties of the lithosphere, as thickness and total strength. The thickest (50-70 km) and strongest mechanical lithospheres correspond to the coldest zones (with heat flow lower than or equal to 50 mW m-2), i.e., the Io- nian and Levantine mesozoic basins, the Adriatic and Eurasian foreland zones and NW Greece. Heat flows larger than 65 mW m-2, generally observed in extensional zones (Tyrrhenian, Sicily Channel, Northern Aegean, Macedonia and Western Turkey), are mostly related to mechanical lithospheres thinner than 20 km. The characteristics of strength envelopes, and in particular the presence of soft layers in the crust, suggest a reasonable interpretation of some large-scale features which characterize the tectonic evolution of the Central- Eastem Mediterranean.


Author(s):  
Gerassimos Papadopoulos

According to Imamura (1937: 123), the term tunami or tsunami is a combination of the Japanese word tu (meaning a port) and nami (a long wave), hence long wave in a harbour. He goes on to say that the meaning might also be defined as a seismic sea-wave since most tsunamis are produced by a sudden dip-slip motion along faults during major earthquakes. Other submarine or coastal phenomena, however, such as volcanic eruptions, landslides, and gas escapes, are also known to cause tsunamis. According to Van Dorn (1968), ‘tsunami’ is the Japanese name for the gravity wave system formed in the sea following any large-scale, short-duration disturbance of the free surface. Tsunamis fall under the general classification of long waves. The length of the waves is of the order of several tens or hundreds of kilometres and tsunamis usually consist of a series of waves that approach the coast with periods ranging from 5 to 90 minutes (Murty 1977). Some commonly used terms that describe tsunami wave propagation and inundation are illustrated in Figure 17.2. Because of the active lithospheric plate convergence, the Mediterranean area is geodynamically characterized by significant volcanism and high seismicity as discussed in Chapters 15 and 16 respectively. Furthermore, coastal and submarine landslides are quite frequent and this is partly in response to the steep terrain of much of the basin (Papadopoulos et al. 2007a). Tsunamis are among the most remarkable phenomena associated with earthquakes, volcanic eruptions, and landslides in the Mediterranean basin. Until recently, however, it was widely believed that tsunamis either did not occur in the Mediterranean Sea, or they were so rare that they did not pose a threat to coastal communities. Catastrophic tsunamis are more frequent on Pacific Ocean coasts where both local and transoceanic tsunamis have been documented (Soloviev 1970). In contrast, large tsunami recurrence in the Mediterranean is of the order of several decades and the memory of tsunamis is short-lived. Most people are only aware of the extreme Late Bronge Age tsunami that has been linked to the powerful eruption of Thera volcano in the south Aegean Sea (Marinatos 1939; Chapter 15).


2020 ◽  
Author(s):  
M. Carmen Alvarez-Castro ◽  
Silvio Gualdi ◽  
Pascal Yiou ◽  
Mathieu Vrac ◽  
Robert Vautard ◽  
...  

<p>Windstorms, extreme precipitations and instant floods seems to strike the Mediterranean area with increasing frequency. These events occur simultaneously during intense tropical-like Mediterranean cyclones. These intense Mediterranean cyclones are frequently associated with wind, heavy precipitation and changes in temperature, generating high risk situations such as flash floods and large-scale floods with significant impacts on human life and built environment. Although the dynamics of these phenomena is well understood, little is know about their climatology. It is therefore very difficult to make statements about the frequency of occurrence and its response to climate change. Thus, intense Mediterranean cyclones have many different physical aspects that can not be captured by a simple standard approach. </p><p>The first challenge of this work is to provide an extended catalogue and climatology of these phenomena by reconstructing a database of intense Mediterranean cyclones dating back up to 1969 using the satellite, the literature and reanalyses. Applying a method based on dynamical systems theory we analyse and attribute their future changes under different anthropogenic forcings by using future simulations within CMIP framework. Preliminary results show a decrease of the large-scale circulation patterns favoring intense Mediterranean cyclones in all the seasons except summer.</p>


2015 ◽  
Vol 36 (11) ◽  
pp. 3873-3891 ◽  
Author(s):  
Andrés Merino ◽  
Mario Fernández-Vaquero ◽  
Laura López ◽  
Sergio Fernández-González ◽  
Lucía Hermida ◽  
...  

Phytotaxa ◽  
2015 ◽  
Vol 233 (1) ◽  
pp. 94 ◽  
Author(s):  
PEDRO PABLO FERRER-GALLEGO ◽  
Ángel Romo ◽  
Roberto Roselló ◽  
Emilio Laguna ◽  
Juan Bautista Peris

The genus Jasione Linnaeus (1753: 163) (Campanulaceae Juss.) is represented by ca. 16 species distributed throughout Europe and the Mediterranean Region, from coastal dunes to alpine zones, and growing on a wide variety of substrates as well (Sales & Hedge 2001b). The genus shows a high degree of polymorphism, which can be partially caused by its representation accross a wide range of ecological niches. This variability reaches its maximum expression within the Iberian Peninsula (Bokhari & Sales 2001).


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