On the drought in the Balearic Islands during the hydrological year 2015–2016

Abstract. During the hydrological year 2015–16 (September to August) a severe drought affected the Balearic Islands, with substantial consequences (alleviated partially by desalination plants) on water availability for consumption from reservoirs and aquifers and also on the vegetation cover. In particular, a plague of Xilella fastidiosa reached a relatively alarming level for the case of the almond and olive trees. The expansion of this infestation could be attributed to, or at least favored by, the extreme drought. In this paper we analyze this anomalous episode in terms of the corresponding water balance in comparison with the balance obtained from long-term climatological data. It is shown that the drought was the result of a lack of winter precipitation, the lowest in 43 years, which led to a shortage of water storage in the soil. In several meteorological stations analyzed, evaporation was greater than precipitation during all the months of the year. In terms of attribution, it is found that during the 2015–16 winter the atmospheric circulation over the North Atlantic was largely westerly and intense, with high values of the NAO index that were reflected in high pressures over the Iberian Peninsula and the western Mediterranean.

Download Full-text

On the drought in the Balearic Islands during the hydrological year 2015–2016

Natural Hazards and Earth System Science ◽

10.5194/nhess-17-2351-2017 ◽

2017 ◽

Vol 17 (12) ◽

pp. 2351-2364 ◽

Cited By ~ 2

Author(s):

Climent Ramis ◽

Romualdo Romero ◽

Víctor Homar ◽

Sergio Alonso ◽

Agustí Jansà ◽

...

Keyword(s):

High Pressures ◽

Winter Precipitation ◽

Western Mediterranean ◽

Balearic Islands ◽

Severe Drought ◽

The North ◽

Nao Index ◽

Olive Trees ◽

Desalination Plants

Abstract. During the hydrological year 2015–2016 (September to August) a severe drought affected the Balearic Islands, with substantial consequences (alleviated partially by desalination plants) on water availability for consumption from reservoirs and aquifers and also on the vegetation cover. In particular, a plague of Xylella fastidiosa reached an alarming level for almond and olive trees. The expansion of this infestation could be attributed to, or at least favored by, the extreme drought. In this paper we analyze this anomalous episode in terms of the corresponding water balance in comparison with the balance obtained from long-term climatological data. It is shown that the drought was the result of a lack of winter precipitation, the lowest in 43 years, which led to a shortage of water storage in the soil. In several meteorological stations analyzed, evaporation was greater than precipitation during all the months of the year. In terms of attribution, it is found that during the 2015–2016 winter the atmospheric circulation over the North Atlantic was largely westerly and intense, with high values of the NAO index that were reflected in high pressures over the Iberian Peninsula and the western Mediterranean.

Download Full-text

A captorhinid-dominated assemblage from the palaeoequatorial Permian of Menorca (Balearic Islands, western Mediterranean)

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691021000268 ◽

2021 ◽

pp. 1-21

Author(s):

Rafel MATAMALES-ANDREU ◽

Francesc X. ROIG-MUNAR ◽

Oriol OMS ◽

Àngel GALOBART ◽

Josep FORTUNY

Keyword(s):

Western Mediterranean ◽

Balearic Islands ◽

Distribution Area ◽

Lower Permian ◽

Incertae Sedis ◽

The North ◽

Low Latitudes ◽

High Fibre ◽

Successful Group ◽

Neighbouring Island

ABSTRACT Moradisaurine captorhinid eureptiles were a successful group of high-fibre herbivores that lived in the arid low latitudes of Pangaea during the Permian. Here we describe a palaeoassemblage from the Permian of Menorca (Balearic Islands, western Mediterranean), consisting of ichnites of small captorhinomorph eureptiles, probably moradisaurines (Hyloidichnus), and parareptiles (cf. Erpetopus), and bones of two different taxa of moradisaurines. The smallest of the two is not diagnostic beyond Moradisaurinae incertae sedis. The largest one, on the other hand, shows characters that are not present in any other known species of moradisaurine (densely ornamented maxillar teeth), and it is therefore described as Balearosaurus bombardensis gen. et sp. nov. Other remains found in the same outcrop are identified as cf. Balearosaurus bombardensis gen. et sp. nov., as they could also belong to the newly described taxon. This species is sister to the moradisaurine from the lower Permian of the neighbouring island of Mallorca, and is also closely related to the North American genus Rothianiscus. This makes it possible to suggest the hypothesis that the Variscan mountains, which separated North America from southern Europe during the Permian, were not a very important palaeobiogeographical barrier to the dispersion of moradisaurines. In fact, mapping all moradisaurine occurrences known so far, it is shown that their distribution area encompassed both sides of the Variscan mountains, essentially being restricted to the arid belt of palaeoequatorial Pangaea, where they probably outcompeted other herbivorous clades until they died out in the late Permian.

Download Full-text

A Regime View of the North Atlantic Oscillation and Its Response to Anthropogenic Forcing

Journal of Climate ◽

10.1175/2009jcli3087.1 ◽

2010 ◽

Vol 23 (6) ◽

pp. 1291-1307 ◽

Cited By ~ 90

Author(s):

Tim Woollings ◽

Abdel Hannachi ◽

Brian Hoskins ◽

Andrew Turner

Keyword(s):

North Atlantic Oscillation ◽

North Atlantic ◽

Anthropogenic Forcing ◽

The Third ◽

The North ◽

Nao Index ◽

Future Behavior ◽

Real Change ◽

The North Atlantic Oscillation

Abstract The distribution of the daily wintertime North Atlantic Oscillation (NAO) index in the 40-yr ECMWF Re-Analysis (ERA-40) is significantly negatively skewed. Dynamical and statistical analyses both suggest that this skewness reflects the presence of two distinct regimes—referred to as “Greenland blocking” and “subpolar jet.” Changes in both the relative occurrence and in the structure of the regimes are shown to contribute to the long-term NAO trend over the ERA-40 period. This is contrasted with the simulation of the NAO in 100-yr control and doubled CO2 integrations of the third climate configuration of the Met Office Unified Model (HadCM3). The model has clear deficiencies in its simulation of the NAO in the control run, so its predictions of future behavior must be treated with caution. However, the subpolar jet regime does become more dominant under anthropogenic forcing and, while this change is small it is clearly statistically significant and does represent a real change in the nature of NAO variability in the model.

Download Full-text

Hydrography and Circulation West of Sardinia in June 2014

10.5194/os-2017-45 ◽

2017 ◽

Cited By ~ 1

Author(s):

Michaela Knoll ◽

Ines Borrione ◽

Heinz-Volker Fiekas ◽

Andreas Funk ◽

Michael P. Hemming ◽

...

Keyword(s):

Eastern Mediterranean ◽

Potential Temperature ◽

Atlantic Water ◽

Western Mediterranean ◽

Anticyclonic Eddy ◽

Intermediate Water ◽

Potential Density ◽

Sea Trial ◽

The North

Abstract. In the mainframe of the REP14-MED sea trial in June 2014, the hydrography and circulation west of Sardinia, observed by means of gliders, shipborne CTD instruments, towed devices, and vessel-mounted ADCPs, are presented and compared with previous knowledge. So far, the circulation is not well known in this area, and the hydrography is subject to long-term changes. Potential temperature, salinity, and potential density ranges, as well as core values of the observed water masses were determined. Modified Atlantic Water (MAW), with potential density anomalies below 28.72 kg m−3, showed a salinity minimum of 37.93 at 50 dbar. Levantine Intermediate Water (LIW), with a salinity maximum of about 38.70 at 400 dbar, was observed within a range of 28.72 < σΘ [kg m−3] < 29.10. MAW and LIW showed slightly higher salinities than previous investigations. During the trial, LIW covered the whole area from the Sardinian shelf to 7°15' E. Only north of 40° N was it tied to the continental slope. Within the MAW, a cold and saline anticyclonic eddy was observed in the southern trial area. The strongest variability in temperature and salinity appeared around this eddy, and in the southwestern part of the domain, where unusually low saline surface water entered the area towards the end of the experiment. An anticyclonic eddy of Winter Intermediate Water was recorded moving northward at 0.014 m s−1. Geostrophic currents and water mass transports calculated across zonal and meridional transects showed a good agreement with vessel-mounted ADCP measurements. Within the MAW, northward currents were observed over the shelf and offshore, while a southward transport of about 1.5 Sv occurred over the slope. A net northward transport of 0.38 Sv across the southern transect decreased to zero in the north. Within the LIW, northward transport of 0.6 Sv across the southern transects were mainly observed offshore, and decreased to 0.3 Sv in the north where they were primarily located over the slope. This presentation of the REP14-MED observations helps to further understand the long-term evolution of hydrography and circulation in the Western Mediterranean, where considerable changes occurred after the Eastern Mediterranean Transient and the Western Mediterranean Transition.

Download Full-text

Centennial to millennial-scale variability of Holocene climate and environmental dynamics in the western Mediterranean (Lake Sidi Ali, Middle Atlas, Morocco)

10.5194/egusphere-egu21-8650 ◽

2021 ◽

Author(s):

Johannes Schmidt ◽

Cathleen Kertscher ◽

Markus Reichert ◽

Helen Ballasus ◽

Birgit Schneider ◽

...

Keyword(s):

North Atlantic ◽

Climate Changes ◽

Western Mediterranean ◽

Future Climate ◽

Holocene Climate ◽

The Holocene ◽

The North ◽

Middle Atlas ◽

Environmental Responses

The Western Mediterranean region including the North African desert margin is considered one of the most sensitive areas to future climate changes. In order to refine long-term scenarios for hydrological and environmental responses to future climate changes in this region, it is important to improve our knowledge about past environmental responses to climatic variability at centennial to millennial timescales. During the last two decades, the recovery and compilation of Holocene records from the subtropical North Atlantic and the Mediterranean Sea have improved our knowledge about millennial-scale variability of the Western Mediterranean palaeoclimate. The variabilities appear to affect regional precipitation patterns and environmental systems in the Western Mediterranean, but the timescales, magnitudes and forcing mechanisms remain poorly known. To compare the changes in Holocene climate variability and geomorphological processes across temporal scales, we analysed a 19.63-m long sediment record from Lake Sidi Ali (33&#176;03&#8217; N, 5&#176;00&#8217; W, 2080 m a.s.l.) in the sub-humid Middle Atlas that spans the last 12,000 years (23 pollen-based radiocarbon dates accompanied with 210Pb results). We use calibrated XRF core scanning records with an annual to sub-decadal resolution to disentangle the complex interplay between climate changes and environmental dynamics during the Holocene. Data exploration techniques and time series analysis (Redfit, Wavelet) revealed long-term changes in lake behaviour. Three main proxy groups were identified (temperature proxies: 2ky, 1ky and 0.7ky cycles; sediment dynamic proxies: 3.5ky, 1.5ky cycles; hydrological proxies: 1.5ky, 1.2ky, 0.17ky cycles). For example, redox sensitive elements Fe and Mn show 1ky cycles and higher values in the Early Holocene and 1.5ky cycles and lower values in the Mid- to Late Holocene. All groups show specific periodicities throughout the Holocene, demonstrating their particular climatic and geomorphological dependencies. Furthermore, we discuss these periodicities relating to global and hemispheric drivers, such as the North Atlantic Oscillation (NAO), El-Ni&#241;o Southern Oscillation (ENSO), Innertropical Convergence Zone variability (ITCZ) and North Atlantic cold relapses (Bond events).

Download Full-text

Coupled decadal variability of the North Atlantic Oscillation, regional rainfall and karst spring discharges in the Campania region (southern Italy)

Hydrology and Earth System Sciences ◽

10.5194/hess-16-1389-2012 ◽

2012 ◽

Vol 16 (5) ◽

pp. 1389-1399 ◽

Cited By ~ 21

Author(s):

P. De Vita ◽

V. Allocca ◽

F. Manna ◽

S. Fabbrocino

Keyword(s):

Time Series ◽

North Atlantic Oscillation ◽

Air Temperature ◽

North Atlantic ◽

Karst Spring ◽

The North ◽

Nao Index ◽

The North Atlantic ◽

The North Atlantic Oscillation

Abstract. Thus far, studies on climate change have focused mainly on the variability of the atmospheric and surface components of the hydrologic cycle, investigating the impact of this variability on the environment, especially with respect to the risks of desertification, droughts and floods. Conversely, the impacts of climate change on the recharge of aquifers and on the variability of groundwater flow have been less investigated, especially in Mediterranean karst areas whose water supply systems depend heavily upon groundwater exploitation. In this paper, long-term climatic variability and its influence on groundwater recharge were analysed by examining decadal patterns of precipitation, air temperature and spring discharges in the Campania region (southern Italy), coupled with the North Atlantic Oscillation (NAO). The time series of precipitation and air temperature were gathered over 90 yr, from 1921 to 2010, using 18 rain gauges and 9 air temperature stations with the most continuous functioning. The time series of the winter NAO index and of the discharges of 3 karst springs, selected from those feeding the major aqueducts systems, were collected for the same period. Regional normalised indexes of the precipitation, air temperature and karst spring discharges were calculated, and different methods were applied to analyse the related time series, including long-term trend analysis using smoothing numerical techniques, cross-correlation and Fourier analysis. The investigation of the normalised indexes highlighted the existence of long-term complex periodicities, from 2 to more than 30 yr, with differences in average values of up to approximately ±30% for precipitation and karst spring discharges, which were both strongly correlated with the winter NAO index. Although the effects of the North Atlantic Oscillation (NAO) had already been demonstrated in the long-term precipitation and streamflow patterns of different European countries and Mediterranean areas, the results of this study allow for the establishment of a link between a large-scale atmospheric cycle and the groundwater recharge of carbonate karst aquifers. Consequently, the winter NAO index could also be considered as a proxy to forecast the decadal variability of groundwater flow in Mediterranean karst areas.

Download Full-text

Past African dust inputs in the western Mediterranean area controlled by the complex interaction between the Intertropical Convergence Zone, the North Atlantic Oscillation, and total solar irradiance

Climate of the Past ◽

10.5194/cp-16-283-2020 ◽

2020 ◽

Vol 16 (1) ◽

pp. 283-298 ◽

Cited By ~ 3

Author(s):

Pierre Sabatier ◽

Marie Nicolle ◽

Christine Piot ◽

Christophe Colin ◽

Maxime Debret ◽

...

Keyword(s):

Mediterranean Area ◽

Total Solar Irradiance ◽

Western Mediterranean ◽

Saharan Dust ◽

Climatic Forcing ◽

African Dust ◽

The North ◽

The North Atlantic Oscillation ◽

Wavelet Analyses

Abstract. North Africa is the largest source of mineral dust on Earth, which has multiple impacts on the climate system; however, our understanding of decadal to centennial changes in African dust emissions over the last few millenniums is limited. Here, we present a high-resolution multiproxy analysis of sediment core from high-elevation Lake Bastani, on the island of Corsica, to reconstruct past African dust inputs to the western Mediterranean area over the last 3150 cal BP. Clay mineralogy with palygorskite and a clay ratio associated with geochemical data allow us to determine that terrigenous fluxes are almost exclusively related to atmospheric dust deposition from the western Sahara and Sahel areas over this period. High-resolution geochemical contents provide a reliable proxy for Saharan dust inputs with long-term (millennial) to short-term (centennial) variations. Millennial variations have been correlated with the long-term southward migration of the Intertropical Convergence Zone (ITCZ), with an increase in dust input since 1070 cal BP. This correlation suggests a strong link with the ITCZ and could reflect the increased availability of dust sources to be mobilized with an increase in wind and a decrease in precipitation over western and North Africa. For centennial to decadal variations, wavelet analyses show that since 1070 cal BP, the North Atlantic Oscillation (NAO) has been the main climatic forcing, with an increase in Saharan dust input during the positive phase, as suggested by previous studies over the last decades. However, when the ITCZ is in a northern position, before 1070 cal BP, wavelet analyses indicate that total solar irradiance (TSI) is the main forcing factor, with an increase in African dust input during low TSI. With climate reanalysis over the instrumental era, during low TSI we observe a significant negative anomaly in pressure over Africa, which is known to increase the dust transport. These two climatic forcing factors (NAO, TSI) modulate Saharan dust inputs to the Mediterranean area at a centennial timescale through changes in wind and transport pathways.

Download Full-text

Coastal climatology of the North-Western Mediterranean area for long-term and short-term risk assessment.

10.5194/egusphere-egu2020-19382 ◽

2020 ◽

Author(s):

Carlo Brandini ◽

Stefano Taddei ◽

Valentina Vannucchi ◽

Michele Bendoni ◽

Bartolomeo Doronzo ◽

...

Keyword(s):

Risk Assessment ◽

High Resolution ◽

Mediterranean Area ◽

Western Mediterranean ◽

Climate Trends ◽

Short Term ◽

The North ◽

The Mediterranean ◽

North Western

In this work we present the results obtained through a dynamic downscaling of the ERA5 reanalysis dataset (hindcast) of ECMWF, using high-resolution meteorological and wave models defined on unstructured computation grids along the Mediterranean coasts, with a particular focus on the North-Western Mediterranean area. Downscaling of the ERA5 meteorological data is obtained through the BOLAM and MOLOCH models (up to a resolution of 2.5 km) which force an unstructured WW3 model with a resolution of up to 500 m along the coast. Models were validated through available meteorological stations, wave buoy data and X-band wave radars, the latter for the purposes of wave spectra validation.On the one hand, this allowed, by extracting the time series of some attack parameters of the waves along the coast, and according to the type of coast (rocky coasts, sandy coasts, coastal structures etc.), to compute the return periods and to characterize the impact of any individual storm.&#160;On the other hand, it is possible to highlight some trends observed in the last 30 years, during which recent research is showing an increasing evidence &#160;of some changes in global circulation at regional to local scales. These changes also include effects of wind rotation, wave regimes, storm surges, wave-induced coastal currents and coastal morphodynamics. For example, in the North-Western Mediterranean extreme events belonging to cyclonic weather-types circulation with stronger S-SE components (like the storm of October 28-30th 2018 and many others), rather than events associated with perturbations of Atlantic origin and zonal circulation, are becoming more frequent. These long-term wind/wave climate trends can have consequences not only in the assessment of long-term risk due to main morphodynamic variations (ie. coastal erosion), but also in the short-term risk assessment.This work was funded by the EU MAREGOT project (2017-2020) and ECMWF Special Project spitbran &#160;&#8220;Evaluation of coastal climate trends in the Mediterranean area by means of high-resolution and multi-model downscaling of ERA5 reanalysis&#8221; (2018-2020).

Download Full-text