scholarly journals The European 2015 drought from a climatological perspective

2017 ◽  
Vol 21 (3) ◽  
pp. 1397-1419 ◽  
Author(s):  
Monica Ionita ◽  
Lena M. Tallaksen ◽  
Daniel G. Kingston ◽  
James H. Stagge ◽  
Gregor Laaha ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Geopotential Height ◽  
Western Europe ◽  
North Atlantic Ocean ◽  
Western Mediterranean ◽  
Daily Maximum ◽  
Summer Drought ◽  
Drought Conditions ◽  
The Mediterranean

Abstract. The summer drought of 2015 affected a large portion of continental Europe and was one of the most severe droughts in the region since summer 2003. The summer of 2015 was characterized by exceptionally high temperatures in many parts of central and eastern Europe, with daily maximum temperatures 2 °C higher than the seasonal mean (1971–2000) over most of western Europe, and more than 3 °C higher in the east. It was the hottest and climatologically driest summer over the 1950–2015 study period for an area stretching from the eastern Czech Republic to Ukraine. For Europe, as a whole, it is among the six hottest and driest summers since 1950. High evapotranspiration rates combined with a lack of precipitation affected soil moisture and vegetation and led to record low river flows in several major rivers, even beyond the drought-hit region. The 2015 drought developed rather rapidly over the Iberian Peninsula, France, southern Benelux and central Germany in May and reached peak intensity and spatial extent by August, affecting especially the eastern part of Europe. Over the summer period, there were four heat wave episodes, all associated with persistent blocking events. Upper-level atmospheric circulation over Europe was characterized by positive 500 hPa geopotential height anomalies flanked by a large negative anomaly to the north and west (i.e., over the central North Atlantic Ocean extending to northern Fennoscandia) and another center of positive geopotential height anomalies over Greenland and northern Canada. Simultaneously, the summer sea surface temperatures (SSTs) were characterized by large negative anomalies in the central North Atlantic Ocean and large positive anomalies in the Mediterranean basin. Composite analysis shows that the western Mediterranean SST is strongly related to the occurrence of dry and hot summers over the last 66 years (especially over the eastern part of Europe). The lagged relationship between the Mediterranean SST and summer drought conditions established in this study can provide valuable skill for the prediction of drought conditions over Europe on interannual to decadal timescales.

scholarly journals The European 2015 drought from a climatological perspective

2016 ◽  
Author(s):  
Monica Ionita ◽  
Lena M. Tallaksen ◽  
Daniel G. Kingston ◽  
James H. Stagge ◽  
Gregor Laaha ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Geopotential Height ◽  
Western Europe ◽  
North Atlantic Ocean ◽  
Standardized Precipitation Index ◽  
Daily Maximum ◽  
Summer Drought ◽  
Contributing Factors ◽  
The Mediterranean

Abstract. The summer drought of 2015 affected a large portion of continental Europe and was one of the most severe droughts in the region since summer 2003. The summer was characterized by exceptionally high temperatures in many parts of central and eastern Europe, with daily maximum temperatures 2 °C warmer than the seasonal mean (1971–2000) over most of western Europe, and more than 3 °C warmer in the east. High evapotranspiration rates combined with a lack of precipitation affected the soil moisture content and vegetation stress and led to record low river flows in several major European rivers. This paper analyses the European summer drought of 2015 from a climatological perspective, including its origin, spatial and temporal development, and how it compares with the 2003 event. It discusses the main contributing factors controlling the occurrence and persistence of the event: temperature and precipitation anomalies, blocking episodes and sea surface temperatures (SST). Central Europe experienced during the summer of 2015 widespread areas of negative Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) values, present from May onwards. Similar to the summer drought of 2003, the upper level atmospheric circulation over Europe was characterized by a positive 500 hPa geopotential height anomalies flanked by a large negative anomaly to the north and west (i.e. over the central North Atlantic Ocean extending to northern Fennoscandia) and another center of positive geopotential height anomalies over Greenland and northern Canada. Simultaneously, the summer SST was characterized by large negative anomalies in the central North Atlantic Ocean and large positive anomalies in the Mediterranean basin. The SST dipole-like anomalies between the central Atlantic and the Mediterranean Sea suggest a possible "atmospheric teleconnection" between the two regions, which in turn may affect the drought conditions over Europe. In an accompanying paper, the hydrological perspective of the summer 2015 drought is presented. Together, these two papers summarize a collaborative initiative of members of UNESCO’s FRIEND-Water program to perform a timely Pan-European assessment of the 2015 summer drought.

scholarly journals Bluefin tuna reveal global patterns of mercury pollution and bioavailability in the world's oceans

2021 ◽  
Vol 118 (38) ◽  
pp. e2111205118
Author(s):  
Chun-Mao Tseng ◽  
Shin-Jing Ang ◽  
Yi-Sheng Chen ◽  
Jen-Chieh Shiao ◽  
Carl H. Lamborg ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Pacific ◽  
Thermohaline Circulation ◽  
North Atlantic Ocean ◽  
North Pacific Ocean ◽  
Bluefin Tuna ◽  
Anthropogenic Contamination ◽  
Global Patterns ◽  
The Mediterranean

Bluefin tuna (BFT), highly prized among consumers, accumulate high levels of mercury (Hg) as neurotoxic methylmercury (MeHg). However, how Hg bioaccumulation varies among globally distributed BFT populations is not understood. Here, we show mercury accumulation rates (MARs) in BFT are highest in the Mediterranean Sea and decrease as North Pacific Ocean > Indian Ocean > North Atlantic Ocean. Moreover, MARs increase in proportion to the concentrations of MeHg in regional seawater and zooplankton, linking MeHg accumulation in BFT to MeHg bioavailability at the base of each subbasin's food web. Observed global patterns correspond to levels of Hg in each ocean subbasin; the Mediterranean, North Pacific, and Indian Oceans are subject to geogenic enrichment and anthropogenic contamination, while the North Atlantic Ocean is less so. MAR in BFT as a global pollution index reflects natural and human sources and global thermohaline circulation.

Analysing and projecting spatial drought conditions of the Seine catchment based on ocean-atmosphere oscillations over interannual and decadal scales

2020 ◽  
Author(s):  
Kwok Pan Chun ◽  
Qing He ◽  
Bastien Dieppois ◽  
Nicolas Massei ◽  
Matthieu Fournier
Keyword(s):  
Atlantic Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Sea Surface ◽  
Positive Phase ◽  
The North ◽  
Drought Conditions ◽  
The North Atlantic

<p>Midlatitude droughts are affected by the tropical disturbances, which are linked to sea-surface temperature patterns in the Pacific and Atlantic Oceans. The combined effects of these two ocean basins manifest themselves in the variation of streamflows, from land surface filtering. In this study, we have developed a framework to explore the effects of global sea surface temperature variations along with atmospheric teleconnection patterns, on local hydroclimatic conditions related to droughts over the Seine catchment, a main waterway in northern France. Using the Standardized Runoff-discharge Index (SRI) to quantify hydrological drought conditions over the Seine, the North Atlantic Oscillation (NAO) index was found to be a significant driver for the upstream dryness between 2001 and 2015. The El Nino Southern Oscillation (ENSO) index was also found to be a significant forcing variable, but for the Seine downstream. The Atlantic Multidecadal Oscillation (AMO) and the West Mediterranean Sea (WMED) indices were significant over almost the whole Seine River basin. Results show that the drought spatial patterns of the Seine River vary differently with the atmospheric and oceanic oscillations from interannual to decadal scales. Over a small catchment with a drainage area around 78,700 square kilometres, the spatial drought variations in the Seine catchment appear to be usual, and they are likely to be related to regional conditions which drive local land surface mechanisms linked with microclimates or geological processes. In general, during the negative phase of AMO and the positive phase of ENSO, the sea surface temperature of the North Atlantic Ocean is low. The positive phase of NAO also lowers sea surface temperatures of the North Atlantic Ocean and the West Mediterranean Sea. Droughts are likely to occur at the Seine during the negative phase of AMO and the positive phase of NAO, because the cold North Atlantic Ocean has less evaporation and provides less moisture to France. Based on these results, a statistical downscaling model is developed to relate SRI to atmospheric and oceanic oscillation indices, which are derived from the Institut Pierre Simon Laplace climate model (IPSL-CM5) outputs. Using this statistical downscaling model and scenarios of Representative Concentration Pathways (RCP4.5 and RCP8.5), the drought conditions of the Seine are projected for the mid- and long-term future (2050s and 2080s). Diverse drought results are obtained. Based on relative importance of oscillation indices, the implications of diverse projections for general drought managements in midlatitude regions related to tropical sea surface temperature disturbances and atmospheric teleconnections are discussed.</p>

scholarly journals The Structure of the Columellar Muscle System in Clio Pyramidata and Cymbulia Peroni (Theocosomata, Gastropoda)

1979 ◽  
Vol 48 (2) ◽  
pp. 111-126 ◽  
Author(s):  
Trudy Pafort-van Iersel ◽  
S. van der Spoel
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Larval Stage ◽  
North Atlantic Ocean ◽  
Phylogenetic Relation ◽  
Muscle System ◽  
The North ◽  
The North Atlantic ◽  
The Asymmetry ◽  
The Mediterranean

The phylogenetic relation between Clio pyramidata Linnaeus, 1767, and Cymbulia peroni De Blainville, 1818, has been studied with regard to the structure of their muscle systems. Specimens of both species collected from the North Atlantic Ocean and the Mediterranean were sectioned 5 μm thick and stained with Haematoxilin-Eosin, Crossmon or Azan for histological purposes or they were studied as cleared dissected or entire animals. The columellar muscle and subectodermal wing muscles of both species are described. It is concluded that Clio shows neoteny since it develops without metamorphosis. The asymmetry in anatomy proves that both Clio and Cymbulia descend from spiralised ancestors. For Clio two primitive characters are discussed which may be due to the “larval stage” of the adult but which also affirm the possible relation of molluscs to a coelenterate-like ancestor. Original structures found in Cymbulia are also discussed in the light of a possible phylogenetic relation between Thecosomata and Coelenterata, more in particular Conulata.

scholarly journals The Quasi-Biweekly Oscillation of Summer Rainfall in Southern China and Its Relationship With the Geopotential Height Anomaly Over the North Atlantic Ocean

2021 ◽  
Vol 9 ◽  
Author(s):  
Qian Huang ◽  
Xinyu Yin ◽  
Suxiang Yao
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Geopotential Height ◽  
North Atlantic Ocean ◽  
Southern China ◽  
Summer Precipitation ◽  
Height Anomaly ◽  
Geopotential Height Anomaly ◽  
The North ◽  
The North Atlantic

Summer precipitation in East Asia has significant quasi-biweekly (10–30-day) oscillation characteristics. By using gauge-based precipitation and ERA-Interim reanalysis data, the basic mode of the quasi-biweekly oscillation of summer precipitation in East Asia and the related circulation from 1979 to 2012 were analyzed. It was found that the middle and lower reaches of the Yangtze River and its south in China were among the key areas for the 10- to 30-day oscillation of summer precipitation. After selecting typical summer precipitation events with 10- to 30-day oscillation characteristics in key areas and conducting composite analysis, it is found that in the dry (wet) phase of quasi-biweekly precipitation in southern China, it is controlled by quasi-biweekly anticyclone (cyclone) at 500 hPa above the key area. During the evolution of quasi-biweekly precipitation, the ridge of the Northwest Pacific Subtropical High is located between 20 and 22°N latitude, and there is no significant variability in the large-scale background circulation. Furthermore, composite analysis of the precursory signal at 500 hPa during quasi-biweekly precipitation in southern China found that there was an obvious quasi-biweekly geopotential height anomaly over the North Atlantic Ocean almost 30 days before the peak day of quasi-biweekly precipitation. While the quasi-biweekly geopotential height anomaly at 500 hPa in the North Atlantic propagates eastward, it also leads the cold air to transport southward. Cold air from high latitudes and warm air from low latitudes converge in southern China, which affects the quasi-biweekly oscillation of precipitation. Hysteresis synthesis of precipitation based on 500 hPa geopotential height’s quasi-biweekly oscillation events over the North Atlantic Ocean comes to almost the same conclusion. Therefore, the 500 hPa geopotential height quasi-biweekly anomaly in the North Atlantic may have important prediction significance for an extended-range forecast of summer rainfall in China.

Discospirina (Miliolina, Foraminiferida) from the Coral Sea off northeastern Australia: a new record

1991 ◽  
Vol 65 (2) ◽  
pp. 332-334 ◽  
Author(s):  
George C. H. Chaproniere
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Mediterranean Area ◽  
Anterior Wall ◽  
The North ◽  
Coral Sea ◽  
Initial Stage ◽  
The North Atlantic ◽  
The Mediterranean

Discospirina is a milioline genus previously recorded as fossil only from the Miocene to Pleistocene of the Mediterranean, and is found living in the same area and into the North Atlantic Ocean (Adams, 1959, 1967, 1973; Adams etal., 1983; Radford, 1976). It is readily recognized by its large, fragile, very thin test, with annular chambers surrounding a coiled initial stage; the concentric chambers are subdivided by numerous internal septa that fall short of the anterior wall of each chamber (Adams, 1959). The specimens illustrated by Brady (1884, PI. 65, figs. 6, 7) from the Atlantic Ocean were referred to Discospirina tenuissima by Barker (1960), but Adams (1959) considered this to be a junior synonym for D. italica, giving the species a range from late Miocene to Recent. Adams (1959) noted that there were more septa per annular chamber in the Recent than in the fossil forms from the Mediterranean area, and the Coral Sea forms appear to resemble the Miocene ones in this respect.

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