0000000000221163
AUTHOR
Albin Ullmann
Extreme dry spell detection and climatology over the Mediterranean Basin during the wet season
The E-OBS precipitation gridded data set v.10.0 is used to detect very long dry spell (VLDS) events over the entire Mediterranean Basin for the 1957–2013 period, during the wet season (September to April). The main objective is to characterize these events as climatic objects, in terms of location, spatial extent, duration, and temporal variability. In this study, 76 VLDS events were detected in the Mediterranean Basin and grouped into four spatial patterns: scattered localized (with 25 events), northeast Mediterranean (11 events), West Mediterranean (15 events), and southeast Mediterranean (25 events). Each pattern shows seasonality in events. Most of the scattered localized, northeast, an…
How abrupt change in surface temperature impacts water cycle over France ?
Along with the rapid warming tendency of the last decades over France, a shift in air temperaturehas been detected in 1987/88, delimiting two main climate periods from 1959 to 2019. Evidence of pre- andpost-shift runoff seasonal differences suggest an impact of this abrupt warming on water cycle evolution. Asyearly precipitation slightly evolve during the studied period, evapotranspiration appears to be one of themain drivers of the hydrological cycle evolution. Spring is marked by a strong increase in evaporativedemand, followed in summer by a rise in water stress and a drying of soil water content. Besides temporaldisparities, this local water cycle evolution depicts different spatial res…
SURCOTES MARINES DANS LE GOLFE DU LION ET FORCAGES ATMOSPHERIQUES : VARIABILITE CONTEMPORAINE ET FUTURE (1950-2100)
Sea surges in the Gulf of Lions are mainly forced by southerly and south-easterly winds. This regional-scale atmospheric circulation is leading by a strong zonal gradient between low pressure system over the Bay of Biscay and high pressure over central Europe. This synoptic-scale circulation mostly happens during “Greenland Above” weather regime. In the second half of the 20th century, a slow increase of the sea-level pressure over central Europe increased the probability of having “Greenland Above” weather types associated with a southerly atmospheric circulation in the Gulf of Lions, thus leading to strong surges. A linear regression is used to simulate the interannual variability of high…
Variabilité de la température entre 1951 et 2014 en Allemagne associée à l’évolution de la floraison des pommiers.
Apple tree bloom onset in Germany has advanced by 2 days/decade in 1951-2014 and by 3 days/decade in 1988-2014, behaving similarly in respect to its evolution since 1951 and its sensitivity to temperature to other species’ phenological spring phases. The evolution however was not linear; by conducting a split moving-window dissimilarity analysis (SMWDA) we were able to detect the “break-period” 1987-1989 which coincides with a breakpoint that has been identified in the phases of the North Atlantic Oscillation (NAO). We observed distinct spatial patterns with apple bloom advancing from southwest to northeast and, most interestingly, a longitudinal gradient in the trend of apple bloom onset r…
North-Atlantic Oscillation and regional-scale sea-surge variability in Gulf of Lions during the 20th century
Article soumis; International audience; Sea-surge variations recorded at three tide-gauge stations (Grau-de-la-Dent, Sète, and Port-Vendres) around the Gulf of Lions (Northwest Mediterranean Sea) are mostly locally forced by onshore winds blowing from 90° to 180° related to an atmospheric depression usually centered between the Bay of Biscay and the British Island, which is more prevalent during the negative phase of the North-Atlantic Oscillation (NAO). During the second half of the 20th century, the long-term increase of sea-surge height at Grau-de-la-Dent finds no counterpart in the positive deviation of the NAO. The relationship between the monthly frequency of sea surges > 20 cm at Gra…
Recent changes in measured wind in the NE Atlantic and variability of correlation with NAO
The paper deals with wind measurements, recorded since the 1950s, at twelve meteorological stations along a transect near the westernmost European border, between 64° and 44° N. Extreme wind speed tends to decrease sharply near the northern boundary (at Reykjavick), near the middle of the study area (at Shannon and Valentia) and near the southern boundary (at Brest and Cap Ferret), to increase at Thorshavn, with less significant trends at the other stations. Average wind speeds confirm the above tendencies, with an additional increasing speed at Lerwick, Kirkwall, Malin Head, Belle-Ile and Cap Ferret. To compare changes in wind activity, the data have been subdivided into three periods: unt…
How abrupt change in surface temperature impacts water balance over France? A case-study of bread wheat cultivated areas.
Agricultural risk management is a major challenge for decision makers, public authorities and agricultural insurance companies, as crop losses linked to climate hazard are expected to increase in the context of climate change (Boucher et al., 2019). The present work is part of a PhD in partnership between Groupama insurance company (Domaine Assurance Récolte) and Biogeosciences laboratory (University of Burgundy). This collaborative research aims at depicting how, with the abrupt surface temperature warming, climate hazard evolution has affected water balance over France, and related agro-climatic risks.Since 1980s over western Europe, the warming trend intensifies strongly, consistent with…
Niveaux marins extrêmes dans le Golfe du Lion : variabilité contemporaine et future (1905-2100).
13 pages; National audience
Cambios en la frecuencia de los Regímenes de Tiempo sobre la región Euro-Atlántica y Mediterránea y su relación con las temperaturas anómalas sobre el Mar Mediterráneo
An exercise has been carried out to assess to what extent the Euro-Atlantic Weather Regimes (WR), described from the ERA-interim Reanalysis in the summer season, projects onto a pool of AGCMAMIP simulations in which sea surface temperatures (SST) are prescribed from observations. Although the model simulations present some biases in the spatial structure and seasonality of WRs, exhibiting also less variability, they are able to capture main WR over the region in summer season: +Middle East –Middle East, +NAO, -NAO. WR paradigm is used to quantify changes in the atmosphere under warmer/colder than normal conditions over the Mediterranean Sea. To address this problem, firstly, changes in the …
Types de temps et risque d'inondation et d'érosion en Camargue : diagnostique et prévision au 21ème siècle (1993-2100)
High sea surges and waves are the two mains hydro-meteorological phenomenon associated with coastal flooding and erosion in Camargue. For the period 1993-2002, high monthly frequencies of strong surges are usually associated with high frequency of strong waves. These two phenomenons mainly occur during weather type showing a deep low pressure system over the Bay of Biscay associated with high pressure over Central Europe. The monthly frequency of such weather regime indicates the probability of occurrence of high surges and waves along Camargue's coast. During the 21st century, the frequency of this specific weather regime could stay stationary for the A1b climate change scenario.
La rupture climatique de 1987 en France : quels effets sur l’humidité des sols ?
Cet article présente les caractéristiques spatio-temporelles de l’humidité des sols à l’échelle de la France entre deux sous-périodes (1959-1987 et 1988-2019). Les principaux résultats montrent un assèchement généralisé des sols, surtout au printemps et en été, notamment pour trois secteurs : le sud-ouest, le nord-est et le pourtour méditerranéen. L’assèchement des sols peut s’expliquer par un important réchauffement des températures, généralisé et significatif à l’échelle de l’ensemble du territoire, mais bien plus marqué dans le sud-ouest et le nord-est, au printemps et en été. Cette élévation importante des températures entre les deux sous-périodes semble expliquer une très forte hausse …
Sea surges at Monaco and Nice: present-day and future variability (1998-2100).
Sea surges arerapid increase of the level of the sea under atmospheric conditions that could lead to coastal submersion havingstrong impacts especially for coastal towns of the French Riviera such as Nice and the principality of Monaco.Interannual variability of the highest surges at Monaco is robustly simulates by a linear regression usingbarometric conditions over [3-10°E]-[40-45°N] as a predictor. According to 15 global circulation models,highest surges at Monaco could stay stationary for two different climate change scenarios (RCP4.5 andRCP8.5).
Conditions atmosphériques associées aux chutes de grêles en Bourgogne.
A network of 96 hail pads is installed in Burgundy since 2014. Hailfalls in this part of France are mainly recorded from Avril to September and usually at the end of the afternoon when the surface air has been warmed enough to trigger an upward lift. Atmospherically speaking, hailfalls in Burgundy are associated with southward winds blowing from the Mediterranean Sea (Gulf of Lions) according to a strong negative barometric anomaly centered over Germany and extended southwestward until the south of Spain. A weak northwestward wind is at the same time also blowing until the northern part of Burgundy creating a thermal air-mass conflict and therefore a convective available potential energy wh…
Weather Regimes in the Euro-Atlantic and Mediterranean Sector, and Relationship with West African Rainfall over the 1989–2008 Period from a Self-Organizing Maps Approach
Abstract Weather regimes (WRs) have been defined over the Euro-Mediterranean region (15°–70°N, 60°W–60°E) from May to October using the daily sea level pressure, 700-hPa geopotential height, and specific humidity from the European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA)-Interim over the 1989–2008 period. Computations are based on a neural network classification technique referred to as self-organizing maps, and the WRs produced can be used by the scientific community for comparison with other periods, projection onto model outputs, seasonal prediction, or teleconnection studies. The article particularly examines the relationship between WRs and West Africa (WA) rainfall,…
Les types de temps associés aux risques d’inondations et d’érosions en Camargue : éléments de diagnostic et de prospectives pour le 21e siècle (1993-2100)
Les fortes surcotes marines et les fortes vagues sont les principaux aléas météo-marins associés aux risques de submersion et d’érosion du littoral camarguais. Sur la période 1993-2002, une forte fréquence mensuelle de très hautes surcotes marégraphiques est généralement associée à une forte fréquence de très hautes vagues. Ces deux phénomènes locaux se produisent principalement lorsqu'une dépression autour du Golfe de Gascogne est associée à des hautes pressions sur l’Europe Centrale. La fréquence mensuelle de ce type de temps nous renseigne sur la probabilité d’occurrence de fortes surcotes marégraphiques et vagues en Camargue. Au 21e siècle, la fréquence du type de temps associé aux plus…
Changement climatique et surcotes marines, quel avenir pour les plages camarguaises ?
2 pages; National audience
Extreme dry spells over the Mediterranean Basin during the wet season: assessment of HyMeX/Med-CORDEX regional climate simulations (1979-2009).
16 pages; International audience; Exceptional dry spells, in this study referred to as very long dry spells (VLDS), are natural hazards to which the Mediterranean region is extremely vulnerable, with socio‐economic and environmental impacts. In this study, they are characterized in terms of location, spatial extent, duration, temporal variability and associated atmospheric circulations. The main objective is to assess the performance of five HyMeX/Med‐CORDEX regional climate simulations to detect and reproduce VLDS in comparison with the E‐OBS observed daily gridded data. Models accurately reproduce the occurrence of precipitation around the Mediterranean Basin, and therefore the occurrence…
Épisodes secs en hiver dans le bassin méditerranéen : variabilité et forçages atmosphériques (1957-2013).
The mean number of dry days in winter increased in the Mediterranean Basin during the 1957-2013 period,mainly because of dry spells becoming longer. The shortest events (Very Short Dry Spells) were less frequentwhereas longer events (Short Dry Spells, Medium Dry Spells and Long Dry Spells) were more frequent on theMediterranean Basin. 76 very long events (Very Long Dry Spells – VLDS) occurred during the 1957-2013period. A hierarchical clustering analysis of these VLDS events allows to detect 5 mainly Mediterraneanconfigurations: North-West Mediterranean, West Mediterranean, North-East Mediterranean, South-EastMediterranean and localized events.
Time evolution of observed July–September sea surface temperature-Sahel climate teleconnection with removed quasi-global effect (1900–2008)
[1] Using sea surface temperature (SST), precipitation, and atmospheric information, this statistical study revisits the questions of the July–September SST-Sahel teleconnection variability after removing impact of quasi-global SSTs over the period 1900–2008. The eastern Mediterranean and the Indian Ocean dominate the relationship, both in terms of intensity and time stability, with significant values in 52% and 47% of years, respectively. More than two thirds of the rainy seasons classified as dry (wet) and 16 out of 18 (12 out of 15) of those classified as very dry (very wet) are concomitant of negative (positive) differences between the Mediterranean and the Indian Ocean. Correlations wi…
Types de configurations pluviométriques sur le bassin méditerranéen, forçages atmosphériques et évènements intenses (1979-2013).
Sixrecurrent and redundant daily rainfall patterns have been extracted over the Mediterranean area from 1979 to 2013: five areassociated to regionals rainfall excess (South-West Mediterranean, Mid-North Mediterranean, East Mediterranean, WestMediterranean and north-west Mediterranean) and one to generalized deficit. Each rainfall pattern is associated with atypical barometric spatial configuration leading to local wind bringing moisture to the coast leading to specific local rainfallsurplus. Rainfall patterns also explain a large part of the spatial characteristics and the probability of occurrence of intenseevents. For example, more than 20% of days of “West-Mediterranean” rainfall pattern…
Très longs épisodes secs hivernaux dans le bassin méditerranéen : variabilité spatio-temporelle et impact sur la production céréalière en Espagne.
This study concerns the long winter sequences without rain at the whole Mediterraneanbasin scale. Objectives are (i) to define theses extreme events as geographical and climatological objectscharacterized by a location, a spatial extension and a temporal length and (ii) measured impacts of these eventson the cereal production in Spain. 76 events of very long dry spells (eVLDS) are detected over the 1957-2013period. These eVLDS are grouped into 4 typical recurrent configurations at the Mediterranean basin scale: North-East, West, Scattered & Localised and South-East. The eVLDS have a greater impact on barley, wheat and oatyields (winter crops grown through rainfed agriculture) than rainfall …