Time variability of cyclonic geostrophic circulation in the Mediterranean

Guijarro, José Antonio; Jansà, A.; Campins, Joan

doi:10.5194/adgeo-7-45-2006

Cited by 15 publications

(20 citation statements)

References 10 publications

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“…In fact, other studies suggest no actually significant trend, an increase of weak cyclones in the western Mediterranean in the period 1978(Trigo et al, 2000, a positive trend in the eastern Mediterranean, though not in the rainy season (Maheras et al, 2001). Nevertheless, in a 45 yr record, Guijarro et al (2006), show a significant decrease in the cyclonic circulation in the western Mediterranean, and an increase in the eastern Mediterranean.…”

Section: According To the Results Of Climatic Models (Sres A1b) Itmentioning

confidence: 93%

Long term precipitation trends and variability within the Mediterranean region

Philandras

Nastos

Kapsomenakis

et al. 2011

Nat. Hazards Earth Syst. Sci.

207

115

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Abstract. In this study, the trends and variability of annual precipitation totals and annual rain days over land within the Mediterranean region are analyzed. Long term groundbased observations concerning, on one hand, monthly precipitation totals and rain days from 40 meteorological stations within the Mediterranean region were obtained from the Hellenic National Meteorological Service and the World Climate Data and Monitoring Programme (WCDMP) of the World Meteorological Organization. On the other hand, high spatial resolution (0.5 • × 0.5 • ) gridded monthly data CRU TS 3.1 were acquired from the Climatic Research Unit, University of East Anglia, for the period 1901-2009. The two datasets were compared by means of trends and variability, while the influence of the North Atlantic Oscillation (NAO) in the Mediterranean precipitation was examined. In the process, the climatic changes in the precipitation regime between the period 1961-1990 (reference period) and the period 2071-2100 (future climate) were presented using climate model simulations (RACMO2.1/KNMI). The future climate projections were based on SRES A1B.The findings of the analysis showed that statistically significant (95 % confidence level) negative trends of the annual precipitation totals exist in the majority of Mediterranean regions during the period 1901-2009, with an exception of northern Africa, southern Italy and western Iberian peninsula, where slight positive trends (not statistically significant at 95 % CL) appear. Concerning the annual number of rain days, a pronounced decrease of 20 %, statistically significant (95 % confidence level), appears in representative meteorological stations of east Mediterranean, while the trends are insignificant for west and central Mediterranean. Additionally, NAO index was found to be anticorrelated with the Correspondence to: P. T. Nastos (nastos@geol.uoa.gr) precipitation totals and the number of rain days mainly in Spain, southern France, Italy and Greece. These correlations are higher within the rain season (October-March) than the entire year. Based on the results of regional climate model RACMO2.1/KNMI, precipitation is very likely to decrease almost 20 % in the period 2071-2100 compared to 1961-1990

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Section: According To the Results Of Climatic Models (Sres A1b) Itmentioning

confidence: 93%

Long term precipitation trends and variability within the Mediterranean region

Philandras

Nastos

Kapsomenakis

et al. 2011

Nat. Hazards Earth Syst. Sci.

207

115

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“…Behaviour in MJ, as well as the higher correlation coefficient in the warm period (MJ, JA and SO) between sub-periods, supports the idea of a northward expansion of the tropical warm air dome (associated with high 500-GH values) during late spring, consistent with the idea of an earlier establishment of the Mediterranean summer conditions. But the equally strong secular increase of 500-GH in MA, without a parallel correspondence in the near-surface temperature tendency and with a weaker correlation of both variables, suggests that a substantial fraction of the MA 500-GH increase can be associated with the decrease in the cyclonic activity over the Mediterranean, a fact clearly detected in Guijarro et al (2006). Note that the frequency of moderate or intense cyclones in the Western Mediterranean is relatively high from November to April and declines from May to October (Guijarro et al, 2006;Homar et al, 2007).…”

Section: Local Near-surface Temperature Versus 500 Hpa Geopotential Hmentioning

confidence: 93%

“…This is arguably due to the masking effect of the low‐level temperatures onto SLP. The Mediterranean (dry) anticyclonic summer weather and (wet) cyclonically disturbed winter (Trigo et al , ; Barry and Chorley, ; Guijarro et al , ) is not reflected on the SLP observation in Palma (Figure ). The annual SLP maximum occurs in winter, particularly in January, when the Western Mediterranean cyclonic activity is strongest.…”

Section: Mediterranean Climate Mediterranean Summermentioning

confidence: 97%

Extension of summer climatic conditions into spring in the Western Mediterranean area

Jansà

Homar

Romero

et al. 2016

Intl Journal of Climatology

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From a local point of view, in May/June, there is an important and positive 2 m temperature trend at Palma (Mallorca), which is simultaneous and highly correlated with a strong increase in the 500 hPa geopotential height. This study analyses this fact as well as the observed tendencies in a wider seasonal and geographical context. We confirm the particularly high correlation between 2 m temperature and 500 hPa geopotential during the warm months as opposed to the much weaker correlation in winter. This suggests that mechanisms for thermal changes act differently throughout the year in this region. Besides the direct radiative effect, warm season near‐surface temperatures are linked to the presence of deep anticyclones, which effectively determine the northern edge of the Hadley cell. Accordingly, the strong warming trend in the area of Palma during the warm months of the year is purportedly related to the poleward extension of the Hadley cell. The fact that May/June shows the highest low‐level temperature trend among all bi‐monthly series is a common regional feature over a relatively wide area over the Western Mediterranean. Different geographical patterns emerge in other periods of the year. In July/August, the strongest low‐level warming area drifts to the east‐northeast, towards Ukraine and Russia. Coincidentally, the 500 hPa geopotential tendencies show a coherent pattern, with an intense positive trend ridge over the Western Mediterranean area in May/June, and a displacement of this ridge to the north‐east in July/August. We show the connection between 500 hPa geopotential height and near‐surface temperature by means of a multiple lineal regression that attributes half of the local temperature tendency in Palma to the intensification of a 500 hPa ridge centred over the Western Mediterranean and surroundings.

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“…Finally, Guijarro et al . (), showed a significant decrease in the cyclonic circulation in the western Mediterranean, and an increase in the eastern Mediterranean.…”

Section: Introductionmentioning

confidence: 93%

Long‐term precipitation trend analysis in Europe and in the Mediterranean basin

Caloiero

Frustaci

2018

Water & Environment J

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The spatiotemporal analysis of a region's precipitation climate regime could be particularly interesting for many fields of applied sciences, such as climatology, hydrology and water resources management. In this study, the precipitation trends at seasonal and annual scale, over a large area of the northern Hemisphere have been analysed based on a globally gridded precipitation data sets of monthly observations. In particular, among the several data sets available in literature, with spatial resolutions of 0.5° longitude/latitude, in this work the Global Precipitation Climatology Centre Full Data Reanalysis Version 6 data set has been used. The broad extension of the area under investigation allowed a better understanding of trend precipitation patterns over space. In fact, yearly results evidenced a marked negative rainfall tendency in the eastern Mediterranean (more than −20 mm/10 years) and in North Africa (until −16 mm/10 years), while a relatively large positive trend (more than 20 mm/10 years) in central and northern Europe has been observed.

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Time variability of cyclonic geostrophic circulation in the Mediterranean

Cited by 15 publications

References 10 publications

Long term precipitation trends and variability within the Mediterranean region

Long term precipitation trends and variability within the Mediterranean region

Extension of summer climatic conditions into spring in the Western Mediterranean area

Long‐term precipitation trend analysis in Europe and in the Mediterranean basin

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