Rapid and sudden advection of warm and dry air in the Mediterranean Basin

Bueso, Jordi Mazón; Pino, David; Barriendos, Mariano

doi:10.5194/nhess-14-235-2014

Cited by 5 publications

(1 citation statement)

References 21 publications

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“…The heat waves exacerbate more the bioclimatic conditions in urban agglomerations, where the urban heat island (UHI) has been well established (Nastos and Matzarakis 2008;Poupkou et al 2011;Matzarakis and Nastos 2011a;Giannaros and Melas 2012), causing increasing number of casualties (Robine et al 2008;Nastos and Matzarakis 2012). Despite the heat wave, there is another type of extreme event within shorter time scale (a few hours), characterized as flash heat (Mazon et al 2014), due to its rapid adiabatic temperature rise, usually associated with the Föhn winds descending the lee of a mountain barrier.…”

Section: Introductionmentioning

confidence: 97%

Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island, Greece

Nastos

Bleta

Matsangouras

2016

Theor Appl Climatol

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Crete Island is located in the southmost border of East Mediterranean basin, facing exacerbating atmospheric conditions (mainly concentrations of particulates) due to Saharan dust outbreaks. It is worth to note that these episodes are more frequent during spring and autumn, when mild biometeorological conditions become intolerable due to the synergy of the so called Föhn winds. Cretan mountains, especially Psiloritis Mt. (summit at 2456 m), are orientated perpendicularly to the southwest air mass flow, generating the Föhn winds. Propagating from the leeward of the mountains, these dry, hot winds have an effect on prevailing biometeorological conditions. While descending to the lowlands on the leeward side of the range, the wind becomes strong, gusty, and desiccating. This wind often lasts less than an hour to several days, with gradual weakening after the first or the second day. Sometimes, it stops very abruptly. In this work, the authors examined and analyzed the abrupt changes of human thermal perception within specific case studies during which Föhn winds appeared in Heraklion city at the leeward of Psiloritis Mt, associated with extreme Saharan dust episodes, observed within the period 2006-2010. In order to verify the development of Föhn winds, Meteorological Terminal Aviation Routine Weather Reports (METARs, meteorological observations every half hour), were acquired from the Heraklion meteorological station installed by the Hellenic National Meteorological Service (HNMS). The biometeorological conditions analyzed are based on human thermal bioclimatic indices such as the Physiologically equivalent temperature (PET) and the Universal Thermal Climate Index (UTCI). METAR recordings of meteorological variables, such as air temperature, vapor pressure, wind speed, and cloudiness, were used as input variables in modeling the aforementioned thermal indices, so that to interpret the grade of the thermophysiological stress. The PET and UTCI analysis was performed by the use of the radiation and bioclimate model, BRayMan,^which is well-suited to calculate radiation fluxes and human biometeorological indices. The results of the performed analysis showed even an increase of air temperature from 20 to 30°C within 5 h, associated with a decrease in the vapor pressure from 11.5 to 9.3 hPa. In addition, the wind speed at 10 m increased from 5.1 to 20.1 m/s, 3.7 to 14.3 m/ s with respect to 1.1 m height, during the events of Föhn winds. The biometeorological analysis has given evidence that slight/moderate heat stress classes of the examined thermal indices appear during Saharan dust episodes. Such conditions are uncommon at the beginning of spring season, indicating that Saharan dust episodes are not only responsible for acute health impacts but also for adverse biometeorological conditions, due to the very likely development of Föhn winds towards the wider area of Heraklion, a coastal city in the eastern Mediterranean.

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Section: Introductionmentioning

confidence: 97%

Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island, Greece

Nastos

Bleta

Matsangouras

2016

Theor Appl Climatol

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Analysis of synoptic weather patterns of heatwave events

et al. 2023

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Heatwaves (HWs) are expected to increase both in duration and intensity in the next decades, but little is known about their synoptic and mesoscalar behavior, which is especially important in mid-latitude regions. Most climate research has focused on temperature analysis to characterize HWs. We propose that a combination of temperature and synoptic patterns is a better way to define and understand HWs because including atmospheric circulation patterns provides information about different HW structures that can irregularly affect the territory, and illustrate this approach at the regional and urban scales using the Iberian Peninsula and the Metropolitan Area of Barcelona as case studies. We first select HW events from 1950 to 2020 and apply a multivariate analysis to identify synoptic patterns based on mean sea level pressure, geopotential height at 500 hPa, and maximum daily 2 m temperature. The results indicate that four synoptic patterns reproduce at least 50% of the variance in HWs, namely, “stationary and stable”, “dynamic and advective”, “stationary and advective”, and “dynamic, advective and undulated”. Next, we apply the analysis to the Representative Concentration Pathway future scenarios (RCPs) 4.5 and 8.5 from the Coordinated Regional Climate Downscaling Experiment (CORDEX) to determine how these synoptic trends can change in the future. The analysis shows that the four synoptic patterns continue to explain 55 to 60% of the variance in HWs. Future HW events will be characterized by an increase in geopotential height at 500 hPa due to the northward shift of the anticyclonic ridge. This is especially true for RCP8.5, which simulates business as usual incrementing fossil fuel use and additionally shows an increase in atmospheric dynamism in north advections from all directions in comparison with RCP4.5. These findings point to the importance of considering the geopotential height in HW prediction, as well as the direction of advections.

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Temporal changes in extreme high temperature, heat waves and relevant disasters in Nanjing metropolitan region, China

Liu

Zhang

et al. 2014

Nat Hazards

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Rapid and sudden advection of warm and dry air in the Mediterranean Basin

Abstract: Abstract. Rapid advection of extremely warm and dry air is studied during two events in the Mediterranean Basin. On

Cited by 5 publications

References 21 publications

Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island, Greece

Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island, Greece

Analysis of synoptic weather patterns of heatwave events

Temporal changes in extreme high temperature, heat waves and relevant disasters in Nanjing metropolitan region, China

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