Expansion of summer to spring in the Western Mediterranean Agustí Jansà (1), Víctor Homar (1), Romu Romero (1), José A. Guijarro (2), Climent Ramis (1) (1) Departament Física/Universitat de les Illes Balears, Palma (2) Delegació a Illes Balears/Agència Estatal de Meteorologia, Palma [email protected]REUNIÓN PREDIMED 2014A. 5-6 Junio 2014 Sala Seminarios Física. 3r piso Mateu Orfila. UIB.
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Expansion of summer to spring in the Western Mediterranean
REUNIÓN PREDIMED 2014A. 5-6 Junio 2014 Sala Seminarios Física. 3r piso Mateu Orfila. UIB. Expansion of summer to spring in the Western Mediterranean. Agustí Jansà (1), Víctor Homar (1), Romu Romero (1), José A. Guijarro (2), Climent Ramis (1) - PowerPoint PPT Presentation
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Expansion of summer to spring in
the Western Mediterranean
Agustí Jansà (1), Víctor Homar (1), Romu Romero (1), José A. Guijarro (2), Climent Ramis (1)
(1) Departament Física/Universitat de les Illes Balears, Palma
(2) Delegació a Illes Balears/Agència Estatal de Meteorologia, [email protected]
Climatic mediterraneity: Mediterranean summer vs. subtropical anticylonic domain
Surface temperature trends: May/June maximum
Local correlation between surface temperature and 500 hPa geopotential height: seasonal differences
Regional structure of 500 hPa geopotential height trends: seasonality
Particular study of May/June: detection and evolution of main patterns, contribution of them to surface temperature trend
Discussion: Tropical region, Hadley cells and mediterraneity expansion
Indication of insufficiency of climatic models simulations
Climatic mediterraneity = Köppen’s Cs type = Temperate, not arid, seasonal, with dry season, during summer
Example: Palma - airport
Temperatures - Palma aeroport
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G F M A M J J A S O N D
Pluges - Palma aeroport
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G F M A M J J A S O N D
Climatic mediterraneity: Mediterranean summer vs. subtropical anticylonic domain
The Mediterranean climate is characterised by alternating between mid-latitude and subtropical circulations
G500
Mediterranean summer is characterised by the subtropical anticyclonic domain (Hadley cell edge)
Alternating between mid-latitude disturbances and subtropical anticyclone dominance is not evident at mean sea level, due to the hydrostatic effect of the warm/cold low level air masses.
The upper levels offer an opportunity to visualise the alternating, its changes and its tendencies.
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1016
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MSLP
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G850
5450
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G500
Time evolution, from local point of view (over Palma, AEMET and NCEP reanalysis)
The 2D streamfunction could provide a better way to explore the time evolution of the Hadley cell extension and external edge position.
Northern Hadley cell (NHC)
Southern Hadley cell (SHC)
When taking planetary zonal averages, the NHC tends to disappear during the northern hemisphere summer (effect of the monsoon circulation)
Dimas & Wallace, 2003
We want to repeat the right figure, but for a zonal average only referred to Iberian/W-Mediterranean longitudes
Surface temperature trends: May/June maximum
Temperatures mitjanes anuals Aeroport Palma(sèrie original, sense homogeneitzar)