Spatiotemporal variability of daily precipitation concentration and its relationship to teleconnection patterns over the Mediterranean during 1975–2015

Abstract

This study has addressed the spatiotemporal distribution of the daily rainfall concentration and its relation to the teleconnection patterns across the Mediterranean (MR). Daily concentration index (CI) and the ordered n index ( nor) are used at annual time scale to reveal the statistical structure of precipitation across the MR based on 233 daily rainfall series for the period 1975–2015. Eight teleconnection patterns, North Atlantic Oscillation (NAO), Mediterranean Oscillation (MO), Western Mediterranean Oscillation (WeMO), Upper‐Level Mediterranean Oscillation index (ULMO), East Atlantic (EA) pattern, East Atlantic/West Russia (EATL/WRUS) pattern, Scandinavia (SCAND) pattern and Southern Oscillation (SO) at annual time scale are selected. The spatiotemporal patterns in precipitation concentration indices, annual precipitation and their teleconnections with previous large‐scale circulations are investigated. Results show a strong connection between the CI and the nor (r = 0.70, p < .05) which present the same relative areas of high and low concentration. The annual values range from 0.57 to 0.70 for CI and 0.49 to 0.71 for nor index which show a high daily precipitation concentration across the MR. Trend analysis demonstrated mostly significant increasing trends for both indices. This increase is mainly found in south France, northern coastlands of the Iberian Peninsula (IP), Greece and Tunisia. An inverse relationship between the number of rainy days and concentration indices is evident. Both of WeMO and MO can play an important role in modulating rainfall in the northwest Mediterranean. The positive EATL/WRUS phase is mainly connected with positive precipitation mean anomalies in the eastern Mediterranean and vice versa in the west. The high daily precipitation concentration values over south France, northeast Spain, Croatia and Tunisia are linked to the low values of WeMO and high values of EA. These results could pave the way for new possibilities regarding the projection of precipitation concentration and precipitation irregularity in downscaling techniques.

Intra-annual variability of the Western Mediterranean Oscillation (WeMO) and occurrence of extreme torrential precipitation in Catalonia (NE Iberia)

“…Furthermore, many studies have also statistically correlated several teleconnection indices (El Niño-Southern Oscillation, North Atlantic Oscillation, Arctic Oscillation, Mediterranean Oscillation, Western Mediterranean Oscillation, etc.) with precipitation series for the Iberian Peninsula at different timescales (Rodó et al, 1997;Rodríguez-Puebla et al, 2001;Trigo et al, 2004;Lopez-Bustins et al, 2008;González-Hidalgo et al, 2009;Ríos-Cornejo et al, 2015a;Merino et al, 2016). Among these indices, the Western Mediterranean Oscillation (WeMO) was found to be the index most statistically and significantly correlated with annual, monthly and daily precipitation on the littoral fringe of eastern Spain (Martin-Vide and Lopez-Bustins, 2006;González-Hidalgo et al, 2009).…”

“…Previous studies have associated extreme daily precipitation events in Spain with synoptic patterns Peña et al, 2015); these studies have addressed several different tropospheric levels (Romero et al, 1999;Merino et al, 2016;Pérez-Zanón et al, 2018). Furthermore, many studies have also statistically correlated several teleconnection indices (El Niño-Southern Oscillation, North Atlantic Oscillation, Arctic Oscillation, Mediterranean Oscillation, Western Mediterranean Oscillation, etc.)…”

Precipitation in peninsular Spain: Influence of teleconnection indices and spatial regionalisation

“…Some studies have determined the main areas of influence within the Iberian Peninsula of the different teleconnections (Gonzalez‐Hidalgo et al ., 2009; Rios‐Cornejo et al ., 2015), as well as for the Mediterranean Basin (Mathbout et al ., 2019). A good example in this sense is the work of Gonzalez‐Hidalgo et al .…”

Linking crop yields in Tuscany, Italy, to large-scale atmospheric variability, circulation regimes and weather types

“…WAM originates in the Gulf of Guinea when the Intertropical Convergence Zone (ITCZ) makes its arrival, to establish itself at 10°N–12°N in its mature phase (Thorncroft et al ., 2011). In this phase, the southerly desert winds driven by the Saharan Heat Low (SHL) encounter the moist northerly monsoonal winds (Mathbout et al ., 2019). Thus, the precipitation over the Sudan-Sahel region is positively related to the ITF's latitude (Lélé and Lamb, 2010).…”