Estancamiento atmosférico en la región euromediterránea : variabilidad espaciotemporal e impacto en la calidad del aireAir stagnation in the Euro-Mediterranean región : spatiotemporal variability and impact on air quality

Abstract

Air stagnation occurs under stable weather conditions, weak winds in the lower tomid-troposphere and absence of precipitation. These conditions minimize the horizontal dispersion and vertical mixing of air masses as well as the scavenging of air pollutants, favouring their accumulation in the lower atmospheric layers (e.g. Leibensperger et al.,2008; Jacob and Winner, 2009; Tai et al., 2010; Dawson et al., 2014). In the last few years, several studies have developed meteorological indices to identify stagnant conditions conducive to enhanced air pollution (Wang and Angell, 1999;Horton et al., 2012, 2014; Wang et al., 2016, 2018; Cai et al., 2017; Zou et al., 2017; Feng et al., 2018, 2020; Huang et al., 2018). Despite sharing common features, such socalled air stagnation indices (ASIs) are defined based on different meteorological variables and their applicability may be geographically dependent. Most previous studies on air stagnation have either been conducted on global and hemispheric scales (Horton et al.,2012, 2014; Wang et al., 2018), or have been confined to the US (Wang and Angell, 1999; Leibensperger et al., 2008; Tai et al., 2010) or China (Huang et al., 2017, 2018; Wanget al., 2016; Zou et al., 2020). However, although southern Europe has been identified as a climate hot spot where climate models project strong increases in air stagnation frequency (Horton et al., 2014), a systematic analysis of air stagnation and its impact on air quality has not been carried out hitherto for Europe and the Mediterranean region...