Abstract
Abstract. Analogous to the circumstances in wintertime, the increasing severity of autumnal haze pollution over the Beijing–Tianjin–Hebei (BTH) region may also lead to impairment of the socioeconomic development and human health in this region. Despite man-made aerosol emissions, the interannual variability of autumnal (September–October–November) haze days (AHDs) in the BTH region (AHDBTH) is apparently tied to the global and regional meteorological anomalies. The present study suggests that an above-normal AHDBTH is closely associated with the simultaneous sea surface temperature (SST) warming in two regions (over the North Atlantic subtropical sector, R1, and over the western North Pacific sector, R2). When the autumnal SST warming in both R1 and R2 is significant, the likelihood of a higher AHDBTH is greatly enhanced. Observational and simulation evidence demonstrated how remote SST anomalies over R1 and R2 influence variation of AHDBTH via two different pathways. Firstly, SST warming in R1 can induce a downstream midlatitudinal Rossby wave train, leading to a barotropic high-pressure and subsidence anomaly over the BTH region. Secondly, SST warming in R2 can also result in air subsidence over the BTH region through an anomalous local meridional cell. Through these two distinct pathways, localized meteorological circumstances conducive to a higher AHDBTH (i.e., repressed planetary boundary layer, weak southerly airflow, and warm and moist conditions) can be established.
Highlights
Aerosol particles (APs) are ubiquitous in the ambient air
Motivated by a lack of in-depth understanding with respect to the interannual variations of the AHDs in the BTH region (AHDBTH), in the present study we explored the related climate anomalies tied to the AHDBTH
We have substantiated that an above-normal AHDBTH is closely correlated with the simultaneous sea surface temperature (SST) warming in two key regions (R1 over the North Atlantic subtropical sector and R2 over the western North Pacific sector), and once the SON SST warming in both R1 and R2 is remarkably significant, their joint cliwww.atmos-chem-phys.net/19/1521/2019/
Summary
Aerosol particles (APs) are ubiquitous in the ambient air. Through aerosol-induced thermal forcing, APs can exert profound impacts on regional and large-scale circulation F. Wang et al, 2014; Li et al, 2017; Seo et al, 2017; Chen et al, 2018; Luan et al, 2018), severe haze weather with low visibility can readily occur Li et al, 2016; Ding et al, 2017; Seo et al, 2017; Chen et al, 2018) F. Wang et al, 2014; Li et al, 2017; Seo et al, 2017; Chen et al, 2018; Luan et al, 2018), severe haze weather with low visibility can readily occur (Chen et al, 2012; C. Li et al, 2016; Ding et al, 2017; Seo et al, 2017; Chen et al, 2018)
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