Mechanism for synoptic and intra-seasonal oscillation of visibility in Beijing-Tianjin-Hebei region
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ORIGINAL PAPER
Mechanism for synoptic and intra-seasonal oscillation of visibility in Beijing-Tianjin-Hebei region Xin Li 1 & Caixia Yu 2,3 & Xueliang Deng 2,3 & Dongyan He 4 & Zhijun Zhao 1 & Huisi Mo 1 & Jiajia Mo 1 & Yanxing Wu 1 Received: 19 August 2020 / Accepted: 11 November 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Based on the station observation data from 1980 to 2016, the atmospheric circulation anomalies affecting the synoptic and intraseasonal oscillation (ISO) of visibility in the Beijing-Tianjin-Hebei (BTH) region were investigated. Results show that the synoptic variability of visibility over the BTH region was affected by Rossby waves moving from west to east. When the BTH region is on the eastern flank of a trough or the western flank of a ridge in the mid-troposphere, the anomalous southerly wind in the mid- and low troposphere played a key role in reducing the visibility, possibly by weakening the wind speed of the prevailing northwesterly winter monsoon, enhancing the stability in the boundary layer, and increasing relative humidity. The continuous low-visibility days usually began when surface high-pressure system moved eastward from East Asia continent into the sea, and it terminates when the next cold high-pressure system invades the BTH region from the west. The essential atmospheric circulation anomalies affecting the intra-seasonal variability of visibility in the BTH region are the intra-seasonal seesaw between Siberian High (SH) and Aleutian Low (AL). An anomalous southerly wind appears over the BTH region when the Siberian High and the Aleutian Low are weaker at intra-seasonal time scale, and it results in intra-seasonal low-visibility events possibly through reduced total wind speed, enhanced static stability, and enhanced relative humidity as well. No propagating feature of the intra-seasonal atmospheric circulation anomalies is identified.
1 Introduction The Beijing-Tianjin-Hebei (BTH) region is located in North China. Due to the rapid urbanization and industrialization over the past decades, the air quality over the BTH region has been getting worse (Streets et al. 2007; Chan and Yao 2008; Wang et al. 2010; Gao et al. 2011; Zhu et al. 2018). More and more haze days have been detected during winter and spring (Niu et al. 2010; Ding and Liu 2014; Wang et al. 2015), especially during winter (Chen and Wang 2015; Wang et al. 2018), such as the long-lasting and widespread haze episode in January
* Xueliang Deng [email protected] 1
Institute for Environmental and Climate Research, Jinan University, Guangzhou, China
2
Anhui Institute of Meteorology, Key Laboratory of Atmospheric Science and Satellite Remote Sensing, Hefei 230031, China
3
Shouxian National Climatology Observatory, Shouxian 232200, China
4
Anhui Climate Center, Hefei 230031, China
2013 (Wang et al. 2014; Zhang et al. 2014). Air pollution featured by visibility impairment is harmful to traffic and other economic activities (Huang et al. 2014; Chen and Wang 2015; Li et al.
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