Applying the anomaly-based weather analysis on Beijing severe haze episodes

Qian, Weihong; Huang, Jing

doi:10.1016/j.scitotenv.2018.07.408

Cited by 19 publications

(6 citation statements)

References 40 publications

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“…However, for a local dust or fog or air pollution event, strong wind often plays a scavenging effect to those events. For a Beijing haze case, Qian and Huang (2019) found that the haze occurred during a period of weak anomalous southwesterly wind while it scavenged after the start of a strong anomalous northeasterly wind in the lower troposphere. One also needs to keep in mind that not all strong cyclones or cold fronts bring dust from Mongolia to northern China in spring.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…A dust storm caused by strong winds is a physical process of rapid release of anomalous atmospheric energy over desert areas and then moves to other places. Dust storm is one of the weather extremes similar to haze episodes and fog events (Qian & Huang, 2019; Qian, Leung, Chen, et al., 2019). These weather extremes can be visually more striking in spatial structure if they are described by an approach of anomaly based weather analysis (Qian, Du, et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

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Anomaly Based Synoptic Analysis and Model Prediction of Six Dust Storms Moving From Mongolia to Northern China in Spring 2021

Qian

Leung²,

Ren

et al. 2022

JGR Atmospheres

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Six dust storms that originated from Mongolia and moved to northern China in Spring 2021 are investigated by the anomaly variable‐based analysis method, which is compared to the traditional total‐variable based analysis method. Strong surface wind is a force to form dust storms as commonly known in current practice. However, dust area depicted by total‐wind model product analysis and operational forecast has a large bias to observation even for leading 24 hr. The analysis method of anomaly based variables showed that the domain of an airborne dust storm observed from satellite images is usually located between two neighboring convergence lines of 850 hPa anomalous winds. This connection of dust storm associated with the anomalous wind convergence extends southwestward from an anomalous cyclone and moves from Mongolia to northern China or Northeast China. It is thermodynamically associated with an anomalous thermal contrast, which has a spatial structure of wind, temperature, and geopotential height anomalies in the troposphere. We further found that numerical weather prediction products of the ECMWF model are able to indicate the anomalous wind pattern with lead times of 4–8 days by applying the anomaly based analysis approach. Therefore, this approach can not only depict dust area better but also reveal predictors much easier compared to the traditional total‐variable or full‐field‐based analysis method.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anomaly Based Synoptic Analysis and Model Prediction of Six Dust Storms Moving From Mongolia to Northern China in Spring 2021

Qian

Leung²,

Ren

et al. 2022

JGR Atmospheres

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“…which separates the temporal climatological component and anomalous component from any atmospheric observation or model product in traditional weather analysis, has been proven to be useful in extracting extreme weather signals. The methods used in this study were the same as those employed in Qian (2017) and Qian and Huang (2019). Readers are referred to those two papers for detailed definitions and formulae, but briefly:…”

Section: Methodsmentioning

confidence: 99%

“…Dense fog days are weather extremes like heavy rainfall, tornados, or hailstorms. It is recommended to study extreme weather events via anomaly-based weather analysis (Qian, 2015), of which the advantages have already been demonstrated in research on heavy rainfall (Jiang et al, 2016;Qian et al, 2016a), heat waves (Chen et al, 2017), cold surges (Qian et al, 2016b), severe haze (Qian and Huang, 2019), and tornados/hailstorms (Qian et al, 2017). In the present work, we examine whether the anomaly-based weather analysis method can also be applied to fog episodes with visibility less than 1 km for more than 24 hours.…”

Section: Introductionmentioning

confidence: 99%

Applying Anomaly-based Weather Analysis to the Prediction of Low Visibility Associated with the Coastal Fog at Ningbo-Zhoushan Port in East China

Qian

Leung

Chen³

et al. 2019

Adv. Atmos. Sci.

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Low visibility episodes (visibility < 1000 m) were studied by applying the anomaly-based weather analysis method. A regional episode of low visibility associated with a coastal fog that occurred from 27 to 28 January 2016 over Ningbo-Zhoushan Port, Zhejiang Province, East China, was first examined. Some basic features from the anomalous weather analysis for this case were identified: (1) the process of low visibility mainly caused by coastal fog was a direct response to anomalous temperature inversion in the lower troposphere, with a warm center around the 925 hPa level, which was formed by a positive geopotential height (GPH) anomaly in the upper troposphere and a negative GPH anomaly near the surface; (2) the positive humidity anomaly was conducive to the formation of coastal fog and rain; (3) regional coastal fog formed at the moment when the southwesterly wind anomalies transferred to northeasterly wind anomalies. Other cases confirmed that the low visibility associated with coastal fog depends upon low-level inversion, a positive humidity anomaly, and a change of wind anomalies from southwesterly to northeasterly, rain and stratus cloud amount. The correlation coefficients of six-hourly inversion, 850−925-hPa-averaged temperature, GPH and humidity anomalies against visibility are −0.31, 0.40 and −0.48, respectively, reaching the 99% confidence level in the first half-years of 2015 and 2016. By applying the anomaly-based weather analysis method to medium-range model output products, such as ensemble prediction systems, the anomalous temperature−pressure pattern and humidity−wind pattern can be used to predict the process of low visibility associated with coastal fog at several days in advance.

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“…At the same time, the weakening of East Asian winter monsoon circulation (Li et al ., 2016; Wu et al ., 2016), the positive Arctic Oscillation phase (Yin et al ., 2015a) and the positive phase of East Atlantic‐West Russia tele‐connection (Yin et al ., 2017) have been reported to intensify the atmospheric stability in central‐eastern China and motivate the anomalous anticyclone in Northeast Asia. And then the descending motion is intensified, the boundary layer is lowered and the southerly anomalies are strengthened to cause the occurrence of the pollution processes over the BTH region (Wu et al ., 2017; Pei et al ., 2018; Qian and Huang, 2019). However, there are controversial views that during the peak stage of heavy pollution, the BTH region is located in the west of the local anomalous anticyclone in Northeast Asia and is mainly controlled by the ascending motion.…”

Section: Introductionmentioning

confidence: 99%

Effects of the East Asian subtropical westerly jet on winter persistent heavy pollution in the Beijing–Tianjin–Hebei region

Mei

Wang

Liu

et al. 2021

Intl Journal of Climatology

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Based on the daily average concentration of PM2.5, 15 typical persistent heavy pollution episodes (PHPEs) in the Beijing–Tianjin–Hebei (BTH) region during the winters of 2013–2019 are identified. And then the impact of the intra‐seasonal variations of the 200‐hPa subtropical westerly jet (SWJ) on the PHPEs is investigated. The results show that the SWJ affects the lifecycle of the PHPEs in the BTH region mainly through the meridional shift and intensity variation. In particular, the intensity variation has a closer relationship with the vertical velocity and low‐level meridional wind to affect the PHPEs. In the developing stage of the PHPEs, the SWJ shifts northward and strengthens. The BTH region is on the left side of the entrance of the SWJ and the vertical secondary circulation intensifies the descending motion in situ. As a result, the atmospheric boundary layer is compressed to sink rapidly, a temperature inversion in the lower levels appears and the atmospheric stability is enhanced. Finally, the atmospheric environment is favourable for the rapid accumulation of pollutants and the occurrence of the PHPEs. In the peak stage, the southward withdrawal and weakening of the SWJ favour the anomalous ascending motion and low‐level southerly anomalies over the BTH region. The dominant role of the dynamic descending motion is replaced by the low‐level southerly anomalies to enhance the PHPEs, by transporting more warm‐humid air to the BTH region. In the weakening stage, the SWJ moves northward and intensifies again. The low‐level southerly anomalies weaken to contribute to the dissipation of the pollutants.

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Applying the anomaly-based weather analysis on Beijing severe haze episodes

Cited by 19 publications

References 40 publications

Anomaly Based Synoptic Analysis and Model Prediction of Six Dust Storms Moving From Mongolia to Northern China in Spring 2021

Anomaly Based Synoptic Analysis and Model Prediction of Six Dust Storms Moving From Mongolia to Northern China in Spring 2021

Applying Anomaly-based Weather Analysis to the Prediction of Low Visibility Associated with the Coastal Fog at Ningbo-Zhoushan Port in East China

Effects of the East Asian subtropical westerly jet on winter persistent heavy pollution in the Beijing–Tianjin–Hebei region

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