English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Reduced mobility and less anthropogenic activity under special case circumstances over various parts of the world have pronounced effects on air quality The objective of this study is to investigate the impact of reduced anthropogenic activity on air quality in the mega city of Shanghai, China Observations from the highly sophisticated multi-axis differential optical absorption spectroscope (MAX-DOAS) instrument were used for nitrogen dioxide (NO2) and formaldehyde (HCHO) column densities In situ measurements for NO2, ozone (O3), particulate matter (PM2 5) and the air quality index (AQI) were also used The concentration of trace gases in the atmosphere reduces significantly during annual Spring Festival holidays, whereby mobility is reduced and anthropogenic activities come to a halt The COVID-19 lockdown during 2020 resulted in a considerable drop in vertical column densities (VCDs) of HCHO and NO2 during lockdown Level-1, which refers to strict lockdown, i e , strict measures taken to reduce mobility (43% for NO2;24% for HCHO), and lockdown Level-2, which refers to relaxed lockdown, i e , when the mobility restrictions were relaxed somehow (20% for NO2;22% for HCHO), compared with pre-lockdown days, as measured by the MAX-DOAS instrument However, for 2019, a reduction in VCDs was found only during Level-1 (24% for NO2;6 62% for HCHO), when the Spring Festival happened The weekly cycle for NO2 and HCHO depicts no significant effect of weekends on the lockdown After the start of the Spring Festival, the VCDs of NO2 and HCHO showed a decline for 2019 as well as 2020 Backward trajectories calculated using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated more air masses coming from the sea after the Spring Festival for 2019 and 2020, implying that a low pollutant load was carried by them No impact of anthropogenic activity was found on O3 concentration The results indicate that the ratio of HCHO to NO2 (RFN) fell in the volatile organic compound (VOC)-limited regime

Ground-Based MAX-DOAS Observations of Tropospheric NO2 and HCHO During COVID-19 Lockdown and Spring Festival Over Shanghai, China