ABSTRACT

The lockdowns imposed worldwide to curb the coronavirus diseases (COVID-19) spread has positive effects on the environment. However, it is unclear what fraction is caused by weather and what is related to lockdown. Here we used Global Navigation Satellite System (GNSS) height anomaly time series to quantify the spatio-temporal characteristics of lockdown-induced noise anomalies at 231 selected sites over mainland China. The results indicated that apparent declines (0.52 mm) in noise in 6 days (24–29 January 2020) after the lockdown in Wuhan resulted in drastically reduced human activities, which accounts for 71% of the total noise decrease. The lockdown effects persisted for 8 weeks and reached the maximum in the third week (6–12 February 2020) with reduced GNSS noise anomalies occurring at 81% of the GNSS sites. With the control of pandemic, increased noise anomalies occurred at more than 60% of the sites during the 9th week, which correlated well with the easing of lockdown in many cities in China. We concluded that this study provides new insights to quantifying the effects of human activities on geodetic measurements during the COVID-19 lockdown.