Objectives This paper aims to explore the characteristics of changes in urban socioeconomic activities during a public health emergency. Three major urban agglomerations, including Los Angeles, Dallas and New York, are selected as the study areas.

Methods First, the difference value of average nighttime light intensity and nighttime light stability are constructed based on nighttime light data to reflect the spatiotemporal variation characteristics of urban nighttime light levels during different surge periods of the duration of public emergencies. Then, based on the objective weighting method and mobility big data, the travel willingness index and scene mobility index are constructed to characterize the spatial and temporal differences of regional mobility in different surge periods.

Results The results show that, in the first surge period, the level of urban nighttime light decreases greatly and urban economic activities are affected significantly, while in the second surge period, economic activities in most cities recover to a good level. The change of urban social activities in the first surge period is mainly reflected as the decrease of scene mobility index, while in the second surge period, both scene mobility index and travel willingness index decrease to different degrees. Combined with social distancing policies in different regions, the trend of mobility can be well explained according to the surge.

Conclusions By using nighttime light data and mobility big data to represent the changes of urban social and economic activities, we can understand the impacts of the rebound of public health emergency on urban social and economic activities, in order to provide scientific reference for the development of social and economic policies corresponding to the possible public health emergencies in the future.