Consistent weekly cycles of atmospheric NO2, CO, and CO2 in a North American megacity from ground-based, mountaintop, and satellite measurements

The weekday-weekend effect of anthropogenic emissions in cities, driven by the associated weekly changes human activities, provides a unique opportunity to assess sensitivity observation networks (e.g., ground-based and space-borne instruments) on urban emissions. In this study, we focus cycle amplitudes nitrogen dioxide (NO2), carbon monoxide (CO), (CO2) Los Angeles (LA) megacity, where significant activities exists. addition, abundant observations are being produced continuously from existing ground-based, mountaintop, satellite platforms monitor air quality LA. From our analysis, agreement can be found different platforms. For NO2, 30%–35% Sunday decline relative mid-week mixing ratios observed both observations. CO, drops mountain-top 13%–20%. TROPOMI instrument with its high spatial resolution detailed information reduction tropospheric NO2 CO columns Sundays. pattern is good traffic density Impact due prevailing winds coast afternoon also observed. CO2, show that XCO2 enhancement above background OCO-2 has (15%–20%) consistent TCCON. This CO2 megacity directly detected reported for first time. investigate cycles stable isotopic composition (δ13C) observations, which demonstrates variation fossil fuel usage Finally, using COVID-19 lockdown period as an example short-term perturbation emissions, amplitude became larger during primarily because volume light-duty vehicles. study highlights consistencies effectiveness observing monitoring LA megacity.