Seasonal and diurnal variations of near-surface atmospheric CO_2 concentration within a residential sector of the urban CO_2 dome of Phoenix, AZ, USA

摘要

Over most of an entire year (315 days), we obtained 1-min averages of near-surface (2-m height) atmospheric CO_2 concentration, temperature and wind speed in a residential area of a suburb of Phoenix, AZ. Daily minimum CO_2 concentrations, which occurred during the afternoon, were nearly invariant over the year, averaging 390.2±0.2 ppm. Daily maximum CO_2 concentrations, however, which occurred at night, varied seasonally with the air temperature, exhibiting a mean peak of 490.6 ppm about 2 h before midnight during the coldest part of the year (December-January) and 424.3 ppm just before sunrise during the warmest part of the year (July-August).