Objective The aim was to quantify the impact of natural environmental factors on the accuracy of soil CO₂ flux measurement, to clarify the effects of wind turbulence and moisture on CO₂ transport in the medium, and analyze the potential sources of error and bias of the closed chamber method in this context.

Method A soil carbon flux calibrator was used to investigate the measurement performance of the confined air chamber under two different wind turbulence conditions using three types of quartz sand with different porosities as reference media.

Result It showed that the flux results measured by the confined air chamber in the absence of wind were essentially equal to those of the calibrator, whereas the flux results measured by the confined air chamber were underestimated under turbulent conditions, with underestimation ranging from 13%-65% for the fine quartz sand and 22%-68% for the medium quartz sand. The underestimation was increased again under wind-water interaction, with underestimations ranging from 55%-86% for fine quartz sand and 72%-89% for medium quartz sand flux underestimations. Measurements in the confined air chambers were more accurate in the absence of wind, whereas flux measured in the confined air chambers were underestimated in turbulent conditions, and this underestimation was even more pronounced under the interaction of wind and water.

Conclusion The flux results measured in a closed chamber are closer to the actual carbon flux situation, it is recommended to measure in a windless environment and avoid direct measurement after rain as much as possible.