In the early stages of a coalfield fire, CO₂ emissions are relatively low, and it is challenging to detect CO₂ concentrations in the soil surface due to the impact of surface temperature and wind. Investigating CO₂ concentration changes under surface temperature and wind conditions can provide experimental evidence and theoretical foundation for selecting optimal sampling locations and time. Using an automated monitoring platform for shallow soil CO₂, this study analyzed how surface wind speed and temperature affect the diffusion of CO₂ gas of surface sands. The effects of surface wind and temperature on CO₂ concentrations growth at different depths of the shallow surface were studied experimentally. When the surface temperature was 40 ℃ higher than the ambient temperature, the decrease of CO₂ concentrations for coarse sands with permeability of 2.13 × 10^-9 m² was most significant under high surface temperature conditions. However, the effect of high surface temperature on fine sands with permeability of 1.1 × 10^-12 m² was insignificant. Coarse sand with high medium permeability was most vulnerable to the fluctuation of surface wind speed. The surface CO₂ concentrations decreased by 93% at a depth of 22 cm in the coarse sands on the downwind side of the surface compared to natural convection conditions. In comparison, the CO₂ concentrations decreased by 37.5% on the upwind sides under small wind speeds. The coupling effect of high temperature and wind speed on the surface had a greater disturbance depth on fine and medium sands than low windy conditions. In addition, detecting shallow surface concentrations of CO₂ for the localization of fire sources was more advantageous during low temperature detection periods. In order to describe gas diffusion at the surface, mathematical and physical equations were developed. A combination of experimental and simulation theory was used to predict the depth of penetration of shallow surface gas by wind speed and temperature. The critical Darcy–Rayleigh number for temperature disturbance to shallow surface gas was approximately 6.3 when using medium and coarse sands with high permeability. Simulations show that the wind-induced penetration depth was 40.8 cm for coarse sand and 23.5 cm for medium sand at a surface wind speed of about 0.4 m/s combined with the experiments. It is necessary to detect CO₂ concentrations at least at depth of 23.5 cm in conditions of low surface wind speed, particularly in the overlying medium with high porosity.

煤田火灾初期，CO ₂排放量相对较低，且受地表温度和风的影响，土壤表面CO ₂浓度检测具有挑战性。研究地表温度和风力条件下CO ₂浓度变化可以为选择最佳采样地点和时间提供实验证据和理论基础。本研究利用浅层土壤CO ₂自动化监测平台，分析了地表风速和温度对表层沙体CO ₂气体扩散的影响。实验研究了地面风和温度对浅表不同深度CO ₂浓度增长的影响。当地表温度比环境温度高40 ℃时，渗透率为2.13×10 ^-9 m ²的粗砂在高地表温度条件下CO ₂浓度降低最为显着。但地表温度高对渗透率为1.1×10 ^-12 m ²的细砂影响不显着。介质渗透性高的粗砂最容易受到表面风速波动的影响。与自然对流条件相比，地表顺风侧粗砂中22 cm深度处的地表CO ₂浓度降低了93%。相比之下，小风速下上风侧CO ₂浓度下降了37.5%。地表高温与风速的耦合作用对细、中砂的扰动深度较低风条件更大。 此外，在低温探测期间，探测浅层CO ₂浓度对于火源定位更有优势。为了描述表面的气体扩散，建立了数学和物理方程。实验和模拟理论相结合，通过风速和温度来预测浅表气体的渗透深度。当使用高渗透率的中砂和粗砂时，对浅层地表气体温度扰动的临界达西-瑞利数约为 6.3。结合实验模拟表明，在表面风速约为0.4 m/s时，粗砂的风致穿透深度为40.8 cm，中砂的风致穿透深度为23.5 cm。在低表面风速条件下，特别是在高孔隙率的上覆介质中，需要检测至少23.5cm深度处的CO ₂浓度。