Abstract: At some flux sites, the alpine zone surrounding the measuring tower is affected by complex topography and strong wind, which results in the distortion of atmospheric CO₂ flux. The goal of this study was to carry out a numerical experiment with the eddy covariance system in moraine area of the Koxkar Glacier in the Tianshan Mountains, and to evaluate the integral of footprint function over the considered domain and distance of the corresponding farthest point from the sensor with the ART (Agroscope Reckenholz Tanikon) Footprint Tool base on the Kormann Meixner method. Results are as follows: ① The prevailing wind direction in snow accumulation period was NW, and its frequency accounted for 53.31%. NW wind evolved gradually into NNW one in snow melting season and early ice-glacial ablation season; ② Atmospheric CO₂ sank during the majorly typical period and even snow accumulation period, because soluble substances reacted chemically under snow-ice melting; ③ Temporally, the proportion of more than 80% 0.5 h CO₂ flux data of footprint function in each period was in an order of >snow accumulation period (95.96%)>snow melting period (93.75%)>intense glacial ablation season (86.30%)>early glacial ablation season (82.35%). The footprint distance to the farthest point was almost in reverse order, which meant that the major areas of CO₂ flux contribution were relatively concentrated, and the effect of CO₂ flux change at the glacial terminal and on the ridges could be ignored; ④ Under the stable atmosphere in the daytime, the CO₂ flux (78.55±2.08)% was slightly higher than that under the unstable atmosphere (77.72±1.41)% at night, but they were significantly lower than the interpretated ones.

Key words: CO₂ flux, flux footprint, eddy covariance system, prevailing wind direction, Koxkar Glacier, Tianshan Mountains