The diurnal cycle of dust aerosols on Mars is studied by analyzing lidar observations at the Phoenix landing site under cloud- and fog-free conditions and in the absence of elevated, long-range transported dust layers. There is a pronounced diurnal cycle in the dust-layer height with minimum heights of 4–6 km occurring between 11:00 and 17:00 local time. The ratio of the aerosol optical depth (AOD) within the lowermost 2 km to the total AOD reaches peak values at the same time. This can be explained by local dust emissions driven by the diurnal cycle of heating and cooling in the boundary layer. Analysis of wind and pressure measurements show that the gustiness of surface winds and the frequency of convective vortices undergo diurnal variations resembling those of AOD, indicating that these processes are the main drivers for local dust emissions.

中文翻译：

---

凤凰城激光雷达测量的火星尘埃排放与当地气象条件的关系


通过分析凤凰城着陆点在无云无雾条件下以及没有升高的远距离输送尘埃层的情况下的激光雷达观测结果，研究了火星上尘埃气溶胶的昼夜循环。沙尘层高度存在明显的昼夜周期，最低高度为 4-6 公里，发生在当地时间 11:00 至 17:00 之间。最下方2公里内的气溶胶光学深度（AOD）与总AOD的比值同时达到峰值。这可以用边界层的昼夜加热和冷却循环驱动的局部粉尘排放来解释。对风和气压测量的分析表明，地面风的阵风和对流涡旋的频率经历了类似于AOD的日变化，表明这些过程是当地粉尘排放的主要驱动因素。