抛物线沙丘是一种重要的风积地貌类型，广泛分布于半干旱、半湿润的沙质草原环境，以及沙质海岸、湖岸和干旱沙漠边缘。其形态及演变过程与植被的时空分布关系密切。对抛物线沙丘表面气流和形态演变的研究有助于了解植被与地貌过程之间的响应机制，为防沙治沙提供依据。本文通过实地考察结合遥感影像分析，对中国抛物线沙丘的类型进行了划分，确定了不同成因机制下的抛物线形沙丘类型，主要包括风蚀坑抛物线形沙丘、新月形沙丘转化抛物线形沙丘和灌丛沙堆抛物线形沙丘三种。在对库布齐灌丛沙堆抛物线形沙丘表面气流观测和沉积物粒径分析的基础，本文初步推断了抛物线形沙丘的形成演变机制。抛物线沙丘不同观测高度风速沿纵轴断面具有较为一致的变化规律。在两翼间风速较低，气流平缓加速，风速廓线随高度很好的呈对数分布规律。当气流到达抛物线沙丘迎风坡后，风速廓线不符合对数分布规律，受地势上升的影响气流加速显著，越过顶部后扩散，坡脚风速显著降低。抛物线沙丘横断面各观测高度风速也具有较为一致的变化规律。抛物线沙丘相同部位北翼风速要高于南翼。横断面中轴点处近地表风速较两翼内侧坡脚较高，而离地面较高观测高度处风速由北翼内侧坡脚、中轴点向南翼内侧坡脚逐渐减小。抛物线沙丘丘体顶部气流复杂且不稳定，风速在中轴两侧较高，且同一观测高度东南侧出风口要高于东北侧出风口。抛物线沙丘横断面粒径复杂，没有一致的规律性，显著的受植被分布的影响。但抛物线沙丘丘体表面沉积物粒径分布随地形变化具有较为一致的规律性。在迎风坡，随着地形的上升，地表的侵蚀能力增大，粒径趋于粗化。在背风坡，较细颗粒可以被气流带到较远处，随着地形的下降粒径趋于减小。以上观测结果与灌丛沙堆的时空分布相结合，我们推断库布齐灌丛沙堆抛物线形沙丘的形成和演变大致经历了形成期、扩展期和退化期三个阶段。抛物线形沙丘和新月形沙丘在一定条件下可以相互转变。

Parabolic dunes, one of the most important eolian deposit landforms, are widely distributed in semiarid and subhumid sandy grasslands, sandy coast and lakeshore, and arid desert fringe. Their morphology and evolution is close related with temporal and spatial distribution of vegetation. Research on the flow dynamics and morphological evolution of parabolic dunes is helpful to understand the responsive mechanism between vegetation and morphological process and provide the theoretical base to combating desertification. Combining investigation in the field with interpretation of remote sensing images, we classified parabolic dunes in China according to their different formation mechanisms. Most of parabolic dunes in China could be subsumed into three main subtypes i.e., blowout-parabolic dunes, crescent-parabolic dunes, and nebkha-parabolic dunes. Based on measurement of flow dynamics and analysis of sediment particle sizes on the surface of typical parabolic dunes in the Hobq desert, we concluded their formation and evolution mechanism. Wind speeds at different heights showed the same change trend along the longitudinal section of parabolic dunes. A relatively low speed area was formed between the two arms where flow accelerated steadily and the wind speed profiles presented logarithmic behavior. When flow moved onto the windward slope of parabolic dunes, the profiles showed non-logarithmic behavior. Wind speeds at different heights increased forced by the rising windward face of parabolic dunes, and expanded in the leeward region. In the cross section, wind speeds at different heights also showed the same change trend. At the same geomorphological locations, wind speeds at north arm were higher than that of south arm. Near-surface wind speeds at the flat ground between the two arms were higher than that of both toes of inner slopes of both arms. However, wind speeds at higher heights decreased from the toe of inner slope of north arm, point at the flat ground between the two arms to the toe of inner slope of south arm in sequence. In terms of the flow dynamics over crest of the body of parabolic dunes, the highest speeds happened on both sides of the medial axis of the longitudinal section rather than the medial point. Meanwhile, at the same observing heights wind speeds at the southeast outlet were higher than that of the northeast outlet. Flow over the crest of parabolic dunes was unsteady and complicated. The distribution of sediment particle sizes in typical cross sections was affected by vegetation significantly and therefore didn’t show any common pattern. However, on the body of parabolic dunes the distribution of sediment particle sizes changed in accordance with topography. Sediment particle sizes tended to larger as flow compressed and accelerated forced by the rising windward face of parabolic dunes. On the lee of parabolic dunes, sediment particle sizes decreased from the crest to the toe of slope because finer particles could be brought to more distant area by wind flow. Based on the results above along with the temporal and spatial distribution of vegetation, we concluded that the formation and evolution of parabolic dunes in Hobq desert could be divided into three stages i.e., forming stage, developing stage and deteriorating stage. There probably was a mutual transformation relationship between barchan dunes and parabolic dunes under the influence of vegetation particularly nebkhas.