求翻译：2008年4月至6月兰州大学与中国科学院、中国气象局、美国马里兰大学和美国能源部大气辐射观测(ARM)项目进行了中美沙尘暴联合观测试验。本文利用系留探空资料分析了张掖地区边界层气象变化特征及风向变化规律。结果表明：温度和位温层结曲线存在贴地逆温，白天处于不稳定状态，高层存在逆温层；湿度雨天比湿大，晴天比湿小，但都存在逆湿层；下层风速较小，中层风速切变大，上层风速较大，低空和上空存在着两个大气扩散区；风向在观测时间内主要盛行东南风。结果有助于研究和了解张掖地区大气边界层内沙尘气溶胶的数值模拟和空气污染物的扩散规律。是什么意思？

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In April 2008 to June, Lanzhou University and Chinese Academy of Sciences, China Meteorological Administration, the United States University of Maryland and the United States Department of Energy (atmospheric radiation observations ARM) project for the Sino-US joint experiment dust storms. This arti

From April, 2008 to June Lanzhou University and Chinese Academy of Science, Chinese Meteorological bureau, American Maryland University and the United States Department of Energy atmospheric radiation observed the (ARM) project to carry on the Chinese and American sand storm combined observation exp

Between April 2008 and Lanzhou University, Chinese Academy of Sciences, China Meteorological Administration, United States University of Maryland and the United States Department of energy's atmospheric radiation observations (ARM) project for the Sino-American joint sand-dust storm observation test

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