中国北方农牧交错带是中国一个重要的农牧业生态区，由于其特殊的地理位置，导致其非常容易受到人类活动、气候变化等多种因素的影响。季风降水作为直接影响该地区生态气候的关键因素，它的演变将直接影响到农牧交错带的生态格局，因此研究季风降水的变化情况以及其影响因素对农牧交错带应对气候变化具备十分重要的意义。近些年中国东部地区饱受污染的影响，并且中国东部地区大量的气溶胶的累积，其辐射效应对东亚夏季风在中国的传播造成了巨大的影响。基于此，从中国中东部地区的气溶胶辐射效应对农牧交错带季风降水的影响出发，基于逐小时降水数据和气溶胶光学厚度数据讨论了中东部地区气溶胶与农牧交错带降水特征之间的相关关系，分析在中国东部地区气溶胶的辐射效应对农牧交错带季风降水的影响。
    首先，分析中国东部地区气溶胶时空分布特征及其与农牧交错带季风降水开始时间的联系。分析农牧交错带季风降水开始时间与东部气溶胶的关系发现东部陆地和长三角海域的气溶胶浓度差异越大则东北农牧交错带季风降水开始时间越早；随着东部陆地气溶胶浓度增加东北农牧交错带季风降水开始时间提前；而华北和西北农牧交错带季风降水开始时间并没有表现出与东部地区气溶胶之间存在明显的联系。结合探空数据，分析得到东北农牧交错带925-850hPa风速在季风降水开始早的年份要平均高于季风降水开始晚的年份大约12%。推测东部地区气溶胶辐射效应同过减弱季风前期的风速来推迟季风降水的开始。此外，农牧交错带在降水事件发生时850hPa的风向较大概率为东南向（45°~225°）。
    其次，对农牧交错带降水特征进行分析。重点分析农牧交错带季风降水总量和季风降水强度。分析不同的降水特征表明，季风降水总量在2000年以来处于整体上升趋势，且农牧交错带季风降水初期降水量整体也在逐步增加。季风降水开始时间与季风初期降水量之间存在十分强烈的负相关关系，而与季风降水总量之间的相关关系不明显。其余降水强度特征除小时平均降水之外均与农牧交错带季风降水量之间存在十分明显的正相关关系。通过分析发现农牧交错带小时平均降水量在下降而日降水量、降水天数以及降水小时数均在增加，表明农牧交错带降水格局也正在发生变化：从降水猛烈、急促向着降水持久、均匀转变。
    最后，分析农牧交错带季风降水量与东部各区域气溶胶以及海陆气溶胶差异之间的相关关系。发现东北农牧交错带季风初期降水量随着东部陆地区域气溶胶以及东部陆地和长三角海域的气溶胶差异增大而增加，而季风降水总量则随着长三角海域和东部陆地区域的气溶胶差异的增大而减少。华北农牧交错带季风初期降水量与珠三角海域气溶胶含量之间存在明显的正相关关系，而华北农牧交错带季风降水总量则与东部各区域的气溶胶以及其海陆气溶胶差异之间没有表现出明显的关系。对于西北农牧交错带，研究发现其季风初期降水量以及季风降水总量均与东部地区气溶胶含量之间没有表现出明显的关系。整体来看，通过对东部地区气溶胶辐射效应与农牧交错带降水之间的关系的研究，本研究揭示了农牧交错带降水与东部气溶胶辐射效应之间的联系，为深度研究气溶胶辐射效应对农牧交错带降水的影响奠定了基础。

The agro-pastoral ecotone (APE) in northern China is an important ecological region of agriculture and animal husbandry in China. Due to its special geographical location, it is very vulnerable to human activities, climate change and other factors. As a key factor directly affecting the ecological climate of the region, the evolution of monsoon precipitation will directly affect the ecological pattern of the APE. Therefore, it is of great significance to study the changes of monsoon precipitation and its influencing factors for the APE to cope with climate change. In recent years, eastern China has been affected by pollution, and the accumulation of a large number of aerosols in eastern China has a great impact on the spread of East Asian summer monsoon (EASM) in China. Based on this, from China's central and eastern regions of aerosol radiation effect on the influence of monsoon precipitation in the APE, based on the hourly precipitation data and aerosol optical thickness (AOD) data, the relationship between the aerosol radiation effect in central and eastern China and the precipitation characteristics in the APE was discussed, and the influence of aerosol radiation effect on the monsoon precipitation in the APE in eastern China was analyzed.
    Firstly, the spatial and temporal distribution of aerosols in eastern China and its relationship with the start time of monsoon precipitation in the APE are analyzed. The relationship between the start time of monsoon precipitation and the aerosol in the eastern part of the APE was analyzed. It was found that the greater the aerosol concentration difference between the eastern land and the Yangtze River Delta (YRD), the earlier the start time of monsoon precipitation in the APE in Northeast China and North China was. And with the increase of aerosol concentration in the eastern land, the start time of monsoon precipitation in the northeastern APE was earlier. However, the start time of monsoon precipitation in the North China APE and Northern APE does not show an obvious relationship with the aerosol in the eastern region. Combined with the radiosonde data, the wind speed of 925-850hPa in the APE in Northeast China is about 12% higher on average in the years with early monsoon precipitation than in the years with late monsoon precipitation. It is speculated that the aerosol radiation effect in the eastern region may delay the onset of monsoon precipitation by weakening the wind speed in the early monsoon. In addition, the probability of wind direction at 850hPa is southeast (45°~225°) in the APE during the precipitation event.
    Secondly, the characteristics of precipitation in APE are analyzed. The total monsoon precipitation and the intensity of monsoon precipitation in APE are analyzed. The analysis of different precipitation characteristics shows that the total monsoon precipitation is in the overall upward trend since 2000, and the cumulative precipitation in the early stage of monsoon precipitation in the APE is also gradually increasing. There is a strong negative correlation between the start time of monsoon precipitation and the cumulative precipitation in May and June, but the correlation with the total monsoon precipitation is not significant. There is a strong positive correlation between the other precipitation intensity characteristics except the hourly average precipitation and the monsoon precipitation in the APE. Through analysis, it was found that the average hourly precipitation in the APE is decreasing while the daily precipitation, precipitation days and precipitation hours are increasing, which indicates that the precipitation pattern in the APE is also changing: from heavy and rapid precipitation to persistent and uniform precipitation.
    Finally, the correlation between the total monsoon precipitation in the APE and the difference of sea-land aerosol and aerosol in the eastern region was analyzed. It was found that the initial monsoon precipitation in the Northeast APE increased with the increase of aerosol in the eastern land region and the difference of eastern land and YRD, while the total monsoon precipitation decreased with the increase of aerosol difference in the YRD and the eastern land regions. There is a significant positive correlation between the initial monsoon precipitation in the North China APE and the aerosol content over the Pearl River Delta (PRD), but there is no significant correlation between the total monsoon precipitation in the North China APE and the aerosol differences in the eastern regions and the sea-land aerosol differences. For the Northwest China APE, it is found that there is no obvious relationship between the initial monsoon precipitation, the total monsoon precipitation and the aerosol content in eastern China. On the whole, through the study on the relationship between aerosol radiation effect in eastern China and the monsoon precipitation in the APE, this study reveals the relationship between precipitation in the APE and the eastern aerosol radiation effect, which lays a foundation for the deep study of the influence of aerosol radiation effect on APE precipitation.