黄土高原黄土的成因:沙尘气溶胶源汇模拟与黄土堆积

黄土高原是重要的降尘区还是沙尘源区这一科学问题至今未有确切定论.本文利用北半球气溶胶区域气候模式NARCM,根据1995~2004年10a的模拟数据,分析了中国区域沙尘起沙量、沉降量以及沙尘的盈亏空间分布及风场,得到如下结论:1)沙漠及沙漠化地区是起沙量最大的区域、沉降量高值区集中在沙漠、沙漠化地区及其下风方向.黄土高原起沙量很小,而沉降量远大于起沙量.2)沙尘源区是沙漠及沙漠化地区,其余的地区则是沙尘汇区,降尘量由西北向东南递减.3)黄土高原因太行山和秦岭阻挡,处在最大的沙尘汇区.黄土高原的黄土是冰期和间冰期交替、经过漫长年代沙尘沉降的结果,模拟分析结论为黄土的风成学说提供了有力的证据.

The causes of loess formation over Loess Plateau: simulated dust aerosol sources and sinks and loess accumulation

There is a scientific debate argument whether Loess Plateau is an important region of dust aerosol sinks or sources. Based on the 10-year (1995~2004) aerosol simulations of the northern aerosol regional climate model NARCM, the spatial distribution of dust aerosol emissions, depositions and budgets as well as wind field were analyzed. The simulation analysis showed 1) the highest dust emissions appeared in the desert and desertification areas, while the highest dust depositions were concentrated over the desert and desertification areas as well as their immediately downwind region.The dust depositions largely exceeded the dust aerosol emission in Loess Plateau with the low dust emissions. 2) Desert and desertification area were the main dust sources, the rest of areas were dust sinks. Dust depositions declined from the northwest to the Southeast.3) Due to the barrier of the Taihang and Qinling Mountains, the Loess Plateau was the largest dust sink region with the highest depositions. The loess over Loess Plateau was accumulated by dust depositions over the long term evolution of glacial and interglacial periods. The dust aerosol simulation provided a solid evidence for the theory of eolian loess.