A Review of Recent Study Advances in Climatic Environment on China Loess Plateau

The Loess Plateau is a plateau that covers an area of about 640,000 km² in the upper and middle reaches of China's Yellow River. The Loess Plateau was formed over long geologic times, and some works of writing have provided valuable information about climate environment change from samples taken from the deep layer of its silty soil, data observed by satellite instrumentation, and historical documents. The Loess Plateau was highly fertile and easy to farm in ancient times, which contributed to the development of early Chinese civilization around the Loess Plateau. In medieval times of China, people stayed here to grow rice. Centuries of deforestation and over-grazing, exacerbated by China’s population increase, have resulted in degenerated ecosystems, desertification, and poor local economies; in fact, the soil of this region has been called the most highly erodible soil at 22 Ma BP, and the fine-grained silt was picked up by strong prevailing westerly winds. Huge dust clouds moved and redeposited over loess plateau areas. Due to the nature of loess soil and its ability to slope in vertical columns when flooding occurs, the stabilized soil-layers were eroded into the corrugated, sharply-dissected bluffs we see today. During the last Ice Age, sometime the north monsoon retreated and south-east monsoon more devoloped and vast amounts of watervapor and heatresource flowed into the plateau region. The sediment was deposited on the floodplain, creating huge soil flats. When meltwaters receded, these mud flats were exposed. The Loess plateau has a rich archaeological heritage. The region in response to global climate change on China's loess plateau, showed that the climate became warmer and drier in autumn over the plateau; Winter rainfall was trending up; the west part of the plateau became wet; the east part became arid in summer. The seasonal and regional characteristics were very clear.The sensitivity regions of rainfall were different, moving westward and southward from spring to winter. Some of rain items, such as the rainfall day, maximum rainfall in a day and rainfall during continuum continual rain, had sensitivity of rainfall in response to regions in the annual timescale; the rain items had obvious differences on remarkable phases, and had interdecadal timescale periods. The water of soil absorption changed in a whole year. Different crops had different effects on vertical distribution of soil moisture. The water of soil became lost during the crop growth period, in store-water times instead. The crop output and surface air temperature data in the time-domain can detect the most predominant modes coupling them. It is more sensitive for the output and temperature in wheat, corn and flax, respectively, which implies that the output sensitivity to temperature is higher west of the Yellow River, lower in the Loess Plateau. The crops in response to the rainfall and temperatures were different in other periods. The crops do well in the long periods whereas they decay in short periods in less rainfall times. The temperature displayed obvious periods in cold times, on the contrary in warm times. The main characteristic of soil water was arid. The change of soil water had an obvious effect on the variance of rainfall and temperature with climate, decade-days and short period oscillation. The warm-drought climate developed from the fact that the quantity of total and low cloud became reduced. Whole consistent region response was most characteristic of the warm-drought climate evolvement.