Relationship between Snow Cover and Sand-dust Weather Days in Early Summer and Winter——Taking Central Inner Mongolia as Example
Based on meteorological observation data from earth surface,an analysis on the relationship between sand-dust weather days and days of snow cover≥1.0cm in early spring and winter in central Inner Mongolia autonomous region is performed against different spatial levels.The result shows that there is a negative interrelation between sand-dust weather days and snow cover days,which varies due to the difference of climate feature and the change of season.The negative interrelation between sand-dust weather days and snow cover days in winter is more marked than in early spring.The negative interrelation in cool temperate semi-arid climate region in early spring is more significant than in other regions.
It is widely believed that structural variables such as inequitable land distribution, lack of rural employment opportunities, and rural-urban wage and amenity gaps influence population movements in developing countries. Yet quantitative evidence is scant. In this paper a multilevel model is used to investigate the effects of individual-, household-, and areal-level factors on rural-urban out-migration in the Ecuadorian Sierra. Data from a detailed survey carried out in 1977–1978 and from government macro-areal statistics are used to investigate factors affecting the out-migration of youths aged 12–25. Preliminary conclusions are presented on the usefulness of multilevel models in studying migration and policy implications for Ecuador.