Collaborative Research: Sensitivity of Regional Climate Due to Land-cover Changes in the Eastern United States Since 1650

本项目利用模式模拟研究自17世纪中期以来美国东部土地利用和土地覆盖变化对气候的影响。该项目基于一个新的数据集“重建历史土地覆盖和生物物理参数”数据集，该数据集使用36个土地覆盖类别来描述美国东部（97W子午线以东，穿过堪萨斯州）四个代表性年份的土地覆盖：1650年、1850年、1920年和1992年。1650年至1920年期间出现了大规模的森林砍伐和耕地转化，随后在1920年至1992年期间出现了部分重新造林，所有这些都被记录在历史土地覆盖数据集中。从森林到草地或农田的变化可以在几个方面影响气候。例如，农作物和草的反照率较高，它们的颜色比森林浅，因此反射回更多的入射阳光，这可能导致地表温度降低。历史土地覆盖数据集也记录了湿地的减少，这可能是降雨的后果。使用陆地-大气区域气候模式进行模拟，以评估美国东部气候中不同陆地表面条件对气候条件（主要是温度和降雨）的影响。研究土地利用和土地覆盖变化对气候的影响具有社会和科学意义，因为它可以帮助我们确定可能需要适应和缓解战略的人为气候变化。除了其研究成果的社会价值外，该项目还将通过主要研究人员在当地初中和高中的推广活动产生更广泛的教育影响。该项目还将资助一名研究生，从而为该研究领域的下一代科学工作者提供教育和培训。

This project uses model simulations to study the effect of land use and land cover change on the climate of the eastern US since the mid-1600s. The project is based on a new dataset, the "Reconstructed Historical Land Cover and Biophysical Parameter" dataset, which uses 36 land-cover categories to describe landcover over the eastern US (east of the 97W meridian, which runs through Kansas) for four representative years: 1650, 1850, 1920, and 1992. The period from 1650 to 1920 saw extensive deforestation and conversion to cropland, which was followed by partial reforestation from 1920 to 1992, all of which is captured in the historical land cover dataset. The change from forest to grassland or cropland can affect climate in several ways. For example, the higher albedo of crops and grasses, which are lighter in color than forests and thus reflects back more incident sunlight, could cause a reduction in surface temperature. The historical land cover dataset also documents a reduction in wetlands, which could be consequential for rainfall. Simulations using a land-atmosphere regional climate model are used to assess the impact of the different land surface conditions on climatic conditions (primarily temperature and rainfall) in the eastern US climate.Research on the climatic effects of land use and land cover change is of societal as well as scientific interest, as it can help us to identify human-induced climate changes which are likely to require strategies for adaptation and mitigation. In addition to the societal value of its research findings, the project will have educational broader impacts through the outreach activities of the principal investigators at local middle and high scools. The project will also support a graduate student, thereby providing education and traning for the next generation of the scientific workforce in this research area.