城市台站周边热岛效应和土地利用与覆盖变化关系

以合肥市气象站为中心,利用1990～2006年的Landsat TM影像,获取不同半径圆形缓冲区范围内下垫面土地分类信息以及对应年份的气温年均值、极值、日定时数据资料,分析了下垫面各土地类型及其变化和站点周边热岛效应的关系.分析得出:城市热岛与建设用地有着最强正相关,与林草地和耕地有着显著负相关,与夜晚水体有着较强正相关.下垫面类型对城市热岛的影响随着每天的不同时刻而变化.4种下垫面类型对城市热岛的影响范围上,建设用地一般在6km以内、林草地4km以内、耕地在4km时最显著,水体则随着距离的增加,其影响范围缓慢上升到8 km.同时,通过分析土地利用年变化和城市热岛效应变化的关系,进一步验证了城市发展对城市热岛效应起着至关重要的作用.最高温和14时(北京时间)热岛强度年变化与土地利用年变化有着较强的相关性.另外,迁站后热岛效应明显减弱.最后,重点探讨了下垫面类型和热岛效应关系的可能原因.

Relationships between Urban Heat Island Effect and Land Use and Land Cover Change around Urban Weather Stations

Based on the Landsat TM remote sensing images from 1990 to 2006, the relationship between different types of underlying surfaces and Urban Heat Island (UHI) by analyzing various underlying surfaces from different radius circular buffer zones (with Hefei Weather Station as their center) and their corresponding air temperatures (annual average temperaeure, maximum temperaeure,minimum temperaeure, and fixed time data). It is found that a very strong positive correlation between construction land and UHI and a negative correlation between woodland/grassland and UHI. There is a relatively strong positive correlation between water body and UHI at night. The influence of different types of underlying surfaces on UHI varies with different hours everyday. As far as range of influence is concerned, construction land is within 6 km; woodland/grassland is within 4 km; farmland influence reaches its peak at 4 km; influence of water body reaches 8 km slowly. At the same time, through analyzing the relationship between yearly Land Use and Land Cover Change (LUCC) and UHI, the authors give more evidence of the vital effect laid by city development on UHI. There is a relatively strong correlation between the maximum temperature and the annual variation of heat island intensity at 1400 LST and the yearly variation of LUCC. By the way, UHI decreases dramatically after the moving out of Hefei Weather Station. At last, the possible reasons for how the correlation between different underlying surfaces and UHI can be formed are discussed.