利用LANDSAT-5 TM影像提取地表温度、植被覆盖度和归一化湿度指数(NDMI)等信息,结合景观生态学方法探讨广州市不同区域城市植被和NDMI对地表温度的调节作用.结果表明:植被覆盖度、NDMI和地表温度两两之间有较强的线性相关性,但不同区域植被覆盖度、NDMI与地表温度的相关程度存在明显差异;提高相同植被覆盖度时,中心城区的降温效果最好,其次是处于中心城区北缘的近郊区;不同区域森林公园对周围热环境的影响程度不同,960~1080m缓冲区内平均温度与公园内部平均温度之差分别为4.69℃(白云山)、1.27℃(马仔山)和0.41℃(流溪河);高植被覆盖度可增加热力景观多样性和不同景观之间的结合度,促进低温斑块内部与其他斑块如高温斑块间的能量交换,起到控制热岛效应的效果;增加环境湿度与提高植被覆盖度对热力景观格局所形成的作用相当.
By using Landsat-5 TM images,the land surface temperature(LST),vegetation cover,and normalized difference moisture index(NDMI) in different areas of Guangzhou were extracted,and the effects of vegetation cover and NDMI on the land surface temperature of the City were studied,based on the landscape ecological methodologies.There existed good linear correlations among the vegetation cover,land surface temperature,and NDMI,but the correlation coefficients for any two of the three items differed obviously with different areas.If the vegetation cover in different areas of Guangzhou was improved to the same level,urban center had the best cooling effect,followed by the suburbs in the north edge of urban center.The forest parks in different areas of the City also had different cooling effect on the surrounding environment.The difference of the average temperature between the 960-1080 m buffer zone and the inner park were 4.69 ℃ in Baiyun Mountain,1.27 ℃ in Mazaishan,and 0.41 ℃ in Liuxihe.High vegetation cover could increase the thermal landscape heterogeneity and the aggregation among different landscapes,and promote the energy exchange between the lower temperature patches and higher temperature patches,playing an important role in controlling hot island effect.NDMI and vegetation cover had the same effects on the formation of thermal landscape pattern.