环形热岛格局演变过程的遥感分析

ANALYSIS ABOUT EVOLUTION OF ANNULAR URBAN HEAT ISLAND BASED ON REMOTE SENSING

城市热岛效应的空间格局在一定程度上可以反映城市规划和管理的成败得失,也是城市大气污染的驱动因素之一。使用2000、2003、2004、2006、2008和2010年2～3月下午成都的6次NOAA/AVHRR(National Oceanicand Atmospheric Administration/Advanced Very High Resolution Radiometer)卫星遥感数据反演亮温,采用均值-标准差法将热岛强度分为7个等级,用面积加权平均法将研究区强度分为高温、中温和低温3类。结果表明:(1)热岛空间格局呈现巨大变异,由前期的中心型演变为中期的环型,后期是热岛环的形态和高温中心的调整阶段;(2)研究区的强度为前期强,2004年迅速减弱,高温类的强度2004年比2003年减弱2.59℃,2004年之后的平均减弱率仅为0.24℃/a;(3)城市东北部和西南部高温区的温度梯度出现逆向升降趋势。由于地表温度对城市气温有重要影响,热岛形态的变化是人们从更复杂角度分析大气污染机制、设计热岛数值模型和进行城市规划的客观依据。

The spatial layout of urban heat-island can reflect the success or failure of urban planning and management to some extent,and it is one of the drivers of urban air pollution too.According to the NOAA/AVHRR（National Oceanic and Atmospheric Administration/Advanced Very High Resolution Radiometer）data on the afternoon of February and March in Chengdu City（2000,2003,2004,2006,2008 and 2010）,the inversion of brightness temperatures introduced the mean and sigma method to divide the intensity of heat-island into seven levels,and the area weighted average method to divide the intensity of research region into three kinds：high,medium and low temperatures.The results indicated that：（1）.the spatial layout changed greatly,the center-shaped in prophase changed into the annular-shaped in metaphase,and the anaphase was an adjustment phase of high-island shape and high-temperature center;（2）.the intensity of research region was high in prophase,then weakens in 2004 in which the intensity of high-temperature decreases by 2.59℃ compared with 2003,and the average decreasing rate after 2004 was only 0.24℃ per year;（3）.the temperature gradient of urban northeast and southwest showed reverse rising and lowering.Since surface temperature plays an important role in urban temperature,the shape change of heat-island is an objective evidence for us to analyze the mechanism of air pollution,the design of heat-island data model,and the urban planning more finely.