物联网技术支持下的城市热环境时空变化分析

Spatio⁃temporal variation analysis of urban thermal environment based on Internetof Things technology

热环境是城市生态系统最为关键的大气环境要素之一,开展城市热环境研究的前提是在时空维度上获取足量的热环境参数。利用先进的物联网技术构建了在线式热环境监测设备,收集2022年10月16日至24日广州大学校园气温、风速、太阳辐射和地面温度四种热环境参数,分析小尺度下城市热环境的时空变化特征。研究结果表明:1)不同测点之间的风速特征具有一定的相关性,极个别测点的风速特征与其它测点相关性仅在0.5左右,显示其小气候的独特性;2)不同测点风速和热岛强度变化时空差异明显,即使距离靠近的测点,受邻近建筑和植被特征的影响热环境特征会有所差异,各测点的日间风速大,热岛强度较为明显,夜间风速较小,热岛强度较弱;3)地面温度与气温的相关性达0.8左右,这种相关性在夜间表现更为密切,并且这种关系受风速的影响不大。研究结果反映了城市热环境参数在小尺度上的高度异质性,并揭示了物联网技术在城市热环境监测领域的可行性、便捷性和高效性。

The urban thermal environment is a comprehensive physical environment system that integrates various external factors related to heat within a city,which affects the survival and development of its residents.Thermal environment is regarded as one of the most important ecological parameters in both natural and urban ecosystems.It is well established that obtaining adequate space⁃time⁃related thermal environment parameters is a prerequisite for conducting urban thermal environment studies.However,the stations of urban meteorological stations managed by government departments are relatively scattered,and the data obtained cannot express the microclimate conditions within the city.Scholars can obtain rich data on urban thermal environment parameters by independently setting up on⁃site monitoring points,but this requires significant economic costs.Currently,domestic and foreign scholars have achieved the goal of efficient monitoring of the ecological environment using Internet of Things(IoT)technology.Monitoring urban thermal environment by using Internet of Things(IoT)technology can effectively address these issues.In this study,we selected Guangzhou University as research area and developed a series of innovative thermal environment field measurement devices based on Internet of Things(IoT)technology to collect air temperature,wind speed,solar radiation,and land surface temperature simultaneously online.Specifically,ten measuring sites were selected to record the four thermal environmental parameters mentioned above between October 16 and 24,2022.The results were as follows:1)The two boundary parameters,solar radiation,and wind speed shaped the basic characteristics of the thermal environment in the study area. There was a strong correlation between thewind speeds of different sites, while very few sites had very low correlation between the wind speeds, indicating theuniqueness of the microclimate. 2) The variations of wind speed and heat island intensity at different sites were significantlydifferent both temporally and spatially. Even with the close distance between measurement points, the characteristics of thethermal environment were influenced by the surrounding buildings and vegetation. The wind speed and heat island intensitywere higher at each measuring site during the daytime and vice versa at night. 3) The correlation between land surfacetemperature and air temperature was more than 0. 8, and this correlation was stronger at night than during the day.Interestingly, this relationship was also not greatly influenced by wind speed. The results of this study revealed the highheterogeneity of the urban thermal environment at a local scale and demonstrated the feasibility, convenience, and efficiencyof IoT technology for urban thermal environment monitoring.