基于遥感的城市绿色空间演化过程的温度效应研究——以福州主城区为例

Temperature effect under the green space evolution based on remote sensing:a case study of Fuzhou,China

以福州主城区绿色空间为研究对象,基于遥感手段,研究绿色空间的复杂演化对地表温度扰动的影响。研究发现:(1)1993-2016年,福州主城区下垫面绿色空间损失和扩张面积分别为46.50km^2和4.73km^2,面积差达到41.77km^2。(2)不同温度区的分布格局发生了较大变化,冷岛区面积大幅减少,热岛区面积显著增加。从各温度等级内的土地利用分布来看,低温区内分布较多湿地和水体,次低温区以林/草地为主。(3)城市热岛重心与城市重心的迁移方向有关;而城市冷岛重心与城市绿色空间的分布关系密切。(4)不同绿色空间演化过程引起的降温效应大小依次为:绿色空间扩张>绿色空间不变>绿色空间交换>绿色空间损失。绿色空间扩张带来的平均降温幅度约为5.0℃,而绿色空间损失引起的平均增温约为7.0℃。不同的演化过程下,通过增加等面积的绿色空间,并不能抵消先前绿色空间损失带来的升温。因此,科学合理的绿色空间规划对于有效缓解城市热岛至关重要。

Taking the urban green space(UGS)in the main urban area of Fuzhou as the research object,the relationship between the UGS evolution and the change of land surface thermal environment was obtained based on the remote sensing inversion of land surface temperature(LST)and the extraction of land use and land cover(LULC).The results showed that:(1)From 1993 to 2016,the area of UGS Loss and UGS Expansion were 46.50 km^2 and 4.73 km^2 respectively,with the area difference as high as 41.77 km^2.The land surface temperature difference(ΔLST)caused by the UGS Loss was the largest,while theΔLST caused by the other three evolution types was slightly lower than the averageΔLST.(2)There was a trend that the urban cold island(UCI)decreased sharply and an opposite trend of the urban heat island(UHI)in 23 years.The distribution of the LULC in temperature grades was obviously different.The low temperature zone was distributed with more wetlands and waters.The sub-low temperature zone was given priority to forest/grass,while the UHI area was more distributed with the construction land and bare land.(3)The space gravity method illuminated that there was a close relationship between the UHI and the urban center of gravity,which was negative correlation with UGS location.The UCI was the contrary in the case.(4)The cooling effect caused by different types of UGS evolution was quantified which was in order as:UGS Expansion>UGS Unchanged>UGS Exchanged>UGS Loss.The calculation showed that the average cooling effect of UGS Expansion was about 5.0℃,while the warming effect of UGS Loss was about 7.0℃.Increasing the same area of UGS cannot offset the warming effect caused by the UGS loss previously during different evolution process.Therefore,the scientific and rational UGS planning is very important to relieve UHI effect.