顾及时空背景的遥感生态指数适用性分析——以粤港澳大湾区为例

Applicability Analysis of RSEI Considering Spatio-temporal Background:A Case Study of Guangdong-Hong Kong-Macao Greater Bay Area

以粤港澳大湾区为例,基于Google Earth Engine云平台,从影像完整度、PC1贡献率与稳定性和样区纯净度三方面,探讨研究区空间尺度、传感器类型和影像合成时间窗口对RSEI反演结果影响的差异性,并基于最适宜方案反演粤港澳大湾区生态环境变化特征。结果表明:1)传感器类型通过影响湿度、干度、绿度、热度4个指标分量导致RSEI反演结果产生差异且影响效果最显著,不同合成时间窗口因气候与物候差异导致RSEI反演结果出现波动;2)不同空间尺度的RSEI反演方案效果受影像完整度和空间分辨率影响,在满足空间分辨率的前提下,传感器单景覆盖度越高、合成时间窗口跨度越短,反演效果越好,对于以城市群为代表的中尺度研究对象,MODIS季度合成反演效果最佳;3)2000-2020年粤港澳大湾区生态环境质量整体呈上升趋势,RSEI值表现出以珠江口为中心向外递增的半圈层结构,具有明显空间异质性。研究结果可为开展基于RSEI的生态环境研究提供参考,同时为大湾区建设生态宜居湾区提供理论支撑。

Taking Guangdong-Hong Kong-Macao Greater Bay Area as an example,based on the Google Earth Engine cloud platform,this paper uses the evaluation methods of image integrity,PC1 contribution rate and stability,as well as sample area purity to discuss the influence of spatial scale,sensor type and image synthesis time window on RSEI(remote sensing based ecological index)inversion results.And based on the optimum inversion scheme,the ecological environment changes of Guangdong-Hong Kong-Macao Greater Bay Area are retrieved.The results show that:1)The influence of sensor types on the four index components(humidity,dryness,greenness and heat)leads to the differences of RSEI inversion results,and the influence degree is the highest.The RSEI inversion results fluctuate due to the difference of climate and phenology of images from different synthesis time windows.2)The RSEI inversion schemes in different spatial scales are regulated by image integrity and spatial resolution,on the premise of proper spatial resolution,the higher the single image covers and the shorter the synthesis time spans,the better the inversion results are.On the mesoscale research objects represented by urban agglomerations,seasonal MODIS synthetic inversion results have the best performance.3)The overall ecological environmental quality of Guangdong-Hong Kong-Macao Greater Bay Area from 2000 to 2020 shows an upward trend,and the RSEI values show a semi-ring structure with the Pearl River Estuary as the center increasing from the inside out,with obvious spatial heterogeneity.The applicability assessment of the RSEI inversion scheme in this paper can provide some reference for the subsequent research on the ecological environment based on RSEI,and the RSEI timing assessment of Guangdong-Hong Kong-Macao Greater Bay Area will provide theoretical support for the construction of an ecologically livable world-class bay area.