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Lidar is a powerful active remote sensing technique to monitor the planetary boundary layer (PBL), and there have already been many algorithms to retrieve the planetary boundary layer height (PBLH) using aerosol lidars. However, the algorithm suitable for all atmospheric conditions doesn't exist. This study evaluates the capability of nine lidar algorithms under different pollution scenarios in terms of the instantaneous performance and the diurnal evolution, which are derived from classical theories and expressed as GM, LGM, CRGM, IPM, VAR, VGM, WCT, WCTD, and POLARIS in this paper. Based on the nine algorithms, the continuous PBLHs are obtained from the observation dataset of a Beijing urban site in 2017. In order to verify the lidar results, the statical comparison analysis with radiosonde is also presented. On the premise of the inversion hypothesis, such as sufficient mixing in the PBL, the consistency of lidar results was the best, with the difference being not more than 200 m. And what's different from our cognition is that the concentration of pollutants near the ground under the light pollution condition makes the lidar results tend to be consistent. In fact, LGM prefers to get higher PBLHs because of filtering the information near the ground, whereas POLARIS is apt to underestimate unless the actual morphology can be captured by the depolarization ratio. VAR and IPM are more vulnerable to the conspicuous stratification. GM, CRGM, and WCTD have better consistency with radiosonde and capture the evolution characteristic no matter in clean or polluted days. Compared with the clean days, PBLH from lidar algorithms under the polluted condition reduced about 500 m overall, as well as the standard deviation. Generally speaking, the comprehensive comparison provides a reference to choose the proper lidar algorithm when retrieving the PBLH. GM is appropriate for the detection of clean days, while CRGM is robust for polluted days. WCTD is more suitable for the judgment of PBLH in the morning and evening and will underestimate at noon. As to the situation with cloud, WCTD is also the best choice. • The nine algorithms are compared both internally and with radiosonde. • The difference of lidar results with sufficient mixing is not more than 200 m. • GM, WCT and WCTD are robust to meet the retrieval requirements. • WCTD is much better for the inversion of residual layer height at night. [ABSTRACT FROM AUTHOR]

In the acceleration of industrialization and urbanization, brownfield is an important resource for land regeneration and restoration targeting to recover its ecosystem function. Landfills, as a type of brownfield distributed in the highly populated areas, occupy massive land resources. The ecological restoration of landfills becomes an engineering approach to achieve multiple effects of society, environment, and economy. This paper aims to monitor and assess the restoration microclimatic effects of landfills restoration in China with remote sensing data and techniques. We selected representative landfill restoration projects, including Nanhaizi Park in Beijing, Nanhu Park in Tangshan, and Tianziling Park in Hangzhou, as the study cases. Using the Landsat imagery, the scenes of the pre-restoration, mid-restoration, and post-restoration were retrieved, and the surface energy balance equation was applied to calculate normalized difference vegetation index (NDVI), land surface temperature (T s), and evapotranspiration (ET), representing vegetation conditions and hydro-heat microclimate conditions. The study areas are divided into four subzones and extracted the calculated values for statistics and comparison. We defined an indicator of restoration intensity (RI) using the different subzones to the outer contour distance radius and restoration phases to evaluate the spatial-temporal restoration degrees. The spatial pattern dynamics was displayed in the urbanization context in the cases of Beijing and Tangshan. We examined and quantified the relations between RI and the key indicators, NDVI, T s , and ET. The overall results revealed that with higher restoration intensity, NDVI and ET became higher, and T s became lower. It suggested that the ecological restoration on the landfills brought better vegetation, cooling, and humidification effects for the microclimatic environment. Our research has the implications for monitoring and assessing the climatic effects of ecological restoration in the brownfield regeneration in a macroscopic and ecosystem perspective. Unlabelled Image • With satellite dataset, we developed a way to monitor vegetation and microclimatic changes in the restored landfills. • The indicator to quantify the ecological restoration intensity was invented with spatial distance and restoration phase. • Overall, with higher restoration intensity, vegetation and evapotranspiration improved, and surface temperature declined. [ABSTRACT FROM AUTHOR]