Satellite and reanalysis precipitation estimates of high quality are widely used for hydrological modeling, especially in ungauged or data-scarce regions. To improve flood simulations by merging different precipitation inputs or directly merging streamflow outputs, this study comprehensively evaluates the accuracy and hydrological utility of nine corrected and uncorrected precipitation products (TMPA-3B42V7, TMPA-3B42RT, IMERG-cal, IMERG-uncal, ERA5, ERA-Interim, GSMaP, GSMaP-RNL, and PERSIANN-CCS) from 2006 to 2018 on a daily timescale using the Coupled Routing and Excess Storage (CREST) hydrological model in two flood-prone tributaries, the Beijiang and Dongjiang Rivers, of the Pearl River Basin, China. The results indicate that (1) all the corrected precipitation products had better performance (higher CC, CSI, KGE’, and NSCE values) than the uncorrected ones, particularly in the Beijiang River, which has a larger drainage area; (2) after re-calibration under Scenario II, the two daily merged precipitation products (NSCE values: 0.73–0.87 and 0.69–0.82 over the Beijiang and Dongjiang Rivers, respectively) outperformed their original members for hydrological modeling in terms of BIAS and RMSE values; (3) in Scenario III, four evaluation metrics illustrated that merging multi-source streamflow simulations achieved better performance in streamflow simulation than merging multi-source precipitation products; and (4) under increasing flood levels, almost all the performances of streamflow simulations were reduced, and the two merging schemes had a similar performance. These findings will provide valuable information for improving flood simulations and will also be useful for further hydrometeorological applications of remote sensing data.

Ozone (O₃) pollution is a serious issue in China, posing a significant threat to people’s health. Traffic emissions are the main pollutant source in urban areas. NO_X and volatile organic compounds (VOCs) from traffic emissions are the main precursors of O₃. Thus, it is crucial to investigate the relationship between traffic conditions and O₃ pollution. This study focused on the potential relationship between O₃ concentration and traffic conditions at a roadside and urban background in Guangzhou, one of the largest cities in China. The results demonstrated that no significant difference in the O₃ concentration was observed between roadside and urban background environments. However, the O₃ concentration was 2 to 3 times higher on sunny days (above 90 μg/m³) than on cloudy days due to meteorological conditions. The results confirmed that limiting traffic emissions may increase O₃ concentrations in Guangzhou. Therefore, the focus should be on industrial, energy, and transportation emission mitigation and the influence of meteorological conditions to minimize O₃ pollution. The results in this study provide some theoretical basis for mitigation emission policies in China.

Urban color represents the visual skin of a city, embodying regional culture, historical memory, and the contemporary spirit. However, while the existing studies focus on pedestrian-level facade colors, the “fifth facade” from a bird’s-eye view has been largely overlooked. Moreover, color distortions in traditional remote sensing imagery hinder precise analysis. This study targeted 56 Chinese coastal cities, decoding the spatiotemporal patterns of their fifth facade color (FFC). Through developing an innovative natural color optimization algorithm, the oversaturation and color bias of Sentinel-2 imageries were addressed. Several color indicators, including dominant colors, hue–saturation–value, color richness, and color harmony, were developed to analyze the spatial variations of FFC. Results revealed that FFC in Chinese coastal cities is dominated by gray, black, and brown, reflecting the commonality of cement jungles. Among them, northern warm grays exude solidity, as in Weifang, while southern cool grays convey modern elegance, as in Shenzhen. Blue PVC rooftops (e.g., Tianjin) and red-brick villages (e.g., Quanzhou) serve as symbols of industrial function and cultural heritage. Economically advanced cities (e.g., Shanghai) lead in color richness, linking vitality to visual diversity, while high-harmony cities (e.g., Lianyungang) foster livability through coordinated colors. The study also warns of color pollution risks. Cities like Qingdao exposed planning imbalances through color clashes. This research pioneers a systematic and large-scale decoding of urban fifth facade color from a remote sensing perspective, quantitatively revealing the dilemma of “identical cities” in modernization development. The findings inject color rationality into urban planning and create readable and warm city images.

Estuarine and coastal ecosystems are facing significant threats from compounded pressures, such as land-based pollution and mariculture activities. These ecosystems confront severe challenges, including increasing environmental burdens and declining ecological health. Traditional evaluation methods that rely on statistical data struggle to meet the requirements for refined management of estuarine and coastal water environments. Taking Qinzhou Bay as a case study, this research incorporated multi-source data (including water quality indicators retrieved from remote sensing imagery, mariculture distribution, and land use information) into an integrated ecological health assessment system that combined remotely sensed data with the Pressure–State–Response (PSR) model. This approach enables a spatially continuous and quantitative evaluation of ecological health conditions for August 2015 (flood season), December 2015 (non-flood season), May 2022 (flood season), and December 2022 (non-flood season). The results indicated significant seasonal differences in the ecological health of Qinzhou Bay, with conditions generally better during the non-flood season than the flood season. Based on a comparison between the indicative estimation for 2015 and the inversion results for 2022, the overall ecological health index in 2022 showed an increasing trend, although some nearshore and estuarine areas experienced a declining trend. This study incorporated multi-source data, including remote sensing, into the PSR model framework, thereby advancing ecological health assessment from conventional discrete station-based evaluation to spatially continuous assessment. The effectiveness of this methodological approach in identifying spatiotemporal variations in the ecological health of estuarine and coastal zones was validated, providing scientific support for the refined management of estuarine and coastal water environments and ecological restoration.