Evapotranspiration (ET) cooling of urban spaces is an effective and economical way to improve the urban thermal environment. However, the distribution of urban ET rate is typically unknown owing to the high heterogeneity of urban land covers, which limits the application of many conventional techniques for measuring ET, such as ground-based observations and satellite remote sensing. In this study, an improved approach called "UAV + IRs + 3T", combining unmanned aerial vehicle (UAV), thermal infrared remote sensing, and a threetemperature model (3T), was developed for estimating urban ET and validated by Bowen ratio method. Results showed that the proposed method could accurately measure urban LE with R2 = 0.95, MAE = 21.98 W m- 2, RMSE = 30.33 W m- 2, RRMSE =19.65%. The proposed method could obtain urban ET with an ultra-high spatial resolution (approximately 15.5 cm) and temporal resolution (once per hour). Furthermore, 9 plant species distributed across the 18 sample plots showed significant differences in mean intra-day ET rates. Even for the same plant species at different sites, such as Ficus concinna and Zoysia matrella, their average intra-day ET rates differed by 50% and 400%, respectively. These large differences could be attributed to artificial pavement and infrastructure, different artificial irrigation methods, and difference in artificial and natural shade. In conclusion, there is spatio-temporal variability in urban ET rates, which can be precisely revealed by the proposed method. Therefore, the "UAV + IRs + 3T" method has the potential for a wide range of applications in urban environmental planning.

柴油车是城市氮氧化物和颗粒物污染的主要来源之一.以一种新型的发动机前端空气净化技术(warp air clean,WAC)为研究对象,研究其对7辆柴油货车在怠速和自由加速阶段的减排效果.结果表明:WAC对柴油货车一氧化碳(CO)、氮氧化物(NOx)、碳氢化合物(HC)和颗粒物数量(particulate number,PN)的平均减排率分别为12.2％、2.9％、3.9％和11.3％;不同排放标准下,WAC对国Ⅲ车辆的净化效果更佳.同一排放标准下,轻型柴油车的减排效果要优于重型柴油车;怠速(空挡)阶段,WAC对使用年限长、排放标准低的车辆净化效果更佳;自由加速阶段,WAC对CO、NOx和HC的净化作用主要表现为降低车辆加速过程中气体污染物排放的峰值,最高分别可达70.6％、50.0％和38.6％.

In response to a decline in pan evaporation over the last 60 years under global warming of water bodies, we designed an experiment with water bodies heated naturally to different temperatures to investigate the physics of pan evaporation and explore the effect of water temperature. In this study, we developed a new aerodynamic model for pan evaporation by combining a free convention sub‐model that couples Fick's First Law of Diffusion with boundary layer theory and a forced convection sub‐model based on convection mass transfer. Both the improved aerodynamic model and the two sub‐models have a higher accuracy and stability (|PBIAS| < 6%, root mean squared Error [RMSE] < 0.65 mm d −1 , and Nash‐Sutcliffe efficiency [NSE] > 0.8). Sensitivity analysis shows that water temperature is the most sensitive parameter to evaporation ( S 1 = 0.58, S T = 0.78). The mechanism of rising water temperature on evaporation is not only due to the strengthening in mass diffusion (under windless conditions), but also in the promotion in mass convection (under windy conditions). The integrated effects of mass diffusion and mass convection could result in an increase in evaporation of 0.8 mm d −1 , as mean water temperature rises by 1°C. These results would be useful for evaporation estimation of the warming global water.

利用一对设置在相同气象条件下的黑白标准A型蒸发器皿,观测两者气象要素、水温及蒸发量等动态特征,并根据现有的6个蒸发模型,探究水温对器皿蒸发量的影响.结果表明:1)设计的观测方法可以用于研究水温对器皿蒸发的影响.黑皿与白皿之间的水温和蒸发速率呈现明显的差异,在50天的观测期内,二者平均水温差为0.4℃,平均日蒸发量差为1.1 mm/d;2)在太阳辐射及其他气象要素相同的条件下,黑白皿水温差每升高1.0℃,由水温驱动的日蒸发量差异为0.808 mm/(d·℃);3)在水温升高条件下,没有考虑水温的经典蒸发模型的估值小于观测值,并且估值的误差也有所增加.

通过对城市单株乔木蒸散发特征及其冷岛响应的三维观测和数值分析,定量解析植被冷岛效应的成因.研究结果表明:1)小叶榕各部位冷岛强度绝对值基本上在3.0℃ 以上,其中前部最强能达到-5.19℃,顶部能达到-3.57℃;2)早上,东侧(前部和右部)的叶片蒸散发率先升高,正午顶部蒸散发达最强,西边(左部,后部)的叶片蒸散发较晚达到峰值,夜间各部位的蒸腾量非常微弱,不超过0.05 mm/h;3)城市乔木整体的冷岛效应强度与其蒸散发的相关系数为0.70,显著性低于0.01,蒸散发每升高1 mm/h,整树可降低3.56℃,顶部的蒸散发对顶部的冷岛效应贡献最明显(Spearman相关系数为-0.61),顶部、前部和右部的蒸散发对整树的冷岛效应贡献最大(相关系数绝对值均大于0.60),各部位蒸散发对整树冷岛效应贡献顺序为前部>顶部>右部>左部>后部>底部,即东侧和顶部>西侧>底部.

叶绿素a浓度是表征水体富营养化程度的重要指标,通过遥感手段反演叶绿素a浓度是实现水体富营养化监测的一个有效途径,已衍生出了一系列叶绿素a浓度反演算法.这些算法各有所长,适用范围也各自有别.由于水体光学特征差异,盲目套用这些算法难以取得预期效果.为了推动水质遥感的进一步发展,从遥感反演的原理和数据源出发,对国内外利用遥感技术反演水体叶绿素a浓度的算法进行综述.根据算法结构设计的不同,将反演算法分为6大类,分别为荧光峰和反射峰算法、波段算法、指数算法、智能算法、基于水体分类的算法体系以及分析类算法,系统地梳理各类算法并分析算法特征.从算法适用的叶绿素a浓度区间和水体类型等角度出发,总结各类算法的适用范围,评述各类算法的优缺点,以期为环境和遥感工作者提供参考.主要结论如下:①Ⅱ类水体算法外推适应性较弱,应建立并补充实测数据集,研究各类水体光学特性异同点,构建基于水体分类的通用算法体系;②无人机技术与高光谱传感器的结合可为内陆水体水质监测提供新思路;③应结合机器学习算法与机理模型,发展物理原理约束的高精度反演模型.

以深圳市6种常见的园林植物为对象,研究其单位面积滞尘量及其粒径组成特征,探究植物叶片表面的微观形貌结构以及滞留颗粒物的组分和分布特征,分析气象因子对植物滞尘的影响.结果表明:1)6种园林植物的单位叶面积滞尘量排序为黄金榕(0.74±0.21 g/m2)>鹅掌藤(0.42±0.26 g/m2)>对叶榕(0.24±0.26 g/m2)>龙船花(0.20±0.07 g/m2)>沿阶草(0.18±0.10 g/m2)>鸡蛋花(0.15±0.10 g/m2);2)6种园林植物滞尘以粒径 α>10μm的颗粒物为主,质量占比为59.21％～88.92％(黄金榕除外),鹅掌藤对 α>10μm颗粒物的滞尘能力最强(0.34±0.20 g/m2),黄金榕对3μm<α<10μm(0.51±0.15 g/m2)和0.15μm<α<3μm(0.14±0.07 g/m2)颗粒物的滞留能力最强;3)6种园林植物叶表面的气孔、褶皱、沟槽、絮状凸起和绒毛等微观形貌有利于叶片对颗粒物的截留,叶片滞留颗粒物的元素组成主要为O,Si和Al;4)6种园林植物叶表滞留的大颗粒物(α>10μm)易受风速和温度的影响.研究结果对深圳市园林植物配置具有指导意义,并可为通过植物滞尘效应改善空气质量提供一定的理论依据.