近水面温湿度变化特征及水面蒸发量计算差异性分析

水面蒸发是水循环的主要途径之一，气象要素是影响水面蒸发的重要因素。为分析温度和湿度与水面蒸发量的关系，通过野外试验对水面上25 cm和35 cm处气温和相对湿度进行监测。同时，利用修正的Penman-Monteith方程计算了水面蒸发量，并与气象站数据计算结果进行比对。结果表明：近水面不同高度处相对湿度与气象站监测结果差异显著，差值均值在12%左右；近水面处气温和气象站监测气温的差异与距离水面高度有关，水面上25 cm和35 cm处气温和气象站气温的差值分别为(1.5±1.0)℃和(1.8±2.0)℃。水面蒸发量计算结果表明：气象站气象数据计算的水面蒸发量最大，而利用水面上25 cm和35 cm处气温和相对湿度计算的水面蒸发量近似。本研究为利用气象站数据计算水面蒸发量及结果修正提供了数据支撑。     

地铁车站深基坑钢支撑体系轴力预测及安全预警模型研究∗

随着我国基坑开挖数量和规模的不断增长，基坑事故率也随之上升，钢支撑轴力是衡量基坑围护支撑体系稳定性的重要指标之一。钢支撑轴力可利用传感器进行监测，但传感器失效后，该监测点将无法准确监测支撑轴力数据。故此，为保证基坑围护钢支撑体系的稳定，以宁波市某地铁车站深基坑的钢支撑体系作为研究对象，通过两道钢支撑架设之间的轴力变化进行分析，对钢支撑轴力数据进行预测，并对钢支撑体系进行安全预警。首先，由于轴力监测传感器存在“浴盆曲线”特性，故所得原始监测数据具有贫信息、小样本的特点，在此特性基础上，对基坑钢支撑轴力数据进行检验与处理，使之符合灰色预测模型建立条件；其次，建立灰色预测模型，并对模型的精度进行计算和后验差检验；最后，以灰色预测模型所得数据为基础，结合钢支撑的变形特征和指标，建立置信区间估计法安全预警模型，取显著性水平α=5%、α=2% 作为分界点，对深基坑的钢支撑体系进行预警等级划分，并判断当前钢支撑体系的运行状态。结果表明∶灰色预测模型精度良好，同时得出钢支撑体系处于安全的运行区间，模型判定结果与该地铁车站深基坑的钢支撑体系的实际情况相符，证明这种预测及安全预警模型可以用于判断钢支撑体系的稳定性。     

Local production,downward and regional transport aggravated surface ozone pollution during the historical orange-alert large-scale ozone episode in eastern China

Increasing severe and persistent ozone pollution in China has resulted in serious harm to human health in recent years, yet the precise pollution sources are poorly known because there is few knowledge on large-scale extreme ozone episodes. Here, we studied the formation of the historical orange-alert regional ozone episode in eastern China on 6 June, 2021, by combining process analysis, integrated source apportionment modelling, and chemical and meteorological data. Results show that during the pollution episode, 94% of cities in eastern China suffered ozone pollution, and 39% had daily maximum 8-h average ozone concentrations higher than 100 ppb. This is explained by favorable local ozone formation and transports provided by the prevailing northwestern winds in the upper air, and by sinking atmospheric motions favoring the persistence of high surface ozone concentrations. During daytime, local photochemical production induced an ozone increase of 0.3–28.4 ppb h^?1 and vertical transport induced an ozone increase of 0.4–56.1 ppb h^?1. As a consequence, vertical downward transport of ozone generated in the upper air by photochemical reactions aggravated surface ozone pollution. Surface ozone concentrations include 25.8–53.9% of ozone from local provincial emissions, 0–42.6% of ozone from inter-regional transports from neighboring regions, 4.6–23.1% of ozone from outer-regional transport, and 13.6–52.9% of ozone from boundary conditions in the selected cities. Overall, our findings show that favorable meteorological conditions promoted the chemical productions of ozone on the surface and at high altitudes, thus resulting in this heavy ozone pollution. In addition, regional and vertical downward transports of aloft ozone further aggravated the surface ozone pollution, leading to the large-scale extreme ozone pollution episode.