In situ measurements of wind‐driven salt fluxes through constructed channels in a coastal wetland ecosystem

A suite of instruments was deployed in a coastal wetland ecosystem in the Albemarle estuarine system, North Carolina (USA), to characterize wind‐driven transport of saltwater through a constructed (man‐made) channel. Flow velocity, electrical conductivity, and stage were measured in a representative channel over a 2‐month period from May to July 2014, during which 4 wind tides were observed. Collected data show that thousands of metric tons of salt were advected through the channel into coastal wetlands during each event, which lasted up to 4 days. The results reveal that as much as 36% of advected salts accumulated in the wetlands, suggesting that the cumulative effects of these events on the health of coastal wetlands in the Albemarle system may be substantial due to the abundance of constructed channels and the frequency of wind‐driven tidal events. This study is the first to quantify wind‐driven salt fluxes through constructed channels in coastal wetland settings.     

Effects of intensive aquifers exploitation on groundwater salinity in coastal wetlands

The coastal plain of the Río de la Plata constitutes a large wetland which develops on the right margin of the river estuary. Anthropic activities such as intensive exploitation of groundwater carried out in the vicinity of the wetland can modify the natural hydrological regime. The aim of this work is to asses the effects of intensive aquifer exploitation in coastal wetlands using hydrogeological models. Such models allow to evaluate changes in the environmental conditions of wetland at regional level. The hydrogeological model exposed in this work shows how the intensive groundwater exploitation affects the wetland area, generating important variations both in the groundwater flows and in the salinity of the groundwater. Identification of these modifications to the environment is important to generate guidelines leading to minimize these affectations.     

A hybrid integrated deep learning model for the prediction of citywide spatio-temporal flow volumes

ABSTRACT

The spatio-temporal residual network (ST-ResNet) leverages the power of deep learning (DL) for predicting the volume of citywide spatio-temporal flows. However, this model, neglects the dynamic dependency of the input flows in the temporal dimension, which affects what spatio-temporal features may be captured in the result. This study introduces a long short-term memory (LSTM) neural network into the ST-ResNet to form a hybrid integrated-DL model to predict the volumes of citywide spatio-temporal flows (called HIDLST). The new model can dynamically learn the temporal dependency among flows via the feedback connection in the LSTM to improve accurate captures of spatio-temporal features in the flows. We test the HIDLST model by predicting the volumes of citywide taxi flows in Beijing, China. We tune the hyperparameters of the HIDLST model to optimize the prediction accuracy. A comparative study shows that the proposed model consistently outperforms ST-ResNet and several other typical DL-based models on prediction accuracy. Furthermore, we discuss the distribution of prediction errors and the contributions of the different spatio-temporal patterns.     

Assessment of 2DH and pseudo‐3D modelling platforms in a large saline aquatic system: Lake Urmia,Iran

The main objective of this paper is to provide comparative quantitative examinations on the capabilities of two‐dimensional horizontal and pseudo‐three‐dimensional (3D) modelling approaches for simulating spatial and temporal variability of the flow and salinity in Lake Urmia, Iran. The water quality in the lake has been an environmentally important subject partly because this shallow hypersaline aquatic ecosystem is considered to be one of the largest natural habitats of a unique multicellular organism, Artemia urmiana. This brine shrimp is the major food source for many of the protected and rare shorebirds that visit the lake. A. urmiana can grow and survive in certain ranges of salinity, and their disappearance could lead to an alteration of existing equilibria. The lake has also experienced considerable man‐made changes during the past three decades. A newly built crossing embankment almost divided the lake into two northern and southern halves. A relatively small opening of 1.25 km in the new embankment provides water connections between the two halves. As a result, the flow and salinity regimes have been significantly changed. This might have had adverse serious impacts on the lake ecosystem. In the current study, the two‐dimensional horizontal hydrodynamic model has been found to provide reasonable predictions for the flow regime in the lake, whereas its salinity predictions have not been consistent with the field observations. The pseudo‐3D model has produced results fairly close to the salinity measurements and its temporal and spatial variations. The pseudo‐3D model has been used for evaluating the embankment effects on the lake hydrodynamics and on the salinity conditions. The effectiveness of introducing a different number or length of openings in the embankment for restoring the pre‐embankment conditions has also been examined. These remedy options have been found not to offer substantial improvements to the lake's existing ecosystem. Copyright © 2013 John Wiley & Sons, Ltd.     

Estimating absolute salinity (SA) in the world׳s oceans using density and composition

The practical (S_p) and reference (S_R) salinities do not account for variations in physical properties such as density and enthalpy. Trace and minor components of seawater, such as nutrients or inorganic carbon affect these properties. This limitation has been recognized and several studies have been made to estimate the effect of these compositional changes on the conductivity–density relationship. These studies have been limited in number and geographic scope. Here, we combine the measurements of previous studies with new measurements for a total of 2857 conductivity–density measurements, covering all of the world׳s major oceans, to derive empirical equations for the effect of silica and total alkalinity on the density and absolute salinity of the global oceans and to recommend an equation applicable to most of the world׳s oceans. The potential impact on salinity as a result of uptake of anthropogenic CO₂ is also discussed.     

基于Meta-Gaussian模型的中国农业干旱预测研究

在全球气候变化背景下,干旱愈加频发,有效且可靠的农业干旱预测对于保障粮食安全和水资源安全具有重要意义。以标准化降水指数（SPI）和联合标准化土壤湿度指数（JSSI）分别表征气象干旱和农业干旱,以前期的气象干旱和农业干旱指数作为预测因子,在1~3个月预见期下基于Meta-Gaussian（MG）模型对中国1961—2015年6—8月的农业干旱进行预测,并采用Brier Skill Score（BSS）和纳什效率系数（NSE）评价MG模型的预测性能。结果表明：① 将1个月、3个月、6个月、9个月和12个月时间尺度的标准化土壤湿度指数（SSI）结合起来得到的JSSI能够对中国农业干旱的综合状况进行客观评价。② 以中国2010年和2014年遭受严重的干旱事件为例,预见期为1~3个月时,除新疆南部、青海西部以及内蒙古西部等沙漠地区外,MG模型对6—8月农业干旱预测结果的分布范围与实际干旱的分布区域较吻合,预见期越短,吻合越好。③ 预见期为1个月时,6—8月BSS ≥ 0.5的面积比例分别为0.714、0.642和0.640,NSE ≥ 0.5的面积比例分别为0.903、0.829和0.837,表明MG模型能够对中国大部分区域的农业干旱作出可靠的预测。本文结果可为中国农业干旱的监测、预警及干旱决策提供科学指导。     

Method for UAV-based 3D topography reconstruction of tidal creeks

It is common to obtain the topography of tidal flats by the Unmanned Aerial Vehicle(UAV) photogrammetry,but this method is not applicable in tidal creeks.The residual water will lead to inaccurate depth inversion results,and the topography of tidal creeks mainly de-pends on manual survey.The present study took the tidal creek of Chuandong port in Jiangsu Province,China,as the research area and used UAV oblique photogrammetry to reconstruct the topography of the exposed part above the water after the ebb tide.It also proposed a Trend Prediction Fitting (TPF) method for the topography of the unexposed part below the water to obtain a complete 3D topography.The topography above the water measured by UAV has the vertical precision of 12 cm.When the TPF method is used,the cross-section should be perpendicular the central axis of the tidal creek.A polynomial function can be adapted to most shape of sections,while a Fourier function obtains better results in asym-metrical sections.Compared with the two-order function,the three-order function lends itself to more complex sections.Generally,the TPF method is more suitable for small,straight tidal creeks with clear texture and no vegetation cover.     

地理空间传感网融合服务技术与应用

随着遥感数据网、传感网、物联网和人工智能的发展,逐渐形成空天地海立体化、集成化和一体化的地理空间传感网。地理空间传感网感知资源呈现出多源、异构和分散的特征,面向多层次用户个性化、即时化和智能化应用需求,存在异构资源共享管理、多协议实时接入、时空无缝感知、自动化感知和精准预测等技术挑战。静态地理信息服务由于无法提供鲜活的地理信息,难以满足地理事件的综合监测、决策预警和聚焦应用需求,急需发展地理空间传感网融合服务技术和实时动态地理信息服务平台。本文围绕信息物理网环境下空天地海观测平台的观测高效共享和融合服务问题,提出了传感网观测共享信息模型和点面观测协同无缝重建模型,突破了观测在线接入、集成管理、星地融合、时空预测和聚焦服务等地理空间传感网融合服务关键技术,研制了包含“感—联—知—控”等功能的传感网时空信息网络感知服务系统GeoSensor,介绍了GeoSensor在流域、海洋和城市等典型应用。未来将进一步发展“人—水—城”智能感知认知理论,突破“空天地海人”群智感知、空间智能和认知服务技术,开展长江经济带应用。     

Another Year of Record Heat for the Oceans

Changes in ocean heat content(OHC), salinity, and stratification provide critical indicators for changes in Earth’s energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth’s climate system. In 2022, the world’s oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum.According to IAP/CAS data, ...     

安徽省2021年梅雨期降水预报检验分析

检验梅雨期降水的预报效果,对于提升梅雨期降水预报能力、减少梅雨期降水带来的人员伤亡和经济财产损失有着重要的意义。文章对安徽省2021年梅雨期（6月10日—7月10日）六个客观模式和一个主观订正预报产品进行了检验分析,其中包含了三个区域模式数值预报（中国气象局中尺度天气数值预报系统（简称CMA-MESO）、中国气象局上海数值预报模式系统（简称CMA-SH9）、安徽WRF）、三个全球模式数值预报（中国气象局全球同化预报系统（简称CMA-GFS）、欧洲中期天气预报中心确定性预报模式（简称ECMWF）、美国国家环境预报中心全球预报系统（简称NCEP-GFS））和安徽智能网格主观订正预报的降水产品,进行了检验分析,结果表明：传统检验中安徽智能网格和区域模式对晴雨准确率的预报效果优于全球模式,又以CMA-MESO最优;在暴雨及以上量级的强降水预报中,传统检验表明安徽智能网格预报的得分最高（23.83）,ECMWF模式则是客观模式预报中效果最好的（20.12）,CMA-SH9次之（19.34）;通过对除安徽智能网格以外的各个客观数值模式进行的MODE空间检验可知,不同数值模式间暴雨预报误差原因不尽相同,ECMWF与各区域数值模式主要是由雨区位置的预报偏差,尤其是纬度偏差导致的,NCEP-GFS全球模式对降水强度和雨区面积的预报偏弱偏小比较明显,CMA-GFS在强降水方面的预报可参考性较差;各个主客观预报暴雨及以上量级预报,整体表现出较明显的日变化特征,在午夜前后、上午时段TS评分较高,而午后到傍晚评分较低,这个现象或许是梅雨期的午后降水多以地表太阳加热引起的短历时热对流降水为主造成的。