Simulations of the Impact of Lakes on Local and Regional Climate Over the Tibetan Plateau

ABSTRACT

Because of the high elevation and complex topography of the Tibetan Plateau (TP), the role of lakes in the climate system over the Tibetan Plateau is not well understood. For this study, we investigated the impact of lake processes on local and regional climate using the Weather Research and Forecasting (WRF) model, which includes a one-dimensional physically based lake model. The first simulation with the WRF model was performed for the TP over the 2000–2010 period, and the second was carried out during the same period but with the lakes filled with nearby land-use types. Results with the lake simulation show that the model captures the spatial and temporal patterns of annual mean precipitation and temperature well over the TP. Through comparison of the two simulations, we found that the TP lakes mainly cool the near-surface air, inducing a decreasing sensible heat flux for the entire year. Meanwhile, stronger evaporation produced by the lakes is found in the fall. During the summer, the cooling effect of the lakes decreases precipitation in the surrounding area and generates anomalous circulation patterns. In conclusion, the TP lakes cool the near-surface atmosphere most of the time, weaken the sensible heat flux, and strengthen the latent heat flux, resulting in changes in mesoscale precipitation and regional-scale circulation.     

Characterization of sudden and sustained base flow jump hydrologic behaviour in the humid seasonal tropics of the Panama Canal Watershed

Base flows are important for tropical regions with pronounced dry seasons, which are facing increasing water demands. Base flow generation, however, is one of the most challenging hydrological processes to characterize in the tropics. In many years during the May–December wet season in the Panama Canal Watershed (PCW), base flows in rivers abruptly increase. This increase persists until the start of the December–April dry season. Understanding this unusual base flow jump (BFJ) behaviour is critical to improve water provisioning in the seasonal tropics, especially during droughts and extended dry seasons. This study developed an integrated approach combining piecewise regression on cumulative average base flow and sensitivity analysis to calculate the timing and magnitude of BFJ. Rainfall, forest cover, mean land surface slope, catchment area, and estimated subsurface storage were tested as predictors for the occurrence and magnitude of the BFJs in seven subcatchments of the PCW. Sensitivity analysis on correlated predictors allowed ranking of predictor contributions due to isolated and cross-correlation effects. Correlations between observed BFJs and BFJs predicted by watershed and rainfall-related predictors were 0.92 and 0.65 for BFJ timing and magnitude, respectively. Forest cover was the second most significant predictor after cumulative rainfall for jump magnitude, owing to larger subsurface storage and groundwater recharge in forests than pastures. Catchments in the mountainous eastern PCW always generated larger jumps due to their higher rainfall and greater forest cover than the western PCW catchments. The cross-correlations between predictors contributed to more than 50% of the jump variances. The results demonstrate the importance of rainfall gradient and catchment characteristics in affecting the sudden and sustained BFJs, which can help inform land management decisions intended to enhance water supplies in the tropics. This study underscores the need for more research to further understand the hydrological processes involved in the BFJ phenomenon, including better BFJ models and field characterizations, to help improve tropical ecosystem services under a changing environment.     

Energy flux partitioning and evapotranspiration in a sub‐alpine spruce forest ecosystem

In this study, we examined the year 2011 characteristics of energy flux partitioning and evapotranspiration of a sub‐alpine spruce forest underlain by permafrost on the Qinghai–Tibet Plateau (QPT). Energy balance closure on a half‐hourly basis was H + λE = 0.81 × (R_n ? G ? S) + 3.48 (W m^?2) (r² = 0.83, n = 14938), where H, λE, R_n, G and S are the sensible heat, latent heat, net radiation, soil heat and air‐column heat storage fluxes, respectively. Maximum H was higher than maximum λE, and H dominated the energy budget at midday during the whole year, even in summer time. However, the rainfall events significantly affected energy flux partitioning and evapotranspiration. The mean value of evaporative fraction (Λ = λE/(λE + H)) during the growth period on zero precipitation days and non‐zero precipitation days was 0.40 and 0.61, respectively. The mean daily evapotranspiration of this sub‐alpine forest during summer time was 2.56 mm day^?1. The annual evapotranspiration and sublimation was 417 ± 8 mm year^?1, which was very similar to the annual precipitation of 428 mm. Sublimation accounted for 7.1% (30 ± 2 mm year^?1) of annual evapotranspiration and sublimation, indicating that the sublimation is not negligible in the annual water balance in sub‐alpine forests on the QPT. The low values of the Priestley–Taylor coefficient (α) and the very low value of the decoupling coefficient (Ω) during most of the growing season suggested low soil water content and conservative water loss in this sub‐alpine forest. Copyright © 2013 John Wiley & Sons, Ltd.     

基于滨海环境资源特点的大连旅游承载状态评价

旅游环境承载力涉及多维度属性相互制约影响,而传统方法中对于各属性间影响程度及游客偏好选择的判定则较多依赖于个体的主观感知。因此,针对处理多属性综合评价中存在的模糊性及主观性,提出基于蒙特卡罗模拟修正的模糊综合评价模型。结果表明,借助上述模糊综合评价修正模型针对大连滨海旅游环境承载力进行解释与分析,成功缓解了在模型度量与数据分析环节所出现的主观偏误缺陷,从而有效提升了大连市滨海旅游景区有关阈值综合评价体系的科学性与稳健性。评价结果表明,当前大连市滨海旅游环境承载力状态可以判定为“适载”;在影响滨海旅游环境承载力的6项要素中,游憩环境要素与气候要素的评价分数较高,最低评分数值指标为景区游客管理状态。     

Reconstruction of the Cenozoic deformation of the Bohai Bay Basin,North China

A well‐constrained plate deformation model may lead to an improved understanding of sedimentary basin formation and the connection between subduction history and over‐riding plate deformation. Building quantitative models of basin kinematics and deformation remains challenging often due to the lack of comprehensive constraints. The Bohai Bay Basin (BBB) is an important manifestation of the destruction of the North China Craton, and records the plate kinematic history of East Asia during the Cenozoic. Although a number of interpretations of the formation of the BBB have been proposed, few quantitative basin reconstruction models have been built to test and refine previous ideas. Here, we developed a quantitative deformation reconstruction of the BBB constrained with balanced cross‐sections and structural, stratigraphic and depositional age data. Our reconstruction suggests that the basin formation process was composed of three main stages: Paleocene‐early Eocene (65–42 Ma) extension initiation, middle Eocene‐early Oligocene (42–32.8 Ma) extension climax and post‐Oligocene (32.8–0 Ma) post‐extensional subsidence. The deformation of the BBB is spatially heterogeneous, and its velocity directions rotated clockwise during the basin formation process. The reconstruction supports the interpretation that the BBB formed via strike‐slip faulting and orthogonal extension and that the basin is classified as a composite extensional‐transtensional basin. We argue that the clockwise rotation of the basin velocity field was driven by the counter‐clockwise rotation in the direction of Pacific Plate subduction. The kinematics of the BBB imply that the Pacific Plate may have been sufficiently coupled to the over‐riding East Asian Plate during the critical period of Pacific Plate reorganization. The new reconstruction provides a quantitative basis for studies of deformation processes not only in the vicinity of the BBB, but also more broadly throughout East Asia.     

An optimized baseflow separation method for assessment of seasonal and spatial variability of baseflow and the driving factors

Baseflow is an important component of river or streamflow. It plays a vital role in water utilization and management. An improved Eckhardt recursive digital filter(IERDF) is proposed in this study. The key filter parameter and maximum baseflow index(BFImax) were estimated using the minimum smoothing method to improve baseflow estimation accuracy. The generally considered BFImax of 0.80, 0.50 and 0.25 according to the drainage basin's predominant geological characteristics often leads to significant errors in the regions that have complex subsurface and hydrologic conditions. The IERDF improved baseflow estimation accuracy by avoiding arbitrary parameter values. The proposed method was applied for baseflow separation in the upstream of Yitong River, a tributary of the Second Songhua River, and its performance was evaluated by comparing the results obtained using isotope-tracer data. The performance of IERDF was also compared with nine baseflow separation techniques belonging to filter, BFI and HYSEP methods. The IERDF was also applied for baseflow separation and calculation of rainfall infiltration recharge coefficient at different locations along the Second Songhua River's mainstream for the period 2000–2016. The results showed that the minimum smoothing method significantly improved BFImax estimation accuracy. The baseflow process line obtained using IEDRF method was consistent with that obtained using isotope 18 O. The IERDF estimated baseflow also showed stability and reliability when applied in the mainstream of the Second Songhua River. The BFI alone in the river showed an increase from the upstream to the downstream. The proportion of baseflow to total flow showed a decrease with time. The intra-annual variability of BFI was different at different locations of the river due to varying climatic conditions and subsurface characteristics. The highest BFI was observed at the middle reaches of the river in summer due to a water surplus from power generation. The research provided valuable information on baseflow characteristics and runoff mode determination, which can be used for water resources assessment and optimization of economic activity distribution in the region.     

文化消费者对黄梅戏展演空间感知的模式与价值寻求：方法−目的链理论的应用

以安庆黄梅戏会馆和再芬黄梅公馆为例,基于方法?目的链理论模型,解读文化消费者对黄梅戏展演空间属性的感知评价、层次处理和价值导向的转变。研究发现：不同层次的空间属性在文化消费者的感知与体验中实现着新的组合与重构,由此形成了基于舞台展演内容、文化呈现形式以及演出环境氛围为主体的3种空间感知模式。结合文化消费者感知的心理结构与路径,黄梅戏展演空间被消费者建构为娱乐空间、情感空间和社交空间,空间的多元化意义和价值得到彰显。方法?目的链理论从消费者的感知与需求出发,探索文化空间意义生成路径,实现了文化空间与消费者之间的双向信息交换。     

地方小吃空间扩散格局与模式——基于中国四大知名地方小吃POI数据的研究

以中国四大知名地方小吃门店兴趣点（POI）大数据为主要数据源,基于密度、距离与加权平均中心方法分析地方小吃空间集聚与扩散格局,采用空间自相关、聚类和异常值分析以及热点分析方法研究地方小吃空间集聚关联特征以及空间扩散模式。结果表明：① 地方小吃在不同尺度上的空间扩散格局存在显著差异,东部地区和中西部省会城市是地方小吃的主要集聚地;② 地方小吃的空间集聚表现出自相关特征,邻域扩散、等级扩散和跳跃式扩散等扩散模式相互融合;③ 地方小吃空间扩散的冷热点集聚区分异明显,反映出不同小吃认可群体范围的差异以及中国各地饮食习惯的空间分异;④ 饮食文化扩散与人口迁移扩散具有空间重合性,经济发展水平较高、人口净流入地区对不同饮食文化的包容性较强。     

高中生在线学习问题的案例研究——以“地理高考专题复习”慕课为例

新冠疫情防控时期,我国开展了大规模在线教学的试验,目前亟需对在线教学效果进行总结与反思。本文基于疫情期间“地理高考专题复习”慕课的1.6万多名全样本在线学习日志,利用大数据分析方法,结合访谈调查,证实学生自主化、个性化的在线学习存在着行为参与度低、认知水平浅、情意品质低等问题,并着重分析了问题的主要成因,提出优化在线课程设计与管理、改进在线教学方式、提升师生信息素养等建议。     

绿色金融如何影响中国城市环境污染？——以雾霾污染为例

文章将绿色金融纳入环境规制的分析框架,以2016－2019年中国289个地级以上城市雾霾污染为例,使用空间杜宾模型探讨绿色金融、环境规制、产业结构、技术水平对雾霾治理的影响,侧重分析了绿色金融与其他因素的交互作用。结果表明：绿色金融具有空间溢出效应,本地绿色金融可以降低周边地区雾霾污染;绿色金融能够与环境规制协同互补,以优化产业结构、提升技术水平的方式促成雾霾治理。绿色金融的结构效应弱于环境规制,在中部地区并不显著;绿色金融的技术效应强于环境规制,能够激励不同地区技术创新。文章启示,绿色金融与环境规制能够相互增益,应建立区域间绿色金融合作机制,增强绿色金融的普惠性,助力区域产业转型和污染治理。