Interactions between Vegetation and Climatic Factors in Typical Arid and Humid Regions of China Based on NDVI

According to the distribution of arid and humid regions in China,the typical arid region (Erjina),the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau) and the typical humid region (Poyang Lake basin) were selected as the study areas.Based on NDVI data from 1982 to 2000 and meteorological observing data of three study areas from 1981 to 2000,the interactions between vegetation NDVI and climatic factors (temperature and precipitation) in typical arid and humid regions were discussed in this study.The results showed that in the responses of vegetation to climatic factors,vegetation in the typical arid region (Erjina) was more sensitive to precipitation,while vegetation in the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau) was more sensitive to both temperature and precipitation,and vegetation in the typical humid region (Poyang Lake basin) was more sensitive to temperature.As for effects of vegetation on climatic factors,there was a remarkable negative correlation between vegetation NDVI in the past winter and temperature in the present summer,and also a significant positive correlation between vegetation NDVI in the past winter and precipitation in the present summer.However,in the typical semi-arid/semi-humid region (Guanzhong basin/Loess Plateau),there was a significant positive correlation between vegetation NDVI in the present spring and temperature in the present summer.

Evapotranspiration and humidity variations in response to land cover conversions in the Three Gorges Reservoir Region

A new land cover classification system was established for the Three Gorges Reservoir Region(TGRR) after considering the continuity of inundation and the natural characteristics of land cover. The potential evapotranspiration(PET) was predicted using a modified Penman-Monteith(P-M) model. The region's ratio of precipitation to evapotranspiration was calculated as the humidity index(HI). The data obtained was used to analyze climatic responses to land cover conversions from the perspectives of evapotranspiration and humidity variations. The results show that, from 1997 to 2009, the average annual PET increased in the early years and decreased later. In terms of overall spatial distribution, a significant reciprocal relationship appeared between annual PET and annual HI. In 1997,the annual PET was higher in the lower reaches than in the upper reaches of the TGRR, but the areas with high PET shifted substantially westward by 2003. The annual PET continued to increase in 2006, but the areas with high PET shrank by 2009. In contrast, the annual HI showed varying degrees of localized spatial variability. Over the three periods, the dominantforms of land cover conversions occurred from evergreen cover to seasonal green cover, from seasonal green cover to evergreen cover, and from seasonal green cover to seasonally inundated areas, respectively. These accounted for 48.0%, 38.4%, and 23.8% of the total areas of converted land covers in the three periods, respectively. During the period between 1997 and 2003, the main forms of land cover conversions resulted in both positive and negative growths in the average annual PET, while all of them pushed down the average annual HI. From 2003 to 2006, the reservoir region experienced neither a decrease in the annual PET nor an increase in the annual HI. The period between 2006 and 2009 saw a consistent downward trend in the annual PET and a consistent upward trend in the annual HI.

Spatial-temporal characteristics and influencing factors of relative humidity in arid region of Northwest China during 1966–2017

Playing an important role in global warming and plant growth,relative humidity(RH)has profound impacts on production and living,and can be used as an integrated indicator for evaluating the wet-dry conditions in the arid and semi-arid area.However,information on the spatial-temporal variation and the influencing factors of RH in these regions is still limited.This study attempted to use daily meteorological data during 1966–2017 to reveal the spatial-temporal characteristics of RH in the arid region of Northwest China through rotated empirical orthogonal function and statistical analysis method,and the path analysis was used to clarify the impact of temperature(T),precipitation(P),actual evapotranspiration(ETa),wind speed(W)and sunshine duration(S)on RH.The results demonstrated that climatic conditions in North Xinjiang(NXJ)was more humid than those in Hexi Corridor(HXC)and South Xinjiang(SXJ).RH had a less significant downtrend in NXJ than that in HXC,but an increasingly rising trend was observed in SXJ during the last five decades,implying that HXC and NXJ were under the process of droughts,while SXJ was getting wetter.There was a turning point for the trend of RH in Xinjiang,which occurred in 2000.Path analysis indicated that RH was negatively correlated to T,ETa,W and S,but it increased with increase of P.S,T and W had the greatest direct effects on RH in HXC,NXJ and SXJ,respectively.ETa was the factor which had the greatest indirect effect on RH in HXC and NXJ,while T was the dominant factor in SXJ.

THE DISTRIBUTION REGION AND THE DISTRIBUTIVE TEMPERATURE AND HUMIDITY THRESHOLD OF OSIER WEEVIL IN CHINA

A distribution map of osier weevil (Crytorrynchus lapathi L.) was drown up based on widely collecting information and field survey. The results showed that Osier weevil has a widespread in China, stretching from 33°21' to 51°42' N latitude and 83°00' to 132°58' E longitude, and distributes in forms of big or small patches or sports uncontinously. According to the analysis of meteorological data, the temperature and humidity threshold for osier weevil's distribution were determined by methods of PCA (Principle Component Analysis) and RA(Relativity Analysis): January temperature is -30~ 0℃. Annual temperature -4~13℃, Annual precipitation from 411~ 1,136 min.The areas with January temperature under 0℃, annual temperature above 0℃ and annual precipitation of 400~ 800 mm are the optimum distributing places for osier weevil in China.

Application of natural ventilation of residential buildings in hot-humid regions

The current ventilation condition of the hot and humid regions was analyzed through on-site investigation. It is found that residents in this region expect to improve indoor thermal environment through natural ventilation as much as possible. Then,it comes to a conclusion by the field test that natural ventilation has certain practical effect on improving indoor thermal environment. CFD simulation software is employed to verify the test result. Based on PMV modified model,and according to norms,geography and climate combined with the measured and simulated results,the application of the time and effectiveness of natural ventilation in hot and humid region were analyzed,to some extent,providing a basis for reducing the air-conditioner's runtime with natural ventilation.

基于野外观测实验的中国东部湿润区降雨入渗模拟分析——以宁波画龙溪流域为例

本文以中国东部湿润区典型小流域浙江宁波画龙溪为例,将野外原位定点观测与模型模拟分析相结合,建立了HYDRUS-1D土壤水模拟模型,选取2016年9月29日、2016年10月7日典型降雨事件分别对模型进行率定和验证,并对2016―2020年不同降雨强度下不同土地利用类型的场次土壤水分入渗开展了观测与模拟,以揭示中国东部湿润区不同土地利用类型下的降雨-入渗规律。结果表明:(1)从土壤水分变化过程模拟来看,HYDRUS-1D模型模拟土壤水分动态变化特征具有较高的精度,90%模拟结果的纳什效率系数达到0.80以上。(2)在同等降雨强度下,4种土地利用类型土壤下渗量从大到小依次为农田、杨梅林、坡耕地、竹林。下渗率受降雨量及降雨强度影响较大,不同土地利用下土壤下渗量随着降雨强度增强而显著增加。(3)土壤下渗量同时也受到降雨历时与前期降雨情况深刻影响。当降雨强度从小雨逐级增加到大暴雨,各土地利用类型下渗量略微增加,但增加量均小于5%。对于历时短、强度高的极端降雨事件,降雨强度超过了下渗强度,形成超渗产流,将出现降雨量大但下渗量反而小的现象。本研究成果可为中国东部湿润区农业生产、三水转化规律等提供理论参考。

甘肃省植被时空动态变化及其归因分析

甘肃省作为中国西部生态安全屏障的重要组成部分,其植被覆盖变化直接关系中国西部的生态安全。采用2000-2020年植被覆盖度(FVC)数据,并从自然和人文影响方面选取16个影响因子,涵盖气候、地形地貌、土壤、人类活动,利用趋势分析法、地理探测器模型和偏最小二乘结构方程建模(PLS-SEM),从甘肃省不同干湿区、不同时间节点的角度探究其植被覆盖的变化特征及驱动力。结果表明,1)2000-2020年,甘肃省FVC整体持续改善,高植被覆盖度显著增加,其中陇东高原、陇中高原和疏勒河南部地区改善最为明显。2)不同干湿区的植被覆盖变化差异显著。干旱和半干旱区植被改善较慢,受降水量波动和土地利用方式影响大;而半湿润和湿润区植被改善明显,得益于良好的气候条件、生态工程的推动以及土壤有机碳含量的增加。3)降水和土地利用对FVC解释力最大,“退耕还林工程”对FVC的增加起到积极作用,但不合理的土地利用和城市化等也引起植被退化。随着时间推移,气候对FVC的影响一直在积极增加,不合理人类活动对FVC的负面影响相对稳定且较大,部分抵消了退耕还林的正面效果。此外,土壤有机碳含量对FVC的影响显著下降,且间接受到气候的正向影响。4)利用PLS-SEM模型,可有效分离自然与人为因素对植被覆盖的驱动作用,也可探究因素间的作用强度与途径。该研究增强了对区域植被动态变化规律的理解,也为生态恢复和环境管理提供了科学支持。

基于水文模型的山东半岛典型流域产流模式探讨

为明晰山东半岛半湿润地区流域产流模式,以龙角山水库流域为例,利用28场洪水资料,以新安江模型和垂向混合产流模型作为蓄满产流和混合产流的代表,探讨半湿润地区流域产流模式。结果表明:(1)垂向混合产流模型的洪峰流量、峰现时间和径流深三个预报项目的平均合格率,在率定期和验证期分别为81.7%和91.7%,达到甲级精度,且模拟结果地面径流与壤中流占比大,对洪峰过程的模拟吻合度高。(2)新安江模型所有预报项目的平均合格率,在率定期和验证期分别为73.3%和83.3%,达到乙级精度,其模拟结果地下径流占比大,对退水过程模拟吻合度高。本研究确定了混合产流模式在龙角山水库流域的适用性要优于蓄满产流模式,对明晰山东半岛半湿润地区产流规律具有促进作用。

严寒地区地铁站冬季热湿环境实测研究

地铁站是城市公共交通的重要组成部分,对市民出行质量和体验有着重要影响。以哈尔滨地铁2号线为代表,选取五个代表车站研究严寒地区冬季地铁站公共区域的热湿环境与热舒适性,采用现场实测和问卷调查的方法进行分析与评价,并基于HDR指标对哈尔滨地铁站各公共区域的热环境进行评估。研究表明地铁站公共区域的95%情况下符合对温湿度的要求,能够满足对地铁站的基本要求。根据投票结果得出,地铁站公共区域热环境与湿环境80%以上的乘客可以接受且HDR值在冬季规定舒适范围内,满足热舒适的要求。该研究可为严寒地区地铁站冬季通风运行提供理论参考,有利于营造良好的热湿环境。

严寒地区车站湿热环境耦合节能改造研究

在“双碳”目标下,针对乡村建筑节能发展不足的问题,文中以杜尔伯特烟筒屯车站为案例,探索了东北乡村建筑的节能改造策略。结合乡村环境、居民习惯及经济成本,通过增加保温层、增设被动式阳光间及优化室外环境等措施。通过绿建斯维尔软件模拟分析,结果显示改造后车站全年节能约35%,冬季室温提升10℃,有效提升了建筑能效与舒适度。为乡村建筑节能改造提供了实践参考,助力乡村绿色建筑发展。

1961—2020年新疆区域性强冷空气及寒潮时空分布特征

选用1961—2020年新疆99个气象站气温、降水观测日资料,通过相关分析、线性趋势分析等方法,分析了新疆全年区域性强冷空气和寒潮的特征,并应用降水资料对新疆全年强冷空气和寒潮过程的干湿状况进行了识别。结果表明:(1)新疆区域性强冷空气和寒潮频次均有减少的趋势,在21世纪10年代更为显著,这种减少主要体现在秋季强冷空气与秋季寒潮频次的减少;(2)新疆寒潮在冬季3个月的发生频次较为接近;春季与秋季寒潮在11月最多,3月和4月次之;超强寒潮时间主要集中在冬季的12月和1月,强寒潮发生的频率则在2月最高;(3)新疆寒潮过程最低气温有所上升,降温幅度有所减小;过程平均降水量以及最大降水量自20世纪90年代以来较之前明显增加;新疆冬季区域性寒潮的降温幅度比春秋季区域性寒潮过程高1℃左右;(4)寒潮过程中最低气温和降水量最大中心基本出现在阿尔泰山及天山山区。新疆春秋季寒潮多为正常或干过程;冬季寒潮过程有76.4%为正常偏干,较湿和湿过程有85.7%集中在20世纪90年代以来。对寒潮过程干湿状况进行初步识别,有助于更全面地认识新疆寒潮的气候新特征,为防灾减灾服务;(5)冬季北疆及天山大多数站点是72 h达到寒潮标准,而南疆则更多是在24 h达到寒潮标准。

温湿效应下寒区水泥路面的破坏模式

为探究我国北方水泥路早期破坏原因,以黑龙江省在役期水泥路为对象,结合数值模拟手段分析环境荷载、轴型、轴重耦合作用下水泥路面的力学性能。结果表明:轴载-温湿度耦合下,水泥路表面最大拉应力急剧增长,约为轴载-路面自重下的14倍;随着轴重增加,板顶拉应力由非线性发展转为线性;多轮轴间的应力叠加作用导致水泥路表面最大拉应力不断增大,其中三轴双轮为单轴双轮的1.079倍,不同轮轴作用下的应力增长趋势均符合二段式模型;轴载-温湿耦合作用是水泥路出现面层-底层拉裂破坏的重要因素,超载及多轮轴间的应力叠加效应是板角出现破碎性破坏的主要原因;建立的二段式回归模型能较好地描述不同轴数、轴重下水泥路表面拉应力发展趋势。

二阴区紫叶莴笋新品种引进筛选试验

为提高永登县紫叶莴笋的产量和品质,提升商品价值,增加农民收入,2023年在永登县武胜驿镇旅顺村巍林农业生态科技开发有限公司生产基地开展紫叶莴笋新品种引进筛选试验,对引进的12个紫叶莴笋新品种进行田间观察记载及产量品质分析。结果表明,满地红莴苣一号和吉品红蒄2个莴笋品种在生理性状、产量品质及抗病性等方面优于其他参试品种,适宜在永登县武胜驿镇、民乐乡、坪城乡等高海拔二阴区推广种植。

Quantitative Analysis of the Outdoor Thermal Comfort in the Hot and Humid Summertime of Shenzhen, China

Outdoor thermal comfort has always been a major issue due to its irreplaceable role in maintaining good health and energy use. Thus,quantitative analysis of outdoor thermal comfort and discussions on influential factors seem very necessary to achieve the climate-conscious urban design. Therefore,an outdoor thermal comfort questionnaire survey and the simultaneous field measurement were conducted in six different places during the hot and humid summertime in Shenzhen. The results show that the overall weather conditions during the investigation can be expressed with high temperature and high humidity with strong solar radiation. The micro-meteorological parameters of six test sites vary greatly due to their different regional spatial layouts.Moderate range of air temperature( Ta) is between 28 to 30 ℃ while that of relative humidity( RH) mainly concentrates in 60%-70% with the thermal sensation votes. The main influential factors impacting outdoor thermal comfort are obtained and Tahas the greatest effect. The overall thermal comfortable ranges in Shenzhen are expressed by the range of 28. 14-32. 83 ℃ of PET and 24. 74-30. 45 ℃ of SET*. With the correlation analysis between the characteristic parameters of regional spatial layout and thermal climate and thermal comfort,it reveals that increasing the coverage ratio of water and green space( S) helps lower Taand increase RH. The global solar radiation( G) has a significant negative correlation with the height of buildings( H) and a positive correlation with sky view factor( SVF). Overall,reasonable configuration of the regional spatial layout contributes to providing a thermal comfortable environment.

高寒阴湿区陇薯6号脱毒原种肥密配套模式研究

为探讨高寒阴湿区栽培陇薯6号脱毒原种的最佳氮磷肥用量及密度,为推广和应用该品种提供理论依据。利用二次通用旋转组合试验设计,构建了氮肥(X1)、磷肥(X2)和栽培密度(X3)三因素与陇薯6号脱毒原种产量(Y)之间的回归模型:Y=38.139+2.519X1-3.662X12-1.719X22-1.719X32。对模型解析寻优的结果表明,高寒阴湿区陇薯6号脱毒原种块茎产量大于33 t/hm^(2)的最优栽培方案为:施N 168.22~204.87 kg/hm^(2)、P2O5104.98~165.02kg/hm^(2),密度为47497~57503株/hm^(2)。

严寒地区大学学生宿舍冬季热舒适性探讨

宿舍是大学生的一个重要生活场所,在严寒地区冬季室内热舒适性对学生的学习效率和休息质量有着较大影响。本文对长春市某大学南北向两间宿舍的空气温度、空气湿度、气流速度和黑球温度进行了测量,并计算了房间的PMV值,通过对居住大学生的热舒适评价进行调查,探讨影响严寒地区大学学生宿舍冬季热舒适性的因素及提高严寒地区大学学生宿舍冬季热舒适性的方法。结果表明朝向是影响宿舍热舒适的主要因素,北向宿舍的热舒适度低于南向宿舍的热舒适度,提高服装热阻可以有效提高热舒适度。

考虑湿度气压影响的瓷绝缘子沿面类辉光放电仿真及其紫外光谱特性分析

为研究湿度和气压对瓷绝缘子沿面类辉光放电日盲紫外波段光辐射的影响机制,结合试验和仿真模型,从宏观、微观两个角度分析了湿度和气压对放电点日盲紫外波段光辐射产生过程的影响特性。该文首先搭建了污秽瓷绝缘子放电试验平台,利用光谱仪测量了不同湿度和气压下240~280 nm日盲紫外波段的放电发射光谱。根据发射光谱的特征谱线,确定了放电时产生日盲紫外波段光辐射的激发态N2和NO分子的具体退激跃迁反应。基于试验,利用有限元软件建立了瓷绝缘子沿面类辉光放电的二维仿真模型,主要考虑了25种粒子和37个化学反应,其中包括与产生日盲紫外波段光辐射有关的2种激发态粒子及9个相关化学反应。在模型中分别改变湿度和气压,得出了2种激发态粒子的粒子数密度及生成速率的变化特性,与试验中不同湿度和气压下的日盲紫外波段光辐射强度的变化特性进行对比分析可知,湿度、气压通过影响2种激发态粒子的产生与淬灭过程,改变了光辐射的强度。

湿热地区城市静态水体能量分配特征研究--以广州荔湾湖为例

城市水体作为一种基于自然的解决方案,被视为调节城市气候、改善城市热环境的重要工具。研究水体的能量分配特征是认识和把握水体对城市热环境影响的关键。然而,由于缺乏系统的量化方法和充分的数据支撑,水体的能量分配,即水体与周边环境能量交换的物理过程,尚未完全明晰。基于能量平衡理论,以广州荔湾湖为例,通过冬、夏两季的连续系统观测,得到湿热地区城市湖泊各能量分项的分配特征。结果表明:一、辐射通量在湖泊的能量平衡中具有双重作用,在白天短波辐射是主要能量输入源,在夜间长波辐射冷却是重要的散热形式;二、各能量分项受天气条件的影响不同,晴朗少云的“理想”天中净辐射通量Q*和潜热通量QE显著大于雨天和阴天多云等其他天气条件,而显热通量QH在这三种天气条件下的差异较小;三、季节对湖泊能量分配有显著影响,在高温高湿的夏季,蓄热通量Qs的平均日累计占比最大,即大部分净辐射分配给了蓄热;在凉爽干燥的冬季,QE占比最大,即大部分能量输入转化为了潜热。可为考察城市静态水体能量分配特征提供研究方法参考,并为认识和把握水体的气候调节效应提供湿热地区的数据支撑,进而推进基于蓝色基础设施的气候适应型城市建设。

FAO-PM法估算季节性冰冻地区路基土潜在蒸发蒸腾量

为准确估算东北东部山地润湿冻区(Ⅱ_(1)区)路基土平衡湿度,引入联合国粮农组织Penman-Monteith法(FAO-PM)估算气候因素控制型路基土潜在蒸发蒸腾量,以解决Thornthwaite法在负温时潜在蒸发蒸腾量计算值为0的问题。详细阐述了FAO-PM模型中5个气候因素的具体含义,并给出算例说明计算流程;根据Ⅱ_(1)区内6个气象台站月均气象数据计算得到各地路基土潜在蒸发蒸腾量;分析主要气候因素对路基土潜在蒸发蒸腾量的影响规律与程度。研究表明:Ⅱ_(1)区各地路基土全年潜在蒸发蒸腾总量为71.14~87.37 cm,负温时该值为8.27~12.39 cm,占全年总量的9.8%~15.7%;潜在蒸发蒸腾量与各地平均气温的显著正相关关系可在一定程度上削弱与其他气候因素的负相关关系;负温条件下,路基的潜在蒸发蒸腾量与平均气温、平均风速和平均日照时数呈正比,与平均相对湿度呈反比;FAO-PM法估算的逐月潜在蒸发蒸腾量与气象站实测数据的误差范围为0.47~13.22 cm,负温时误差范围为0.47~4.31 cm。因此,FAO-PM法适用于估算公路自然区划Ⅱ_(1)区路基土潜在蒸发蒸腾量,且具有可接受的估算误差。

湿热地区大学校园室外步行环境微气候评价研究——以华南理工大学为例

以华南理工大学五山校区为例,对湿热地区大学校园步行环境的热环境和风环境进行评价研究,探究周边水体、树木遮阴和建筑遮阴三个主要因素对步行环境微气候的影响,研究不同因素的组合与风环境指标差值以及热环境指标差值的相关性。选取夏季和春季具有代表性的不同因素组合测点的单日测量数据,研究华南理工大学步行环境春夏两季的日间风环境指标和热环境指标变化特征,评价不同因素组合在步行环境设计和优化过程中的作用和区别,以此得出多种步行环境微气候舒适的局部模型,以期为湿热地区大学校园的室外步行环境微气候改善提供参考借鉴。