试谈地下水蒸发入渗规律

浅层地下水的蒸发、入渗,通常为大气降水在不同岩石内部的垂向运移。饱气带中的水分向上运移,潜水处于蒸发。水分向下运移,潜水接受补给便处于入渗。浅层地下水的入渗受地下水位埋深、岩性、降雨量、降雨时间等因素控制。降雨入渗补给的滞后时间长短与一次降水强度大小、水位埋藏深、浅有关。深部岩层长期有入渗量补给,主要是降雨的迟后作用及空气中水分在温差变化条件下的再分配。浅层地下水的蒸发不但与气象因素有关,而且与岩性、水位埋深、降雨强度等因素有关。在浅部,潜水的蒸发主要受气象因素制约。深部则受岩性、水位埋深影响。水位每浅5厘米,蒸发量便增加1.O毫米。埋深越浅,年蒸发量越大。水位埋深小于1.2米时,潜水蒸发折算系数与水位埋深和水面蒸发度均呈直线反比关系;水位埋深大于1.2米时,潜水蒸发折算系数与水位埋深呈指数曲线关系。在地下水资源评价中,对蒸发天数计算,不应都按365天算,应按实际而定。     

融合土地覆盖和土壤水分产品的近地表空气温度空间化方法

空气温度是评价人居环境的重要指标,与人类的生产生活息息相关;其观测对于水文、环境、生态和气候变化等方面的研究具有重要意义。传统的大范围空气温度观测数据一般通过气象站点获取,但由于气象观测站点空间分布离散稀疏的特点,所获取的数据不能精确描述空间连续的空气温度变化情况。因此,实现基于遥感数据的近地表空气温度精准估算具有重要的现实意义。本研究基于精细的地表覆盖类型、空间连续的土壤水分、地表温度（LST）数据,并结合其他辅助数据,构建了近地表空气温度空间化模型,并对近地表空气温度影响因子进行评估,发现地表覆盖类型对近地表空气温度的影响最大,土壤水分为最活跃的影响因素,经验证,模型精度较高,R²接近0.85,RMSE为0.5℃。本研究获取的精确空间连续的近地表空气温度信息,能够充分表达其空间异质性,为农业气象灾害灾变过程监测、农作物生长过程模拟、区域气候变化分析等研究提供良好的近地表空气温度数据支撑。     

基于蒸发法和联合测定仪测定土壤水分特征曲线和非饱和渗透系数的试验研究

为确定以蒸发法为基础设计的土壤水分特征曲线和非饱和渗透系数联合测定仪的可靠性和适用范围,选取粉黏壤土、壤土和壤砂土3种土样进行试验研究。在自然蒸发作用下,利用联合测定仪获得蒸发通量、含水量和土柱表面下方5,10 cm处的基质吸力,以线性假设理论为基础处理实测数据,利用HYDRUS-1D软件进行模拟和反演,输入实测基质吸力和通量数据确定土壤水力参数,利用RETC软件对已处理数据进行VG-Mualem模型拟合。结果表明,含水率符合线性假设理论,基质吸力线性变化不是很理想,但除砂土之外的土样可以通过降低蒸发速率和缩短2次测量时间间隔来解决这个问题;试验数据的拟合效果好,与模拟结果的误差较小,试验前期所测非饱和渗透系数与模拟值误差较大,主要跟含水率接近饱和时水力梯度的精度不能得到保证有关,可以忽略这些数据来改进。使用蒸发法和联合测定仪测定土壤水分特征曲线和非饱和渗透系数具有比较好的可靠性。     

岩质边坡非饱和带水汽运移机制及其生态学意义

岩质边坡非饱和带水分对于边坡植物生长具有重要的生态学意义.目前对岩质边坡非饱和带水汽运移的系统性研究还很少,现有研究大部分集中在大气与岩体的接触面和凝结水能否生成的定性层面,而未将边坡非饱和带作为一个系统整体来研究.为了阐明岩质边坡非饱和带的水汽运移机制及其与边坡植物生长之间的关系,运用热力学和系统科学的理论,开展边坡温湿度监测试验,进行了详细的水汽运移机制的研究.研究发现,岩质边坡非饱和带内的水汽运移驱动力为水汽分压梯度,水汽从水汽分压大的位置向水汽分压小的位置运移.冬季时,水汽从边坡深部向浅部运移,夏季时,水汽从大气向边坡深部运移.岩质边坡非饱和带内存在水汽饱和带,夏季范围较大,冬季范围收缩.同时,通过对岩质边坡复绿植物的成活率进行监测分析,论述了岩质边坡非饱和带内的水汽内循环机制及其生态学意义.本文对于研究岩体非饱和带水文学、探索植物水分来源、指导岩质边坡复绿乃至干旱半干旱带的生态修复都有极为重要的理论和现实意义.     

基于多源数据的农业干旱监测模型构建

在全球气候变暖的大背景下,干旱事件发生越来越频繁,严重危害我国的粮食生产安全。构建准确的干旱监测模型不仅能够及时地反映出干旱事件的发生,同时可以为地方政府制定减灾保产措施提供科学支撑和保障。传统的气象干旱监测方法因为缺乏对植被本身需水状态和土壤供水信息的考虑旱情判定结果往往比实际情况偏重,而遥感监测指标大多只考虑了植被或土壤等单方面因素具有局限性,目前已有的综合干旱监测模型大多以气象指标为因变量,一方面需要数据资料较多参数复杂,另一方面模型准确度依赖于气象指标对当地农业干旱的响应能力,而同一气象指标在不同区域适应性存在差异,因此同样存在局限性。本文以河南省的冬小麦为研究对象,利用2001-2011年的EOS-MODIS数据产品以及气象站点监测数据,计算了标准化降水蒸散指数SPEI、植被状态指数VCI、温度状态指数TCI、温度植被状态指数TVDI,同时结合河南省农业气象灾害旬报对冬小麦受灾的记录,构建了基于决策树的定性农业干旱监测模型。测试集结果表明,模型综合了大气异常信息、植被状态信息以及土壤水分信息,优于单个指标的监测结果。另外,基于此模型监测了河南省2009年4-5月的干旱事件,结果与实情相符,能够较好地反映农业旱情的发生和空间演变情况。     

微波与光学遥感协同反演旱区地表土壤水分研究

土壤水分是水文循环中的关键因素,尤其对旱区的生态环境具有十分重要的意义。微波遥感是反演土壤水分的有效手段,而植被是影响土壤水分反演精度的重要因素。因此,对土壤水分的反演需要考虑植被的影响。本文以内蒙古乌审旗为研究区,利用Radarsat-2雷达数据与TM光学数据,对旱区稀疏植被覆盖地表土壤水分反演进行研究。利用TM数据,分别选取NDVI和NDWI指数对植被含水量进行反演,通过水云模型消除植被层对土壤后向散射系数的影响;在此基础上,根据研究区地表植被特性,提出一种基于AIEM 模型的反演土壤水分的改进算法,反演了不同粗糙度参数、不同极化（VV极化和HH极化）条件下的研究区土壤水分。反演结果与野外实测数据的对比结果表明,本文提出的基于地表植被特性的土壤水分改进算法,具有更好的适应性;土壤水分反演模式\begin{array}{c}M{v}_{\mathit{\sigma vv}\left(1\right)}^{\mathit{lh}}\end{array}（VV极化方式下采用NDVI去除植被影响的反演模式）更适合于旱区考虑稀疏植被覆盖影响的地表土壤水分的反演。     

神农架大九湖PAHs多介质归趋模拟

选择美国环境保护署EPA优控污染物NaP（萘）、Phe（菲）、Fla（荧蒽）、BaA（苯并蒽）、Chr（屈）、Pyr（芘）和BaP（苯并芘）7种多环芳烃（polycyclic aromatic hydrocarbons,简称PAHs）作为研究对象,采用Level Ⅲ逸度模型对神农架大九湖地区PAHs多介质归趋进行了模拟,并利用神龙架大九湖大气、土壤、水体和沉积物中PAHs的实际监测数据对模型进行了验证;同时,将气候因素（温度、降水）对环境介质中PAHs转化的影响整合进模型中,探讨了气候变化对PAHs归趋的影响。结果表明:模型计算值与研究区PAHs监测值吻合良好,说明模型参数的选取合理可靠;不同PAHs的相间迁移通量具有一定差异,2环和3环PAHs则以沉积物向水体、水体向大气迁移为主,表现出由沉积物向水体和大气释放的特点,而4环和5环PAHs以大气向土壤和水体向沉积物迁移为主,体现出由大气向土壤和沉积物沉降的特点;温度与水-气、土-气和水-沉积物界面交换净通量存在明显的正相关关系,降水量与水-气、土-气界面交换净通量呈负相关关系,但与水-沉积物界面交换净通量呈正相关关系。本研究结果表明应重视因气候变化而引起的土壤、水体、沉积物的内源释放所造成的二次污染。      

四川盆地区表层土壤湿度时空变化特征分析

分析常年土壤干湿状况及其影响因子,是监测评价四川盆地区土壤水分变化的基础,有利于农业干旱防灾减灾.利用四川盆地区农业气象站近17年0～20cm的逐句土壤湿度观测资料,运用旋转正交函数分解(REOF)、相关分析、趋势倾向率分析等方法,对四川盆地区表层土壤相对湿度的时空变化特征进行分析,并分区域选取代表站建立表层土壤湿度与气温、降水量、日照时数的多元回归方程.结果表明,盆地表层土壤相对湿度空间分布大致是从南到北逐渐减小;年际变化呈现弱的上升趋势;常年季节变化呈双峰型特点,秋季高,春季低,夏季波动明显,初夏高盛夏低;表层土壤干湿状况总体呈现出冬春季相对偏干、夏秋季相对偏湿的季节变化.盆地表层土壤湿度变化与气温、日照显著负相关,与降水显著正相关性,气温、日照、降水因子分别对盆地东北部、中南部、西北部表层土壤湿度变化影响大.     

四川盆地区表层土壤湿度时空变化特征分析

分析常年土壤干湿状况及其影响因子,是监测评价四川盆地区土壤水分变化的基础,有利于农业干旱防灾减灾.利用四川盆地区农业气象站近17年0～20cm的逐旬土壤湿度观测资料,运用旋转正交函数分解(RE-OF)、相关分析、趋势倾向率分析等方法,对四川盆地区表层土壤相对湿度的时空变化特征进行分析,并分区域选取代表站建立表层土壤湿度与气温、降水量、日照时数的多元回归方程.结果表明,盆地表层土壤相对湿度空间分布大致是从南到北逐渐减小;年际变化呈现弱的上升趋势;常年季节变化呈双峰型特点,秋季高,春季低,夏季波动明显,初夏高盛夏低;表层土壤干湿状况总体呈现出冬春季相对偏干、夏秋季相对偏湿的季节变化.盆地表层土壤湿度变化与气温、日照显著负相关,与降水显著正相关性,气温、日照、降水因子分别对盆地东北部、中南部、西北部表层土壤湿度变化影响大.     

郑州市饮用天然矿泉水成因探讨

郑州市已开发的饮用天然矿泉水属锶硅酸水。本文根据矿泉水形成水文地质条件,水文地球化学环境,探讨了锶及偏硅酸的成因。认为:锶的形成主要是方解石、文石和硬石膏含锶矿物经溶滤作用,锶离子伴随钙离子进入水溶液,钙离子与岩(土)吸附的钠离子发生交替吸附,水溶液蒸发浓缩、锶相对聚集而形成;而偏硅酸主要是含CO_2水溶液使长石风化、水解SiO_2溶解度随温度升高增大而形成。指出沉积岩区的锶硅酸水与碳酸盐岩和长石砂岩有关,提出对郑州矿泉水资源要合理开发利用,避免因过量开采或成井止水不佳引起“矿水”淡化。     

RADIATION BALANCE AND MICROCLIMATIC FEATURES OF MARSH IN THE SANJIANG PLAIN

Radiation balance, soil temperature and the temperature and humidity of air were measured in marshes and reclaimed farmlands of the Sanjing Plain. Soil-heat flux was calculated with two different methods. Through the analysis of a lot of data, the daily variations and the law of vertical distribution of microclimate factors on marsh surface was obtained. It is found that after marshes are reclaimed, radiation balance increases, both soil temperature at different depths and air temperature of various height near ground layer rise, and air humidity decreases obviously. Therefore, one should take the establishment of artificial ecosystem of growing paddy and reed and breeding fish as the main development direction of marshes, at the same time, protect some marshes in order to prevent the environment from getting dry, and maintain regional ecological balance.     

Winter climate change and sea ice-atmosphere interaction at high northern latitudes in ERA40 dataset

1 IntroductionGreen house gases, such as CO2,CH4, N2O and so on are released to the atmosphereconstantly by human activities. These gases insert positive radiative forcing to the climate.Meanwhile, aerosol, which are also released by human activities, ins…     

上海夏季雾霾的影响因素研究

由于对流层中气象因素变化剧烈且蕴含大量的水蒸气和颗粒物,雾霾的发生也极易改变卫星信号的传播路径,从而导致对流层延迟发生变化,因此重点研究气象因素与雾霾之间的相关性问题。通过上海市2016年62 d(DOY 153～214)的大气中污染物含量资料与天顶对流层延迟比较分析发现,大气中每种污染物含量基本呈现相似的走势,天顶对流层延迟随PM2.5含量增加而增大,且在日值数据的比较中发现,上海夏季的PM2.5含量与气压、气温和相对湿度成正相关关系,与风速、降水量呈负相关关系。     

Transpiration rates of Carex Meyeriana in relation to micrometerological factors in a mountain valley wetland

In order to reveal transpiration rates of wetland plants and its relationships to micro- meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry （July） and wet （September） of 2003, respectively. Results showed that the tendency of ＂decreasing after increasing＂ was obvious in wet season. However, a relatively stable trend was observed for the transpiration in dry season.. Generally, the photon flux density of Carex meyeriana was higher in wet season than that in dry season. However, the variabilities of leaf temperature, air temperature and relative humidity were similar in both seasons. Higher transpiration rates of Carex meyeriana leaves were observed in July （varied from 40 to 150 mol.m^-2.s^-1） compared to those （varied from 7 to 14 mol.m^-2.s^-1） in September. Transpiration rates were significantly correlated with air temperature （P〈0.01）, leaf temperature （P〈0.01）, and wind speed （P〈0.05）, but correlationship between relative humidity and photo flux density was not significant （P〈0.05）.     

Elevated Ducts and Low Clouds over the Central Western Pacific Ocean in Winter Based on GPS Soundings and Satellite Observation

Both low clouds and elevated ducts are common phenomena in the oceanic atmosphere. Low clouds affect elevated ducts by changing the structure of atmospheric temperature and humidity. However, due to the limitation of met-ocean measurements, research on them is still scattered. This paper presents the distribution of elevated ducts and clouds over the central Western Pacific Ocean(WPO) based on Global Position System(GPS) sounding data and Himawari-8 satellite products from November 2015 to January 2016. Results show that the frequency of elevated ducts detected by ship-based GPS soundings was as high as 77% over the central WPO. The height and frequency of elevated ducts are closely related to the low clouds. If there are no clouds, the occurrence probability and mean base height of the elevated ducts are 14% and 730 m, respectively. By comparison, the occurrence probability and mean base height increase up to 24% and 1471 m, respectively, in the presence of cumulus(Cu) clouds, and 22% and 1511 m, respectively, in the presence of stratocumulus(Sc) clouds. Elevated ducts occur near the cloud top. The analysis of geopotential height and wind fields from the European Centre for Medium-Range Weather Forecasts(ECMWF) reanalysis dataset(ERA-interim) shows that the study area is covered by a strong and stable subtropical high, and slowly sinking dry air masses inside the subtropical high are above the moist boundary-layer air mass. The appearance and evolution of low clouds will adjust the temperature and humidity structure of the lower troposphere. If there are no clouds, the marine boundary layer(MBL) is the classic mixed boundary layer. Humidity gradient and subsidence inversion are formed atop the mixed layer. When low clouds are present, long wave radiation and entrainment atop clouds form a strong temperature inversion and humidity gradient, which strengthen elevated ducts. However, when Sc clouds are decoupled, a weaker temperature inversion and humidity gradient may occur between the surface mixed layer and subcloud layer, leading to a weak elevated duct atop the mixed layer.     

植被变化引起我国气候变化的数值模拟

使用区域气候模式RegCM3,进行植被变化对中国区域气候影响的数值模拟试验。模拟结果表明：植被退化使气候变得更加恶劣,退化区降水减少,大气变得干燥,气温升高;而植被增加使得降水增加,大气湿度增大,气温降低。地表植被的变化可通过地气问相互作用激发出大气偏差风环流,从而影响大范围气候,乃至全球气候。     

植被变化引起我国气候变化的数值模拟

使用区域气候模式RegCM3,进行植被变化对中国区域气候影响的数值模拟试验。模拟结果表明：植被退化使气候变得更加恶劣,退化区降水减少,大气变得干燥,气温升高;而植被增加使得降水增加,大气湿度增大,气温降低。地表植被的变化可通过地气问相互作用激发出大气偏差风环流,从而影响大范围气候,乃至全球气候。     

1011号台风“凡亚比”粤西暴雨二次加强过程的分析

为了能够深入了解1011号台风"凡亚比"粤西暴雨过程发生发展机制,采用天气学诊断方法、Ncep1°×1°再分析资料和观测降水资料对凡亚比登陆后在广东西部地区造成的两次暴雨过程进行了研究。通过初步诊断分析得到以下结论:粤西暴雨二次增强的主要原因是强冷空气侵入和水汽输送增加,二次增强过程偏南风主导的水汽条件造成了暴雨增强。假相当位温的垂直剖面显示暴雨主要发生在等值线密集陡峭的区域,等值线的斜率增加对暴雨二次增强有指示作用。湿位涡在暴雨区为上正下负的垂直分布形式,对流层上层高值位涡向下传递,高层干冷空气与低层暖湿气流交汇促使降水增加。     

Transpiration Rates of Carex Meyeriana in Relation to Micrometerological Factors in a Mountain Valley Wetland

In order to reveal transpiration rates of wetland plants and its relationships to micro-meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry (July) and wet (September) of 2003, respectively. Results showed that the tendency of "decreasing after increasing" was obvious in wet season. However, a relati...     

Future variation in mountainous discharge in arid northwestern China: A basin case study

To better understand the variation in mountainous discharge(MD) in the future, a basin case study was conducted in the upstream Taolai River Basin(UTRB) in arid northwestern China. The Blaney-Criddle(B-C) equation, Budyko framework, and water balance method were coupled for MD calculations. The outputs of 10 global climate models(GCMs) are synthesized to confirm the future changes in air temperature and precipitation under 3 selected Representative Concentration Pathway(RCP) scenarios. The climate elasticity(CE) method was used to determine the variation in MD, and the influence of climate factors on that was quantitatively analyzed. The results reveal that the coupling framework of the three methods is suitable for MD determination in the UTRB. The weight-based synthesis of the 10 GCM outputs shows overall increases in temperature(T) and precipitation(P) under the 3 scenarios during most of the time until 2099. The above climate change leads to an increase in MD. According to CE analysis, the positive effectiveness of precipitation is greater than the negative effectiveness of temperature on MD variation, and the increase in precipitation would induce more MD in the UTRB. Uncertainty analysis reveals that GCM outputs dominate in predicting precipitation, while the RCP scenarios influence temperature more. Overall, under the background of climate change, the risk of extreme floods during wet years might increase, and a water deficit will still occur during normal and dry years. The study provides a case example for better understanding MD responses to climate change in the upper reaches of inland river basins. Findings are helpful for reasonable water resource development and utilization in the middle and lower reaches of these basins in the future. As in the Taolai River Basin, considering the future water demand across the whole basin, the development of watersaving technologies and reasonable industrial structures is crucial for a sustainable future.