黄河源区高寒草地-大气间水热交换通量特征          下载免费PDF全文

罗琪  张廷龙  李振朝  李照国 《气象与减灾研究》2022,45(3):207-215

利用黄河源区玛曲观测站2016年涡动相关系统和微气象梯度塔观测资料,分析了高寒草地 大气间水热交换通量的特征。结果表明：夜间地表各通量值很小,净辐射和感热通量为负值,潜热通量的值较小但始终为正。日出后随着太阳辐射和地表加热作用各通量迅速增大,在14时左右达到峰值。暖季（6—8月）夜间感热通量占净辐射的比例(H/Rn)高于感潜通量占净辐射的比例(LE/Rn),日出后LE/Rn开始升高而H/Rn减小,日间LE/Rn大于H/Rn。冷季（12月—次年2月）H/Rn始终大于LE/Rn,感热通量在冷季的能量分配中占据主导地位。暖季LE/Rn、H/Rn均随土壤温度升高而升高。冷季H/Rn与5 cm深度土壤温度表现出了更为明显的二次关系,随着温度升高先降低后升高,当温度小于-7 ℃时H/Rn降低,大于-6 ℃时H/Rn增大。暖季H/Rn随着土壤湿度增大先降低后升高,LE/Rn先升高后降低。在0—1.5 kPa,暖季饱和水汽压差与LE/Rn、H/Rn均呈线性关系,并随着饱和水汽压差增大,LE/Rn增大而H/Rn减小;1.5 kPa之后,LE/Rn、H/Rn变化特征均保持其原有趋势。  相似文献   

金华地区一次强对流天气过程的环境条件与中尺度特征          下载免费PDF全文

龚俊强  叶妍婷  黄嘉仪  汪子琪 《气象与减灾研究》2023,46(4):269-277

利用常规观测资料、ERA5再分析资料、FY-2G卫星TBB数据和双偏振雷达资料等,对2022年6月29日浙江省金华地区一次强对流过程的环境条件与中尺度特征进行了分析。结果表明：1） 充沛的不稳定能量、较低的抬升凝结高度和中等强度的0—3 km垂直风切变为此次强对流过程的发生发展提供了良好环境条件。2） 触发机制主要为边界层辐合线;低层强烈辐合、高层强烈辐散的配置,为对流提供了良好的动力条件;源源不断的水汽供应和水汽辐合,致使暴雨天气的产生和维持。3） 降雹时刻风暴单体雷达回波具有高反射率因子、高垂直累积液态含水量、旁瓣回波、大于55 dBz强回波伸展高度超过-20 ℃层、回波悬垂结构和有界弱回波区等特征;双偏振参量对应较小的差分反射率和较大的差分相移率,湿雹特征明显。  相似文献   

The effects of elevation on thermal bioclimatic conditions in Uludağ (Turkey)     

O. Çalişkan  N. Türkoğlu  A. Matzarakis 《Atmósfera》2013,26(1):45-57

This study compares the thermal bioclimatic conditions recorded at Bursa (100 m) and Uluda? (1878 m) meteorological stations at 7:00, 14:00 and 21:00 LST (local standard time) between 1975 and 2006, by using the physiologically equivalent temperature (PET), which is calculated from meteorological parameters. The effects of elevation-dependent environmental and atmospheric conditions on thermal perception (i.e., PET) values were analyzed and assessed. The analysis showed that the mean annual difference between PET values in Bursa and Uluda? was 12 ºC. The difference was lower in winter (9 ºC PET) and higher in summer (15 ºC PET). The highest difference between PET values occurred in the afternoon (16 ºC PET) and the lowest difference occurred in the morning (8.4 ºC PET). The differences occur as a result of high altitude and higher surface albedo due to snowfall, which leads to lower PET values and thus to less comfortable thermal conditions. The mean PET values of Bursa and Uluda? decrease 0.67 ºC every 100 m.  相似文献   

Characterising the distribution of near-shore submarine groundwater discharge along a coastline using 222Rn and electrical conductivity     

M. A. Short  S. Lamontagne  P. G. Cook  R. Cranswick 《Australian Journal of Earth Sciences》2013,60(2):319-331

The spatial and temporal distribution of near-shore fresh submarine groundwater discharge (SGD) was characterised from the coastal aquifers of the Willunga Basin, South Australia, an extensive aquifer system that supports an important viticultural region. Measurements of electrical conductivity (EC) and ²²²Rn (radon) activity were collected at 19 sites along the coastline during the Southern Hemisphere spring (2011) and summer (2013). At each site, samples were collected from the surf zone as well asporewater from beach sediment in the intertidal zone. Surf-zone radon activity ranged from <5 to 70mBq L^–1, and intertidal porewater radon ranged over two orders of magnitude (220–36 940 mBq L^–1) along the Willunga Basin coastline during both surveys. Overall, surf-zone and porewater EC was lower in the spring 2011 survey than in the summer 2013 survey. Porewater EC was similar to that of coastal water at most sites along the coastline, except at three sites where porewater EC was found to be lower than coastal water during both surveys, and three sites where evaporated seawater was observed in the summer survey. Based on the patterns in radon and EC along the coastline, two sites of localised fresh SGD were identified, in addition to a groundwater spring that is known to discharge to the coast. The results indicate that near-shore fresh SGD occurs as localised seeps rather than diffuse seepage along the entire coastline. The apparent absence of groundwater discharge at most locations is also consistent with current evidence suggesting that extensive groundwater pumping within the basin has resulted in seawater intrusion across much of the coastline. These observations also suggest that previous studies are likely to have over-estimated SGD rates from the Willunga Basin because they assumed that SGD occurred along the entire coastline.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987113000297   总被引：1，自引：0，他引：1  

Haoshu Tang  Yanjing Chen 《地学前缘(英文版)》2013,4(5):583-596

This paper compiles lithostratigraphic and geochronological data obtained for the Palaeoproterozoic glacial diamictite-bearing successions,and thereby provides insights into understanding the geological processes causing the Huronian Glaciation Event.The majority of evidence for appearances of this glaciation event can be related to the Kenorland supercontinent breakup,allied to significant atmospheric change,as well as blooms of biogeochemical oxygenic photosynthesis.In this paper,the Huronian Glaciation Event is constrained to have occurred synchronously during 2.29-2.25 Ga,accompanied by dramatic environmental changes characteristic of the Great Oxidation Event which includes the pre- 2.3 Ga hydrosphere oxidation and the post-2.3 Ga atmosphere oxygenation.  相似文献   

基于层次分析法的矿山岩土工程系统环境质量多目标评价模型     

娄昊  木日根 《世界地质》2013,32(3):606-611

矿山开发给矿区环境带来了负面影响,对矿山环境质量进行评价是实现矿业可持续发展的必要手段。笔者建立了矿山岩土工程环境质量多目标评价指标体系,运用层次分析法确定出各个评价指标的权重; 规定了分级规则,并对各个评价指标进行了分级; 建立了矿山岩土工程体系环境质量多目标综合评价模型,并将该模型应用于矿山实际,得出该矿山环境质量较差,需及时采取措施进行治理。  相似文献   

西藏佩枯错盆地晚更新世以来的孢粉组合特征及其古气候意义     

边彦明  余佳  邵兆刚  韩建恩  贺承广 《地球学报》2013,34(1):87-94

西藏佩枯错盆地晚更新世以来河湖相沉积剖面的孢粉分析显示,该地区在晚更新世早期的127—72kaB.P.时期,气候温和湿润,植被以针阔叶混交林为主;至66—56kaB.P.时期,气候转变为温凉略干,植被转为疏林草原;在56—49kaB.P.时期,气候温凉潮湿,植被又转为针阔叶混交林为主的森林草原;而在49—46kaB.P.时期,气候温和偏干,植被转为疏林草原;在46—31kaB.P.时期,气候寒凉湿润,植被表现为温度进一步下降的疏林草原;在31—15kaB.P.时期,环境向寒冷方向发展,植被转为高寒草原;自11kaB.P.(全新世初期)开始,气候由温暖偏干转变为温凉偏湿,植被由灌丛草原转变为森林灌丛草原。这表明自晚更新世以来,该区气候环境是在逐渐变干的总趋势上,经历了多次明显的冷暖与干湿波动。  相似文献   

长株潭近地表大气尘矿物特征及环境指示意义     

赵晓斌  张广平  吴堑虹 《四川地质学报》2013,(2):189-191

通过X射线粉末衍射(XRD)、扫描电镜/能谱(SEM/EDX)方法对长沙、株洲和湘潭(以下简称长株潭)地区近地表大气尘中矿物成份进行分析研究,结果显示大气尘中含有石英、石膏、方解石、白云石、硫酸镉等23种自然矿物,还含有SiS2、Cadmium Arsenide(Cd3As2)、RhZn、Cr2Nb、NiTi、HfMo2等14种非自然矿物;近地表大气尘矿物形貌特征显示Cd元素主要富集在有矿物颗粒的地方,且呈近浸染状分布,能谱半定量分析,Cd含量可达4%,表明Cd易被吸附在矿物表面。分析长株潭地区大气尘中矿物成份、空间分布特征及其来源,对长株潭城市一体化具有及其重要的环境指导意义。  相似文献   

环境场对东海登陆热带气旋陆地路径的影响   总被引：9，自引：8，他引：9  

钟元  余晖  王东法 《热带气象学报》2006,22(4):313-320

采用合成分析的方法，对比分析了在华东南部沿海登陆，维持较短陆地路径和维持较长陆地路径的两类热带气旋的环境场变化，结果表明：环境场对登陆热带气旋的陆地路径的维持有重要影响。当西北太平洋副热带高压迅速加强西伸；中低层低压环流迅速减弱；中低层环境热力条件差，海洋水汽输送中断；高层水平流场呈纬向型，青藏高原反气旋环流相对较弱而西北太平洋副热带高压反气旋环流强大，中纬带西风急流强大时，环境场的配置使热带气旋周围的高层水平辐散弱并衰减，低层水平辐合弱并衰减，热带气旋的对流被抑制，仅能维持较短路径很快就减弱消亡。反之，当西北太平洋副热带高压减弱东退，西风槽南压；低层低压环流长时间维持；中低层环境热力条件好，海洋水汽输送通畅；高层水平流场呈经向型，青藏高原反气旋环流相对强大而西北太平洋副热带高压反气旋环流减弱东退，中纬带西风急流较弱，低空东南风急流强大时，环境场的配置使热带气旋周围高层水平辐散强并维持，低层水平辐合强并维持，热带气旋的对流通畅，能维持较长生命史和较长的路径。  相似文献   

表生环境下闪锌矿氧化反应模拟实验     

潘自平  叶霖  谯文浪  刘铁庚 《岩石矿物学杂志》2013,32(6):985-994

采用混合流反应器装置,进行了表生环境条件下闪锌矿氧化动力学模拟实验研究,选择Fe³⁺和O₂为氧化剂,实验条件为:温度20～55℃,pH=1.0～7.8、氧化剂Fe³⁺浓度1.0×10^-5～1.0×10^-2 mol/L,氧气流量0.5 L/min。实验结果表明,在Fe³⁺为氧化剂时,闪锌矿氧化速率随着Fe³⁺浓度的增加、温度升高、pH值降低而增加,且氧化过程中Zn和Cd的释放速率大致相同,其反应的活化能分别为Ea(Zn) 41.75 kJ/mol或Ea(Cd) 42.51 kJ/mol,表明闪锌矿氧化速率主要受矿物表面反应控制;而以氧气作为氧化剂时,随着pH值的变化闪锌矿的氧化机理发生变化,在pH值小于5.95范围内,闪锌矿氧化速率随着pH值的增加而降低,进入碱性范围后,随着pH值增加,闪锌矿氧化速率反而增加。对实验数据进行双对数处理并建立了闪锌矿的氧化速率公式。  相似文献