黄海海洋对台风“灿鸿”外围过程响应的观测研究     

冀承振  葛勇  李健  于博  刘清容 《海洋学报》2020,42(1):46-53

2015年9月台风“灿鸿”经过黄海海域的QF111浮标,该浮标观测到黄海海洋的温度和流速响应。受台风影响,黄海海表温度有明显的下降,降温幅度在2~4°C,且在台风路径右侧形成了海表面温度低于20°C的低温斑块。流速的响应主要表现为台风过境期间流速增强,达1.2~1.5 m/s,呈现出全水深强化的特征。风一直对海洋有能量输入,且在台风过境期间风输入海洋的能量最大,旋转功率谱的分析结果表明台风输入海洋的能量向海洋内部传播。黄海海域由台风激发出的近惯性振荡衰减较快,近惯性振荡e折时间尺度约为2 d。  相似文献   

Comparison of two methods for ground level vapour sampling and influence of meteorological parameters on its stable isotopic composition at Roorkee,India          下载免费PDF全文

P. Purushothaman  M. S. Rao  B. Kumar  Y. S. Rawat  G. Krishan  Pooja Devi 《水文研究》2014,28(3):882-894

Ground level vapour (GLV) samples were collected at Roorkee, Uttarakhand, India using two methods: liquid condensation (LC) at 0 °C and cryogenic trap (CT) at ?78 °C for the period 2009–2011. The study reveals that there is a considerable fluctuation in stable isotopic composition of GLV throughout the year. The study area receives complex moisture source during different seasons, which is evident from the moisture flux received during different seasons. The isotopic composition of the GLV in both methods shows depleted nature during rainout process. CT method shows exact isotopic signature of GLV because of maximum trapping of air moisture and its condensation, whereas LC method shows depleted or enriched character because of the prevalence of kinetic and diffusive fractionation. The d value shows that LC method acts as magnifier of the CT method and clearly shows seasonal effect than the clustered CT method. Hence, to decipher the original isotopic signature of GLV, isotopic composition of GLV_LC can be converted to GLV_CT by deriving an empirical relationship with changing season and locations. Meteorological parameters show varied behaviour with GLV_{CT and LC} because of moisture sources in all seasons. The GLV_{CT and LC} method shows significant correlation with meteorological parameters when the region is dominated by single moisture source. The GLV_LC method magnifies the correlation with meteorological parameters when the region is influenced by more than one source. The study shows that the GLV_LC methods can be used in place of GLV_CT when the objective is to understand the influence of different moisture sources on GLV. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

一次引发强降水的东北冷涡的演变机理及能量特征研究     

傅慎明  孙建华  张敬萍  李崴 《气象》2015,41(5):554-565

采用NCEP CFS 0.5°×0.5°的再分析资料,中国气象局常规地面观测资料和FY 2E卫星TBB资料对2013年7月上旬的一次引发强降水过程的东北冷涡典型个例进行了深入分析和诊断,研究表明:（1）本例冷涡的发展期是其降水和对流活动的最活跃时期,其对应的最小TBB在-60℃以下,最强6 h降水可达124 mm,南海、黄海和日本海是冷涡降水的主要水汽源地。（2）本例东北冷涡是一个深厚的斜压涡旋系统,其最强斜压区和动能大值区主要位于涡旋外围;冷涡的冷心结构主要位于对流层中高层和对流层低层。（3）涡度收支表明,与对流活动密切相关的垂直涡度平流是本次冷涡产生的主导因子;涡度垂直输送和辐合作用是冷涡快速发展的主导因子;而辐散作用则最终导致了冷涡的消亡。（4）能量收支表明,旋转风动能制造是冷涡生成过程中动能的主要产生方式,而冷涡发展期,旋转风动能输送是冷涡动能维持的主导因子。  相似文献   

蒸发过程中水体稳定同位素富集与空气湿度的关系   总被引：1，自引：0，他引：1  

马洪云  尹立河  张俊  黄金廷  王晓勇  董佳秋 《地质通报》2015,34(11):2087-2091

通过同位素分馏模型的物理意义分析及实验模拟分析,探讨空气湿度对蒸发过程水体稳定同位素富集过程的影响机理,研究认为:1空气相对湿度决定了扩散系数和自由空气同位素组成对分馏系数的影响比例,空气相对湿度越小,分馏系数受扩散分馏系数影响越大,分馏系数受自由空气水汽同位素组成影响则越小,反之亦然;2空气相对湿度与蒸发残余水体氢氧稳定同位素富集程度具有负相关性,即空气湿度越大越不利于残余水体重同位素富集;3模拟残余水体同位素丰度对空气相对湿度的敏感性呈负指数关系。在无外界气态水介入的蒸发实验中,残余系数为0.194条件下,当相对湿度小于80%时,H、O稳定同位素模拟结果对湿度的敏感性均小于0.0002,即相对湿度变化对模拟残余水体同位素丰度影响很小;当湿度大于80%时,湿度变化对模拟结果的影响呈指数关系急剧增加,湿度大于80%的蒸发实验需要准确观测相对湿度值。  相似文献   

Influence of Mass and Radius of Ice Crystals on Hydrometeors,Internal Energy,and Kinetic Energy:A Numeric Model Study          下载免费PDF全文

RAN Ling-Kun  QI Yan-Bin  LI Na 《大气和海洋科学快报》2014,(1)

Two cloud-scale experiments with two different ice-phase schemes were carried out for a precipitation event that occurred in eastern China in 2005.The results were analyzed to examine the influences of the change of ice-particle mass and radius on hydrometeors,internal energy,and kinetic energy,as well as the primary factors responsible.It was found that the ice content increases notably and the snow content decreases due to the change.This is the consequence of the modulation of cloud microphysical processes.In particular,the Bergeron process and the accretion of snow and cloud ice are markedly influenced.The differences of internal energy and kinetic energy between the two experiments are caused by adjustments to pressure-flux divergence,the coupling of temperature and divergence,and gravitational work,and the reason is that these three factors result in differences of local changes of internal and kinetic energy.  相似文献   

Influence of surface forcing on near-surface and mixing layer turbulence in the tropical Indian Ocean     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

An autonomous upwardly-moving microstructure profiler was used to collect measurements of the rate of dissipation of turbulent kinetic energy (ε) in the tropical Indian Ocean during a single diurnal cycle, from about 50 m depth to the sea surface. This dataset is one of only a few to resolve upper ocean ε over a diurnal cycle from below the active mixing layer up to the air–sea interface. Wind speed was weak with an average value of ~5 m s⁻¹ and the wave field was swell-dominated. Within the wind and wave affected surface layer (WWSL), ε values were on the order of 10⁻⁷–10⁻⁶ W kg⁻¹ at a depth of 0.75 m and when averaged, were almost a factor of two above classical law of the wall theory, possibly indicative of an additional source of energy from the wave field. Below this depth, ε values were closer to wall layer scaling, suggesting that the work of the Reynolds stress on the wind-induced vertical shear was the major source of turbulence within this layer. No evidence of persistent elevated near-surface ε characteristic of wave-breaking conditions was found. Profiles collected during night-time displayed relatively constant ε values at depths between the WWSL and the base of the mixing layer, characteristic of mixing by convective overturning. Within the remnant layer, depth-averaged values of ε started decaying exponentially with an e-folding time of 47 min, about 30 min after the reversal of the total surface net heat flux from oceanic loss to gain.  相似文献   

Calcium and magnesium‐limited dolomite precipitation at Deep Springs Lake,California     

PATRICK MEISTER  CAROLINA REYES  WILL BEAUMONT  MIGUEL RINCON  LISA COLLINS  WILLIAM BERELSON  LOWELL STOTT  FRANK CORSETTI  KENNETH H. NEALSON 《Sedimentology》2011,58(7):1810-1830

Dolomite [Ca,Mg(CO₃)₂] precipitation from supersaturated ionic solutions at Earth surface temperatures is considered kinetically inhibited because of the difficulties experienced in experimentally reproducing such a process. Nevertheless, recent dolomite is observed to form in hypersaline and alkaline environments. Such recent dolomite precipitation is commonly attributed to microbial mediation because dolomite has been demonstrated to form in vitro in microbial cultures. The mechanism of microbially mediated dolomite precipitation is, however, poorly understood and it remains unclear what role microbial mediation plays in natural environments. In the study presented here, simple geochemical methods were used to assess the limitations and controls of dolomite formation in Deep Springs Lake, a highly alkaline playa lake in eastern California showing ongoing dolomite authigenesis. The sediments of Deep Springs Lake consist of unlithified, clay‐fraction dolomite ooze. Based on δ¹⁸O equilibria and textural observations, dolomite precipitates from oxygenated and agitated surface brine. The Na‐SO₄‐dominated brine contains up to 500 mm dissolved inorganic carbon whereas Mg²⁺ and Ca²⁺ concentrations are ca 1 and 0·3 mm , respectively. Precipitation in the subsurface probably is not significant because of the lack of Ca²⁺ (below 0·01 mm ). Under such highly alkaline conditions, the effect of microbial metabolism on supersaturation by pH and alkalinity increase is negligible. A putative microbial effect could, however, support dolomite nucleation or support crystal growth by overcoming a kinetic barrier. An essential limitation on crystal growth rates imposed by the low Ca²⁺ and Mg²⁺ concentrations could favour the thermodynamically more stable carbonate phase (which is dolomite) to precipitate. This mode of unlithified dolomite ooze formation showing δ¹³C values near to equilibrium with atmospheric CO₂ (ca 3‰) contrasts the formation of isotopically light (organically derived), hard‐lithified dolomite layers in the subsurface of some less alkaline environments. Inferred physicochemical controls on dolomite formation under highly alkaline conditions observed in Deep Springs Lake may shed light on conditions that favoured extensive dolomite formation in alkaline Precambrian oceans, as opposed to modern oceans where dolomites only form diagenetically in organic C‐rich sediments.  相似文献   

栉孔扇贝对镉的富集及释放规律的研究   总被引：1，自引：0，他引：1  

吴志宏  孙福新  王颖  刘天红  毛阳  王远红 《中国海洋大学学报(自然科学版)》2011,41(10):93-97

通过暴露染毒方法研究了栉孔扇贝对镉离子(Cd2+)的35d富集与30d释放规律。结果表明:栉孔扇贝对镉有很强的富集性,体内的镉含量与暴露溶液里的Cd2+浓度呈正相关;栉孔扇贝对镉的释放速率随着暴露水体中镉浓度的增加而减慢。应用双箱动力学模型,通过非线性拟合得到了栉孔扇贝对Cd2+的吸收速率常数k1随着外部水体中镉浓度的增大而减小,生物富集系数BCF则随着外部水体中镉浓度的增大而减少。当镉浓度为0.05mg/L时BCF仅为3 730,而当镉浓度为0.000 5mg/L时BCF达到1.79×1011。平衡状态下栉孔扇贝体内镉含量(CAmax)随着水体中镉浓度增加急剧下降,与水体中镉浓度呈负相关;排出速率常数k2、生物学半衰期B1/2与低浓度镉无明显相关性,随着镉浓度的增大k2显著降低而B1/2显著增大。验证了双箱动力学模型适用于栉孔扇贝对Cd2+的生物富集与释放规律研究。  相似文献   

Characteristics of turbulence over the semi-fixed desert area north of Xinjiang,China     

Ali Mamtimin  Yu Wang  Hajigul Sayit  Xing Hua Yang  Fan Yang  Wen Huo  Chenglong Zhou  Lili Jin 《地球表面变化过程与地形》2021,46(12):2365-2378

As the largest fixed and semi-fixed desert in China, the Gurbantünggüt Desert undergoes a long period of snow cover in the winter and the rapid growth of ephemeral plants in the spring, presenting obvious seasonal changes in the underlying desert surface type, which can lead to variation in the turbulence of the near-surface boundary layer turbulence over the desert. In this study, gradient tower data and eddy covariance data from 2017 were analysed to investigate the turbulence characteristics of the different surface boundary layers in the hinterland of the Gurbantünggüt Desert. The results indicate that stable atmospheric conditions in the desert occur exclusively during the early morning and at night in the desert, and the onset and duration of this stable state varies seasonally. Two regimes of intermittent turbulence occur during the night, a weak turbulent regime that occurs when the wind speed is less than the threshold and a strong turbulent regime when the wind speed exceeds the threshold, and different wind speed thresholds were observed at each level. These parameters follow a seasonal pattern of summer (July) > spring (April) > autumn (October) > winter (January) in terms of magnitude. The mean turbulence intensities of the along-wind, cross-wind and vertical wind are 0.5, 0.47 and 0.14, respectively, with I_u > I_v > I_w. The normalized standard deviation of the wind velocity components (σ_u, σ_v and σ_w) generally satisfies a 1/3 power-law relation. Our results show that the night-time turbulence regime classification for the Gurbantünggüt Desert strongly depends on meteorological and orographic features, and the intermittent turbulent events have the non-stationarity of the flow in common. The results can contribute to the study of land surface processes, climate change and desertification in inland arid desert areas.  相似文献   

天然黄铁矿对阳离子有机染料RhB吸附特性研究   总被引：1，自引：0，他引：1  

蔡宽  熊世威  张欣欣  李瑞萍  黄应平 《岩石矿物学杂志》2014,33(2):370-376

以黄铁矿作为吸附剂研究罗丹明B(Rhodamine B,RhB)的吸附特性,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对黄铁矿进行了表征。考察了接触时间、溶液pH值、离子强度、温度等对黄铁矿吸附RhB的影响。结果表明,在吸附平衡时间120 min、pH值4.0时,吸附量达到最大值21.3 mg/g。升高温度,黄铁矿对RhB的吸附量逐渐增大。而离子强度对吸附几乎没有影响。实验数据与Langmuir吸附模型拟合良好,整个吸附动力学模型符合准二级吸附动力学模型。热力学研究证实了该吸附过程是自发进行的。通过对吸附反应结束后的黄铁矿进行煅烧处理,去除表面吸附的RhB,结果表明煅烧一次的黄铁矿仍然可以吸附废水中约50%的RhB,具有重复利用的价值。  相似文献