The Observation of Ice-Nucleating Particles Active at Temperatures above–15°C and Its Implication on Ice Formation in Clouds     

Kai Bi  Xincheng Ma  Yunbo Chen  Shizuo Fu  Huiwen Xue 《Acta Meteorologica Sinica》2018,32(5):734-743

A series of measurements of ice-nucleating particles (INPs) were performed at two sites in Beijing. At the Beijing Meteorological Service (BMS) site, which was an urban site, no INPs were found to be active above–15°C. However, at the Yanjiaping (YJP) site, which was a rural site, the concentration of INPs active at temperatures above–15°C was found to be as high as 1.73 g^–1. Two parameterizations were constructed by respectively fitting the data obtained at BMS site and YJP site. The two parameterizations, as well as another parameterization from the literature, were implemented into a parcel model to investigate the effect of INPs active above–15°C on phase partitioning in mixed-phase clouds. At a vertical velocity of 0.01 m s^–1, which is typical for stratiform clouds associated with frontal systems, the INPs active above–15°C nucleate ice crystals at low levels. The growth of these ice crystals remarkably reduces both the maximum liquid water mixing ratio and the altitude where the maximum liquid water mixing ratio is reached. When the vertical velocity of the parcel is increased to 0.1 m s^–1 or an even higher value, the evolution of liquid water mixing ratio is not controlled by the INPs active above–15°C but those active below–15°C.  相似文献   

Understanding the dynamical mechanism of year-to-year incremental prediction by nonlinear time series prediction theory          下载免费PDF全文

Bi Shu-Ting  Wang Peng-Fei  Pan Xin-Nong  Li Chao-Fan 《大气和海洋科学快报》2018,(1)

基于年际增量预测(YIP)方法的数学原理,推导得出新的非线性时间序列预测(NP)方法,并从理论上证明了两种预测方法在一定条件下的等效性。以长江中下游地区的夏季降水为例,新的NP方法在使用年际增量作为强迫项时,可以取得与YIP相当的预测效果。而且,通过调整重构维数等参数,能够将预测模型重构于高于一维的相空间中,进而可获得更好的预测效果。研究发现YIP方法除了有物理基础外,还有隐含的动力基础,新NP模型有助于提高短期气候预测的水平。  相似文献   

Arctic multiyear sea ice variability observed from satellites: a review     

Bi  Haibo  Liang  Yu  Wang  Yunhe  Liang  Xi  Zhang  Zehua  Du  Tingqin  Yu  Qinglong  Huang  Jue  Kong  Mei  Huang  Haijun 《中国海洋湖沼学报》2020,38(4):962-984

In comparison with seasonal sea ice(first-year ice,FY ice),multiyear(MY) sea ice is thicker and has more opportunity to survive through the summer melting seasons.Therefore,the variability of wintertime MY ice plays a vital role in modulating the variations in the Arctic sea ice minimum extent during the following summer.As a response,the ice-ocean-atmosphere interactions may be significantly affected by the variations in the MY ice cover.Satellite observations are characterized by their capability to capture the spatiotemporal changes of Arctic sea ice.During the recent decades,many active and passive sensors onboard a variety of satellites(QuikSCAT,ASCAT,SSMIS,ICESat,CryoSat-2,etc.) have been used to monitor the dramatic loss of Arctic MY ice.The main objective of this study is to outline the advances and remaining challenges in monitoring the MY ice changes through the utilization of multiple satellite observations.We summarize the primary satellite data sources that are used to identify MY ice.The methodology to classify MY ice and derive MY ice concentration is reviewed.The interannual variability and trends in the MY ice time series in terms of coverage,thickness,volume,and age composition are evaluated.The potential causes associated with the observed Arctic MY ice loss are outlined,which are primarily related to the export and melting mechanisms.In addition,the causes to the MY ice depletion from the perspective of the oceanic water inflow from Pacific and Atlantic Oceans and the water vapor intrusion,as well as the roles of synoptic weather,are analyzed.The remaining challenges and possible upcoming research subjects in detecting the rapidly changing Arctic MY ice using the combined application of multisource remote sensing techniques are discussed.Moreover,some suggestions for the future application of satellite observations on the investigations of MY ice cover changes are proposed.  相似文献   

Grain-Size Distribution of Surface Sediments in the Bohai Sea and the Northern Yellow Sea: Sediment Supply and Hydrodynamics     

Ping Yuan  Houjie Wang  Xiao Wu  Naishuang Bi 《中国海洋大学学报(英文版)》2020,19(3):589-600

The grain-size distribution of surface sediments in the Bohai Sea (BS) and the northern Yellow Sea (NYS), and its relationship with sediment supply and hyd  相似文献   

Characteristics of rare-earth elements （REE）, strontium and neodymium isotopes in hydrothermal fluorites from the Bailashui tin deposit in the Furong ore field,southern Hunan Province,China   总被引：3，自引：0，他引：3  

YUAN Shunda  ;PENG Jiantang  ;HU Ruizhong  ;BI Xianwu  ;QI Liang  ;LI Zhaoli  ;LI Xiaomin  ;SHUANG Yan 《中国地球化学学报》2008,27(4):342-350

In this paper the authors present the REE concentrations and Sr and Nd isotopic compositions of fluorites from the Bailashui tin deposit of the Furong ore field, southern Hunan Province. The results showed that the total amount of REE in fluorites is usually low, ranging from 0.705 to 8.785 μg/g with the chondrite-normalized REE distribution patterns similar to those of the Qitianling granites in the study area, characterized by LREE-enrichment patterns with pronounced negative Eu anomalies. The fluorites vary in Sr isotopic composition within the range of 0.7083-0.7091, the values are lower than those of the granites and higher than those of the host carbonate rocks in this area. The εNd（t） values of fluorites vary between -9.4 and ＋10.3, revealing that both the crust- and mantle-source materials were involved in the ore-forming hydrothermal fluids. Combined with previous studies on this ore deposit, the Bailashui tin deposit is temporally and spatially closely related with granitic magmatism in this area. The hydrothermal fluorites are the product of fluid/rock interactions between granitic magmatic hydrothermal fluid and marine carbonate rocks. The REE and F in the ore-forming fluid were derived from the granites, whereas Sr in the ore-forming fluid came mainly from the granitic magmatic hydrothermal fluid and marine carbonate rocks, although variations in Sr isotopic composition cannot be explained by a simple mixture of these two end-members. Evidence demonstrated that the ore-forming fluids are of crustal-mantle mixing origin, but that the fluids were probably incompletely homogenized and this may be caused by inhomogeneous mixing of the fluids of different sources.  相似文献   

江西武山铜矿区花岗闪长斑岩的地球化学和Sr-Nd-Hf同位素组成及成因探讨   总被引：48，自引：29，他引：19  

蒋少涌  李亮  朱碧  丁昕  姜耀辉  顾连兴  倪培 《岩石学报》2008,24(8)

武山铜矿床是位于长江中下游地区九瑞矿集区中的一个大型铜矿床.本文对该矿床中与成矿关系密切的花岗闪长斑岩进行了详细的矿物化学、主量元素、微量元素、Sr-Nd-Hf同位素研究.结果表明,岩体中黑云母富镁,为金云母,其Fe3 /Fe2 组成表明岩浆氧逸度很高;角闪石具有Mg/(Mg Fe)高而Si低的特征,为阳起石和镁质角闪石,角闪石压力计计算表明岩体具有超浅成侵位特征.花岗闪长斑岩具有埃达克岩地球化学特征.岩石具有相对较高的SiO2(64.9%～68.62%,平均66.52%)和Al2O3(14.0%～15.3%,平均14.8%)含量,同时岩石的Mg#很高(0.53～0.71),并具有相对较高的相容元素含量;岩石富集轻稀土((La/Yb)N=27.8～64.5),Eu负异常不明显,岩石同时富集大离子亲石元素,亏损高场强元素,具有较高的Sr/Y比值(35.0～68.2).岩石的初始87Sr/86Sr比值为0.7067～0.7075,εNd(t)值为-4.08～-4.44,锆石的εHf(t)值为-2.1～-7.0.详尽的元素和同位素地球化学特征表明武山花岗闪长斑岩是强烈壳幔相互作用的产物,很有可能是由拆沉的加厚下地壳发生部分熔融,并在其上升过程中与地幔橄榄石发生相互作用而形成的.  相似文献   

Spatial patterns and drivers of fire occurrence in a Mediterranean environment: a case study of southern Croatia     

Katarina Pavlek  Filip Bišćević  Petra Furčić  Ana Grđan  Vesna Gugić  Nino Malešić 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2017,117(1):22-35

Wildfires are an important factor of landscape dynamics in fire-prone environments of the world. In the Mediterranean, one of the most fire-susceptible environments globally, between 45,000 and 50,000 wildfires are recorded every year, causing disturbances in forest and grassland ecosystems. As a Mediterranean country, Croatia faces these problems, averaging over 1000 registered wildfires annually, with the coastal areas dominated by forest fires and continental Croatia by fires on agricultural lands. This research combines various landscape and socio-economic factors in the analysis of fire occurrence in Croatia’s southernmost region of Dalmatia. Around 275 of the largest fires (encompassing 98% of the total burnt area) registered in 2013 were investigated using OLS, and different spatial indices were employed to analyse regional variability in fire distribution. The results revealed that areas more prone to fires are the northern inland areas of Dalmatia and its entire coastal zone. Altitude and vegetation type demonstrated a correlation with fire occurrence, but an increase in population in the study area was also correlated with wildfire occurrence. Regarding vegetation, the grasslands and Mediterranean shrubland (maquis) were found to be the most fire-prone vegetation types in the study region, the distribution of which can be linked to different socio-economic and demographic processes occurring in the Eastern Adriatic.  相似文献   

郑洛地区史前聚落遗址人居环境宜居度指数模糊综合评价   总被引：6，自引：4，他引：2  

毕硕本  凌德泉  计晗  沈香  王军 《地理科学》2017,37(6):904-911

以地貌、土壤、坡向、坡度、高程5个指标构建郑洛地区史前聚落遗址人居环境指数模糊综合评价体系,使用基于地理探测器的因子探测法确定各单因素权重,根据环境驱动因子分级标准及等级值,采用梯形和三角形隶属函数计算单因素评价值,再使用加权平均的综合评价类型和等距法,得到了郑洛地区史前聚落遗址人居环境指数综合等级,运用SPSS数据探索功能,分析宜居度最高地区的具体环境特征,并分别以仰韶后期和龙山时期的实际遗址分布数据对该等级评价系统的准确性进行验证。研究结果表明,该模型评价结果较为准确可靠。  相似文献   

Using lithium isotopes to quantitatively decode continental weathering signal: A case study in the Changjiang (Yangtze River) Estuary     

Cao  Fang  Yang  Shouye  Yang  Chengfan  Guo  Yulong  Bi  Lei  Li  Yuze 《中国科学:地球科学(英文版)》2021,64(10):1698-1708

As the key link connecting the earth's spheres, continental weathering plays an important role in regulating the global biogeochemical cycle and long-term climate change. Siliciclastic sediments derived from large river basins can record continental weathering and erosion signals, and are thus widely used to investigate weathering processes. However, sediment grain size, hydrodynamic sorting and sedimentary recycling complicate the interpretation of sediment weathering proxies. This study presents elemental and lithium isotope compositions of estuarine surface sediments(SS) and suspended particulate matters(SPM) collected from the Changjiang(Yangtze River) Estuary. Based on a simple mass balance model, the proportions of different end-members(i.e., igneous rocks, modern weathering products and inherited weathering products) in sediments were quantitatively calculated and thus the silicate weathering process can be estimated. Overall, the sediments in the Changjiang Estuary are mainly eroded from un-weathered rock fragments(60%), while modern weathering products account for less than40%. The fine-grained SPM contain more shale components(52–66%), and the modern weathering products account for 21–40%. Comparatively, the coarse-grained surface sediments contain more un-weathered igneous rock fragments(63–84%) and less modern weathering products(only 4–18%). The comparison of δ7 Li values with the weathering proxy(Chemical Index of Alteration, CIA) suggests that sediment weathering intensity declines with increasing proportion of un-weathered igneous rock fragments. Additionally, the occurrence of inherited weathering products(i.e., shale) in modern sediments makes it a challenge to simply use CIA and δ7 Li as indicators of weathering intensity. This study confirms that fine-grained particles are more suitable for tracing contemporary weathering process, albeit with the influence of sedimentary recycling. Lithium isotopes combining with the mass balance model can quantitatively constrain the continental weathering processes in large river basins.  相似文献   

新能源发电对电磁观测环境的影响特征—以天津徐庄子台的电磁观测为例          下载免费PDF全文

马永  李宁  徐学恭  毕金孟 《地震学报》2021,43(5):595-604

利用天津市徐庄子地震台的电磁观测数据,针对台站周边观测区域内近年来出现的风电和光伏发电设施,通过野外试验测量,从多个角度深入剖析了不同观测环境中电磁观测数据在时间和空间上的变化形态,分别总结了风力发电、光伏发电的建设和运行状态对电磁观测环境干扰的影响特征。结果显示:风力发电机组对电磁观测环境的影响明显小于光伏发电设备,可视为一个干扰点,需规范其与观测设施的距离;若要确保光伏发电设备不影响电磁观测,需要将每个系统视为一个整体,并使二者保持足够大的距离。   相似文献