Impacts of aerosol chemical composition on microphysics and precipitation in deep convection     

Seoung Soo Lee  Leo J. Donner  Vaughan T.J. Phillips 《Atmospheric Research》2009,94(2):220-237

Aerosols affect precipitation by modifying cloud properties such as cloud droplet number concentration (CDNC). Aerosol effects on CDNC depend on aerosol properties such as number concentration, size spectrum, and chemical composition. This study focuses on the effects of aerosol chemical composition on CDNC and, thereby, precipitation in a mesoscale cloud ensemble (MCE) driven by deep convective clouds. The MCE was observed during the 1997 department of energy's Atmospheric Radiation Measurement (ARM) summer experiment. Double-moment microphysics with explicit nucleation parameterization, able to take into account those three properties of aerosols, is used to investigate the effects of aerosol chemical composition on CDNC and precipitation. The effects of aerosol chemical compositions are investigated for both soluble and insoluble substances in aerosol particles. The effects of soluble substances are examined by varying mass fractions of two representative soluble components of aerosols in the continental air mass: sulfate and organics. The increase in organics with decreasing sulfate lowers critical supersaturation (S_c) and leads to higher CDNC. Higher CDNC results in smaller autoconversion of cloud liquid to rain. This provides more abundant cloud liquid as a source of evaporative cooling, leading to more intense downdrafts, low-level convergence, and updrafts. The resultant stronger updrafts produce more condensation and thus precipitation, as compared to the case of 100% sulfate aerosols. The conventional assumption of sulfate aerosol as a surrogate for the whole aerosol mass can be inapplicable for the case with the strong sources of organics. The less precipitation is simulated when an insoluble substance replaces organics as compared to when it replaces sulfate. When the effects of organics on the surface tension of droplet and solution term in the Köhler curve are deactivated by the insoluble substance, S_c is raised more than when the effects of sulfate on the solution term are deactivated by the insoluble substance. This leads to lower CDNC and, thus, larger autoconversion of cloud liquid to rain, providing less abundant cloud liquid as a source of evaporative cooling. The resultant less evaporative cooling produces less intense downdrafts, weaker low-level convergence, updrafts, condensation and, thereby, less precipitation in the case where organics is replaced by the insoluble substance than in the case where sulfate is replaced by the insoluble substance. The variation of precipitation caused by the change in the mass fraction between the soluble and insoluble substances is larger than that caused by the change in the mass fraction between the soluble substances.  相似文献   

Flood simulation using the gauge‐adjusted radar rainfall and physics‐based distributed hydrologic model     

Byung Sik Kim  Bo Kyung Kim  Hung Soo Kim 《水文研究》2008,22(22):4400-4414

This paper reports the results of an investigation into flood simulation by areal rainfall estimated from the combination of gauged and radar rainfalls and a rainfall–runoff model on the Anseong‐cheon basin in the southern part of Korea. The spatial and temporal characteristics and behaviour of rainfall are analysed using various approaches combining radar and rain gauges: (1) using kriging of the rain gauge alone; (2) using radar data alone; (3) using mean field bias (MFB) of both radar and rain gauges; and (4) using conditional merging technique (CM) of both radar and rain gauges. To evaluate these methods, statistics and hyetograph for rain gauges and radar rainfalls were compared using hourly radar rainfall data from the Imjin‐river, Gangwha, rainfall radar site, Korea. Then, in order to evaluate the performance of flood estimates using different rainfall estimation methods, rainfall–runoff simulation was conducted using the physics‐based distributed hydrologic model, Vflo^?. The flood runoff hydrograph was used to compare the calculated hydrographs with the observed one. Results show that the rainfall field estimated by CM methods improved flood estimates, because it optimally combines rainfall fields representing actual spatial and temporal characteristics of rainfall. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Pilot-scale field model tests for detecting landfill leachate intrusion into the subsurface using a grid-net electrical conductivity measurement system     

Myoung?Hak?Oh  Ju?Hyung?Lee  Gil?Lim?Yoon  Junboum?ParkEmail author 《Environmental Geology》2003,45(2):181-189

The grid-net electrical conductivity measurement system for detecting exact locations of landfill leachate intrusion in the subsurface was developed in this study. Laboratory and pilot-scale field model tests were performed to evaluate the direct application of a grid-net electrical conductivity measurement system for the detection of landfill leachate. A significant increase in electrical conductivity of soil was observed by adding landfill leachate. This can be explained as an increase in electrical conductivity of pore fluid due to an increase in leachate constituents as charge carriers. In pilot-scale field model tests, leachate intrusion locations were accurately identified at the initial stage of landfill leachate release by the grid-net electrical conductivity measurement system. The electrical conductivity of the subsurface before leachate injection lay within a small range of 24.8–43.0 S/cm. The electrical conductivity values in detected points were approximately ten times more than the conductivity values of the subsurface without landfill leachate intrusion. The results in this study indicate that the grid-net electrical conductivity measurement method has a possible application for detecting locations of landfill leachate intrusion into the subsurface at the initial stage, and thus has great potential in monitoring leachate leakage at waste landfills.  相似文献   

Analysis of Epipolar Geometry in Linear Array Scanner Scenes     

Ayman F.  Habib  Michel  Morgan  Soo  Jeong  Kyung-Ok  Kim 《The Photogrammetric Record》2005,20(109):27-47

  相似文献   

Distribution of Cs and Pu in the surface waters of the East Sea (Sea of Japan)     

Dong-Jin Kang  Chang Soo Chung  Suk Hyun Kim  Kyung-Ryul Kim  Gi Hoon Hong   《Marine pollution bulletin》1997,35(7-12):305-312

Surface and subsurface water samples for ¹³⁷Cs and ^239,240Pu analysis were collected in the East Sea (Sea of Japan) during August 1993. The ¹³⁷Cs levels of the surface waters are quite homogeneous in the East Sea (average = 3.1±0.2 mBq kg⁻¹). The ^239,240Pu levels vary from 6 to 10 μBq kg⁻¹ in the surface. ^239,240Pu to ¹³⁷Cs ratios in the surface water are within 0.002 to 0.003. The East Sea may be regarded as a part of the North Pacific Ocean in terms of ¹³⁷Cs dispersal in the surface, where the ¹³⁷Cs contents of the surface seawater seem to be controlled primarily by the atmospheric input. However, since our sampling was made just two months prior to the widely publicized Russian dumping incident on the 17th October 1993, our measurements may provide background data to assess the immediate impact of the Russian dumping on the levels of ¹³⁷Cs and ^239,240Pu in the East Sea.  相似文献   

Investigation of the dynamic behaviour of a storage tank with different foundation types focusing on the soil‐foundation‐structure interactions using centrifuge model tests          下载免费PDF全文

Heon‐Joon Park  Jeong‐Gon Ha  Sun‐Yong Kwon  Moon‐Gyo Lee  Dong‐Soo Kim 《地震工程与结构动力学》2017,46(14):2301-2316

This paper proposes a dynamic centrifuge model test method for the accurate simulation of the behaviours of a liquid storage tank with different types of foundations during earthquakes. The method can be used to determine the actual stress conditions of a prototype storage‐tank structure. It was used in the present study to investigate the soil‐foundation‐structure interactions of a simplified storage tank under two different earthquake motions, which were simulated using a shaking table installed in a centrifuge basket. Three different types of foundations were considered, namely, a shallow foundation, a slab on the surface of the ground connected to piles and a slab with disconnected piles. The test results were organised to compare the ground surface and foundation motions, the slab of foundation and top of structure motions and the horizontal and vertical motions of the slab, respectively. These were used to establish the complex dynamic behaviours of tank models with different foundations. The effects of soil–foundation–structure interaction with three foundation conditions and two different earthquake motions are focused and some important factors, that should be considered for future designs are also discussed in this research. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Characteristics and Ecosystem Changes of Marine Algal Communities in Wangdol-cho on the East Coast of Korea     

Jung  Seung Wook  Rho  Hyun Soo  Choi  Chang Geun 《Ocean Science Journal》2020,55(4):549-562

Ocean Science Journal - This study sought to examine the characteristics and patterns of marine algae community changes in Wangdol-cho in order to establish a theoretical basis for the development...  相似文献   

Effects of surfactants and electrolyte solutions on the properties of soil     

Junboum Park  Cumaraswamy Vipulanandan  Jee Woong Kim  Myoung Hak Oh 《Environmental Geology》2006,49(7):977-989

Biosurfactants are frequently used in petroleum hydrocarbon and dense non-aqueous phase liquids (DNAPLs) remediation. The applicability of biosurfactant use in clayey soils requires an understanding and characterization of their interaction. Comprehensive effects of surfactants and electrolyte solutions on kaolinite clay soil were investigated for index properties, compaction, strength characteristics, hydraulic conductivities, and adsorption characteristics. Sodium dodecyl sulfate (SDS) and NaPO₃ decreased the liquid limit and plasticity index of the test soil. Maximum dry unit weights were increased and optimum moisture contents were decreased as SDS and biosurfactant were added for the compaction tests for mixtures of 30% kaolinite and 70% sand. The addition of non-ionic surfactant, biosurfactant, and CaCl₂ increased the initial elastic modulus and undrained shear strength of the kaolinite–sand mixture soils. Hydraulic conductivities were measured by fixed-wall double-ring permeameters. Results showed that the hydraulic conductivity was not significantly affected, but slightly decreased from 1×10⁻⁷ cm/s (water) to 0.3×10⁻⁷ cm/s for Triton X-100 and SDS. The adsorption characteristics of the chemicals onto kaolinite were also investigated by developing isotherm curves. SDS adsorbed onto soil particles with the strongest bonding strength of the fluids tested. Correlations among parameters were developed for surfactants, electrolyte solutions, and clayey soils.  相似文献   

Origin and depositional environment of fine-grained sediments since the last glacial maximum in the southeastern Yellow Sea: evidence from rare earth elements     

In Kwon Um  Man Sik Choi  Gwang Soo Lee  Tae Soo Chang 《Geo-Marine Letters》2015,35(6):421-431

  相似文献   

Quaternary mud deposits on the Korean shelf—processes,facies, stratigraphy: an introduction and future challenges     

Tae Soo Chang  Dong-Geun Yoo 《Geo-Marine Letters》2015,35(6):405-410

  相似文献