Observation and Numerical Simulation of Cold Clouds and Snow Particles in the Yeongdong Region

The Yeongdong region of the Korean Peninsula is vulnerable to high-impact weather events, because of its complicated geographical characteristics and East Sea effect, such that heavy snowfall episodes have frequently occurred in winter. Snow crystal play an important role in cloud and precipitation physics because it is an essential element for improvement of numerical model, and remote sensing retrieval such as radar and satellite. In this study, the high-temporal resolution (3-hourly) dataset of radiosonde soundings and snow particle photographs during the intensive observation period for 2013–2016 has been used to understand characteristics of snow particles for the different meteorological conditions in the Yeongdong region. We also attempt to simulate two episodes that occurred on 23–24 February and 13–14 December 2016; one has a single-layered cloud and the other has two-layered cloud structure. This study demonstrates that the rimed particles in the first period tend to shift to aggregates of dendrites with the decrease of 850-hPa temperature. In general, the low-level clouds in the Yeongdong region are observed along with the distinctive wind shear and strong inversion in equivalent potential temperature around 2 ~ 3 km above the sea level. The simulation successfully represents the variations of the characteristics of snow particles as well as different cloud structure for both episodes. The observation and model simulations clearly suggest that snow particles primarily depend on the 850-hPa temperature.     

A Simple Method to Find a Neighboring Grid Point on the Cubed-sphere

Recently, there has been increasing interest in the use of cubed-sphere geometry in the geoscientific modeling community. For diverse numerical operations such as remapping and parallel communications, the search of neighbor elements or points is required. Here, we propose a novel and simple method to find a neighboring element or point on the cubed-sphere. This new method can be universally used for any types of cubed-sphere, for example, equi-angular, conformal, uniform-jacobian cubed-sphere etc. Key points to simplify the search algorithm are the definition of rotation counts of panels neighboring the centered panel, and the use of operations to obtain integer quotient and remainder given an index interval from the source point. Along with the introduction of the methodology, some examples using this method is described in this article.     

Toxicity identification in metal plating effluent: implications in establishing effluent discharge limits using bioassays in Korea

Because of complexity and diversity of toxicants in effluent, chemical analysis alone gives very limited information on identifying toxic chemicals to test organisms. Toxicity identification evaluation (TIE) techniques have been widely used to identify toxicants in various samples including industrial wastewater as well as natural waters. In response to new regulation for effluent discharge in Korea, which will be effective from 2011, a necessity of studies emerges that investigates toxicity levels in industrial effluents. This work was a preliminary study examining toxicity levels in effluent from one metal plating factory using Daphnia magna (48 h immobility) and identifying toxicity-causing substances. Toxicity tests showed variability on different sampling occasions and the results of TIE methods indicated that both organic compounds and metals contributed to the observed toxicity in metal plating effluent. Further studies are necessary to help reduce effluent toxicity especially from direct dischargers, who will have to comply with the new regulation.     

Distribution of persistent organic pollutants in bivalves from the northeast coast of China

To assess the levels of organochlorine compounds (OCs) in the Chinese coastal environment, monitoring study using bivalves was conducted in 2005. A total of 21 bivalve samples covering the northeastern coast of China were collected and analyzed. Organochlorine compounds were widely distributed in the Chinese coastal environment, with dichlorodiphenyltrichloroethane (DDT) contamination being particularly prevalent. The overall concentrations of PCBs, DDTs, HCHs, chlordane compounds (CHLs), dieldrin, and endosulfans in bivalves were in the ranges of 3.27-25.4, 54.8-2680, 1.42-25.5, n.d. (not detected)-2.28, n.d.-4.02, and n.d.-9.55 ng g(-1) on a dry weight basis, respectively. The concentrations of DDT and HCH compounds are relatively higher than those from the coastal areas of other Asian countries. DDT metabolites were predominant, suggesting that the degradation of DDT is in progress in the Chinese coastal environment. Still, however, DDTs of high concentration exceeding 1000 ng g(-1) were observed at 19% of the stations surveyed. Among HCH compounds, beta-HCH, which is an isomer with strong persistency, was observed predominantly. Compositions of DDT and HCH compounds imply that fresh input of the two compounds into the Chinese coasts is possibly low.     

Spin state of ferric iron in MgSiO3 perovskite and its effect on elastic properties

Recent studies have indicated that a significant amount of iron in MgSiO₃ perovskite (Pv) is Fe³⁺ (Fe³⁺/ΣFe = 10–60%) due to crystal chemistry effects at high pressure (P) and that Fe³⁺ is more likely than Fe²⁺ to undergo a high-spin (HS) to low-spin (LS) transition in Pv in the mantle. We have measured synchrotron Mössbauer spectroscopy (SMS), X-ray emission spectroscopy (XES), and X-ray diffraction (XRD) of Pv with all iron in Fe³⁺ in the laser-heated diamond-anvil cell to over 100 GPa. Fe³⁺ increases the anisotropy of the Pv unit cell, whereas Fe²⁺ decreases it. In Pv synthesized above 50 GPa, Fe³⁺ enters into both the dodecahedral (A) and octahedral (B) sites approximately equally, suggesting charge coupled substitution. Combining SMS and XES, we found that the LS population in the B site gradually increases with pressure up to 50–60 GPa where all Fe³⁺ in the B site becomes LS, while Fe³⁺ in the A site remains HS to at least 136 GPa. Fe³⁺ makes Pv more compressible than Mg-endmember below 50 GPa because of the gradual spin transition in the B site together with lattice compression. The completion of the spin transition at 50–60 GPa increases bulk modulus with no associated change in density. This elasticity change can be a useful seismic probe for investigating compositional heterogeneities associated with Fe³⁺.     

The Korean emissions trading scheme: business perspectives on the early years of operations

Korea’s domestic emissions trading scheme commenced in January 2015. It targeted mainly industrial and power sectors, and compelled companies to transform how they manage energy efficiency and mitigate GHGs. This study sets out to explore how Korean companies evaluated their allocation position and engaged in emissions trading in the first compliance period, and to identify their views on trading barriers and policy expectations at the start of emissions trading. Questionnaire surveys and on-site interviews targeting Korean companies under the Korean emissions trading scheme were conducted at the start of operations (February to March 2015) and after the first compliance year (May 2016), respectively. Actual operation results are observed and compared with the survey findings. This study extrapolates implications for policy and presents suggestions for the government and the target companies in terms of how to improve the current emissions trading scheme in order to further stimulate emissions trading.

POLICY RELEVANCE

This study attempts to bridge the gap between companies and government policy in operating the domestic emission trading scheme in Korea. Empirical results, based on analysis of company-level data, reveal how businesses perceive K-ETS and how this relates to the operating results, which saw only limited trading of surplus emissions taking place in the early phase. Key barriers to active trading identified in the study include supply–demand imbalance, policy uncertainty and lack of preparedness of companies over carbon pricing. These barriers could be addressed by improved transparency of allowance allocation methods, possibly restricting carry-over of surplus allowances, ending policy uncertainty and providing more information to companies that can support companies’ policy understanding of the carbon pricing based on the market mechanism. Targeted companies should proactively participate in emissions trading in the early phase, in order to learn from it and prepare for the future introduction of auctioning.     

Floodplain effects on the transport of dissolved and colloidal trace elements in the East Pearl River,Mississippi

Substantial work suggests that floodplain wetlands could play a role in modifying fluvial fluxes of dissolved and colloidal trace elements. Yet, few studies have directly addressed this issue. We examined trace elements in the East Pearl River (Mississippi or Louisiana, USA), which is surrounded by wetlands that are temporally more or less connected to the river depending on river stage. Dissolved and colloidal trace element samples, along with ancillary data, including dissolved organic carbon and nutrients, were collected during eight surveys of this system at different flow stages from November 2007 to September 2008. Hydrology of the system is complex due to seasonal changes in water sources as well as potential inputs from the floodplain wetlands and the hyporheic zone. We therefore considered effects including nonconservative mixing of water sources, saltwater intrusion, and floodplain wetland flux requirements needed to support observed downstream concentration changes. During moderately high discharge, fluxes of many elements (e.g., Cd, Fe, Mn, and Zn) increased downstream by 20% or more, with inputs from the floodplain wetlands as the apparent source. At the highest discharge, however, wetland inputs to the river may have been rate‐limited (i.e., the wetland source was flushed faster than biogeochemical processes could regenerate dissolved or colloidal material). At low discharge, other effects, including saltwater intrusion and hyporheic zone interactions, are important. Both redox processes and organic ligands (or dissolved organic carbon), along with the supply of wetland inputs (or removal) relative to river fluxes, appear to be key factors determining floodplain wetland effects. While the behavior of some elements suggests they were dominantly affected by redox processes (Mn and V) or by organic complexation (dissolved Fe and light rare earths), other elements were affected by more than one process in ways that remain obscure (Cu). Overall our results are broadly consistent with previous field, laboratory, and modeling studies and suggest that a better understanding of the sources and transformations of Fe is a key area for future research.     

Estimate of Coastal Water Depth Based on Aerial Photographs Using a Low-Altitude Remote Sensing System

Ocean Science Journal - Observing coastal water depths is very important to understand physical processes of the coastal environment and manage coastal resources. In this study, a low-altitude...