Prediction of East Asian summer precipitation via independent component analysis

A new statistical postprocessing method is proposed for seasonal climate prediction. The proposed method is based on a combination of independent component analysis (ICA) and canonical correlation analysis (CCA). Since the classical CCA cannot handle high-dimensional data wherein the number of variables is larger than the number of observations, ICA is pre-performed to reduce the dimension of the data. It is well known that empirical orthogonal function (EOF) analysis is a popular method for dimension reduction in the climatology community; however, loss of information occurs when the data is not Gaussian distributed. To extend the scope of distribution assumption and improve the prediction ability simultaneously, we propose the ICA-based method. This study focuses on the prediction of future precipitation for the boreal summer (June?CJuly?CAugust; JJA) through 29 years (1979?C2007) on East Asia region. Results of the proposed ICA-based method show an improvement in seasonal climate prediction in terms of correlation and root mean square error as compared with those of the GCM simulation and the EOF/CCA method.     

Applying a coupled hydrometeorological simulation system to flash flood forecasting over the Korean Peninsula

In flash flood forecasting, it is necessary to consider not only traditional meteorological variables such as precipitation, evapotranspiration, and soil moisture, but also hydrological components such as streamflow. To address this challenge, the application of high resolution coupled atmospheric-hydrological models is emerging as a promising alternative. This study demonstrates the feasibility of linking a coupled atmospheric-hydrological model (WRF/WRFHydro) with 150-m horizontal grid spacing for flash flood forecasting in Korea. The study area is the Namgang Dam basin in Southern Korea, a mountainous area located downstream of Jiri Mountain (1915 m in height). Under flash flood conditions, the simulated precipitation over the entire basin is comparable to the domain-averaged precipitation, but discharge data from WRF-Hydro shows some differences in the total available water and the temporal distribution of streamflow (given by the timing of the streamflow peak following precipitation), compared to observations. On the basis of sensitivity tests, the parameters controlling the infiltration of excess precipitation and channel roughness depending on stream order are refined and their influence on temporal distribution of streamflow is addressed with intent to apply WRF-Hydro to flash flood forecasting in the Namgang Dam basin. The simulation results from the WRF-Hydro model with optimized parameters demonstrate the potential utility of a coupled atmospheric-hydrological model for forecasting heavy rain-induced flash flooding over the Korean Peninsula.     

Causes and predictability of the record wet east Australian spring 2010

In 2010 eastern Australia received its highest springtime (September–November) rainfall since 1900. Based on historical relationships with sea surface temperatures (SST) and other climate indices, this record rainfall in 2010 was shown to be largely commensurate with the occurrence of a very strong La Niña event and an extreme positive excursion of the SAM. The pattern and magnitude of the tropical SST anomalies in austral spring 2010 were diagnosed to be nearly perfect to produce high rainfall across eastern Australia. Key aspects of this SST pattern were the strong cold anomaly in the central equatorial Pacific, and the strong warm anomalies in the eastern Indian Ocean and the far western Pacific to the north of Australia. Although the recent upward trend in SSTs in the western Pacific/eastern Indian Ocean warm pool accounted for about 50 % of the SST anomaly surrounding northern Australia in 2010, the contribution by the warming trend in these SSTs to the Australian rainfall anomaly in 2010 was assessed to be relatively modest. The strong positive swing in SAM was estimated to have accounted for upwards of 40 % of the regional anomaly along the central east coastal region and about 10 % of the area mean anomaly across eastern Australia. This contribution by the SAM suggests that a significant portion of the rainfall in 2010 may not have been seasonally predictable. However, predictability arising from the promotion of high SAM by the extreme La Nina event can not be ruled out.     

Use of slow-release fertilizer and biopolymers for stimulating hydrocarbon biodegradation in oil-contaminated beach sediments

Nutrient concentration and hydrocarbon bioavailability are key factors affecting biodegradation rates of oil in contaminated beach sediments. The effect of a slow-release fertilizer, Osmocote, as well as two biopolymers, chitin and chitosan, on the bioremediation of oil-spiked beach sediments was investigated using an open irrigation system over a 56-day period under laboratory conditions. Osmocote was effective in sustaining a high level of nutrients in leached sediments, as well as elevated levels of microbial activity and rates of hydrocarbon biodegradation. Chitin was more biodegradable than chitosan and gradually released nitrogen into the sediment. The addition of chitin or chitosan to the Osmocote amended sediments enhanced biodegradation rates of the alkanes relative to the presence of Osmocote alone, where chitosan was more effective than chitin due to its greater oil sorption capacity. Furthermore, chitosan significantly enhanced the biodegradation rates of all target polycyclic aromatic hydrocarbons.     

Geomorphological and seismostratigraphic evidence for multidirectional polyphase glaciation of the northern Celtic Sea

High-resolution seismic and bathymetric data offshore southeast Ireland and LIDaR data in County Waterford are presented that partially overlap previous studies. The observed Quaternary stratigraphic succession offshore southeast Ireland (between Dungarvan and Kilmore Quay) records a sequence of depositional and erosional events that supports regional glacial models derived from nearby coastal sediment stratigraphies and landforms. A regionally widespread, acoustically massive facies interpreted as the ‘Irish Sea Till’ infills an uneven, channelized bedrock surface overlying irregular mounds and deposits in bedrock lows that are probably earlier Pleistocene diamicts. The till is truncated and overlain by a thin, stratified facies, suggesting the development of a regional palaeolake following ice recession of the Irish Sea Ice Stream. A north–south oriented seabed ridge to the north is interpreted as an esker, representing southward flowing subglacial drainage associated with a restricted ice sheet advance of the Irish Ice Sheet onto the Celtic Sea shelf. Onshore topographic data reveal streamlined bedforms that corroborate a southerly advance of ice onto the shelf across County Waterford. The combined evidence supports previous palaeoglaciological models. Significantly, for the first time, this study defines a southern limit for a Late Midlandian Irish Ice Sheet advance onto the Celtic Sea shelf. © 2020 John Wiley & Sons, Ltd.     

Comparison of Intestine Microbiota Between Wild and Farmed Korean Rockfish,Sebastes schlegelii

Ocean Science Journal - The Korean rockfish, Sebastes schlegeli, is most commonly farmed in sea cages along the coast of Korea; however, detailed information on intestinal microbiota regarding this...     

Soil erosion risk assessment of the Keiskamma catchment,South Africa using GIS and remote sensing

This paper examines the soil loss spatial patterns in the Keiskamma catchment using the GIS-based Sediment Assessment Tool for Effective Erosion Control (SATEEC) to assess the soil erosion risk of the catchment. SATEEC estimates soil loss and sediment yield within river catchments using the Revised Universal Soil Loss Equation (RUSLE) and a spatially distributed sediment delivery ratio. Vegetation cover in protected areas has a significant effect in curtailing soil loss. The effect of rainfall was noted as two pronged, higher rainfall amounts received in the escarpment promote vegetation growth and vigour in the Amatole mountain range which in turn positively provides a protective cover to shield the soil from soil loss. The negative aspect of high rainfall is that it increases the rainfall erosivity. The Keiskamma catchment is predisposed to excessive rates of soil loss due to high soil erodibility, steep slopes, poor conservation practices and low vegetation cover. This soil erosion risk assessment shows that 35% of the catchment is prone to high to extremely high soil losses higher than 25 ton ha⁻¹ year⁻¹ whilst 65% still experience very low to moderate levels of soil loss of less than 25 ton ha⁻¹ year⁻¹. Object based classification highlighted the occurrence of enriched valley infill which flourishes in sediment laden ephemeral stream channels. This occurrence increases gully erosion due to overgrazing within ephemeral stream channels. Measures to curb further degradation in the catchment should thrive to strengthen the role of local institutions in controlling conservation practice.     

An assessment of the utilization of waste resources for the immobilization of Pb and Cu in the soil from a Korean military shooting range

Military shooting range soils contaminated by heavy metals have been subjected to remediation efforts to alleviate the detrimental effects of exposure on humans and the surrounding environment. Waste materials can be used as cost-effective soil amendments to immobilize heavy metals in contaminated soils. In this study, naturally occurring lime-based waste materials including egg shells, oyster shells, and mussel shells were assessed for their effectiveness toward heavy metal immobilization in military shooting range soil in Korea. Soil was treated in batch leaching experiments with 0, 2.5, 5, 10, and 15% of each lime-based waste material. The results showed that the lime-based waste materials effectively reduced water-soluble Pb at an application rate of 2.5% by weight of the soil. Increase in soil pH from 6.6 to 8.0 was considered to be the main chemistry of Pb immobilization, which was supported by the formation of insoluble Pb species at high pH values as confirmed by the visual MINTEQ thermodynamic model. In contrary, water-soluble Cu was increased in the lime-based waste material-treated soils when compared to the untreated soil. This was likely attributed to the formation of soluble Cu?CDOC (dissolved organic carbon) complexes as all lime-based waste materials applied increased DOC contents in the soil. Therefore, care must be taken in selecting the appropriate amendment for immobilizing metals in shooting range soils.     

Multi-proxy evidence for late Holocene anthropogenic environmental changes at Bongpo marsh on the east coast of Korea

We present a multi-proxy record (pollen, microscopic charcoal, magnetic susceptibility, carbon-isotopic composition, total organic carbon [TOC], carbon/nitrogen [C/N] ratios, and particle size) of the late Holocene environmental change and human activities from Bongpo marsh on the east coast of Korea. Mutual interaction between the environment and humans during the late Holocene has not been properly investigated in Korea due to the lack of undisturbed samples with high sedimentation rates. In this study, the history of human responses to late Holocene environmental changes is clearly reconstructed using a multi-proxy paleoenvironmental approach that has not previously been applied in Korea. The evidence from Bongpo marsh indicates that 1) Bongpo marsh began to develop ca. 650 BC as a coastal lagoon was rapidly filled with organic matter, 2) agricultural disturbance around the study site remained slight until ca. AD 600, 3) full-scale intensive agriculture prevailed and the area of deforestation increased between ca. AD 600 and ca. AD 1870, and 4) the land use changed from lowland rice agriculture to upland cultivation when agricultural productivity declined after AD 1870, probably due to severe deforestation and the consequent heavy influx of clastic sediment on rice fields, as described in various historical documents.     

Toxicological impact assessment of heavy metal contamination on macrobenthic communities in southern coastal sediments of Korea

In the heavily industrialized Masan Bay of southern coast, Korea, the potential harmful effects of heavy metals (Cd, Co, Cu, Ni, Pb, Sn, Zn, and Hg) were evaluated in terms of the pollution load index (PLI) and ecological risk assessment index (ERI) methods, and the results obtained were considered alongside the health of the macrobenthic fauna communities. The results revealed that the bay sediments, especially in the inner bay and the outfall area of a sewage treatment plant, are exposed to moderate to serious levels of metal pollution. Hg and Cd contributed the most to the potential toxicity response indices in sediments recently deposited in the bay. The potential ecological risk assessment of heavy metals in the bay was highlighted by the use of the benthic biological pollution index (BPI), suggesting that the ERI is a useful toxicity response index, which can quantify the overall ecological risk level to a target environment.