Ecosystem modelling in the southern Benguela: comparisons of Atlantis,Ecopath with Ecosim,and OSMOSE under fishing scenarios

Ecosystem-based management of marine fisheries requires the use of simulation modelling to investigate the system-level impact of candidate fisheries management strategies. However, testing of fundamental assumptions such as system structure or process formulations is rarely done. In this study, we compare the output of three different ecosystem models (Atlantis, Ecopath with Ecosim, and OSMOSE) applied to the same ecosystem (the southern Benguela), to explore which ecosystem effects of fishing are most sensitive to model uncertainty. We subjected the models to two contrasting fishing pressure scenarios, applying high fishing pressure to either small pelagic fish or to adult hake. We compared the resulting model behaviour at a system level, and also at the level of model groups. We analysed the outputs in terms of various commonly used ecosystem indicators, and found some similarities in the overall behaviour of the models, despite major differences in model formulation and assumptions. Direction of change in system-level indicators was consistent for all models under the hake pressure scenario, although discrepancies emerged under the small-pelagic-fish scenario. Studying biomass response of individual model groups was key to understanding more integrated system-level metrics. All three models are based on existing knowledge of the system, and the convergence of model results increases confidence in the robustness of the model outputs. Points of divergence in the model results suggest important areas of future study. The use of feeding guilds to provide indicators for fish species at an aggregated level was explored, and proved to be an interesting alternative to aggregation by trophic level.     

The retrieval of the Asian dust depolarization ratio in Korea with the correction of the polarization-dependent transmission

The linear particle depolarization ratios were retrieved from the observation with a multiwavelength Raman lidar at the Gwangju Institute of Science and Technology (GIST), Korea (35.11°N, 126.54°E). The measurements were carried out in spring (March to May) 2011. The transmission ratio measurements were performed to solve problems of the depolarization-dependent transmission at a receiver of the lidar and applied to correct the retrieved depolarization ratio of Asian dust at first time in Korea. The analyzed data from the GIST multiwavelength Raman lidar were classified into three categories according to the linear particle depolarization ratios, which are pure Asian dust on 21 March, the intermediate case which means Asian dust mixed with urban pollution on 13 May, and haze case on 10 April. The measured transmission ratios were applied to these cases respectively. We found that the transmission ratio is needed to be used to retrieve the accurate depolarization ratio of Asian dust and also would be useful to distinguish the mixed dust particles between intermediate case and haze. The particle depolarization ratios of pure Asian dust were approximately 0.25 at 532 nm and 0.14 at 532 nm for the intermediate case. The linear particle depolarization ratios of pure Asian dust observed with the GIST multiwavelength Raman lidar were compared to the linear particle depolarization ratios of Saharan dust observed in Morocco and Asian dust observed both in Japan and China.     

Effect of rainfall characteristics on removal efficiency evaluation in vegetative filter strips

The efficiency of a facility to remove non-point source pollution is likely to fluctuate according to conditions such as facility type and rainfall events; therefore, it is required to use a proper method to estimate removal efficiency. This study was conducted to estimate the efficiency of a facility with vegetative filter strips to remove pollutants by using methods previously used for the estimation of removal efficiency and compensate for weaknesses of the known methods. Other ways were presented to estimate an efficiency by which rainfall events were classified according to meteorological condition and amount of rainfall. Rainfall of frequency and summation of load as rainfall of frequency, where the frequencies per rainfall class were considered in efficiency ratio and summation of loads, respectively, seemed to have higher removal efficiencies than those estimated with the previous methods. Although it rained at the basin site, often in small quantity (below 10 mm), the rainfall events of below 10 mm were less frequent, during the monitored rainfall events, which accordingly resulted in low removal efficiencies. However, if the frequencies per rainfall class were considered, overall removal efficiencies of VFS might be increased because the removal efficiencies of the rainfall class under 10?mm was higher than other rainfall classes. Therefore, it is desirable to take into account such factors as effects of rainfall when it comes to measuring the removal efficiency of a non-point source pollutant of a factor, because those facilities are likely to be influenced by meteorological conditions including rainfall characteristics.     

Biosorption characteristics of heavy metals (Ni2+, Zn2+, Cd2+, Pb2+) from aqueous solution by Hizikia fusiformis

Heavy metal ions (Pb²⁺, Cd²⁺, Ni²⁺, and Zn²⁺) were biosorbed by brown seaweed (Hizikia fusiformis), which was collected from Jeju Island of South Korea. The metal adsorption capacity of H. fusiformis improved significantly by washing with water or by base or acid treatments. The maximum sorption by NaOH-pretreated biomass was observed near a slightly acidic pH (pH 4?6) for Pb²⁺, Cd²⁺, Ni²⁺, and Zn²⁺. This result suggests that the treatment of H. fusiformis biomass with NaOH helped increase the functional forms of carboxylate ester units. Kinetic data showed that the biosorption occurred rapidly during the first 60 min, and most of the heavy metals were bound to the seaweed within 180 min. The maximum metal adsorption capacities assumed by a Langmuir model were on the order of Pb²⁺ > Cd²⁺ > Ni²⁺ > Zn²⁺. Equilibrium adsorption data for the heavy metal ions could fit well in the Langmuir model with regression coefficients R ² > 0.97.     

Morphological identification of <Emphasis Type="Italic">Alexandrium</Emphasis> species (Dinophyceae) from Jinhae-Masan Bay,Korea

Outbreaks of paralytic shellfish poisoning (PSP) and dense blooms caused by Alexandrium species in Jinhae-Masan Bay, Korea have been nearly annual events for many years. However, excluding some Alexandrium species responsible for PSP, there are no critical reports on the morphology of Alexandrium species in this bay. To identify the Alexandrium species based on detailed morphological features, vegetative cells collected water samples and established by the incubation of resting cysts isolated from sediment trap samples were analyzed. Four species of Alexandrium were identified: Alexandrium affine, A. fundyense, A. catenella, and A. insuetum. Morphological features of these species were basically consistent with those outlined in previous studies. However, the ventral pore and the connecting pore on the sulcal plate, which have been accepted as diagnostic characteristics for the identification of A. fundyense and A. catenella, need to be reevaluated, indicating that useful morphological features for identifying these two species should be recommended to avoid confusion in the classification of species in genus Alexandrium.     

Critical influence of the pattern of Tropical Ocean warming on remote climate trends

Evidence is presented that the recent trend patterns of surface air temperature and precipitation over the land masses surrounding the North Atlantic Ocean (North America, Greenland, Europe, and North Africa) have been strongly influenced by the warming pattern of the tropical oceans. The current generation of atmosphere–ocean coupled climate models with prescribed radiative forcing changes generally do not capture these regional trend patterns. On the other hand, even uncoupled atmospheric models without the prescribed radiative forcing changes, but with the observed oceanic warming specified only in the tropics, are more successful in this regard. The tropical oceanic warming pattern is poorly represented in the coupled simulations. Our analysis points to model error rather than unpredictable climate noise as a major cause of this discrepancy with respect to the observed trends. This tropical error needs to be reduced to increase confidence in regional climate change projections around the globe, and to formulate better societal responses to projected changes in high-impact phenomena such as droughts and wet spells.     

A scattering-based over-land rainfall retrieval algorithm for South Korea using GCOM-W1/AMSR-2 data

Heavy summer rainfall is a primary natural disaster affecting lives and properties in the Korean Peninsula. This study presents a satellite-based rainfall rate retrieval algorithm for the South Korea combining polarization-corrected temperature (PCT) and scattering index (SI) data from the 36.5 and 89.0 GHz channels of the Advanced microwave Scanning Radiometer 2 (AMSR-2) onboard the Global Change Observation Mission (GCOM)-W1 satellite. The coefficients for the algorithm were obtained from spatial and temporal collocation data from the AMSR-2 and groundbased automatic weather station rain gauges from 1 July - 30 August during the years, 2012-2015. There were time delays of about 25 minutes between the AMSR-2 observations and the ground raingauge measurements. A new linearly-combined rainfall retrieval algorithm focused on heavy rain for the PCT and SI was validated using ground-based rainfall observations for the South Korea from 1 July - 30 August, 2016. The validation presented PCT and SI methods showed slightly improved results for rainfall > 5 mm h^-1 compared to the current ASMR-2 level 2 data. The best bias and root mean square error (RMSE) for the PCT method at AMSR-2 36.5 GHz were 2.09 mm h^-1 and 7.29 mm h^-1, respectively, while the current official AMSR-2 rainfall rates show a larger bias and RMSE (4.80 mm h^-1 and 9.35 mm h^-1, respectively). This study provides a scatteringbased over-land rainfall retrieval algorithm for South Korea affected by stationary front rain and typhoons with the advantages of the previous PCT and SI methods to be applied to a variety of spaceborne passive microwave radiometers.     

Projected Heat Wave Characteristics over the Korean Peninsula During the Twenty-First Century

Climate change is expected to increase temperatures globally, and consequently more frequent, longer, and hotter heat waves are likely to occur. Ambiguity in defining heat waves appropriately makes it difficult to compare changes in heat wave events over time. This study provides a quantitative definition of a heat wave and makes probabilistic heat wave projections for the Korean Peninsula under two global warming scenarios. Changes to heat waves under global warming are investigated using the representative concentration pathway 4.5 (RCP4.5) and 8.5 (RCP8.5) experiments from 30 coupled models participating in phase five of the Coupled Model Inter-comparison Project. Probabilistic climate projections from multi-model ensembles have been constructed using both simple and weighted averaging. Results from both methods are similar and show that heat waves will be more intense, frequent, and longer lasting. These trends are more apparent under the RCP8.5 scenario as compared to the RCP4.5 scenario. Under the RCP8.5 scenario, typical heat waves are projected to become stronger than any heat wave experienced in the recent measurement record. Furthermore, under this scenario, it cannot be ruled out that Korea will experience heat wave conditions spanning almost an entire summer before the end of the 21st century.     

Intercomparison of Planetary Boundary-Layer Parametrizations in the WRF Model for a Single Day from CASES-99

This study compares five planetary boundary-layer (PBL) parametrizations in the Weather Research and Forecasting (WRF) numerical model for a single day from the Cooperative Atmosphere-Surface Exchange Study (CASES-99) field program. The five schemes include two first-order closure schemes—the Yonsei University (YSU) PBL and Asymmetric Convective Model version 2 (ACM2), and three turbulent kinetic energy (TKE) closure schemes—the Mellor–Yamada–Janjić (MYJ), quasi-normal scale elimination (QNSE), and Bougeault–Lacarrére (BouLac) PBL. The comparison results reveal that discrepancies among thermodynamic surface variables from different schemes are large at daytime, while the variables converge at nighttime with large deviations from those observed. On the other hand, wind components are more divergent at nighttime with significant biases. Regarding PBL structures, a non-local scheme with the entrainment flux proportional to the surface flux is favourable in unstable conditions. In stable conditions, the local TKE closure schemes show better performance. The sensitivity of simulated variables to surface-layer parametrizations is also investigated to assess relative contributions of the surface-layer parametrizations to typical features of each PBL scheme. In the surface layer, temperature and moisture are more strongly influenced by surface-layer formulations than by PBL mixing algorithms in both convective and stable regimes, while wind speed depends on vertical diffusion formulations in the convective regime. Regarding PBL structures, surface-layer formulations only contribute to near-surface variability and then PBL mean properties, whereas shapes of the profiles are determined by PBL mixing algorithms.     

Asia-Pacific mussel watch: monitoring contamination of persistent organochlorine compounds in coastal waters of Asian countries

Contamination of persistent organochlorines (OCs) such as PCBs (polychlorinated biphenyls), DDT and its metabolites (DDTs), HCH (hexachlorocyclohexane) isomers (HCHs), chlordane compounds (CHLs), and HCB (hexachlorobenzene) were examined in mussels collected from coastal waters of Asian countries such as Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, Philippines, Far East Russia, Singapore, and Vietnam in 1994, 1997, 1998, 1999, and 2001 to elucidate the contamination status, distribution and possible pollution sources and to assess the risks on aquatic organisms and human. OCs were detected in all mussels collected from all the sampling sites investigated. Considerable residue levels of p,p(')-DDT and alpha-HCH were found in mussels and the concentrations of DDTs and HCHs found in mussels from Asian developing countries were higher than those in developed nations suggesting present usage of DDTs and HCHs along the coastal waters of Asian developing countries. On the other hand, lower concentrations of PCBs detected in mussels from Asian developing countries than those in developed countries indicate that PCBs contamination in mussels is strongly related to industrial and activities. To our knowledge, this is a first comprehensive report on monitoring OCs pollution in the Asia-Pacific region.