Statistical distributions of singular vectors for tropical cyclones affecting Korea over a 10-year period

To investigate the statistical sensitivity distributions of tropical cyclone (TC) forecasts over the Korean Peninsula, total energy (TE) singular vectors (SVs) were calculated and evaluated over a 10-year period. TESVs were calculated using the fifth-generation Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) and its tangent linear and adjoint models with a Lanczos algorithm over a 48-h period. Chosen cases were 21 TCs that affected the Korean Peninsula among 230 TCs that were generated in the western North Pacific from 2001 to 2010. Sensitive regions indicated by TESVs were mainly located near mid-latitude troughs and TC centers but varied depending on TC track and environmental conditions such as subtropical high and mid-latitude trough. The cases were classified into three groups by clustering TC tracks based on the finite mixture model. The two groups that passed through the western and southern sea of the Korean Peninsula had maximally sensitive regions in the mid-latitude trough and largely sensitive regions around the TC center, while the other group that passed straight through the eastern sea of the Korean Peninsula had maximally sensitive regions near the northeastern region of the TC center. Vertically, the former two clustered groups had the westerly tilted TESVs and potential vorticity structures under the mid-latitude troughs at the initial time, indicating the TCs were in a baroclinic environment. Conversely, the straight-moving TCs were not in a baroclinic environment. Based on the results in the present study, the TCs moving toward a fixed verification region over the Korean Peninsula have different sensitivity regions and structures according to their moving tracks and characteristic environmental conditions, which may provide guidance for targeted observations of TCs affecting the Korean Peninsula.     

Biofilm: A crucial factor affecting the settlement of seaweed on intertidal rocky surfaces

We hypothesized that the presence of biofilm accelerated the settlement of dominant seaweed species and maintained high levels of species richness by regulating the blooming of particular species on an intertidal rocky shore. The coverage and species richness of macroalgae on sterile and cleared substrates (225 cm²) were measured to investigate the effects of biofilm on the settlement of macroalgae in intertidal zones at Noryang, Songmoon, and Sangnam in Gawngyang Bay on the southern coast of the Korean peninsula. Green algae coverage on cleared substrates was significantly higher than that on sterile substrates at both Noryang and Songmoon during the study period. This suggests that the presence of biofilm enhances the settlement of green algae by providing various habitat structures and, consequently, may lead to serious ‘green tide’ events. However, the coverage of algae other than green algae and algal species richness on cleared substrates remained high at Sangnam during the experimental period. Biofilm facilitated the settlement of macroalgae and inhibited the blooming of specific algae by inducing inter-specific space competition. Therefore, biofilm plays an important role on seaweed assemblages on intertidal rocky shores by accelerating the settlement of seaweed.     

Numerical study of air chamber for oscillating water column wave energy convertor

Oscillating Water Column (OWC) wave energy converting system is one of the most widely used facilities all over the world.The air chamber is utilized to convert the wave energy into the pneumatic energy.The numerical wave tank based on the two-phase VOF model is established in the present study to investigate the operating performance of OWC air chamber.The RANS equations,standard k-ε turbulence model and dynamic mesh technology are employed in the numerical model.The effects of incident wave conditions and shape parameters on the wave energy converting efficiency are studied and the capability of the present numerical wave tank on the corresponding engineering application is validated.     

Picocyanobacterial abundances and diversity in surface water of the northwestern Pacific Ocean

To understand picocyanobacterial distribution patterns in the northwestern Pacific Ocean, their abundances and genetic diversity were studied using flow cytometry and a barcoded amplicon pyrosequencing approach. At open ocean stations affected by the North Equatorial Current, Prochlorococcus was the predominant picocyanobacteria, and a high-light-adapted ecotype (HLII) made up most of the population. In contrast, at stations in shelf areas of the East China Sea (ECS) and South Sea, Synechococcus was the predominant picocyanobacteria and clade II was dominant. At other ECS stations affected by the Kuroshio Current, both Prochlorococcus and Synechococcus made up similar proportions of the picocyanobacterial community. These results indicate that picocyanobacterial diversity differs among oceanic regions, and that physicochemical properties related to dominant water masses, seem to be important in determining picocyanobacterial diversity.     

Contents and stable isotopic compositions of organic carbon and total nitrogen in the surface sediment of two coastal bays in Korea

Surface sediment from the coastal bays of Gwangyang and Masan in South Korea were analyzed for their contents and isotopic values of organic carbon and total nitrogen. The sources and diagenetic alteration of organic matter were also assessed. Total organic carbon varied from 0.22% to 3.48% (average = 1.40%, n = 75), and C/N ratios varied from 2.4 to 15.2 (average = 8.79, n = 75). δ¹³C_org ranged from −19.92‰ to −25.86‰ (average = −21.21‰, n = 75), and δ¹⁵N_TN ranged from 8.57‰ to 3.93‰ (average = 6.49‰, n = 75). Total organic carbon in both areas was associated with grain-size, with higher contents in finer grained sediment. The high carbon content observed in Masan Bay sediment correlated with its higher C/N ratio. δ¹³C_org and δ¹⁵N_TN varied widely, attributable to various influences such as the input of terrestrial organic matter and diagenetic alteration. The depleted δ¹³C_org and higher δ¹⁵N_TN observed in the sediment of Gwangyang Bay reflected terrestrial supply, implying that biogeochemical processes, i.e. bacterial degradation, were more active in Masan Bay sediment, which showed less depleted δ¹³C_org and higher δ¹⁵N_TN than Gwangyang Bay sediment. δ¹⁵N_TN was the more useful indicator of biogeochemical processes in the highly anoxic sediment. These results indicate that the δ¹³C_org and δ¹⁵N_TN of sedimentary organic matter in coastal bays can indicate the source and degree of diagenetic alteration of sedimentary organic matter.     

Egg production rate of the copepod <Emphasis Type="Italic">Calanus sinicus</Emphasis> off the Korean coast of the Yellow Sea during spring

The egg production rate (EPR) of Calanus sinicus was measured from March 2007 to April 2010 at three stations along the Korean coast of the Yellow Sea (in coastal waters off Saemangum, Yeongheungdo, and Asan Bay) to estimate in situ maximum egg production rate (MEPR) and to understand whether the females were limited in their growth or fecundity in the field. The mean EPR of C. sinicus at each sampling date ranged from 10.3–34.9 eggs female⁻¹ d⁻¹ (mean 23.4 eggs female⁻¹ d⁻¹), and the EPR of individual copepods ranged from 0–81 eggs female⁻¹ d⁻¹. The mean EPR was positively correlated with the body weight of female copepods. The MEPR at each sampling date ranged from 40–81 eggs female⁻¹ d⁻¹ (mean 50.4 eggs female⁻¹ d⁻¹). Over 84% of eggs spawned hatched successfully. The weight-specific growth rate (WSGR) ranged from 0.038–0.111 d⁻¹ (mean 0.082 d⁻¹), indicating that 3.8–11.1% of the carbon in an adult female was produced daily as female growth. The WSGR was negatively correlated with water temperature. The ratio of mean EPR to observed mean MEPR ranged from 20–70% (mean 46%), indicating that ∼54% of a female’s growth might be limited in the field. We suggest that the ratio of observed EPR to mean MEPR of copepod can be applied to understand how the copepod responds to environmental changes, as well as EPR and hatching success.     

Acetylthiocholine (ATC)--cleaving cholinesterase (ChE) activity as a potential biomarker of pesticide exposure in the Manila clam, Ruditapes philippinarum, of Korea

The acetylthiocholine (ATC) - cleaving cholinesterase (ChE) activity in Manila clam, which is widely distributed throughout the coastal environment of Korea, was assayed as a potentially useful biomarker of organophosphorous pesticides (OPs). A clear dose-response relationship was determined between inhibited ChE in adductor muscle of clams and four OPs (methidathion, chlorpyrifos, diazinon, IBP) which are heavily used OPs in Korea. The measured EC(50)-24?h values of methidathion, chlorpyrifos, diazinon, and IBP for Ruditapes philippinarum were 7.16?μg?l(-1), 0.34?mg?l(-1), 3.01?mg?l(-1), and 3.41?mg?l(-1), respectively. In field studies, ChE activity in Manila clams collected from 23 stations in the mid-western coastal region demonstrated spatial variation with statistical differences. These results suggest that ChE activity in R. philippinarum is a potential biomarker for assessing organophosphorous pesticide contamination in coastal environments.     

Synthetic high-resolution near-IR spectra of the Sun for planetary data reductions made from ATMOS/Spacelab-3 and Atlas-3 data

We have constructed synthetic solar spectra for the 2302-4800 cm⁻¹ (2.08-4.34 μm) range, a spectral range where planetary objects mainly emit reflected sunlight, using ATMOS (Atmospheric Trace Molecule Spectroscopy)/Spacelab-3 and Atlas-3 spectra, of which resolution is 0.01 cm⁻¹. We adopted Voigt line profiles for the modeling of line shapes based on an atlas of line identifications compiled by Geller [Geller, M., 1992. Key to Identification of Solar Features. A High-Resolution Atlas of the Infrared Spectrum of the Sun and the Earth Atmosphere from Space. NASA Reference Publ. 1224, vol. III. NASA, Washington, DC, pp. 1-22], who derived solar line positions and intensities from contaminated high-resolution solar spectra obtained by ATMOS/Spacelab-3. Because the ATMOS spectra in these wavelength ranges are compromised by absorption lines of molecules existing in Earth's high-altitude atmosphere and in the compartment of the spacecraft, the direct use of these high-resolution solar spectra has been inconvenient for the data reductions of planetary spectra. We compared the synthetic solar spectra with the ATMOS spectra, and obtained satisfactory fits for the majority of the solar lines with the exception of abnormal lines, which do not fit with Voigt line profiles. From the model fits, we were able to determine Voigt line parameters for the majority of solar lines; and we made a list of the abnormal lines. We also constructed telluric-line-free solar spectra by manually eliminating telluric lines from the ATMOS spectra and filling the gaps with adjacent continua. These synthetic solar spectra will be useful to eliminate solar continua from spectra of planetary objects to extract their own intrinsic spectral features.