Cloud cover retrieved from skyviewer: A validation with human observations

Cloud cover information is used alongside weather forecasts in various fields of research; however, ground observation of cloud cover is conducted by human observers, a method that is subjective and has low temporal and spatial resolutions. To address these problems, we have developed an improved algorithm to calculate cloud cover using sky image data obtained with Skyviewer equipment. The algorithm uses a variable threshold for the Red Blue Ratio (RBR), determined from the frequency distribution of the Green Blue Ratio (GBR), to calculate cloud cover more accurately than existing algorithms. To verify the accuracy of the algorithm, we conducted daily, monthly, seasonal, and yearly statistical analyses of human observations of cloud cover, obtained every hour from 0800 to 1700 Local Standard Time (LST) for the entirety of 2012 at the Gangwon Regional Meteorological Administration (GRMA), Korea. A case study compared daily images taken at 1200 LST in each season with pixel images of cloud cover calculated by our improved algorithm. The selected cases yielded a high correlation coefficient of 0.93 with the GRMA data. A monthly case study showed low root mean square errors (RMSEs) and high correlation coefficients (Rs) for December (RMSE = 1.64 tenths and R = 0.92) and August (RMSE = 1.43 tenths and R = 0.91). In addition, seasonal cases yielded a high correlation of 0.9 and 87% consistency within ± 2 tenths for winter and a correlation of 0.83 and 82% consistency for summer, when cases of cloud-free or overcast conditions are frequent. Annual analyses showed that the bias of GRMA and Skyviewer cloud cover data for 2012 was -0.36 tenth, and the RMSE was 2.12 tenths, with the GRMA data showing more cloud cover. Considering that the GRMA and Skyviewer data were gathered at different spatial locations, GRMA and Skyviewer data were well correlated (R = 0.87) and showed a consistency of 80% in their cloud cover data (consistent within ± 2 tenths).     

Tsunami research in Korea

The tsunamis that have occurred in many places around the world over the past decades have taken a heavy toll on human lives and property. The eastern coast of the Korean Peninsula is not safe from tsunamis and has sustained tsunami damage in the past. The aim of this study is to review the past, present, and future of some aspects of tsunami research in Korea. A composite numerical model comprising propagation and inundation models is described. The paper also covers tsunami mitigation efforts in Korea, and a tsunami hazard map is developed and introduced.     

Monitoring trace metals in seawater using a diffusive gradient in thin film probe in Ulsan Bay,East Sea,Korea: Comparison with transplanted mussels

To evaluate the applicability of a diffusive gradient in thin film (DGT) probe for monitoring dissolved metals in coastal seawater, DGT-labile metal concentrations were compared with total dissolved metal concentrations using spiked and natural seawater samples in the laboratory and transplanted mussels (Mytilus galloprovincialis). This was achieved through the simultaneous deployment of DGT probes and transplanted mussels in Ulsan Bay during winter and summer. DGT-labile metal concentrations were 45% (Cu) ~ 90% (Zn) of total dissolved concentrations, and the order of non-labile concentrations was Cu > Pb > Co ~ Ni > Cd ~ Zn in both metal-contaminated and non-contaminated seawater samples, which was similar to the order of stability of metal complexes in the Irving–Williams series. The overall variability of the DGT probe results within and between tanks was less than 10% (relative standard deviation: RSD) for all the metals tested during a 48-h deployment. The accumulation of metals, as determined by DGT probes, represented the spatial gradients better than the transplanted mussels did for all of the metals tested, and the extent of metal accumulation in mussels differed depending on the metal. The comparison of results for the DGT probe and the transplanted mussels in two seasons (winter and summer) suggested that metal accumulation in mussels was controlled by the physiological factors of mussels and partly by their diet (particulate metal loadings). The DGT probe could be used as a monitoring tool for dissolved metals in coastal seawater because its results explained only labile species. When using the DGT probe, slightly more than half of the total dissolved concentration in seawater samples for all the metals investigated displayed timeintegrated properties and distinct spatial gradients from pristine to metal-contaminated seawater.     

Land response to atmosphere at different resolutions in the common land model over East Asia

Towards a better understanding of hydrological interactions between the land surface and atmosphere, land surface models are routinely used to simulate hydro-meteorological fluxes. However, there is a lack of observations available for model forcing, to estimate the hydro-meteorological fluxes in East Asia. In this study, Common Land Model (CLM) was used in offline-mode during the summer monsoon period of 2006 in East Asia, with different forcings from Asiaflux, Korea Land Data Assimilation System (KLDAS), and Global Land Data Assimilation System (GLDAS), at point and regional scales, separately. The CLM results were compared with observations from Asiaflux sites. The estimated net radiation showed good agreement, with r =0.99 for the point scale and 0.85 for the regional scale. The estimated sensible and latent heat fluxes using Asiaflux and KLDAS data indicated reasonable agreement, with r = 0.70. The estimated soil moisture and soil temperature showed similar patterns to observations, although the estimated water fluxes using KLDAS showed larger discrepancies than those of Asiaflux because of scale mismatch. The spatial distribution of hydro-meteorological fluxes according to KLDAS for East Asia were compared to the CLM results with GLDAS, and the GLDAS provided online. The spatial distributions of CLM with KLDAS were analogous to CLM with GLDAS, and the standalone GLDAS data. The results indicate that KLDAS is a good potential source of high spatial resolution forcing data. Therefore, the KLDAS is a promising alternative product, capable of compensating for the lack of observations and low resolution grid data for East Asia.     

Integrated coastal resources management and community participation in a small island setting

The concept of integrated coastal zone management must be rethought to adapt it to the geography and social conditions of small islands. Because of their size, all small islands are in the coastal zone. Defining the whole of the island and its coastal waters as the management area may weaken a program's effectiveness. An alternative may be to adapt special area management planning to the socio-spatial organization found on small islands. Social conditions on islands, where people live in relatively small cohesive communities, makes resource user participation in planning and management particularly germane. This paper outlines an argument for small islands to use participation as a central strategy of coastal management based on experience with natural resource management efforts on the island of Pohnpei in the Federated States of Micronesia.     

Seasonal Dynamics of Phytoplankton and Environmental Factors around the Chagwi-do off the West Coast of Jeju Island,Korea

The dynamics of phytoplankton abundance with seasonal variation in physicochemical conditions were investigated monthly at 10 stations around the Chagwi-do off the west coast of Jeju Island, Korea, including inshore, middle shore, and offshore in the marine ranching area from September 2004 to November 2005. Water temperature varied from 12.1 to 28.9°C (average 18.8°C), and salinity from 28.9 to 34.9 psu (average 33.7 psu). The chlorophyll a concentration was 0.02-2.05 μg L¹ (average 0.70 μg L¹), and the maximum concentration occurred in the bottom layer in April. A total of 294 phytoplankton species belonging to 10 families was identified: 182 Bacillariophyceae, 52 Dinophyceae, 9 Chlorophyceae, 12 Cryptophyceae, 6 Chrysophyceae, 4 Dictyophyceae, 13 Euglenophyceae, 6 Prymnesiophyceae, 5 Prasinophyceae, and 5 Raphidophyceae. The standing crop was 2.21-48.69x10⁴ cells L¹ (average 9.23x 10⁴ cells L¹), and the maximum occurred in the bottom layer in April. Diatoms were most abundant throughout the year, followed by dinoflagellates and phytoflagellates. A phytoplankton bloom occurred twice: once in spring, peaking in April, and once in autumn, peaking in November. The spring bloom was represented by fourChaetoceros species andSkeletonema costatum; each contributed 10–20% of the total phytoplankton abundance. The autumn bloom comprised dinoflagellates, diatoms, and phytoflagellates, of which dinoflagellates were predominant.Gymnodinium conicum, Prorocentrum micans, andP. triestinum each contributed over 10% of the total phytoplankton abundance.