Estimation and Projection of Non-Linear Relative Sea-Level Rise in the Seto Inland Sea,Japan

Future sea-level rise (SLR) in and around the Seto Inland Sea (SIS), Japan, is estimated in 2050 and 2100 using ensemble empirical mode decomposition (EEMD) and long-term sea-level records. Ensemble empirical mode decomposition, an adaptive data analysis method, can separate sea-level records into intrinsic mode functions (IMFs) from high to low frequencies and a residual. The residual is considered a non-linear trend in the sea-level records. The mean SLR trend at Tokuyama in the SIS from EEMD is 3.00?mm?y^?1 from 1993 to 2010, which is slightly lower than the recent altimetry-based global rate of 3.3?±?0.4?mm?y^?1 during the same period. Uncertainty in SLR is estimated by considering interdecadal variations in the sea levels. The resulting SLR in 2050 and 2100 for Tokuyama is 0.19?±?0.06?m and 0.56?±?0.18?m, respectively. The stations along the coast of the Pacific Ocean display a greater and more rapid SLR in 2100 compared with other stations in the SIS. The SLR is caused not only by mass and volume changes in the sea water but also by other factors, such as local subsidence, tectonic motion, and river discharge. The non-linear trend of SLR, which is the residual from EEMD, is interpreted as the sum of the local factors that contribute to the sea-level budget.     

Evaluation of cloud and precipitation parameterization using a single-column model: A TWP-ICE case study

Cloud and precipitation parameterization schemes are evaluated, and their sensitivity to the method and/or parameters used to determine cloud physical processes is examined using a singlecolumn version of the Unified Model (SCUM). In the experiment for TWP-ICE, cloud fraction is overestimated (underestimated) in the upper (lower) troposphere due to the wet (dry) bias. The precipitation rate is well simulated during the active monsoon period, but overestimated during the suppressed monsoon and clear skies periods. In the moist convection scheme, trigger condition and entrainment process affect the lower tropospheric humidity through the impact on convective occurrence frequency and intensity, respectively. Strengthening the trigger condition and using the adaptive entrainment method alleviate the low-level dry bias. In the microphysics scheme, more large-scale precipitation is produced with prognostic rain, due to rain sedimentation considering vertical velocity of rain drop, than with diagnostic rain. Less ice/snow deposition with the prognostic two-ice category results in lower ice water content and upper-level cloud fraction than with the diagnostic splitting method for the twoice category. In the cloud macrophysics scheme, the prognostic cloud fraction and cloud/ice water content scheme produces a larger cloud fraction and more cloud/ice water content than the diagnostic scheme, mainly due to detrainment from moist convection (cloud source) that surpasses the effect of convective heating and drying (cloud sink). This affects temperature by influencing the radiative, convective, and microphysical processes. The experiment with combined modifications in cloud and precipitation schemes shows that interaction between modified moist convection and cloud macrophysics schemes results in more alleviation of the cold bias not only at the lower levels but also at the upper levels.     

A study on the transition mechanism of a stratus cloud into a warm sea fog using a single column model PAFOG coupled with WRF

The transition mechanism of stratus cloud into warm sea fog over the Yellow Sea near the western coastal area of the Korean Peninsula is investigated using numerical simulation with a 1D turbulence model, PAFOG, coupled with a 3D regional model, WRF. The coupled model system was run in the two approaches, Eulerian and Lagrangian. For the selected warm sea fog case, the model results in the Eulerian approach showed that the bottom of the stratus cloud was lowered by cooling of the air just below the cloud base by turbulent heat loss. The Lagrangian approach showed the lowering of the stratus cloud top, owing to the evaporation of cloud droplets in this region by the entrainment of warm and dry air above the cloud top. The sensitivity test to SST indicated that the timing of water vapor saturation just below the cloud base depended on the magnitude of the turbulent heat flux from the sea surface. The subsidence rate was found to be important: when the subsidence rate was set to be half of the prescribed value, neither the lowering of the stratus cloud top nor the bottom occurred and the model could not produce a fog.     

Chemical Composition Based Aerosol Optical Properties According to Size Distribution and Mixture Types during Smog and Asian Dust Events in Seoul,Korea

This study investigated the optical properties of aerosols involved in different meteorological events, including smog and Asian dust days. Carbonaceous components and inorganic species were measured in Seoul, Korea between 25 and 31 March 2012. Based on the measurements, the optical properties of aerosols were calculated by considering composition, size distribution, and mixing state of aerosols. To represent polydisperse size distributions of aerosols, a lognormal size distribution with a wide range of geometric mean diameters and geometric standard deviations was used. For the optical property calculations, the Mie theory was used to compute single-scattering properties of aerosol particles with varying size and composition. Analysis of the sampled data showed that the water-soluble components of organic matter increased on smog days, whereas crustal elements increased on dust days. The water content significantly influenced the optical properties of aerosols during the smog days as a result of high relative humidity and an increase in the water-soluble component. The absorption coefficients depended on the aerosol mixture type and the aerosol size distributions. Therefore, to improve our knowledge on radiative impacts of aerosols, especially the regional impacts of aerosols in East Asia, accurate measurements of aerosols, such as size distribution, composition, and mixture type, under different meteorological conditions are required.     

A budget analysis of NO x column losses over the Korean peninsula

In this study, the chemical and physical losses of nitrogen oxides (NO_x) over the Korean peninsula were discussed in order to better understand the effects of the NO_x losses on the tropospheric NO₂ columns. Initially, it was found that the physical loss processes due to dry and wet depositions had almost negligible impacts on the NO_x loss processes over the Korean peninsula. In contrast, the hourly NO_x chemical column losses were large at ??10¹⁴ molecules cm^?2 h^?1. The amounts of NO_x removed for 1 hour account for approximately 33?C35% of the episode-averaged tropospheric NO₂ columns during summer over the Korean peninsula. The NO_x chemical column loss rates were 24.1?C70.9 times larger than the NO_x physical column loss rates. In a budget analysis of the NO_x chemical column losses, HNO₃ formation via the reaction of OH + NO₂ had the largest contribution toward the NO_x chemical losses (42?C55% during fall and winter seasons; 76?C77% during spring; 92?C93% during summer). Large amounts of NO_x were also removed by heterogeneous nitrate formation via N₂O₅ condensation during the cold seasons (42?C56%) over the Korean peninsula. The columnar NO_x chemical losses took place mainly due to the two chemico-physical reaction processes, and also showed seasonal variations. PAN (Peroxyacetyl Nitrate) is another NO₂ reservoir of potential importance. If the influence of the PAN-related chemistry on the NO_x budget is considered, it can result in an approximate 69% increase in the NO_x chemical column loss during summer. Such increases in the amounts of NO_x removed for 1 hour due to the formation of PAN were equivalent to 56?C58% of the episode-averaged tropospheric NO₂ columns during summer over the Korean peninsula. Such active NO_x chemical losses during summer are another main factor for the tropospheric NO₂ columns exhibiting their smallest values during summer.     

An assessment of future dryness over Korea based on the ECHAM5-RegCM3 model chain under A1B emission scenario

We analyze the future dryness over Korea based on the projected temperature and precipitation. For fine-scale climate information, the ECHAM5/MPI-OM A1B simulation has been dynamically downscaled using the RegCM3 double-nested system. A 130-year long-term climatology (1971?C2100) from the mother domain (East Asia: 60 km) and nested domain (South Korea: 20 km) is discussed. Based on the intercomparison with CMIP3 participant models, the ECHAM5/MPI-OM provides climatic change information over the East Asia that is not markedly different from other projections. However, the reduction of summer precipitation over Korea is rather different with ensemble mean of CMIP3 participant models. The downscaled results generally follow the behavior of ECHAM5/MPIOM, but substantial fine-scale details are found in the spatial pattern and the change signals become more enhanced at the local scale. In the future projection, significant warming is found regardless of the season and region while the change in precipitation shows a mixed feature with both increasing and decreasing patterns. The increase of temperature enhances the evapotranspiration, and hence the actual water stress becomes more pronounced in the warmer climate. This is related to the negative trends of the self-calibrating Palmer Drought Severity Index (PDSI) to measure the drought condition in Korea. Although PDSI is overall associated with the precipitation variation, its long-term trend tends to be modulated by the temperature trend. It is confirmed that the detrended temperature is shown to mask the decreasing tendency of the PDSI. The result indicates that without an increase in precipitation appropriate for atmospheric moisture demand, future dryness is a more likely condition under global warming.     

Local Meteorological and Synoptic Characteristics of Fogs Formed over Incheon International Airport in the West Coast of Korea

Fogs observed over Incheon international airport (IIA) in the westcoast of Korea from January 2002 to August 2006 are classified into categoriesof coastal fog, cold sea fog, and warm sea fog based on the areal extent of thefogs and the difference between the air temperature (T) and the SST, i.e.,cold sea fog if TSST = T-SST>0^oC and warm sea fog if TSST<0^oC. The numbers of coastal, cold, and warm sea fog casesare 64, 26, and 9. Coastal fogs form most frequently in winter, while cold seafogs occur mostly in summer and warm sea fogs are observed from January to Maybut not in November and December. On average the air gets colder by1.6^oC during the three hours leading up to the coastal fogformation, and an additional cooling of 1.1^oC occurs during thefog. The change in the dew point temperature (T_d) is minimal exceptduring the fog (0.6^oC). Decreases in T for the cold and warmsea fogs are relatively smaller. The average T_d is higher than SSTduring the cold sea fog periods but this T_d is more than4^oC higher than that for the corresponding non-fog days,suggesting that cold sea fogs be formed by the cooling of already humid air(i.e., T_d>SST). Increases of T_d are significant during thewarm sea fog periods (1.4^oC), implying that efficient moisturesupply is essential to warm sea fog formation. Four major synoptic patterns areidentified in association with the observed fogs. The most frequent is a northPacific high that accounts for 38% of cases. Surface or upper inversions arepresent in 77%, 69%, and 81% of the fog periods for coastal, cold, andwarm sea fogs, respectively.     

Machine learning approaches to coastal water quality monitoring using GOCI satellite data

Since coastal waters are one of the most vulnerable marine systems to environmental pollution, it is very important to operationally monitor coastal water quality. This study attempts to estimate two major water quality indicators, chlorophyll-a (chl-a) and suspended particulate matter (SPM) concentrations, in coastal environments on the west coast of South Korea using Geostationary Ocean Color Imager (GOCI) satellite data. Three machine learning approaches including random forest, Cubist, and support vector regression (SVR) were evaluated for coastal water quality estimation. In situ measurements (63 samples) collected during four days in 2011 and 2012 were used as reference data. Due to the limited number of samples, leave-one-out cross validation (CV) was used to assess the performance of the water quality estimation models. Results show that SVR outperformed the other two machine learning approaches, yielding calibration R² of 0.91 and CV root-mean-squared-error (RMSE) of 1.74 mg/m³ (40.7%) for chl-a, and calibration R² of 0.98 and CV RMSE of 11.42 g/m³ (63.1%) for SPM when using GOCI-derived radiance data. Relative importance of the predictor variables was examined. When GOCI-derived radiance data were used, the ratio of band 2 to band 4 and bands 6 and 5 were the most influential input variables in predicting chl-a and SPM concentrations, respectively. Hourly available GOCI images were useful to discuss spatiotemporal distributions of the water quality parameters with tidal phases in the west coast of Korea.     

Competitive adsorption of strontium and fulvic acid at the muscovite-solution interface observed with resonant anomalous X-ray reflectivity

Molecular-scale distributions of Sr²⁺ and fulvic acid (FA) adsorbed on the muscovite (0 0 1) surface were investigated using in situ specular X-ray reflectivity (XR) and resonant anomalous X-ray reflectivity (RAXR). The total amount of Sr²⁺ adsorbed from a 1 × 10⁻² mol/kg SrCl₂ and 100 mg/kg Elliott Soil Fulvic Acid II (ESFA II) solution at pH 5.5 compensated 81 ± 5% of the muscovite surface charge, less than previously measured (118 ± 5%) in an ESFA II-free solution with the same Sr concentration and pH. Inner-sphere (IS) and outer-sphere (OS) Sr²⁺ constituted 87% of the total adsorbed species in IS:OS proportions of 19:81 compared to 42:58 in the solution without FA, suggesting that adsorbed FA competes with the IS Sr²⁺ for surface sites. The coverage of both IS and OS Sr²⁺ decreased even more in a pH 3.5 solution containing the same concentration of FA and 0.5 × 10⁻² mol/kg Sr(NO₃)₂, whereas a significant amount of Sr²⁺ accumulated farther from the surface in the FA layer. The amount of Sr²⁺ incorporated in the ∼10 Å thick FA layer decreased by 79% with decreasing FA concentration (100 → 1 mg/kg) and increasing Sr²⁺ concentration (0.5 × 10⁻² → 1 × 10⁻² mol/kg) and pH (3.5 → 3.6). These results indicate not only that adsorbed FA molecules (and perhaps also H₃O⁺) displace Sr²⁺ near the muscovite surface, but also that the sorbed FA film provides binding sites for additional Sr²⁺ away from the surface. When a muscovite crystal pre-coated with FA after reaction in a 100 mg/kg ESFA II solution for 50 h was subsequently reacted with a 0.5 × 10⁻² mol/kg Sr(NO₃)₂ and 100 mg/kg ESFA II solution at pH 3.7, a significant fraction of Sr²⁺ was distributed in the outer part of the FA film similar to that observed on fresh muscovite reacted at pH 3.5 with a pre-mixed Sr-FA solution at the same concentrations. However, this Sr²⁺ sorbed in the pre-adsorbed organic film was more widely distributed and had a lower coverage, suggesting that pre-sorbed FA may undergo fractionation and/or conformational changes that diminish its capacity, and that of the muscovite (0 0 1) surface, for adsorbing the aqueous Sr cation.     

Diagenesis of the Lower Cretaceous Kanmon Group sandstones, SW Japan

The Kanmon Group (Lower Cretaceous) is a non-marine sequence in the Inner Zone of southwest Japan and is divided into the lower Wakino (lacustrine) and the upper Shimonoseki (fluvial) subgroups. Major diagenetic changes in this group are compaction, iron-oxide cementation, calcite cementation and grain replacement, quartz overgrowth and pore-fill cementation, illite authigenesis, chlorite pore-fill cementation and grain replacement, albitization of feldspar, and grain replacement by pyrite. Two subgroups of the Kanmon Group present no significant differences in general diagenetic features, paragenetic sequence, or the degree of diagenetic changes despite differences in depositional environments (lacustrine vs. fluvial) and stratigraphic positions. However, some differences are recognized in the content and chemistry of authigenic minerals caused by different sandstone framework compositions. The content of authigenic clay minerals is higher in sandstones of the Shimonoseki Subgroup containing abundant volcanic rock fragments. In addition, the composition of chlorite, the most abundant authigenic clay mineral in Kanmon sandstones, is Mg-rich in the volcanoclastic Shimonoseki sandstones, compared to an Fe-rich variety in Wakino sandstones. The original sandstone composition played a significant role in pore-water composition and diagenetic reactions.The Wakino sandstones lost most of its porosity by compaction, whereas Shimonoseki sandstones are only compacted in the vicinity of the basin-bounding fault. The weakly compacted Shimonoseki sandstones, instead, were largely cemented by pore-filling calcite during early diagenesis; cementation prevented compaction during further burial. The Kanmon Group sediments were heated to about 300 °C based on illite crystallinity values.