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Ozone (O3) is an important secondary pollutant that impacts air quality and human health. Eastern Asia has high regional O3 background due to the numerous sources and increasing and rapid industrial growth, which also impacts the Seoul Metropolitan Area (SMA). However, the SMA has also been experiencing increasing O3 driven by decreasing NOx emissions, highlighting the role of the local in situ O3 production on the SMA. Here, comprehensive gas-phase measurements collected on the NASA DC-8 during the National Institute of Environmental Research (NIER)/NASA Korea–United States Air Quality (KORUS-AQ) study are used to constrain the instantaneous O3 production rate over the SMA. The observed NOx oxidized products support the importance of non-measured peroxy nitrates (PNs) in the O3 chemistry in the SMA, as they accounted for ∼49 % of the total PNs. Using the total measured PNs (ΣPNs) and alkyl and multifunctional nitrates (ΣANs), unmeasured volatile organic compound (VOC) reactivity (R(VOC)) is constrained and found to range from 1.4–2.1 s−1. Combining the observationally constrained R(VOC) with the other measurements on the DC-8, the instantaneous net O3 production rate, which is as high as ∼10 ppbv h−1, along with the important sinks of O3 and radical chemistry, is constrained. This analysis shows that ΣPNs play an important role in both the sinks of O3 and radical chemistry. Since ΣPNs are assumed to be in a steady state, the results here highlight the role that ΣPNs play in urban environments in altering the net O3 production, but ΣPNs can potentially lead to increased net O3 production downwind due to their short lifetime (∼1 h). The results provide guidance for future measurements to identify the missing R(VOCs) and ΣPN production.

The interaction between clouds and radiation is a key process within the climate system, and assessing the impacts of that interaction provides valuable insights into both the present-day climate and future projections. Many modeling experiments have been designed over the years to probe the impact of the cloud radiative effect (CRE) on the climate, including those that seek to disrupt the mean CRE effect and those that only disrupt the covariance of the CRE with the circulation. Seven such experimental designs have been added to the Energy Exascale Earth System Model version 1 (E3SMv1) of the US Department of Energy. These experiments include both the first and second iterations of the Clouds On/Off Klimate Intercomparison Experiment (COOKIE) experimental design, as well as the cloud-locking method. This paper documents the code changes necessary to implement such experiments and also provides detailed instructions for how to run them. Analyses across experiment types provide valuable insights and confirm the findings of prior studies, including the role of cloud radiative heating toward intensifying the monsoon, intensifying rain rates, and poleward expansion of the general circulation owing to cloud feedbacks.

In this study, the WRF-Chem v4.4 model was utilized to evaluate the sensitivity of O3 simulations with three bottom-up emission inventories (EDGAR-HTAP v2 and v3 and KORUS v5) using surface and aircraft data in East Asia during the Korea-United States Air Quality (KORUS-AQ) campaign period in 2016. All emission inventories were found to reproduce the diurnal variations of O3 and its main precursor NO2 as compared to the surface monitor data. However, the spatial distributions of the daily maximum 8 h average (MDA8) O3 in the model do not completely align with the observations. The model MDA8 O3 had a negative (positive) bias north (south) of 30° N over China. All simulations underestimated the observed CO by 50 %–60 % over China and South Korea. In the Seoul Metropolitan Area (SMA), EDGAR-HTAP v2 and v3 and KORUS v5 simulated the vertical shapes and diurnal patterns of O3 and other precursors effectively, but the model underestimated the observed O3, CO, and HCHO concentrations. Notably, the model aromatic volatile organic compounds (VOCs) were significantly underestimated with the three bottom-up emission inventories, although the KORUS v5 shows improvements. The model isoprene estimations had a positive bias relative to the observations, suggesting that the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.04 overestimated isoprene emissions. Additional model simulations were conducted by doubling CO and VOC emissions over China and South Korea to investigate the causes of the model O3 biases and the effects of the long-range transport on the O3 over South Korea. The doubled CO and VOC emission simulations improved the model O3 simulations for the local-emission-dominant case but led to the model O3 overestimations for the transport-dominant case, which emphasizes the need for accurate representations of the local VOC emissions over South Korea.

Several studies have reported an increasing trend of surface ozone in South Korea over the past few decades, using different measurement metrics. In this study, we examined the surface ozone trends in South Korea by analyzing the hourly or daily maximum 8 h average ozone concentrations (MDA8) measured at the surface from 2001 to 2021. We studied the diurnal, seasonal, and multi-decadal variations of these parameters at city, province, and background sites. We found that the fourth-highest MDA8 values exhibited positive trends in seven cities, nine provinces, and two background sites from 2001 to 2021. For the majority of sites, there was an annual increase of approximately 1–2 ppb. After early 2010, all sites consistently recorded MDA8 values exceeding 70 ppb, despite reductions in precursor pollutants such as NO2 and CO. The diurnal and seasonal characteristics of ozone exceedances, defined as the percentage of data points with hourly ozone concentrations exceeding 70 ppb, differed between the Seoul Metropolitan Area (SMA) and the background sites. In the SMA, the exceedances were more prevalent during summer compared to spring, whereas the background sites experienced higher exceedances in spring than in summer. This indicates the efficient local production of ozone in the SMA during summer and the strong influence of long-range transport during spring. The rest of the sites showed similar exceedance patterns during both spring and summer. The peak exceedances occurred around 16:00–17:00 in the SMA and most locations, while the background sites primarily recorded exceedances throughout the night. During the spring of the COVID-19 pandemic (2020–2021), ozone exceedances decreased at most locations, potentially due to significant reductions in NOx emissions in South Korea and China compared to the period of 2010–2019. The largest decreases in exceedances were observed at the background sites during spring. For instance, in Gosung, Gangwondo (approximately 600 m above sea level), the exceedances dropped from 30 % to around 5 % during the COVID-19 pandemic. Regional model simulations confirmed the concept of decreased ozone levels in the boundary layer in Seoul and Gangwon-do in response to emission reductions. However, these reductions in ozone exceedances were not observed in major cities and provinces during the summer of the COVID-19 pandemic, as the decreases in NOx emissions in South Korea and China were much smaller compared to spring. This study highlights the distinctions between spring and summer in the formation and transport of surface ozone in South Korea, emphasizing the importance of monitoring and modeling specific processes for each season or finer timescales.

As part of the national space promotion plan and presidential national agendas South Korea’s institutes and agencies under the auspices of the Ministry of Science, Information and Communication Technology and Future Planning (MSIP) are currently developing a lunar mission package expected to reach Moon in 2020. While the officially approved Korean Pathfinder Lunar Orbiter (KPLO) is aimed at demonstrating technologies and monitoring the lunar environment from orbit, a lander – currently in pre-phase A – is being designed to explore the local geology with a particular focus on the detection and characterization of mineral resources. In addition to scientific and potential resource potentials, the selection of the landing-site will be partly constrained by engineering constraints imposed by payload and spacecraft layout. Given today’s accumulated volume and quality of available data returned from the Moon’s surface and from orbital observations, an identification of landing sites of potential interest and assessment of potential hazards can be more readily accomplished by generating synoptic snapshots through data integration. In order to achieve such a view on potential landing sites, higher level processing and derivation of data are required, which integrates their spatial context, with detailed topographic and geologic characterizations. We are currently assessing the possibility of using fuzzy c-means clustering algorithms as a way to perform (semi-) automated terrain characterizations of interest. This paper provides information and background on the national lunar lander program, reviews existing approaches – including methods and tools – for landing site analysis and hazard assessment, and discusses concepts to detect and investigate elemental abundances from orbit and the surface. This is achieved by making use of manual, semi-automated as well as fully-automated remote-sensing methods to demonstrate the applicability of analyses. By considering given boundary conditions, concrete procedures for determining potential landing sites of the Korean lunar lander could be proposed.

We conduct several sets of simulations with a version of NASA's Goddard Earth Observing System, version 5, (GEOS-5) Atmospheric Global Climate Model (AGCM) equipped with a two-moment cloud microphysical scheme to understand the role of biomass burning aerosol (BBA) emissions in Southeast Asia (SEA) in the pre-monsoon period of February–May. Our experiments are designed so that both direct and indirect aerosol effects can be evaluated. For climatologically prescribed monthly sea surface temperatures, we conduct sets of model integrations with and without biomass burning emissions in the area of peak burning activity, and with direct aerosol radiative effects either active or inactive. Taking appropriate differences between AGCM experiment sets, we find that BBA affects liquid clouds in statistically significantly ways, increasing cloud droplet number concentrations, decreasing droplet effective radii (i.e., a classic aerosol indirect effect), and locally suppressing precipitation due to a deceleration of the autoconversion process, with the latter effect apparently also leading to cloud condensate increases. Geographical re-arrangements of precipitation patterns, with precipitation increases downwind of aerosol sources are also seen, most likely because of advection of weakly precipitating cloud fields. Somewhat unexpectedly, the change in cloud radiative effect (cloud forcing) at surface is in the direction of lesser cooling because of decreases in cloud fraction. Overall, however, because of direct radiative effect contributions, aerosols exert a net negative forcing at both the top of the atmosphere and, perhaps most importantly, the surface, where decreased evaporation triggers feedbacks that further reduce precipitation. Invoking the approximation that direct and indirect aerosol effects are additive, we estimate that the overall precipitation reduction is about 40% due to the direct effects of absorbing aerosols, which stabilize the atmosphere and reduce surface latent heat fluxes via cooler land surface temperatures. Further refinements of our two-moment cloud microphysics scheme are needed for a more complete examination of the role of aerosol–convection interactions in the seasonal development of the SEA monsoon.

A model of the radionuclide accumulation in fish taking into account the contribution of different tissues and allometry is presented. The basic model assumptions are as follows. (i) A fish organism is represented by several compartments in which radionuclides are homogeneously distributed. (ii) The compartments correspond to three groups of organs or tissues: muscle, bones and organs (kidney, liver, gonads, etc.) differing in metabolic function. (iii) Two input compartments include gills absorbing contamination from water and digestive tract through which contaminated food is absorbed. (iv) The absorbed radionuclide is redistributed between organs or tissues according to their metabolic functions. (v) The elimination of assimilated elements from each group of organs or tissues differs, reflecting differences in specific tissues or organs in which elements were accumulated. (vi) The food and water uptake rates, elimination rate, and growth rate depend on the metabolic rate, which is scaled by fish mass to the 3/4 power. The analytical solutions of the system of model equations describing dynamics of the assimilation and elimination of 134Cs, 57Co, 60Co, 54Mn and 65Zn, which are preferably accumulated in different tissues, exhibited good agreement with the laboratory experiments. The developed multi-compartment kinetic–allometric model was embedded into the box model POSEIDON-R (Maderich et al., 2018b), which describes transport of radionuclides in water, accumulation in the sediment and transfer of radionuclides through the pelagic and benthic food webs. The POSEIDON-R model was applied for the simulation of the transport and fate of 60Co and 54Mn routinely released from Forsmark Nuclear Power Plant (NPP) located on the Baltic Sea coast of Sweden and for calculation of 90Sr concentration in fish after the accident at Fukushima Dai-ichi NPP. Computed concentrations of radionuclides in fish agree with the measurements much better than calculated using standard whole-body model and target tissue model. The model with the defined generic parameters could be used in different marine environments without calibration based on a posteriori information, which is important for emergency decision support systems.

Besides its negative trend, the interannual and the interdecadal changes in the Arctic sea ice have also been pronounced in recent decades. The three leading modes in the sea level pressure (SLP) variability in the Arctic (70–90∘ N) – the Arctic Oscillation (AO), the Arctic Dipole (AD), and the third mode (A3) – are analyzed to understand the linkage between sea ice variability and large-scale atmospheric circulation in boreal summer (June–August). This study also compares the decadal changes of the modes between the early (1982–1997) and the recent (1998–2017) periods and their influences on the Arctic sea ice extent (SIE). Only the AD mode shows a significant correlation increase with SIE in summer (JJA) from −0.05 in the early period to 0.57 in the recent period. The AO and the A3 modes show a less significant relationship with SIE for the two periods. The AD is characterized by a dipole pattern of SLP, which modulates the strength of meridional surface winds and the Transpolar Drift Stream (TDS). The major circulation change in the late 1990s is that the direction of the wind has been changed more meridionally over the exit region of the Fram Strait, which causes sea ice drift and discharge through that region. In addition, the response of surface albedo and the net surface heat flux becomes larger and much clearer, suggesting a positive sea-ice–albedo feedback in the sea ice variability associated with the AD. The analysis also reveals that the zonal shift of the centers of SLP anomalies and associated circulation change affects a significant reduction in sea ice concentration over the Pacific sector of the Arctic Ocean. This study further suggests that the Pacific Decadal Oscillation (PDO) phase change could influence the spatial pattern change in the AD.

The dynamics and energetics of a head-on collision of internal solitary waves (ISWs) with trapped cores propagating in a thin pycnocline were studied numerically within the framework of the Navier–Stokes equations for a stratified fluid. The peculiarity of this collision is that it involves trapped masses of a fluid. The interaction of ISWs differs for three classes of ISWs: (i) weakly non-linear waves without trapped cores, (ii) stable strongly non-linear waves with trapped cores, and (iii) shear unstable strongly non-linear waves. The wave phase shift of the colliding waves with equal amplitude grows as the amplitudes increase for colliding waves of classes (i) and (ii) and remains almost constant for those of class (iii). The excess of the maximum run-up amplitude, normalized by the amplitude of the waves, over the sum of the amplitudes of the equal colliding waves increases almost linearly with increasing amplitude of the interacting waves belonging to classes (i) and (ii); however, it decreases somewhat for those of class (iii). The colliding waves of class (ii) lose fluid trapped by the wave cores when amplitudes normalized by the thickness of the pycnocline are in the range of approximately between 1 and 1.75. The interacting stable waves of higher amplitude capture cores and carry trapped fluid in opposite directions with little mass loss. The collision of locally shear unstable waves of class (iii) is accompanied by the development of instability. The dependence of loss of energy on the wave amplitude is not monotonic. Initially, the energy loss due to the interaction increases as the wave amplitude increases. Then, the energy losses reach a maximum due to the loss of potential energy of the cores upon collision and then start to decrease. With further amplitude growth, collision is accompanied by the development of instability and an increase in the loss of energy. The collision process is modified for waves of different amplitudes because of the exchange of trapped fluid between colliding waves due to the conservation of momentum.

The APEC Climate Center (APCC) produces climate prediction information utilizing a multi-climate model ensemble (MME) technique. In this study, four different downscaling methods, in accordance with the degree of utilizing the seasonal climate prediction information, were developed in order to improve predictability and to refine the spatial scale. These methods include: (1) the Simple Bias Correction (SBC) method, which directly uses APCC's dynamic prediction data with a 3 to 6 month lead time; (2) the Moving Window Regression (MWR) method, which indirectly utilizes dynamic prediction data; (3) the Climate Index Regression (CIR) method, which predominantly uses observation-based climate indices; and (4) the Integrated Time Regression (ITR) method, which uses predictors selected from both CIR and MWR. Then, a sampling-based temporal downscaling was conducted using the Mahalanobis distance method in order to create daily weather inputs to the Soil and Water Assessment Tool (SWAT) model. Long-term predictability of water quality within the Wecheon watershed of the Nakdong River Basin was evaluated. According to the Korean Ministry of Environment's Provisions of Water Quality Prediction and Response Measures, modeling-based predictability was evaluated by using 3-month lead prediction data issued in February, May, August, and November as model input of SWAT. Finally, an integrated approach, which takes into account various climate information and downscaling methods for water quality prediction, was presented. This integrated approach can be used to prevent potential problems caused by extreme climate in advance.

Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents–Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents–Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.

Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha) using normalized digital surface model (nDSM) from high resolution stereo photography (25cm resolution) and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM) was created by photogrammetric methods(aerial triangulation, digital image matching). Then, digital terrain model (DTM) was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.). Two independent variables from nDSM were used to estimate forest stand volume: crown density (%) and stand height (m). First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri’s ArcGIS and the USDA Forest Service’s FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s–present) will be produced using this stand volume estimation method and a historical imagery archive.

This study presents a novel bias correction scheme for regional climate model (RCM) precipitation ensembles. A primary advantage of using model ensembles for climate change impact studies is that the uncertainties associated with the systematic error can be quantified through the ensemble spread. Currently, however, most of the conventional bias correction methods adjust all the ensemble members to one reference observation. As a result, the ensemble spread is degraded during bias correction. Since the observation is only one case of many possible realizations due to the climate natural variability, a successful bias correction scheme should preserve the ensemble spread within the bounds of its natural variability (i.e. sampling uncertainty). To demonstrate a new bias correction scheme conforming to RCM precipitation ensembles, an application to the Thorverton catchment in the south-west of England is presented. For the ensemble, 11 members from the Hadley Centre Regional Climate Model (HadRM3-PPE) data are used and monthly bias correction has been done for the baseline time period from 1961 to 1990. In the typical conventional method, monthly mean precipitation of each of the ensemble members is nearly identical to the observation, i.e. the ensemble spread is removed. In contrast, the proposed method corrects the bias while maintaining the ensemble spread within the natural variability of the observations.

Southeast Asian seas span the largest archipelago in the global ocean and provide a complex oceanic pathway connecting the Pacific and Indian oceans. The Southeast Asian sea regional sea level trends are some of the highest observed in the modern satellite altimeter record that now spans almost 2 decades. Initial comparisons of global sea level reconstructions find that 17-year sea level trends over the past 60 years exhibit good agreement with decadal variability associated with the Pacific Decadal Oscillation and related fluctuations of trade winds in the region. The Southeast Asian sea region exhibits sea level trends that vary dramatically over the studied time period. This historical variation suggests that the strong regional sea level trends observed during the modern satellite altimeter record will abate as trade winds fluctuate on decadal and longer timescales. Furthermore, after removing the contribution of the Pacific Decadal Oscillation (PDO) to sea level trends in the past 20 years, the rate of sea level rise is greatly reduced in the Southeast Asian sea region. As a result of the influence of the PDO, the Southeast Asian sea regional sea level trends during the 2010s and 2020s are likely to be less than the global mean sea level (GMSL) trend if the observed oscillations in wind forcing and sea level persist. Nevertheless, long-term sea level trends in the Southeast Asian seas will continue to be affected by GMSL rise occurring now and in the future.

Optical measurements using ultraviolet–visible (UV–VIS) spectrophotometric sensors and fluorescent dissolved organic matter (FDOM) sensors have recently been used as proxies of dissolved organic carbon (DOC) concentrations in streams and rivers at a high temporal resolution. Despite the merits of the sensors, temperature changes and particulate matter in water can interfere with the sensor readings, over- or underestimating DOC concentrations. However, little efforts have been made to compare responses of the two types of the sensors to critical interferences such as temperature and turbidity. The performance of a UV–VIS sensor and an FDOM sensor was compared in both laboratory experiments and in situ monitoring in a forest stream in Korea during three storm events. Although the UV–VIS sensor did not require temperature correction in laboratory experiments using the forest stream water, the deviations of its values from the DOC concentrations measured with a TOC analyzer increased linearly as turbidity increased. In contrast, the FDOM sensor outputs decreased significantly as temperature or turbidity increased, requiring temperature and turbidity correction for in situ monitoring of DOC concentrations. The results suggest that temperature correction is relatively straightforward but turbidity correction may not be simple because the attenuation of light by particles can significantly reduce the sensitivity of the sensors in highly turbid waters. Shifts in composition of fluorophores also need to be carefully tracked using periodically collected samples since light absorbance and fluorescence can vary as the concentrations of dominant fluorophores change.

The tsunami generated on 12 July 1993 by the Hokkaido–Nansei–Oki earthquake (Mw = 7.8) brought about a maximum wave run-up of 31.7 m, the highest recorded in Japan during the 20th century, near the Monai Valley on the west coast of Okushiri Island (Hokkaido Tsunami Survey Group, 1993). To reproduce the extreme run-up height, the three-dimensional non-hydrostatic model (Flow Science, 2012), referred to here as the NH-model, has been locally applied with open boundary conditions supplied in an offline manner by the three-dimensional hydrostatic model (Ribeiro et al., 2011), referred to here as the H-model. The area of the H-model is sufficiently large to cover the entire fault region with one-way nested multiple domains. For the initial water deformation, Okada's fault model (1985) using the sub-fault parameters is applied. Three NH-model experiments have been performed, namely without islands, with one island and with two islands. The experiments with one island and with two islands give rise to values close to the observation with maximum run-up heights of about 32.3 and 30.8 m, respectively, while the experiment without islands gives rise to about 25.2 m. The diffraction of the tsunami wave primarily by Muen Island, located in the south, and the southward topographic guiding of the tsunami run-up at the coast are, as in the laboratory simulation (Yoneyama et al., 2002), found to result in the extreme run-up height near Monai Valley. The presence of Hira Island enhances the diffraction of tsunami waves but its contribution to the extreme run-up height is marginal.

The Southern Hemisphere Westerlies (SHW) play a crucial role in large-scale ocean circulation and global carbon cycling. Accordingly, the reconstruction of how the latitudinal position and intensity of the SHW belt changed during the last glacial termination is essential for understanding global climatic fluctuations. The southernmost part of the South American continent is the only continental mass intersecting a large part of the SHW belt. However, due to the scarcity of suitable palaeoclimate archives continuous proxy records back to the last glacial are rare in southern Patagonia. Here, we show an oxygen isotope record from cellulose and purified bulk organic matter of submerged aquatic moss shoots from Laguna Potrok Aike (52° S, 70° W), a deep maar lake located in semi-arid, extra-Andean Patagonia, covering the last glacial–interglacial transition (26 000 to 8500 cal BP). Based on the highly significant correlation between oxygen isotope values of modern aquatic mosses and their host waters and abundant well-preserved moss remains in the sediment record a high-resolution reconstruction of the lake water oxygen isotope (δ18Olw-corr) composition is presented. The reconstructed δ18Olw-corr values for the last glacial are ca. 3‰ lower than modern values, which can best be explained by generally cooler air temperatures and changes in the moisture source area, together with the occurrence of permafrost leading to a prolonged lake water residence time. Thus, the overall glacial δ18Olw-corr level until 21 000 cal BP is consistent with a scenario of weakened or absent SHW at 52° S compared to the present. During the last deglaciation, reconstructed δ18Olw-corr values reveal a significant two-step rise describing the detailed response of the lake's hydrological balance to this fundamental climatic shift. Rapid warming is seen as the cause of the first rise of ca. 2&permil, in δ18Olw-corr during the first two millennia of deglaciation (17 600 to 15 600 cal BP) owing to more 18O enriched precipitation and increasing temperature-induced evaporation. Following this interpretation, an early strengthening of the SHW would not be necessary. The subsequent decrease in δ18Olw-corr by up to 0.7‰ marks a millennial-scale transition period between 15 600 and 14 600 cal BP interpreted as the transition from a system driven by temperature-induced evaporation to a system more dominated by wind-induced evaporation. The δ18Olw-corr record resumes its pronounced increase around 14 600 cal BP. This further cumulative enrichment in 18O of lake water could be interpreted as response to strengthened wind-driven evaporation as induced by the intensification and establishment of the SHW at the latitude of Laguna Potrok Aike (52° S) since 14 600 cal BP. δ18Olw-corr approaching modern values around 8500 cal BP reflect that the SHW exerted their full influence on the lake water balance at that time provoking a prevailing more arid steppe climate in the Laguna Potrok Aike region.

Sulfur hexafluoride (SF6) has a global warming potential of around 22 800 over a 100-year time horizon and is one of the greenhouse gases regulated under the Kyoto Protocol. Around the year 2000 there was a reversal in the global SF6 emission trend, from a decreasing to an increasing trend, which was likely caused by increasing emissions in countries that are not obligated to report their annual emissions to the United Nations Framework Convention on Climate Change. In this study, SF6 emissions during the period 2006–2012 for all East Asian countries – including Mongolia, China, Taiwan, North Korea, South Korea and Japan – were determined by using inverse modeling and in situ atmospheric measurements. We found that the most important sources of uncertainty associated with these inversions are related to the choice of a priori emissions and their assumed uncertainty, the station network as well as the meteorological input data. Much lower uncertainties are due to seasonal variability in the emissions, inversion geometry and resolution, and the measurement calibration scale. Based on the results of these sensitivity tests, we estimate that the total SF6 emission in East Asia increased rapidly from 2404 ± 325 Mg yr−1 in 2006 to 3787 ± 512 Mg yr−1 in 2009 and stabilized thereafter. China contributed 60–72% to the total East Asian emission for the different years, followed by South Korea (8–16%), Japan (5–16%) and Taiwan (4–7%), while the contributions from North Korea and Mongolia together were less than 3% of the total. The per capita SF6 emissions are highest in South Korea and Taiwan, while the per capita emissions for China, North Korea and Japan are close to global average. During the period 2006–2012, emissions from China and from South Korea increased, while emissions from Taiwan and Japan decreased overall.

We present a hierarchical Bayesian method for atmospheric trace gas inversions. This method is used to estimate emissions of trace gases as well as "hyper-parameters" that characterize the probability density functions (PDFs) of the a priori emissions and model-measurement covariances. By exploring the space of "uncertainties in uncertainties", we show that the hierarchical method results in a more complete estimation of emissions and their uncertainties than traditional Bayesian inversions, which rely heavily on expert judgment. We present an analysis that shows the effect of including hyper-parameters, which are themselves informed by the data, and show that this method can serve to reduce the effect of errors in assumptions made about the a priori emissions and model-measurement uncertainties. We then apply this method to the estimation of sulfur hexafluoride (SF6) emissions over 2012 for the regions surrounding four Advanced Global Atmospheric Gases Experiment (AGAGE) stations. We find that improper accounting of model representation uncertainties, in particular, can lead to the derivation of emissions and associated uncertainties that are unrealistic and show that those derived using the hierarchical method are likely to be more representative of the true uncertainties in the system. We demonstrate through this SF6 case study that this method is less sensitive to outliers in the data and to subjective assumptions about a priori emissions and model-measurement uncertainties than traditional methods.

An ocean buoy, UBIM (Ulleung Basin Integrated Mooring), deployed during the spring transition from February to May 2010 reveals for the first time highly resolved temporal variation of biochemical properties of the upper layer of the Ulleung Basin in the southwestern East Sea/Sea of Japan. The time-series measurement captured the onset of subsurface spring bloom at 30 m, and collocated temperature and current data gives an insight into a mechanism that triggers the onset of the spring bloom not documented so far. Low-frequency modulation of the mixed layer depth ranging from 10 m to 53 m during the entire mooring period is mainly determined by shoaling and deepening of isothermal depths depending on the placement of UBIM on the cold or warm side of the frontal jet. The occurrence of the spring bloom at 30 m is concomitant with the appearance of colder East Sea Intermediate Water at buoy UBIM, which results in subsurface cooling and shoaling of isotherms to the shallower depth levels during the bloom period than those that occurred during the pre-bloom period. Isolines of temperature-based NO3 are also shown to be uplifted during the bloom period. It is suggested that the springtime spreading of the East Sea Intermediate Water is one of the important factors that triggers the subsurface spring bloom below the mixed layer.

A mesocosm experiment was conducted to evaluate the influence of photosynthetic performance on the energetic balance of coastal phytoplankton, in relation to community production and autotrophic phytoplankton biomass in future coastal oceans. Natural phytoplankton assemblages were incubated in field mesocosms under ambient condition (control: ca. 400 μatm CO2 and ambient temperature), and two sets of potential future ocean conditions (acidification: ca. 900 μatm CO2 and ambient temperature; greenhouse: ca. 900 μatm CO2 and 3 °C warmer). The photosynthetic performances were estimated by in vivo fluorometry (effective quantum yield (ΦPSII), steady-state light response curves (LCs)) and in situ incorporation of 14C (photosynthesis-irradiance curves). The ΦPSII and rETRm,LC (relative maximum electron transport rate) clearly reduced under acidification, in particular, when phytoplankton were exposed to high light levels. However, PBmax (maximum photosynthetic rate) was the same in the ambient and acidification conditions. Thus, phytoplankton utilized less light under acidification condition, but could still assimilate a similar amount of carbon compared to the ambient condition. The PBmax and α (photosynthetic efficiency) under greenhouse condition were significantly higher than those under ambient condition without any difference in ΦPSII, rETRm,LC and α,LC (electron transport efficiency) between the treatments. Therefore, phytoplankton utilized the same amount of light under greenhouse condition, but could assimilate more carbon than under ambient condition. As a result, Chl a normalized primary production was higher in greenhouse than in other conditions. Nevertheless, the community production did not change between the experimental treatments. The main reason for the lack of a change in primary production under future climate conditions is the control of autotrophic phytoplankton biomass by grazing. Consequently, acidification and greenhouse environments have a potential to increase growth and primary production of phytoplankton by enhancing inorganic carbon assimilation efficiency when top-down regulation is negligible.

The diurnal pattern of the vertical distribution of biogenic pollen in the lower troposphere was investigated by LIDAR. Meteorological data were taken at the ground. Pollen concentrations were measured at the surface using a Burkard 7-day-recording volumetric spore sampler. Aerosol extinction coefficients and depolarization ratios at 532 nm were obtained from LIDAR measurements in spring (4 May–2 June) 2009 in Gwangju, South Korea. Linear volume depolarization ratios varied between 0.08 and 0.14 and were observed only during daytime (09:00–17:00 local time (LT)) during days of high pollen concentration (4 to 9 May). Daily average pollen concentrations ranged 1000–2500 cm−3 in the same period. The temporal evolution of the vertical distribution of the linear volume depolarization ratio showed a specific diurnal pattern. Linear volume depolarization ratios of more than 0.06, were measured near the surface in the morning. High depolarization ratios were detected up to 2 km aboveground between 12:00 and 14:00 LT, whereas high depolarization ratios were observed only close to the surface after 17:00 LT. Low values of depolarization ratios (≤0.05) were detected after 18:00 LT until the next morning. During the measurement period, the daily variations of the high depolarization ratios close to the surface showed correlation to number concentration measurements of pollen. This finding suggests that high depolarization ratios could be attributed to enhanced pollen concentrations. The diurnal characteristics of the high values of depolarization ratios are thought to be closely associated with turbulent transport. Diurnal and vertical characteristics of pollen, if measured continuously, could be used to improve the accuracy of pollen-forecasting models via data assimilation studies.

The Ulleung Basin (UB), located in the southwestern part of the East/Japan Sea (EJS), is considered having an unusually high productivity for a deep basin. Recently changes have been reported in physical, chemical, and biological properties. Here we measured the primary and new productivities in the UB using a 13C-15N dual isotope tracer technique. Measurements took place every month for the first time throughout a year for a better estimate of the annual primary production in the EJS. Temporal variations of temperature, salinity, and density (σt) in the study area were highly seasonal as expected for an ocean in the temperate zone. Nutrient distributions reflected these seasonal fluctuations in the vertical structure of the water column. Diatoms were in general the most dominant phytoplankton ranging from 15.5 to 82.2% with an average of 42.0% (S.D. = ±9.9%). Based on those average daily productivities from our monthly measurements, the annual primary, new, and regenerated production in the UB were 273.0 g C m−2 yr−1, 62.6 g N m−2 yr−1, and 48.7 g N m−2 yr−1, respectively. Our estimated high f ratio (0.59) in the UB, indicated that the predominant nitrogen source for primary production was nitrate. This is comparable with the nitrogen source in a productive coastal-upwelling region. New carbon production by phytoplankton is estimated as 145.6 g C m−2 yr−1 (S.D. = ±40.8 g C m−2 yr−1) which indicates that a large portion (53.9%) of the total annual primary production might potentially be exported from the diatom-dominated euphotic zone to a deeper zone in the UB. Further intense integrated field observations will be necessary to improve our understanding of the current marine ecosystem in the UB as an important biological production area in the EJS.

HCFC-22 (CHClF2, chlorodifluoromethane) is an ozone-depleting substance (ODS) as well as a significant greenhouse gas (GHG). HCFC-22 has been used widely as a refrigerant fluid in cooling and air-conditioning equipment since the 1960s, and it has also served as a traditional substitute for some chlorofluorocarbons (CFCs) controlled under the Montreal Protocol. A low frequency record on tropospheric HCFC-22 since the late 1970s is available from measurements of the Southern Hemisphere Cape Grim Air Archive (CGAA) and a few Northern Hemisphere air samples (mostly from Trinidad Head) using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. Since the 1990s high-frequency, high-precision, in situ HCFC-22 measurements have been collected at these AGAGE stations. Since 1992, the Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected flasks on a weekly basis from remote sites across the globe and analyzed them for a suite of halocarbons including HCFC-22. Additionally, since 2006 flasks have been collected approximately daily at a number of tower sites across the US and analyzed for halocarbons and other gases at NOAA. All results show an increase in the atmospheric mole fractions of HCFC-22, and recent data show a growth rate of approximately 4% per year, resulting in an increase in the background atmospheric mole fraction by a factor of 1.7 from 1995 to 2009. Using data on HCFC-22 consumption submitted to the United Nations Environment Programme (UNEP), as well as existing bottom-up emission estimates, we first create globally-gridded a priori HCFC-22 emissions over the 15 yr since 1995. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions. Our inversion indicates that the global HCFC-22 emissions have an increasing trend between 1995 and 2009. We further find a surge in HCFC-22 emissions between 2005 and 2009 from developing countries in Asia – the largest emitting region including China and India. Globally, substantial emissions continue despite production and consumption being phased out in developed countries currently.

Electron microburst energy spectra in the range of 170 keV to 360 keV have been measured using two solid-state detectors onboard the low-altitude (680 km), polar-orbiting Korean STSAT-1 (Science and Technology SATellite-1). Applying a unique capability of the spacecraft attitude control system, microburst energy spectra have been accurately resolved into two components: perpendicular to and parallel to the geomagnetic field direction. The former measures trapped electrons and the latter those electrons with pitch angles in the loss cone and precipitating into atmosphere. It is found that the perpendicular component energy spectra are harder than the parallel component and the loss cone is not completely filled by the electrons in the energy range of 170 keV to 360 keV. These results have been modeled assuming a wave-particle cyclotron resonance mechanism, where higher energy electrons travelling within a magnetic flux tube interact with whistler mode waves at higher latitudes (lower altitudes). Our results suggest that because higher energy (relativistic) microbursts do not fill the loss cone completely, only a small portion of electrons is able to reach low altitude (~100 km) atmosphere. Thus assuming that low energy microbursts and relativistic microbursts are created by cyclotron resonance with chorus elements (but at different locations), the low energy portion of the microburst spectrum will dominate at low altitudes. This explains why relativistic microbursts have not been observed by balloon experiments, which typically float at altitudes of ~30 km and measure only X-ray flux produced by collisions between neutral atmospheric particles and precipitating electrons.

Data from a field survey of the 2011 Tohoku-oki tsunami in the Sanriku area of Japan is used to plot the distribution function of runup heights along the coast. It is shown that the distribution function can be approximated by a theoretical log-normal curve. The characteristics of the distribution functions of the 2011 event are compared with data from two previous catastrophic tsunamis (1896 and 1933) that occurred in almost the same region. The number of observations during the last tsunami is very large, which provides an opportunity to revise the conception of the distribution of tsunami wave heights and the relationship between statistical characteristics and the number of observed runup heights suggested by Kajiura (1983) based on a small amount of data on previous tsunamis. The distribution function of the 2011 event demonstrates the sensitivity to the number of measurements (many of them cannot be considered independent measurements) and can be used to determine the characteristic scale of the coast, which corresponds to the statistical independence of observed wave heights.

We examine the distribution of aerosols and associated optical/radiative properties in the Gangetic-Himalayan region from simultaneous radiometric measurements over the Indo-Gangetic Plains (IGP) and the foothill/southern slopes of the Himalayas during the 2009 pre-monsoon season. Enhanced dust transport extending from the Southwest Asian arid regions into the IGP, results in seasonal mean (April–June) aerosol optical depths of over 0.6 – highest over Southern Asia. The influence of dust loading is greater over the Western IGP as suggested by pronounced coarse mode peak in aerosol size distribution and spectral single scattering albedo (SSA). Transported dust in the IGP, driven by prevailing westerly airmass, is found to be more absorbing (SSA550 nm−2 at surface (12–15% of the surface solar insolation). Furthermore, based on limited observations of aerosol optical properties during the pre-monsoon period and comparison of our radiative forcing estimates with published literature, there exists a general spatial heterogeneity in the regional aerosol forcing, associated with the absorbing aerosol distribution over northern India, with both diurnal mean surface forcing and forcing efficiency over the IGP exceeding that over Northwestern India. Finally, the role of the seasonal progressive buildup of aerosol loading and water vapor is investigated in the observed net aerosol radiative effect over Northwestern India. The radiative impact of water vapor is found to amplify the net regional aerosol radiative forcing suggesting that the two exert forcing in tandem leading to enhanced surface cooling. It is suggested that water vapor contribution should be taken into account while assessing aerosol forcing impact for this region and other seasonally similar environments.

We propose a method to compute tsunami runup heights that is based on an integration of numerical, 2-D shallow-water modelling and an analytical, 1-D long-wave runup theory. This approach provides a faster forecast of tsunami runup heights than a complicated coastal inundation model. Through simulations of potential tsunami scenarios, this approach can also be applied to long-term tsunami prediction. We tested the model by simulating the historical event in the East (Japan) Sea and found that the estimates of runup heights agreed well with the available observations.

We present atmospheric sulfur hexafluoride (SF6) mole fractions and emissions estimates from the 1970s to 2008. Measurements were made of archived air samples starting from 1973 in the Northern Hemisphere and from 1978 in the Southern Hemisphere, using the Advanced Global Atmospheric Gases Experiment (AGAGE) gas chromatographic-mass spectrometric (GC-MS) systems. These measurements were combined with modern high-frequency GC-MS and GC-electron capture detection (ECD) data from AGAGE monitoring sites, to produce a unique 35-year atmospheric record of this potent greenhouse gas. Atmospheric mole fractions were found to have increased by more than an order of magnitude between 1973 and 2008. The 2008 growth rate was the highest recorded, at 0.29 ± 0.02 pmolmol−1 yr−1. A three-dimensional chemical transport model and a minimum variance Bayesian inverse method was used to estimate annual emission rates using the measurements, with a priori estimates from the Emissions Database for Global Atmospheric Research (EDGAR, version 4). Consistent with the mole fraction growth rate maximum, global emissions during 2008 were also the highest in the 1973–2008 period, reaching 7.4 ± 0.6 Gg yr−1 (1-σ uncertainties) and surpassing the previous maximum in 1995. The 2008 values follow an increase in emissions of 48 ± 20% since 2001. A second global inversion which also incorporated National Oceanic and Atmospheric Administration (NOAA) flask measurements and in situ monitoring site data agreed well with the emissions derived using AGAGE measurements alone. By estimating continent-scale emissions using all available AGAGE and NOAA surface measurements covering the period 2004–2008, with no pollution filtering, we find that it is likely that much of the global emissions rise during this five-year period originated primarily from Asian developing countries that do not report detailed, annual emissions to the United Nations Framework Convention on Climate Change (UNFCCC). We also find it likely that SF6 emissions reported to the UNFCCC were underestimated between at least 2004 and 2005.

Abnormal storm waves cause coastal disasters along the coasts of Korean Peninsula and Japan in the East/Japan Sea (EJS) in winter, arising due to developed low pressures during the East Asia winter monsoon. The generation of these abnormal storm waves during rough sea states were studied and hindcast using an atmosphere-wave coupled modelling system. Wind waves and swell due to developed low pressures were found to be the main components of abnormal storm waves. The meteorological conditions that generate these waves are classified into three patterns based on past literature that describes historical events as well as on numerical modelling. In hindcasting the abnormal storm waves, a bogussing scheme originally designed to simulate a tropical storm in a mesoscale meteorological model was introduced into the modelling system to enhance the resolution of developed low pressures. The modelling results with a bogussing scheme showed improvements in terms of resolved low pressure, surface wind field, and wave characteristics obtained with the wind field as an input.

Version-4 of the Goddard Earth Observing System (GEOS-4) General Circulation Model (GCM) was employed to assess the influence of potential changes in aerosols on the regional circulation, ambient temperatures, and precipitation in four selected regions: India and Africa (current paper), as well as North and South America (companion paper). Ensemble-simulations were carried out with the GCM to assess the aerosol direct and indirect effects, hereafter ADE and AIE. Each simulation was started from the NCEP-analyzed initial conditions for 1 May and was integrated through May-June-July-August of each year: 1982–1987 to provide an ensemble set of six simulations. In the first set, called experiment (#1), climatological aerosols were prescribed. The next two experiments (#2 and #3) had two sets of simulations each: one with 2X and other with 1/2X the climatological aerosols over each of the four selected regions. In experiment #2, the anomaly regions were advectively restricted (AR), i.e., the large-scale prognostic fields outside the aerosol anomaly regions were prescribed while in experiment #3, the anomaly regions were advectively Interactive (AI) as is the case in a normal GCM integrations, but with the same aerosols anomalies as in experiment #2. Intercomparisons of circulation, diabatic heating, and precipitation difference fields showed large disparities among the AR and AI simulations, which raised serious questions about the proverbial AR assumption, commonly invoked in regional climate simulation studies. Consequently AI simulation mode was chosen for the subsequent studies. Two more experiments (#4 and #5) were performed in the AI mode in which ADE and AIE were activated one at a time. The results showed that ADE and AIE work in concert to make the joint influences larger than sum of each acting alone. Moreover, the ADE and AIE influences were vastly different for the Indian and Africa regions, which suggest an imperative need to include them rationally in climate models. We also found that the aerosol induced increase of tropical cirrus clouds would potentially offset any cirrus thinning that may occur due to warming in response to CO2 increase.

The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerly flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer over the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

The 1883 Krakatau volcanic eruption has generated a destructive tsunami higher than 40 m on the Indonesian coast where more than 36 000 lives were lost. Sea level oscillations related with this event have been reported on significant distances from the source in the Indian, Atlantic and Pacific Oceans. Evidence of many manifestations of the Krakatau tsunami was a subject of the intense discussion, and it was suggested that some of them are not related with the direct propagation of the tsunami waves from the Krakatau volcanic eruption. Present paper analyzes the hydrodynamic part of the Krakatau event in details. The worldwide propagation of the tsunami waves generated by the Krakatau volcanic eruption is studied numerically using two conventional models: ray tracing method and two-dimensional linear shallow-water model. The results of the numerical simulations are compared with available data of the tsunami registration.

No abstract available.