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Many volcanic craters and calderas are filled with large amounts of water that can pose significant flood hazards to downstream communities due to their high elevation and the potential for catastrophic releases of water. Explosive volcanic activity, uplift of the lake floor and landslides directed into the lake are some of the possible scenarios that can cause the release of water through a breach. In this paper, we derive a physically based model that uses the mass balance equation to simulate the hydrograph through a breached rim due to water displacement by lake floor uplift or landsliding. The model was applied to the Baekdusan volcano to examine its performance. Then, the hydrograph at the breach of a caldera lake serves as an upstream boundary condition for the subsequent flood-routing model, FLO-2D. The FLO-2D simulation shows that three populated towns are at risk, showing maximum depth up to 10–30 m. The flow converges to the Baishan dam that has a volume capacity of 6.5 km3. The simulation shows the probable inundation zones and maximum depth, and these are to be used for risk assessment.

Water scarcity has been an important issue for many countries. The water scarcity is still growing in some region but may be exacerbated by recent climate change. Both international and domestic reports classified Korea into water scarcity country on the basis of Falkenmark indicator. Korea, however, missed the concept of green water in calculating their annual renewable water resources per capita and erroneously defined them as water scarcity country. A new calculation shows that Korea has no water scarcity with 1712 m3 of annual renewable water resource per capita. Wrong information in Korea was badly used for political propagation and private purpose. This may be happening to other countries. Water resources experts need to include the concept of green water in reanalyzing the annual renewable water resources to provide decision-makers with acceptable guideline. Decision should be made with more reliable ground.

The compilation of a flood hazard map is an efficient technique in managing areas at risk of flooding in the case of a dam-break. A scenario-based numerical modeling approach is commonly used to compile a flood hazard map related to dam-break and to determine the model parameters that capture peak discharge, including breach formation and progress, which are important in the modeling method. This approach might be considered less reliable if an existing model is used without local validation. In this study, a dam-break model is linked to a routing model to identify flood-risk areas in the case of failure of the Sandae Reservoir Gyeongju, Gyeongbuk. Model parameters are extracted from a DEM, and maps of land use and soil texture. The simulation results are compared with on-site investigations in terms of inundation and depth. The model reproduces the inundation zone with reasonable accuracy.

화구호를 가지고 있는 화산에서 분화는 단순히 화산분출물에 의한 피해와 더불어 칼데라 호수에 저장된 많은 양의 물이 방 류하여 대규모의 재해를 유발한다. 최근 백두산 분화의 전조가 관측되고 있고 백두산의 분화 시 천지칼데라호로 인해 예상되는 화산성 홍수의 피해를 추정하고 화산 재해에 대비하여 사회적, 경제, 문화, 정치적 파급 효과에 대한 정보와 적절한 대응방안의 마련이 필요하다. 백두산의 화산활동으로 인하여 천지의 외륜산이 붕괴되고 천지에 저장된 물이 방류될 경우를 가정하여 2차원 평면 흐름 수치모형을 이용하여 잠재적 홍수피해 위험지역을 파악하였다. 방류되는 물의 양은 외륜산 붕괴 메커니즘을 표현하 는 미분방정식을 풀어 시간의 함수로 유량곡선을 작성하였다. 구성된 유량곡선을 수치모형의 상류부 경계조건으로 하였고, 하류 부 경계조건은 백산수고의 수위를 설정하여 10일 동안 송화강 유역으로 흐르는 홍수피해 지역을 모의하였다. 지형자료는 USGS 의 SRTM3 수치 표고 자료를 바탕으로 100 m × 100 m의 격자(Grid)를 생성하였다. 지표면 특성은 인공위성 MODIS자료를 사 용하여 유출곡선지수와 조도계수를 산정하였다. FLO-2D로 모의한 침수지역을 위성영상과 중첩하여 침수면적을 계산한 결과, 외 륜산(outer rim) 붕괴가 발생하고 붕괴율이 10 m/hr인 경우 이도백하부근 도심지 면적 22.4 km 중 80%정도가 침수되며, 붕괴 율이 100 m/hr인 경우 98%의 지역이 침수되는 것으로 나타났다. 주요어: 자연재해, 방재, 칼데라, FLO-2D, 외륜산붕괴

This paper reports the development of a relationship between incoming shortwave solar radiation and bright sunshine duration. The daily temperature range (DTR) is melt into the existing Angstrom equation to include the advection of atmospheric constituents. The proposed DTR plus Angstrom equations were tested against field investigation. Measurements of solar radiation and sunshine duration from 1997 to 2006 at 20 meteorological stations were used to calibrate and validate the suggested equation. The model parameters required to specify the nature of the relationship between solar radiation and sunshine duration were determined by automatically minimizing the difference between the modeled and measured solar radiation. At the 20 meteorological stations, the root mean square error (RMSE) is improved by 6% for the original Angstrom equation with DTR, while 2% for the modified Angstrom equation with DTR. The average value of the coefficient of determination is 0.889 (0.908) for the original (modified) Angstrom equation whereas 0.901 (0.911) for the original (modified) Angstrom equation with DTR. It is encouraging that the newly suggested equation with DTR generally provides better performance than the existing Angstrom equation that is constructed with brightness sunshine duration only.

In compiling flood hazard maps for the case of dam-failure, a scenario-based numerical modeling approach is commonly used, involving the modeling of important parameters that capture peak discharge, such as breach formation and progress. In this study, an earth-dam-break model is constructed assuming an identical mechanism and hydraulic process for all dam-break processes. A focus of the analysis is estimation of the hydrograph at the outlet as a function of time. The constructed hydrograph then serves as an upper boundary condition in running the flood routing model downstream, although flood routing is not considered here. Validation was performed using the record of the Tangjishan dam-break in China. The results were satisfactory, with a coefficient of determination of 0.974, Nash-Sutcliffe Coefficient of Efficiency (NSC) of 0.94, and Root Mean Square Error (RMSE) of . The proposed model will contribute to assessments of potential flood hazards caused by dam-break.

Disasters like mountain landslides and collapse in cutting areas claim many a life and cause economic losses, involving much effort and expenses for their recovery. This study has surveyed and analyzed incident of disasters that had occurred on the sloping sides in Korea for the past 13 years in an effort to relieve damage caused by disasters on the sloping sides. The analysis confirms that while the major cause of disasters on the sloping side was storms in the past, frequency of disasters on sloping sides caused by local downpour is steadily on the rise. In addition, while disasters were concentrated in Gangwon Province, a mountainous region of the country, frequency of disasters occurring on the sloping sides is steadily increasing recently on the sloping sides in downtown areas in Seoul, Gyeonggi-do and so forth, attributing a large percentage of disasters to sloping sides. Data surveyed and analyzed in this study are thought to be applicable as basic data for the establishment of effective measures for the prevention of disasters occurring on the sloping sides in the days to come.

Products of the eruption of Mt. Baekdusan are identified as volcanic materials at the estuaries of the Songhuagang river to north, the Dumangang river to east and the Amnokgang river to west. More speficially, pyroclastic flows, lahars and volcanic floods can affect an area of 400km in radius, centering around Lake Cheonji caldera. However, unlike the millenium eruption, the flow situation has been changed. Because multi-purpose dams and reserviors with a combined pondage of mora than 2 billion tons of water have been built in the rivers of which sources are originated from Lake Cheonji caldera. In addition, the flow of fluids expected to take place when the volcano has erupted is thought to be affected by artificial constructions in both direct and indirect ways. This study calculates the direction of fluids flow by using numerical analyses of pyroclastic flows, lahars and volcanic floods that can occur when the volcano of Mt. Baekdusan has erupted. We also estimate the scope of damages by pyroclastic flows, lahars, volcanic flooding caused by the pondage of the dams and water storages in and around Mt. Baekdusan. Pyroclastic flows transported over the steep slopes at the early times of eruptions move over the mountain slopes, affecting airplanes, and lahars due to leaks of Lake Cheonji could reach as far as major rivers and streams near Mt. Baekdusan. Unlike historical accounts, volcanic flood is expected to be limited in its scope of influence to reservoirs bigger than Lake Cheonji in pondage.

The historical accounts and materials about the eruption of Mt. Baekdusan as observed by the geological survey is now showing some signs of waking from a long slumber. As a response of the volcanic eruption of Mt. Baekdusan, water release may occur from the stored water in Lake Cheonjii caldera. The volcanic flood is crucial in that it has huge potential energy that can destruct all kinds of man-made structures and that its velocity can reach up to 100 km to cover hundreds of kilometers of downstream of Lake Cheonji. The ultimate goal of the study is to estimate the level of damage caused by the volcanic flood of Lake Cheon-Ji caldera. As a preliminary study a scenario-based numerical analysis is performed to build hydrographs as a function of time. The analysis is performed for each scenario (breach, magma uplift, combination of uplift and breach, formation of precipitation etc.) and the parameters to require a model structure is chosen on the basis of the historic records of other volcanos. This study only considers the amount of water at the rim site as a function of time for the estimation whereas the downstream routing process is not considered in this study.

To predict climate-induced change in aquatic environments, it is necessary to understand the thermal constraints of various fish species and to understand the timing of current and projected coastal temperatures. This paper presents a newly developed model of the relationship between air and water temperature that was constructed on the basis of harmonic analysis. The model is novel because it requires only a single variable (air temperature) to predict water temperature and captures the hysteresis patterns of the rising and falling limbs and their historic memories. The model was calibrated and validated with data collected from monitoring buoys in Mikawa Bay, Japan between 2005 and 2009. The model validation showed a good performance with a root mean squared error (RMSE) in the range of 0.8-1.0°C. It is especially encouraging that the suggested model can predict water temperature with a reasonable level of accuracy once an acceptable relationship between air temperature and water temperature has been constructed from previously measured data. DOI: 10.1061/ (ASCE)EE.1943-7870.0000499. © 2012 American Society of Civil Engineers. CE Database subject headings: Temperature effects; Water temperature; Climate change; Hysteresis; Estuaries. Author keywords: Air temperature; Water temperature; Climate change; Harmonic analysis; Hysteresis.

This study presents a methodology for using aerial photographs to improve the accuracy of the topographic survey data which are used to calculate water volumes in urban streams. First, a geographical information system spatial interpolation technique such as inverse distance weight and kriging was applied to construct the terrain morphology for sand-bars and grassed areas using cross-sectional survey data, and validation point data was used to estimate the accuracy of the created topographic data. The minimum distance method using aerial photographs was applied to efficiently extract sand-bar and grassed areas located within the river boundary, and the elevation value of extracted layers was allocated to the water level point value. Water volumes from topographic data derived from aerial photographs show an accuracy of 13% (in the sand-bar segment) and 12% (in the grass segment), compared with the water volume based on the original terrain data. Therefore, the river terrain analysis method using aerial photos is efficient in monitoring the sand-bar and grassed areas located, for example, downstream of dams during the flooding season, and also it can be applied in efficiently calculating water volumes.

Reference evapotranspiration rates are often estimated by using pan evaporation data because pan data are widely available. Conversion of pan evaporation estimates to reference evapotranspiration r...

A local or site-specific water temperature is downscaled from the nation-wide air temperature that represents simulation by General Circulation Model (GCM). Both two-step and one-step method are tested and compared in three sites: Masan Bay, Lake Sihwa, and Nakdong River Estuary. Two-step method uses a linear regression model as the first step that converts nation-wide air temperature into local air temperature, and the corresponding coefficient of determination is in the range of 0.98~0.99. The second step that converts air temperature into water temperature uses a nonlinear curve, so called S-curve, and the corresponding root mean squared error (RMSE) is 2.07 for rising limb in Masan Bay, 1.93 for falling limb in Masan Bay, 2.59 for Lake Sihwa, and 1.58 for Nakdong River Estuary. In a similar way, one-step method is performed to directly convert nation-wade air temperature into local water temperature, and the corresponding RMSE is 2.28 for rising limb in Masan Bay, 1.89 for falling limb in Masan Bay, 2.55 for Lake Sihwa, and 1.52 for Nakdong River Estuary. Consequently both methods show a similar level of performance, and one-step method is recommendable in that it is simple and practical in relative terms.

This study presents a model-based approach for determining the sediment delivery ratio (SDR) on a basin scale in Southern Korea. The study builds a sediment-rating curve using the measured suspended sediment concentration and water discharge. The sediment-rating curve is then used to determine the sediment yield. A geographic information system-embedded empirical model is used to estimate soil erosion. The ratio between the sediment yield and soil erosion is used to compute the SDR. The data spanning the year 2002–2008 are divided into two sets. The first set (2002–2005) is used for calibrating the model and the second set (2006–2008) is used for validating the model. For the soil erosion model, the rainfall-runoff erosivity factor was analyzed separately using the rainfall amount and rainfall intensity. The results show that the rainfall-runoff erosivity factor derived from rainfall intensity gives better performance in calculation of soil erosion than does the rainfall amount. The accuracy of these resu...

It is well known that local calibration is subject to improving the performance of the temperature-based equation because that calibration includes the influence of the local climate characteristics. This paper evaluates different local recalibrations (the regression-based, one-parameter, and three-parameter methods) of the Hargreaves equation at 21 meteorological stations. The FAO-56 Penman-Monteith is used to describe the control condition against which each calibration method is then assessed. The one-parameter method provides the strength for inland areas, while it presents the worst performance for coastal areas. The regression-based calibration provides slightly better performance for coastal areas. It is true that the difference between the estimates of ET o using the different calibration methods is relatively small and that the difference does not provide the benchmark control that is desirable to demonstrate a significant difference. In relative terms, the regression-based and the three-parameter methods can be an alternative for both inland and coastal areas, giving similar level of accuracy. However, the one-parameter presents may be an alternative only for inland areas. This study can provide guidelines for crop production, water resources conservation, irrigation scheduling, and environmental assessment.

The existing chemical index of alteration has a difficulty to evaluate the degree of weathering in biotite granites due to an assumption that K2O content decreases along with Na2O, CaO, and MgO. We found that relative K2O content increases during weathering of biotite granite, as it is retained within such rocks due to (1) the chemical and physical stability of K-feldspar and (2) the formation of illite via incorporation of K ions released from biotite. The calculated ranges of most chemical indexes for biotite granite weathering do not show a good correlation with the weathering grade except the CIW, WIP and V indexes. The range of the CIW, WIP and V indexes according to the weathering grade were very small, and thus small errors in whole-rock chemical analyses can produce large discrepancies in calculated values. Further, the WPI index is a relative weathering index that depends on the composition of a fresh standard sample and cannot be applied to determine the absolute degree of weathering in granites if no protolith is available. We suggest a new weathering index (BWI; Biotite weathering index) based on a decrease in the number of K ions in the interlayer site of biotite during weathering of granite. Newly calculated values show a much wider range than the CIW, WIP and V indexes with a good relationship with a weathering grade. Therefore, it is necessary to establish the new index for a detailed classification of weathering degree.

This paper reports the application of a non-linear relationship between the incoming shortwave solar radiation and bright sunshine duration. The newly suggested equation is a modified form of the existing Angstrom equation. Measurements of solar radiation and sunshine radiation from 1997 to 2006 at 21 meteorological stations were used to calibrate and validate the suggested equation. The model parameters required to specify the nature of the relationship between solar radiation and sunshine duration were determined by automatically minimizing the difference between the modelled and measured solar radiation. At the 21 meteorological stations, the absolute error (AE) is in the range of −0.126–0.158 MJm−2 day−1 for the original Angstrom equation, while it is in the range of −0.089–0.154 MJm−2 day−1 for the modified equation. The root mean square error (RMSE) is also improved by 7–8% for the modified method. The results show that the newly suggested equation generally provides better performance than the existing Angstrom equation. Copyright © 2009 Royal Meteorological Society

This paper presents an inverse square weighted interpolation for predicting the incoming solar radiation ( Rs ) from nearby weather stations. The predicted Rs is applied to the well-known Priestley-Taylor equation for estimating reference evapotranspiration ( ETo ) . This cross-validation estimated bias and error in the final model predictions of the Rs and ETo at the 21 meteorological weather stations in Korea Peninsula. The coefficient of determination and the root-mean-square error (RMSE) for monthly estimates of Rs was in the range of 0.83–0.95 and 17.90–76.34 MJ m−2 day−1 , respectively. The RMSE for monthly estimate of ETo values at inland and coastal areas was 11.08 and 15.01 mm respectively. The estimates of ETo using thus predicted Rs to provide reasonable accuracy. The study can provide further useful guidelines for crop production, water resources conservation, irrigation scheduling, and environmental assessment.

This note is based on the generally accepted fact that soil boundaries are usually gradual rather than abrupt, and this is followed by an application of fuzzy set theory to what are already known to be diffuse boundaries. Sediment yield measurements are used to describe the control condition against which the fuzzy and conventional boundaries are assessed. In terms of the K factor, the fuzzy boundary representation showed less difference (up to 16.8%). The Nash–Sutcliff coefficient of efficiency and the root mean square error for the fuzzy boundary are 0.96 and 1.3× 10−3 , respectively, whereas those for the conventional boundary are 0.76 and 3.4× 10−3 , respectively. The estimation by the soil erosion model shows that the fuzzy representation of geographic boundary is more accurate than the conventional method. But the difference between erosion predictions using conventional boundaries and fuzzy boundaries is relatively small.

This study investigates a construction-induced sea level rise and tide characteristics change, using a regression analysis to separate the local construction effect such as sea-dike/seawalls and global warming from total sea level change. The study also makes it clear why and how the extreme high water level has risen just after constructions at Mokpo harbor in Korea. As a result of the regression analysis, it is found that the high water level rise for the period of 1960–2006 is ∼60 cm, which is summation of four components: ∼23 cm for Youngsan River sea-dike (1981), ∼15 cm for Youngam seawall (1991), ∼8 cm for Geumho seawall (1994), and ∼14 cm for gradual rise (due mainly to global warming). Then, a numerical simulation at Mokpo coastal zone is performed to identify each component, and the results support the premise that the tidal amplification caused by constructions is due mainly to the extinguishment of the tidal choking effect at outer Mokpogu. The tidal flat effect makes the amplification greater at spring tide or extraordinary high tide, which would result in the increase of inundation risk at the Mokpo coastal zone. Frequency distribution of observed high water level data shows increasing trend for both maximum value of astronomical tide component (simulated high water level) and meteorological tide component (surge height) after the coastal constructions. A frequency analysis presents that the high water level for 50 year return period, which is often used for design in practice, is 474 cm before the construction, and while that is 553 cm after the construction. Furthermore, design height might steadily be elevated considering future global sea level rise.

Turbid-water problem of reservoirs due to soil erosion causes a major issue in dam operation. This study presents a methodology to quantitatively analyze the occurrence possibility of turbid-water in four hydrologic basins (Sayeon, Degok, Gwangdong, and Imha Dam basins in S. Korea), quantifying the weighting value of turbid-water occurrence in reservoirs. To do this, the study conducted indoor tests, including laser-assisted particle size analysis, X-ray powder diffraction method analysis, and scanning electron microscope, to give the geologic characteristics such as the distribution of soil particle size, settlement time, landslide, and existing sediment yield. The study used RUSLE models to calculate sediment yield on the basis of soil maps, DEMs, and landcover maps as auxiliary data. This study classified factors for evaluating the possibility of turbid-water occurrence into geology, sediment yield, landslide and soil components, and these evaluation items’ weighting and score are presented using the analytic hierarchy process technique. The suggested method is promising in that it can analyze the risk factor of turbid-water occurrence in basins and that can provide a guideline to estimate the turbid-water occurrence of reservoir in dam construction.

The specification of the land cover characteristics is essential to have runoff simulated by a rainfall-runoff (RR) model in watershed hydrology. The recent availability of land cover map from remotely sensed data makes the specification of the land cover characteristics easier but it is unlikely that the RR models incorporate all spatial scales of the land cover map in need of application. This paper proposes a simple but physically based aggregation method to upscale natural vegetative heterogeneity, which is represented by Manning’s roughness coefficient, to the grid scale used in typical RR model, and it compares the strength of the new method with the conventional methods and uses a hydrologic model to test the sensitivity of using different methods. The results show the new method provides better performance in terms of both the amount and time to peak flow in relative terms. The proposed method provides a reasonably realistic description of area-averaged vegetation nature and characteristics.

To project the effects of climate-induced change on aquatic environments, it is necessary to know the thermal constraints affecting different fish species and to acquire time series of the current and projected water temperature (WT). A regression between the WT at individual stations and the ambient air temperature (AT) at nearby weather stations could represent the easiest practical method of estimating the WT for an entire region. Assuming that the grid-averaged observations of AT correspond to the AT output from a general circulation model (GCM) simulation, this study constructed a regression curve between the observations of the local WT and the concurrent GCM-simulated surface AT, minimizing the difference between the time series of the measured and modeled WT, which implicitly includes downscaling to local conditions. The regression model shows excellent performance in capturing the WT trend in response to the AT of the GCM. The projected WT under the global-warming scenario shows a 1.5–2.5...

Precipitation is the most important component to the study of water and energy cycle in hydrology. In this study we investigate rainfall retrieval uncertainty from different sources of remotely sensed precipitation field and then probable error propagation in the simulation of hydrologic variables especially, runoff on different vegetation cover. Two remotely sensed rainfall retrievals (space-borne IR-only and ground radar rainfall) are explored and compared visually and statistically. Then, an offline Community Land Model (CLM) is forced with in situ meteorological data to simulate the amount of runoff and determine their impact on model predictions. A fundamental assumption made in this study is that CLM can adequately represent the physical land surface processes. Results show there are big differences between different sources of precipitation fields in terms of the magnitude and temporal variability. The study provides some intuitions on the uncertainty of hydrologic prediction via the interaction between the land surface and near atmosphere fluxes in the modelling approach. Eventually it will contribute to the understanding of water resources redistribution to the climate change in Korean Peninsula.

우리민족의 영산으로서 백두산(Fig. 1)은 지리산까 지 이르는 백두대간의 시발점으로서 한반도 모든 산 맥들의 중심점이다. 백두산은 특히 우리민족의 모태 인 단군신화의 얼이 서려있는 성지로 신성시 되어 왔는바, 이는 여진족에게도 마찬가지인 숭배의 대상 이었다. 활화산인 백두산은 약 200만 년 전부터 화산 활동 이 약화되면서 지금의 산세를 형성했는데, 고생대에 서 신생대에 이르는 여러 시대의 지층들이 분포한다. 특히 중생대와 신생대의 구조운동으로 단열구조, 파 열 구조, 단층들이 발달해있다. 기후는 전형적인 고 산 기후이며 기후 변화가 한국에서 가장 심한 곳 중 의 하나인 것으로 알려져 있다. 연 평균 기온은 68 o C이며 최고 기온은 18-20 o C이다. 연평균 상대습도 는 74%이며, 여름에 높고 겨울에 낮은 전형적인 한 반도 특성을 보인다. 북서풍과 남서풍이 강하게 불고 최대 풍속은 40 m s −1 에 달하고 연중 강풍일수는 약 270일이며 천지 부근에서는 강한 돌풍이 자주 발생 한다(www.doopedia.co.kr). 백두산은 북위 41.98 o , 동경 128.08 o 에 위치하며 해 발고도는 2,750 m이고 천지의 최고 수심은 373 m이 다, 최고 수심에서 저수지 면적은 9.2 km 2 로 표면수 위의 해발고도는 2,192 m이다. 저수지 수면에서 가장 높은 칼데라(caldera) 측면은 558 m이고, 16개의 봉우 리에 의해 둘러 싸여져 있는데 이 안에 저장된 수량 은 약 20억 톤으로 추정한다. 백두산 천지에는 북쪽 으로 해발고도가 두드러지게 낮은 지점이 있는데 이 지점으로 물이 흘러나가 이도백하(Erdaobaihe River) 를 거쳐 높이 100 m 길이 1,080 m에 이르는 송화댐 (Songhua lake reservoir)으로 유입된다(Bao et al., 2011). 이 유역은 경사가 0 o 에서 73 o 에 이르는 산과 삼림으로 이루어진 매우 가파른 지형을 이루는데 이 때문에 유속이 매우 빨라 해발고도가 410-2,740 m가 되는 고지대임에도 불구하고 연중 내내 얼지 않고 흐름이 유지되는 특성을 가지고 있다(Bao et al., 2011). 여진족의 전설은 기원전 1000년경에 백두산에서 화산활동이 있었다고 전하고 있으며, 조선왕조실록에 는 1668년, 1702년, 1903년에 소규모 분화를 했다고 기록되어 있다(Wei et al., 2003). 정확한 연대는 불 명하지만 약 1000년 전에 ‘Millennium eruption’이라 고 부르는 대규모 화산활동이 일어났는데(Cui et al., 2000; Horn and Schmincke, 2000), 이는 지난 2000 년 동안 지구상에서 일어난 가장 강한 화산활동이라 고 한다(이는 중국 논문의 주장인데, 저자들이 뉴질 랜드의 루아페후(Ruapehu) 화산관측소를 방문했을 때 그곳의 화산학자는 이 루아페후 화산이 세계에서 최대 규모의 화산활동을 일으킨 화산이라고 알려주었 다). 과거 백두산의 화산분화는 그 규모가 워낙 방대 해서 일본 북해도에서까지 화산재 흔적이 나타나는데, *Corresponding author: klee@daegu.ac.kr *Tel: +82-53-850-6522 *Fax: +82-53-850-6529

This paper is concerned with the effect of precipitation forcing on land surface hydrological variables predicted by a physically based land surface scheme. The aspects considered are the differences in precipitation input across varying sensor measurements and temporal scales of aggregation. Precipitation accumulations at 1-, 2-, 3-, and 6-h time scales are derived on the basis of standard 5-min rain gauge rainfall measurements, hourly rain gauge calibrated WSR-88D radar rainfall estimates, and passive microwave calibrated half-hourly satellite infrared rain retrievals. The spatial resolution of the rainfall estimates is fixed to 1° grid boxes. The off-line community land model (CLM) is used to simulate land surface parameters on the basis of external meteorological forcing parameters. The study region and data consist of two vegetation-distinct (high and low vegetation cover) sites in Oklahoma. The data used include one warm season (May–August 2002) of in situ meteorological data from the Oklahoma Meson...

The backscattering and emission measured simultaneously by radar and radiometer show promise for the estimation of surface variables such as near-surface soil moisture and vegetation characteristics. In this paper, the 10.7 GHz Tropical Rainfall Measuring Mission (TRMM) microwave imager (TMI) channel and 13.8 GHz precipitation radar (PR) observations are simultaneously used for the estimation of the near-surface soil moisture and vegetation properties. The Fresnel model for soil and a simple model for vegetation are used to simulate the passive microwave emission at 10.7 GHz. To determine the PR backscatter signal from a land surface, a theoretical approach is used based on the Geometric Optics Model for simulating bare soil and a semi-empirical water-cloud model for vegetation. The model parameters required in specifying the nature of the soil and vegetation are calibrated on the basis of in situ soil moisture data combined with remotely sensed observations. The calibrated model is subsequently used to retrieve near-surface soil moisture and leaf area index for assumed values of surface roughness and temperature. Algorithm assessment using synthetic passive and active microwave data shows a nonlinearity effect in the system inversion, which results in a varying degree of error statistics in soil wetness and vegetation characteristics retrieval. The technique was applied on TRMM radar/radiometer observations from three consecutive years and evaluated against in situ near-surface (5 cm) soil moisture measurements from the Oklahoma Mesonet showing a consistent performance.

In coming years, Land Data Assimilation Systems (LDAS) two-dimensional (2-D) arrays of the relevant land-surface model) are likely to become the routine mechanism by which many predictive weather and climate models will be initiated. If this is so, it will be via assimilation into the LDAS that other data relevant to the land surface, such as remotely sensed estimates of soil moisture, will find value. This paper explores the potential for using low-resolution, remotely sensed observations of microwave brightness temperature to infer soil moisture in an LDAS with a "mosaic-patch" representation of land-surface heterogeneity, by coupling the land-surface model in the LDAS to a physically realistic microwave emission model. The past description of soil water movement by the LDAS is proposed as the most appropriate, LDAS-consistent basis for using remotely sensed estimates of surface soil moisture to infer soil moisture at depth, and the plausibility of this proposal is investigated. Three alternative methods are explored for partitioning soil moisture between modeled patches while altering the area-average soil moisture to correspond to the observed, pixel-average microwave brightness temperature, namely, 1) altering the soil moisture by a factor, which is the same for all the patches in the pixel, 2) altering the soil moisture by adding an amount that is the same for all the patches in the pixel, and 3) altering the change in soil moisture since the last assimilation cycle by a factor which is the same for all the patches in the pixel.