Typhoon Sanba Research Articles

Impacts of Steering Flows with Different Timescales on the Track of Typhoon Sanba (2012)

Typhoon Sanba (2012), the strongest tropical cyclone (TC) of the year worldwide, moved northward almost along 130° longitude during its lifetime and passed through different background flows from low to high latitudes. The steering flows with different timescales for Sanba are retrieved by using the NCEP reanalysis data with the total wind field separated into: a mean state, an interannual component, an intraseasonal component, and a synoptic component. Our analysis indicates that the intraseasonal timescale wave train (WT) with east–west oriented circulations made the largest contribution to the movement of Sanba. The effects of the environmental steering with different timescales on Sanba’s movement are investigated with numerical simulations using the Weather Research and Forecasting (WRF) model. In the control simulation, total fields from the NCEP reanalysis are used as initial and boundary conditions, and the northward motion of Sanba is well captured. In sensitivity experiments, each of the intraseasonal and interannual components is removed one at a time. The steering vectors associated with these timescales can explain their influences on the movement of Sanba in the experiments. Vorticity budget analyses indicate that the horizontal vorticity advection made the largest contribution to the movement of the storm.

Analysis of Reliability of Weather Fields for Typhoon Sanba (1216)

Analysis of Reliability of Weather Fields for Typhoon Sanba (1216)

FUTURE CLIMATE EXPERIMENTS ON INTENSITY AND STORM SURGE OF TYPHOON SANBA (2012)

The recent progress of the global warming raise concerns the future changes of tropical cyclones (i.e. hurricane, typhoon, and cyclone) and their associated coastal disasters. It is thought that the increases of both the sea surface temperature and ocean heat contents by the global warming could increase the intensity of future tropical cyclones. As a method of quantitative assessment for the impact of global warming on tropical cyclones and their storm surges, “pseudo-global warming downscaling” is generally adopted using a regional climate model and a storm surge model (Takayabu et al., 2015). Estimating the differences of experiments between present and future climate, we can quantify the future changes of typhoon intensity and storm surge by the global warming. Using the high-resolution typhoon model, we carry out a present climate experiment and pseudo-global warming experiments on typhoon intensity and its storm surge of Typhoon Sanba (2012) in this study. Sanba went northward on the west coast of Kyushu Island and caused a storm surge in Ariake Sea, Japan. Sanba had a minimum central pressure of 900 hPa and a maximum wind speed of 55 m/s. The observed maximum sea level anomaly was 104 cm at Oura, Saga Prefecture. To evaluate the impacts of global warming differences (GWDs) on typhoon intensity and storm surge, sensitivity experiments on different months (August, September, and October) in future typhoon season are also made.

Evaluation of Unified Model Microphysics in High-resolution NWP Simulations Using Polarimetric Radar Observations

The UK Met Office Unified Model (UM) is employed by many weather forecasting agencies around the globe. This model is designed to run across spatial and time scales and known to produce skillful predictions for large-scale weather systems. However, the model has only recently begun running operationally at horizontal grid spacings of ∼1.5 km [e.g., at the UK Met Office and the Korea Meteorological Administration (KMA)]. As its microphysics scheme was originally designed and tuned for large-scale precipitation systems, we investigate the performance of UM microphysics to determine potential inherent biases or weaknesses. Two rainfall cases from the KMA forecasting system are considered in this study: a Changma (quasi-stationary) front, and Typhoon Sanba (2012). The UM output is compared to polarimetric radar observations in terms of simulated polarimetric radar variables. Results show that the UM generally underpredicts median reflectivity in stratiform rain, producing high reflectivity cores and precipitation gaps between them. This is partially due to the diagnostic rain intercept parameter formulation used in the one-moment microphysics scheme. Model drop size is generally both underand overpredicted compared to observations. UM frozen hydrometeors favor generic ice (crystals and snow) rather than graupel, which is reasonable for Changma and typhoon cases. The model performed best with the typhoon case in terms of simulated precipitation coverage.

Modelling of Storm-induced Seawater Flooding in the Suyeong River Area, South Korea: A Case Study due to the Storm Surge and Waves during Typhoon Sanba

Yuk, J.-H.; Park, J.H., and Joh, M., 2018. Modelling of Storm-induced Seawater Flooding in the Suyeong River Area, South Korea: A Case Study due to the Storm Surge and Waves during Typhoon Sanba. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 746–750. Coconut Creek (Florida), ISSN 0749-0208.The Suyeong River Area (SRA), located in Busan, a major city on the southeastern coast of South Korea, is frequently damaged by storm-induced seawater flooding. One of the main reasons for seawater flooding is the propagation of storm surges and wind waves through the Suyeong River in the SRA. In this study, a series of prediction systems of storm tides, surges, waves and resultant seawater flooding for the SRA based on unstructured meshes with a high resolution of approximately 10 m covering the entire flood plain and a HPC-based parallel tide-surge-wave model were developed. Meteorological forcing variables such as wind and air pressure calculated by the parametric tropical cyclone model based on typhoon information were used in the storm-surge and wave models. The modeled meteorological data were in good agreement with observations of both the wind and air pressure. The simulated surge heights and wave properties showed good agreement with the observations as well. Waves reached the mid-stream area of the SRA, likely affecting the duration of seawater flooding. The prediction system in this study can reasonably simulate tide-surge-wave and resultant seawater flooding (coastal inundation) during extreme conditions, e.g., storms in the SRA of Busan, South Korea.

A System for Real-time and Continuous Monitoring of Environmental Information to Prevent Disasters off the East Coast of Korea and its application to Typhoon Sanba (2012) case

A System for Real-time and Continuous Monitoring of Environmental Information to Prevent Disasters off the East Coast of Korea and its application to Typhoon Sanba (2012) case

OBSERVATION OF WAVE SPECTRUM UNDER TYPHOON CONDITION

The spatial and temporal variation of wave spectrum under typhoon SANBA, which was the 16th typhoon originating in the northwestern Pacific Ocean in 2012, was examined. The typhoon SANBA passed through the middle of Korean peninsula whereas most of typhoons passed the Straits of Korea (eastern side of Korean peninsula). This unique path of typhoon SANBA provided interesting features of wave conditions. It was believed that wave heights were larger in the right side of the typhoon path because typhoons translation speed and rotational wind field were in the same direction (i.e., dangerous semicircle). However, observational evidence of wave spectrum under typhoon was still rare because of the difficulty in measurement. In this study, wave spectrum analysis under extreme storm condition of typhoon SANBA is given for the left and right sides of the path, including the information of significant wave height, peak period, and dominant wave direction. Wave measurements were obtained by directional wave rider buoys installed at Yeosu and Namhyeongjedo in Korea. Yeosu and Namhyeongjedo are located in each of the left and right of the path of the typhoon SANBA. The measurements provided distinguished wave conditions in each side of navigable semicircle and dangerous semicircle of the typhoon. Therefore it is possible to observe the spatial differences of the wave spectrum across the path of the typhoon, as well as temporal changes of wave spectrum as the typhoon evolves.

Assessment of social vulnerability to natural hazards in South Korea: case study for typhoon hazard

Most often, disaster vulnerabilities are discussed from the perspective of developing countries. This paper extends the argument using an example from a developed country, by focusing on the South Korea during the period from 2009 to 2013. South Korea has suffered from a range of natural hazards throughout its history, and experienced one to three typhoons per year on the average, with most events occurring in August and September. Since 1945, around 17 major typhoons have directly affected South Korea. This study used Self Organizing Map (SOM) and Social Vulnerability Index (SoVI) for data analysis in terms of the number of social vulnerability variables and samples. The dataset used for social vulnerability analysis consisted of 12 variables, which were adopted and adapted from the research literature related to Hurricane Katrina. However, some of the variables employed in this study might be more or less redundant, necessitating the removal of redundant variables from the accurate SOM analysis. Overall, during the period from 2009 to 2013, the variables of ELDRY (elderly population), POPDNSTY (population density), and DISBLD (disabled population) are the dominant variables which frequently appear as the two top variables that lead to an increase in social vulnerability. According to the findings related to the social vulnerability index, nearly half of all regions have positive values, which are categorized as highly vulnerable. As there are growing concerns on the adequacy of using the concept of vulnerability to address loss and damage, an additional approach was attempted by using typhoon hazard examples, e.g. Typhoons Dianmu and Kompasu of 2010, Typhoon Muifa of 2011, and Typhoon Sanba of 2012. Additional factors such as shortest distance from the typhoon track and maximum wind speed were considered together to obtain the weighted correlation between them. Based on the process of this study, SOM has an essential benefit in evaluating SoVI.

Failure mechanism analysis of rainfall-induced landslide at Pingguang stream in Taiwan: mapping, investigation, and numerical simulation

On September 15, 2012, torrential rains carried by the peripheral circulation of Typhoon Sanba and the northeast monsoon induced a translational landslide near Pingguang Road in Xindian District of New Taipei City, Taiwan. The total volume of the landslide was ~162,000 m3. The sliding mass destroyed two houses across the stream and formed a landslide dam at the toe of the slope, constricting the stream. For the purpose of reducing sediment-relative hazard around mountainous area, the paper attempts to explore the dynamics and phenomenon of the landslide on dip slope. This study interpreted remote sensing images and terrestrial LiDAR scanning, conducted onsite surveys to obtain material parameters, and performed simulations using the discrete element method to reconstruction the post-event, in order to elucidate the mechanisms involved in the landslide process. Survey results revealed complex geological conditions with tension cracks spreading in all directions at source area. This facilitated the infiltration of surface runoff into weak surfaces and raised groundwater levels. Slope failure may occur along the stratum boundary once the intrinsic shear strength of regolith drops below a critical value. The results of numerical simulation reveal that at 80 s after the Pingguang stream landslide began, a maximum deposition depth of 20 m had been reached. The sliding mass cut off the stream and pushed the stream flow roughly 35 m to the southeast. Because the slope materials surrounding the study area and the landslide-inducing mechanisms are similar, the top of the slopes to the northwest of the study area requires close monitoring. Finally, a detailed potential landslide mapping and interpretation from the high-resolution digital elevation model also present to prevent further landslides. The investigation indicates that the occurrence of landslide is highly related to seepage effect of accumulated rainfall, toe erosion by surface runoff, and local unstable geological structure.

Effects of Beach Nourishment and the Influence of Irrigation Water Discharge on Byunsan Beach, West Coast, Korea

AbstractByunsan Beach located on the west coast of Korea has been undergoing significant erosion in recent years during and after the construction of a large tidal embankment, the Saemanguem Dike, mostly because of the blocking of the sand supply from rivers. To reduce and prevent beach erosion, the Korean government decided to carry out beach nourishment in May 2012 just before the summer season. In order to monitor the performance of beach nourishment, precise measurements of beach morphology were taken 21 times during a 1‐year period from May 2012 to April 2013 by using a RTK‐GPS system. The result showed that the beach nourishment preserved the beach effectively, based on the fact that most of the additional sand remained on the beach after 1 year. Although a local part of the beach was severely eroded by a heavy volume of irrigation discharge during the summer rainy spell, it recovered within a short period of time. As a major erosional event the whole area of the beach experienced massive erosion in a strong cyclone, Typhoon Sanba, in September 2012, but the beach recovered rapidly after the typhoon. Sediment accumulation also took place during the winter season, retaining the sand and aiding recovery of the beach. Copyright © 2016 John Wiley & Sons, Ltd.

분포형 강우유출모형 KIMSTORM을 이용한 침수실적자료와의 비교를 통한 레이더강우의 효용성 연구

The purpose of this study is to explore the effectiveness of dual-polarization radar rainfall by comapring with the flood inundation record map through KIMSTORM(Grid-based KIneMatic wave STOrm Runoff Model). For Namgang dam () watershed, the Bisl dual-polarization radar data for 3 typhoons (Khanun, Bolaven, Sanba) and 1 heavy rain event in 2012 were prepared. For both 28 ground rainfall data and radar rainfall data, the model was calibrated using observed discharge data at 5 stations with , Nash and Sutcliffe Model Efficiency (ME) and Volume Conservation Index (VCI). The calibration results of , ME and VCI were 0.85, 0.78 and 1.09 for ground rainfall and 0.85, 0.79, and 1.04 for radar rainfall respectively. The flood inundation record areas (SY and MD/SG district) by typhoon Sanba were compared with the distributed modeling results. The spatial distribution by radar rainfall produced more surface runoff from the watershed and simulated higher stream discharge than the ground rainfall condition in both SY and MD/SG district. In case of MD/SG district, the stream water level by radar rainfall near the flood inundation area showed 0.72 m higher than the water level by ground rainfall.

An efficient early warning system for typhoon storm surge based on time-varying advisories by coupled ADCIRC and SWAN

In order to mitigate storm surge impacts, precise surge guidance computations for forecasters must be finished within a short period of time to allow them to provide early warning to the public. For this purpose, a coupled ADCIRC and SWAN model was applied based on multiple scenario-based, deterministic model runs for each time-varying meteorological forecast advisory on a relatively lightweight mesh with 57 k nodes covering the North Western Pacific (NWP) ocean. The mesh was designed to achieve an optimal combination of speed and accuracy on a cost-effective parallel computer with 64 cores. These models were applied for two events in 2012: typhoon Bolaven (on the west coast of Korea) and typhoon Sanba (on the south coast of Korea). The surge results for a 72-h forecast yielded relative surge height error of 34.1 to 46.4 % in ADCIRC + SWAN. The surge results from a meteorological forecast 24 h from landfall improved to 21.7 to 26.8 %. Furthermore, surge elevation results progressively approached measured values (i.e., improved) with each successive typhoon advisory owing to diminishing uncertainties in the meteorological input. In conclusion, this new efficient early warning forecast guidance workflow successfully achieved its goals of real-time storm surge simulations for forecasters, early warning, and understanding of ocean dynamics.

Coupled storm surge and wave simulations for the Southern Coast of Korea

An integrated model system was developed to apply surge-wave coupled simulations to the southern coast of Korea during Typhoon Sanba in 2012. Numerical experiments were carried out to examine the effects of land-dissipated wind on storm surges and the influence of wave-surge coupled simulations on storm surges and surface waves. These numerical experiments used a finite volume ocean model, FVCOM, coupled with a wave model SWAVE. Due to the complex geometry of the coastal area investigated, a high-resolution terrain-following unstructured grid was employed. Atmospheric forcing was generated by a planetary boundary layer model, which was revised by incorporating the effect of the land’s roughness on the typhoon wind. A detailed comparison shows generally good agreement between the measured and simulated wind, surge, and waves. In particular, improved results have been found for the simulation of storm winds and surges when considering the effect of land-dissipated wind. In addition, clearly improved results for storm surges were obtained when adding the coupling effect between waves and surges. The results show a maximum contribution of ~40% by the waveinduced surge to the peak surge height along the coasts. The mean rate of error for peak surge heights decreased from 29.6% to 21.3% after considering the effects of wind dissipation, and decreased again to 17.9% when adding the effects of the waves. These results imply that the effect of wind dissipation caused by land roughness and waves should be taken into account when determining storm surge heights. The results also show the effects of wave-current coupling influences the generation of waves. However, the magnitude of this coupling effect on wave heights was found to be relatively insignificant.

Observation of typhoon-induced seagrass die-off using remote sensing

Satellite remote sensing has been used as an effective tool to monitor and manage seagrass beds, but this tool is not appropriate to use in highly turbid waters along the coast of Korea. In this study, satellite data were used to identify the method for detecting seagrass beds in turbid bay waters and describing temporal changes over the past 24 years. Moreover, we found the cause of seagrass die-off phenomenon by observing the long-term satellite images and evaluating the impact of the typhoon on seagrass beds. All seagrass spectra from different sensors (Landsat TM/ETM+, Aster, Spot-4, and Kompsat-2) have low reflectance in green and high in NIR regions, whereas unvegetated seawater has the opposite spectrum features. A training area in the green band and Mahalanobis Distance Classification algorithm was adopted for classification and mapping of seagrass beds. The error matrix using the in situ reference data for Kompsat-2 image classification was 72.9% accurate. The average area of seagrass beds was 4.6 km2 from May 1990 to January 2012, and it was consistently >4.0 km2. A die-off of seagrass beds was observed in September 2012 after Typhoon Bolaven, Tembin, and Sanba consecutively passed the study site. When Typhoon Sanba passed the study site, it had sustained maximum wind speed (147.6 km h−1) during low tide, unlike the other typhoons. We found that the water column buffer did not have any effect on resistance of seagrass bed to disturbance, which led to greater damage. Additionally, the three sequential typhoons that passed through during the short time probably produced a cumulative effect. These results allow an understanding of past changes, and reveal the sudden and influential changes in seagrass distribution. As seagrass removal might have negative effect on other associated communities, comprehensive monitoring is required to ensure that disturbed seagrass habitats is recovered naturally.

Numerical experiments of storm winds, surges, and waves on the southern coast of Korea during Typhoon Sanba: the role of revising wind force

Abstract. The southern coastal area of Korea has often been damaged by storm surges and waves due to the repeated approach of strong typhoons every year. The integrated model system is applied to simulate typhoon-induced winds, storm surges, and surface waves in this region during Typhoon Sanba in 2012. The TC96 planetary boundary layer wind model is used for atmospheric forcing and is modified to incorporate the effect of the land's roughness on the typhoon wind. Numerical experiments are carried out to investigate the effects of land-dissipated wind on storm surges and waves using the three-dimensional, unstructured grid, Finite Volume Coastal Ocean Model (FVCOM), which includes integrated storm surge and wave models with highly refined grid resolutions along the coastal region of complex geometry and topography. Compared to the measured data, the numerical models have successfully simulated storm winds, surges, and waves. Better agreement between the simulated and measured storm winds has been found when considering the effect of wind dissipation by land roughness. In addition, this modified wind force leads to clearly improved results in storm surge simulations, whereas the wave results have shown only slight improvement. The study results indicate that the effect of land dissipation on wind force plays a significant role in the improvement of water level modeling inside coastal areas.

STORM SURGE SIMULATION IN NAGASAKI DURING THE PASSAGE OF 2012 TYPHOON SANBA

As a result of global warming effect, storm surges generated by extreme weather events such as tropical cyclones, typhoons and hurricanes, significantly impact to the life and property in storm-surge prone coastal low-lying areas. Therefore, numerical modeling systems, comprising meteorological, hydrodynamic and wave simulation capabilities are essential for the storm surge hindcasting and forecasting phases in disaster mitigation and management processes. Accordingly, we assessed the applicability of two meteorological simulation methods; (1) Mesoscale Meteorological Model MM5 and (2) Delft Dashboard (DDB) Tropical Cyclone Tool, together with Delft3D FLOW-WAVE coupled modeling system to simulate the storm surges in Nagasaki coast during the passage of 2012 typhoon SANBA. Storm surge generated by MM5-Delft3D and DDB-Delft3D systems in Nagasaki area were reasonably agreed with the observations. Thus, applicability of both meteorological simulation techniques together with Delft3D FLOW-WAVE coupled modeling system to simulate the storm surge was validated with a reasonable level of accuracy. Further, compared to the MM5-Delft3D system, fast and easy simulation capability of DDB-Delft3D system was identified. However, in terms of accuracy, MM5-Delft3D system demonstrated much better performance in outer regions of the typhoon than the DDB-Delft3D system.

선행강우를 고려한 제주하천 유출특성 분석

The rainfall-runoff characteristics in Jeju Island significantly differ from those in inland, due to highly permeable geologic features driven by volcanic island. Streams are usually sustained in the dry conditions and thereby the rainfall-runoff characteristics changes in terms of initiating stream discharge and its types, depending highly on the antecedent precipitation. Among various the rainfall-runoff characteristics, lag time mainly used for flood warning system in river and direct runoff ratio for determining water budget to estimate groundwater recharge quantity are practically crucial. They are expected to vary accordingly with the given antecedent precipitation. This study assessed the lag time in the measured hydrograph and direct runoff ratio, which are especially in the upstream watershed having the outlet as <TEX>$2^{nd}$</TEX> Dongsan bridge of Han stream, Jeju, based upon several typhoon events such as Khanun, Bolaven, Tembin, Sanba as well as a specific heavy rainfall event in August 23, 2012. As results, considering that the lag time changed a bit over the rainfall events, the averaged lag time without antecedent precipitation was around 1.5 hour, but it became increased with antecedent precipitation. Though the direct run-off ratio showed similar percentages (i.e., 23%)without antecedent precipitation, it was substantially increased up to around 45% when antecedent precipitation existed. In addition, the direct run-off ration without antecedent precipitation was also very high (43.8%), especially when there was extremely heavy rainfall event in the more than five hundreds return period such as typhoon Sanba.

낙동강 유출 부유쓰레기의 거동 특성

낙동강은 하구의 수문 개방 시 연간 수천 톤의 쓰레기가 남해로 유입되어 인근 연안을 이동하며 사회 경제적 피해를 유발하고 있다. 이에 본 연구에서 낙동강 유출 부유쓰레기의 거동 특성을 파악하기 위해 2012년 장마, 태풍 내습 시를 대상으로 피해지로 추정되는 거제도 북동측 해안 1개소에 대한 조사와 부이를 활용한 이동 경로 추적 시험을 수행하였다. 또한, 해양기상 환경에 대한 분석을 통해 부유쓰레기의 이동과 관련된 흐름을 파악하였다. 연구 결과 장마 시기인 7월 16일 초목류를 비롯한 총 40톤 정도의 쓰레기가 흥남해수욕장으로 유입되었다. 또한 9월 14일 태풍 '산바' 내습 시기에 투하된 위치 추적 부이는 가덕도 남쪽 해상을 지나 1 ~ 2일 후 거제도 해안가로 유입되는 결과를 보여주었다. 부유쓰레기와 위치 추적 부이가 거제도 북동측 해안가로 유입될 당시 거제 해역에서 북동풍계열의 풍향이 지배적이었으며 연안으로 유입되는 공통적인 해수 표층 흐름이 나타났다. When the mouth of the Nakdong River, opens its floodgate, thousands of tons of litter should flown into the South Sea, moving towards nearby coast, thus causing serious social and economic damage. For this reason, in the present study, research was performed on one certain area in northeast coast of Geoje island, which is assumed as area damaged due to rainy season and typhoon in 2012, and research for trace of movement route was implemented by using buoy to identify characteristic of movement of floating debris caused from Nakdong River. Flows related to the movement of floating debris was also identified by analyzing ocean meteorological environment. As a result of the study, total 40 tons of litter composed of grasses and trees(or plants litter) were flown into Heungnam beach on 16th, Jul which is the rainy season. Plus, the location tracking buoy, which was dropped when the typhoon SANBA was coming, was passed by southern sea of Gadeok-do and was flown into Geoje beach 1 ~ 2 days after it was dropped. The wind direction was mostly northeasterly wind around the Geoje beach at the time the buoy and floating debris were flown into northeast coast and there was common sea surface currents which was flowing into the coast.

2012年台風16号Sanbaによる暴波浪の最大波高の特性

The strong typhoon Sanba crossed the east side of Japan in September, 2012. The minimum central pressure of the Sanba reached 900 hPa. The typhoon generated wind waves more than 15 m in the significant wave height and gave severe damages to coastal structures. This study analyzed observed wave records at 10 stations along the typhoon track. A series of numerical analysis was performed to understand the characteristics of extreme sea condition by the typhoon. The maximum wave heights were estimated based on the spectral wave model and the nonlinear short wave statistical theory. The observed data shows the nonlinear enhancement of maximum wave height slightly. The estimated maximum wave height by the nonlinear theory shows better agreement with the observed peak of maximum wave height than that by the linear theory.

중위도 기압골과 태풍 산바의 이동속도와의 상호작용에 대한 예측에서 모델 바이어스 경향분석

중위도 기압골과 태풍 이동속도와의 상호작용에 대한 예측에서 한국기상청 전구자료동화예측시스템(GDAPS) 모델 바이어스 경향을 알아보기 위해 태풍 산바 사례가 선정되었다. 이 연구는 태풍 분석 및 예측 시스템(TAPS) 및 기상정보시스템-3(COMIS-3)에 저장된 태풍자료로부터 2012년 9월 15일 00UTC로 초기화 된 한국 기상청 GDAPS 분석장과 예측장을 사용하였다. 먼저 해면기압장은 500 hPa 제트구역과 연관하여 중위도 하층 저기압이 발생됨을 보여주었다. 이후 태풍 산바가 중위도 지역으로 들어온 후, 태풍의 이동속도가 증가될 것이라 예측되었다. 특히, 태풍 산바가 9월 17일 00UTC와 06UTC에 전향을 할 시점에 태풍 산바는 중위도 기압골 전면에서 중위도 서풍대와 상호작용을 하였다. 반면, 기상청 GDAPS 해면기압 예측장은 하층 중위도 저기압의 강도를 분석장보다 약하게 예측하였다. 결국 태풍 산바의 이동속도에 영향을 주는 중위도 순환은 분석장보다 느리게 나타났다. 이 순환은 500 hPa에서 제트가 약화됨으로서 증명되었다. 이런 이유로, 기상청 GDAPS 예측장은 태풍 산바가 중위도 기압골과 상호작용함으로써 느린 이동속도의 바이어스를 나타내었다. Typhoon Sanba was selected for describing the Korea Meteorological Administration (KMA) Global Data Assimilation Prediction System (GDAPS) model bias tendency in forecast for the interaction between mid-latitude trough and movement speed of typhoon. We used the KMA GDAPS analyses and forecasts initiated 00 UTC 15 September 2012 from the historical typhoon record using Typhoon Analysis and Prediction System (TAPS) and Combined Meteorological Information System-3 (COMIS-3). Sea level pressure fields illustrated a development of the low level mid-latitude cyclogenesis in relation to Jet Maximum at 500 hPa. The study found that after Sanba entered the mid-latitude domain, its movement speed was forecast to be accelerated. Typically, Snaba interacted with mid-latitude westerlies at the front of mid-latitude trough. This event occurred when the Sanba was nearing recurvature at 00 and 06 UTC 17 September. The KMA GDAPS sea level pressure forecasts provided the low level mid-latitude cyclone that was weaker than what it actually analyzed in field. As a result, the mid-latitude circulations affecting on Sanba's movement speed was slower than what the KMA GDAPS actually analyzed in field. It was found that these circulations occurred due to the weak mid-tropospheric jet maximum at the 500 hPa. In conclusion, the KMA GDAPS forecast tends to slow a bias of slow movement speed when Sanba interacted with the mid-latitude trough.