Estimation of the PAR Irradiance Ratio and Its Variability under Clear-sky Conditions at Ieodo in the East China Sea

변도성,조양기 한국해양과학기술원 2006 Ocean science journal Vol.41 No.4

Determining photosynthetically active radiation (PAR) is a key part of calculating phytoplankton productivity in a biogeochemical model. We explore the daily and seasonal variability in the ratio of PAR irradiance to total irradiance that occurred at Ieodo Ocean Research Station (IORS) in the East China Sea under clear-sky conditions in 2004 using a simple radiative transfer model (RTM). Meteorological data observed at IORS and aerosol optical properties derived from Aerosol Robotic Network observations at Gosan are used for the RTM.Preliminary results suggest that the use of simple PAR irradiance-ratio values is appropriate in calculating phytoplankton productivity as follows: an average of 0.44 (0.01) in January to an average of 0.48 (0.01) in July, with average daily variabilities over these periods of about 0.016 (0.008) and 0.025 (0.008), respectively. The model experiments demonstrate that variations in the major controlling input parameters (i.e. solar zenith angle, precipitable water vapor and aerosol optical thickness) cause PAR irradiance ratio variation at daily and seasonal timescales. Further, increases (>0.012) in the PAR irradiance ratio just below the sea-surface are positively correlated with high solar zenith angles and strong wind stresses relative to those just above the sea-surface.

국제학술지, 지도, 문서에 나타난 대한해협 해양지명과 경계에 대한 인식 변화

변도성,최병주,DO-SEONG BYUN,BYOUNG-JU CHOI 한국해양학회 2023 바다 Vol.28 No.2

This study aims to examine the history of naming the strait between the Yellow and East China Seas and the East Sea to suggest a consistent nomenclature and to demarcate the geographic region of the strait. Although the strait is internationally known as 'Korea Strait', it is commonly referred to as the 'South Sea' in Korean common usage. This review ultimately recommends the use of 'Korea Strait' as an appropriate geographical name for this area. To support this recommendation, the historical boundaries typically assigned to the Korea Strait were investigated. We also analyzed the evolution of geographical labels assigned to Korea Strait and to the Western and Eastern Channels (labels given to the two maritime areas surrounding Tsushima). Resources for this analysis included historic maps and charts, International Hydrographic Organization Special Publications (S-23), and maps published in the Ocean Science Journal (OSJ) and Journal of Oceanography (JO), which are two international journals representing Korean and Japanese sources, respectively, from 2005 to 2021. In these two international journals, the most frequently used names assigned to the strait of interest were Korea Strait (appearing 42.9% of OSJ maps, and 7.5% of JO maps), and Tsushima Strait (appearing 60.4% of JO maps, and 0% of OSJ maps). Other names were South Sea and Korea Strait/Tsushima Strait. On maps in the two reviewed journals, the boundaries of Korea Strait were defined explicitly or implicitly in five different ways: a broad region between the Yellow and East China Seas and Ulleung Basin (Type 1), the region between Ulleung Basin and Tsushima (Type 2), the western channel of the strait (Type 3-1), the eastern channel of the strait (Type 3-2), and both the western and eastern channels of the strait (Type 4). Overall, Type 1 was the most frequently used boundary, taking up 71.4% of OSJ and 60.4% of JO maps. Lastly, we suggest in this paper that the current flowing through Korea Strait from the East China Sea to the East Sea should be labeled the 'Korea Strait Warm Current' to indicate its full path through the strait. Currently, this current is internationally referred to as the 'Tsushima Warm Current', which does not link well to the commonly used geographic name of the strait.

인천항 협수로에서 S2와 K1 조류분조 조화상수의 월변동성 완화

변도성,조창우,이은일,임세한 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

표층뜰개·인공위성 해수면 고도편차 자료로 구한 동해 표층 지형류 변동성 분석

변도성,최병주,정희석 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

이어도 해양과학기지 풍속 자료의 실시간 운용을 위한 기준 고도 변환 과정

변도성,김효원,이주영,이은일,박경애,우혜진,BYUN, DO-SEONG,KIM, HYOWON,LEE, JOOYOUNG,LEE, EUNIL,PARK, KYUNG-AE,WOO, HYE-JIN 한국해양학회 2018 바다 Vol.23 No.4

운용용으로 사용되는 대부분의 풍속자료는 10 m 기준 고도에서 측정 또는 생산된 자료이다. 이 연구는 이어도 해양과학기지 42.3 m 고도의 옥상 등대에서 측정 중인 풍속을 기준 고도의 풍속으로 변환시켜 국립해양조사원 누리집을 통해 실시간으로 제공하기 위한 사전 연구이다. 이를 위해 2015년에 이어도 기지에서 관측한 풍속을 대표적인 네 종류의 풍속 변환식 - 멱법칙식, 두 종류의 중립벽 로그법칙식(항력계수형, 거칠기 높이형), 대기 안정도 효과를 고려한 벽 로그법칙모델(안정도 고려 거칠기 높이형) -에 적용하였다. 관측 바람을 평가하는데 많이 사용되는 '안정도 고려 거칠기 높이형' 벽 로그법칙모델의 결과와 나머지 풍속 변환식 결과들을 서로 비교하였다. 그 결과 '거칠기 높이형' 벽 로그법칙식과 '안정도 고려 거칠기 높이형' 벽 로그법칙모델 간 편향과 평균 제곱근 편차는 각각 $-0.001m\;s^{-1}$와 $0.122m\;s^{-1}$로 가장 낮아 실시간 현업 운용 측면에서 상호 보완적으로 이 두 변환식을 함께 사용하는 것이 바람직하다는 결론을 도출하였다. 또한 이어도 해역에서 조석에 의한 풍속 관측 고도 변화가 풍속 변환에 미치는 영향을 분석하였다. 이들 변환식에 대한 조석 효과 고려 전후에 대한 비교 실험 결과, 편향과 평균 제곱근 편차는 각각 <$0.0001m\;s^{-1}$와 <$0.012m\;s^{-1}$로 그 영향은 미미하였다. 대기 표면 거칠기 높이를 사용하는 '거칠기 높이형' 벽 로그법칙식과 '안정도 고려 거칠기 높이형' 벽 로그 법칙모델을 이용하여 간편 풍속 변환식의 필수 입력값인 표면 거칠기 높이 값의 적절성에 관해 논의하였으며, 풍속 변환 정확도를 향상시킬 수 있는 표면 거칠기 높이 계산식을 제시하였다. 또한 인공위성 산란계(ASCAT) 풍속자료와 네 종류의 중립 연직 풍속 변환식들의 결과를 비교하여 이들 중 '안정도 고려 거칠기 높이형' 벽 로그법칙모델에서 안정도 항을 뺀 풍속 변환 모델의 정확도가 더 낫다는 결과를 제시하였다. 끝으로 이들 종래 $25m\;s^{-1}$ 이하 풍속에 최적화된 풍속 변환식들로부터 바람 항력계수를 산정 분석하여 강풍(${\geq}33m\;s^{-1}$) 환경에서도 적합한 풍속 변환식으로 개선 필요성에 관해 논의하였다. Most operational uses of wind speed data require measurements at, or estimates generated for, the reference height of 10 m above mean sea level (AMSL). On the Ieodo Ocean Research Station (IORS), wind speed is measured by instruments installed on the lighthouse tower of the roof deck at 42.3 m AMSL. This preliminary study indicates how these data can best be converted into synthetic 10 m wind speed data for operational uses via the Korea Hydrographic and Oceanographic Agency (KHOA) website. We tested three well-known conventional empirical neutral wind profile formulas (a power law (PL); a drag coefficient based logarithmic law (DCLL); and a roughness height based logarithmic law (RHLL)), and compared their results to those generated using a well-known, highly tested and validated logarithmic model (LMS) with a stability function (${\psi}_{\nu}$), to assess the potential use of each method for accurately synthesizing reference level wind speeds. From these experiments, we conclude that the reliable LMS technique and the RHLL technique are both useful for generating reference wind speed data from IORS observations, since these methods produced very similar results: comparisons between the RHLL and the LMS results showed relatively small bias values ($-0.001m\;s^{-1}$) and Root Mean Square Deviations (RMSD, $0.122m\;s^{-1}$). We also compared the synthetic wind speed data generated using each of the four neutral wind profile formulas under examination with Advanced SCATterometer (ASCAT) data. Comparisons revealed that the 'LMS without ${\psi}_{\nu}^{\prime}$ produced the best results, with only $0.191m\;s^{-1}$ of bias and $1.111m\;s^{-1}$ of RMSD. As well as comparing these four different approaches, we also explored potential refinements that could be applied within or through each approach. Firstly, we tested the effect of tidal variations in sea level height on wind speed calculations, through comparison of results generated with and without the adjustment of sea level heights for tidal effects. Tidal adjustment of the sea levels used in reference wind speed calculations resulted in remarkably small bias (<$0.0001m\;s^{-1}$) and RMSD (<$0.012m\;s^{-1}$) values when compared to calculations performed without adjustment, indicating that this tidal effect can be ignored for the purposes of IORS reference wind speed estimates. We also estimated surface roughness heights ($z_0$) based on RHLL and LMS calculations in order to explore the best parameterization of this factor, with results leading to our recommendation of a new $z_0$ parameterization derived from observed wind speed data. Lastly, we suggest the necessity of including a suitable, experimentally derived, surface drag coefficient and $z_0$ formulas within conventional wind profile formulas for situations characterized by strong wind (${\geq}33m\;s^{-1}$) conditions, since without this inclusion the wind adjustment approaches used in this study are only optimal for wind speeds ${\leq}25m\;s^{-1}$.

On Robust Multi-Year Tidal Prediction Using T_TIDE

변도성,Deirdre Erin Hart 한국해양과학기술원 2019 Ocean science journal Vol.54 No.4

A minimum 19 year tidal prediction dataset covering nodal (satellite) modulation effects is required to determine the Lowest Astronomical Tide (LAT) and Highest Astronomical Tide (HAT) datums. In this study, we explore the ability of a widely used conventional standard harmonic prediction program, T_TIDE ‘t_predic.m’ from Pawlowicz et al. (2002), to produce accurate continuous multi-year predictions. Comparisons are made with the more recent tidal prediction program, UTide ‘ut_reconstr.m’ from Codiga (2011). Tidal height records for two different regimes are employed: for diurnal tides data are employed from Cape Roberts in Antarctica, while for semi-diurnal tides data are used from Incheon, Gyeonggi Bay, Korea. Results demonstrate an issue arises in continuous multi-year tidal predictions made via T_TIDE, due to the program’s single calculation (fixed) of nodal modulation corrections (NMC). We explain a modified NMC update method that successfully solves this problem, rendering the program of use for accurate continuous multi-year tidal predictions.

우리나라 조석지각 기준 표기에 대한 고찰

변도성,Byun, Do-Seong 한국해양학회 2007 바다 Vol.12 No.3

현재까지 우리나라에선 연구자마다 각기 다른 세 가지 조석지각 기준(관측지점 경도 기준 지각, 표준시 자오선 기준 지각, 그리니치 자오선 기준 지각)을 사용하여 오고 있다. 이처럼 통일되지 않는 조석지각 정보체계는 전체적인 우리나라 조석의 특성이나 변화를 이해하는데 장애가 되고 있다. 이 연구에서는 올바른 조석지각 기준의 상호전환과 관련하여, 세 가지 지각기준에 관하여 자세히 살펴보았다. 이에 앞서 조석 조화분해 과정에서 분조의 지각이 어떻게 계산되며, 조석예측프로그램에선 계산된 지각이 어떻게 사용되게 되는지 살펴보았다. 또한 이것을 바탕으로 과거 일부 연구에서 불명확하게 기술된 조석지각의 정의에 관하여 논의하였다. Three different tidal phase-lag references have been used by the tidal research community of Korea: Greek kappa (k), Local standard time zone ($135^{\circ}E$) phase-lag (g) and Greenwich phase-lag (G). This ununified tidal information system may induce confusion in understanding tidal characteristics and their variability and impede the development of tidal knowledge in Korea. In this study we closely explore the three phase-lag reference definition with respect to their mutual conversion. We also identify an incorrect phase-lag reference definition used in previous works and discuss what has led to this misunderstanding.

한국 연안에서 1999년부터 2017년까지 해수물성과 대기압 변화에 따른 계절 비천문조와 월평균 해수면 변화

변도성,최병주,김효원 한국해양학회 2021 바다 Vol.26 No.1

The solar annual (Sa) and semiannual (Ssa) tides account for much of the non-uniform annual and seasonal variability observed in sea levels. These non-equilibrium tides depend on atmospheric variations, forced by changes in the Sun's distance and declination, as well as on hydrographic conditions. Here we employ tidal harmonic analyses to calculate Sa and Ssa harmonic constants for 21 Korean coastal tidal stations (TS), operated by the Korea Hydrographic and Oceanographic Agency. We used 19 year-long (1999 to 2017) 1 hr-interval sea level records from each site, and used two conventional harmonic analysis (HA) programs (Task2K and UTide). The stability of Sa harmonic constants was estimated with respect to starting date and record length of the data, and we examined the spatial distribution of the calculated Sa and Ssa harmonic constants. HA was performed on Incheon TS (ITS) records using 369-day subsets; the first start date was January 1, 1999, the subsequent data subset starting 24 hours later, and so on up until the final start date was December 27, 2017. Variations in the Sa constants produced by the two HA packages had similar magnitudes and start date sensitivity. Results from the two HA packages had a large difference in phase lag (about 78°) but relatively small amplitude (<1 cm) difference. The phase lag difference occurred in large part since Task2K excludes the perihelion astronomical variable. Sensitivity of the ITS Sa constants to data record length (i.e., 1, 2, 3, 5, 9, and 19 years) was also tested to determine the data length needed to yield stable Sa results. HA results revealed that 5 to 9 year sea level records could estimate Sa harmonic constants with relatively small error, while the best results are produced using 19 year-long records. As noted earlier, Sa amplitudes vary with regional hydrographic and atmospheric conditions. Sa amplitudes at the twenty one TS ranged from 15.0 to 18.6 cm, 10.7 to 17.5 cm, and 10.5 to 13.0 cm, along the west coast, south coast including Jejudo, and east coast including Ulleungdo, respectively. Except at Ulleungdo, it was found that the Ssa constituent contributes to produce asymmetric seasonal sea level variation and it delays (hastens) the highest (lowest) sea levels. Comparisons between monthly mean, air-pressure adjusted, and steric sea level variations revealed that year-to-year and asymmetric seasonal variations in sea levels were largely produced by steric sea level variation and inverted barometer effect. 비천문조인 연주조(Sa)와 반년주조(Ssa)는 해수특성 변화와 기상 상태에 영향을 받는 비대칭 월평균 해수면의 연변화와 관련이 깊다. 국립해양조사원이 운영하는 21개 조위관측소에서 관측한 1시간 간격의 19년(1999~2017년) 간 해수면 높이 자료에 대하여 두 종류의 조석 조화분해 프로그램(Task2K와 UTide)을 사용하여 Sa와 Ssa의 조화상수를 산출하였다. 조화분해에 사용되는 자료의 시작 시기와 길이에 따른 Sa의 안정도를 조사하였으며, Sa와 Ssa의 조화상수의 분포 특성을 살펴보았다. 먼저, 인천 조위관측소의 20년(1999~2018년) 해수면 관측자료를 1일씩 이동하면서 1년(369일) 조화분해를 수행하고 그 결과를 비교하였을 때, 두 프로그램 모두 자료의 시작 시기에 따라 Sa 조화상수가 불규칙하게 크게 변동한다는 사실을 알 수 있었다. Task2K가 Sa 분조 계산식에 근일점 천문변수를 고려하지 않아서, 두 프로그램 간에 약 78°의 지각 차가 났으며, 이들 진폭 차이는 1 cm 이하였다. 우리나라 연안에서는 Sa 조화상수가 해마다 크게 다르므로, 조위 예측 정확도와 관련하여 안정적인 조화상수 산출에 필요한 적절한 자료 길이를 결정하기 위해 관측자료 길이(1년, 2년, 3년, 5년, 9년, 19년)에 따른 인천 조위관측소의 Sa 조화상수 값의 변동성을 살펴보았다. 대표성 있는 Sa 조화상수를 구하기 위해서 조화분해를 수행할 때 5~9년 동안의 관측자료를 사용하면 조화상수 예측오차가 상당히 줄어들며, 19년 자료를 사용 것이 가장 바람직하다는 결론을 얻었다. Sa 분조의 진폭은 각 해역별로 다른 해양·대기 환경 특성에 의해 서해안에서 15.0~18.6 cm, 제주도를 포함한 남해안에서 10.7~17.5 cm이었으며, 울릉도를 포함한 동해안에서 10.5~13.0 cm이었다. 울릉도 등 동해 일부 해역을 제외하고 우리나라 연안에서 Ssa 분조의 영향으로 인해 연중 최고(최저) 해수면 높이가 발생하는 시기가 늦어(빨라)져서 해수면의 계절변화가 시간적으로 비대칭적인 특성을 보였다. 끝으로, 월평균 해수면, 대기압 보정 해수면, 비부피 높이 간 관계로부터 해수면의 해해변화와 계절변화의 비대칭성에 대기압 효과와 해수밀도가 가장 큰 영향을 끼친다는 사실을 확인하였다.

병자호란 시기 강화도 함락 당일 염하수로의 조석과 조류 추산

변도성,김효원,구범진 한국과학사학회 2017 한국과학사학회지 Vol.39 No.3

On 16 February 1637, Qing troops landed on Ganghwa Island and occupied Ganghwa Castle. According to the conventional narrative, a few Joseon warships bravely fought in vain to deter the enemy from crossing the shallow, narrow Yeomha Waterway while the main fleet cowardly ran away. A close investigation of firsthand accounts of this battle, however, reveals that no Joseon warships blocked this waterway during the Qing ferryboats’ advance. Here the question arises: What kept Joseon’s naval warships from entering this waterway while the Qing boats were able to cross? In exploring possible answers, Joseon's records indicate that the presence and timing of strong tidal currents might have been a crucial obstacle to the warships’ movement. Given the substantive differences in accounts between Joseon and Qing, this paper attempts to verify which account is more accurate, by hindcasting the paleo-tidal currents and tides (PTCT) of the day via two methods: a conventional harmonic prediction method and a correct tidal species modulation with tidal constant correction method. The PTCT results in general, and the timing of the hindcast high tide and slack water period (around 10:30 am) in particular, tally with the Joseon account. Moreover, our results provide new evidence to support the detailed reconstruction of events surrounding the Qing troops’ 1637 landing operation.

조류 조화상수의 월변동성 완화 방법 고찰

변도성 한국해양과학기술원 2011 Ocean and Polar Research Vol.33 No.3

This is a preliminary study of the feasibility of obtaining reliable tidal current harmonic constants, using one month of current observations, to verify the accuracy of a tidal model. An inference method is commonly used to separate out the tidal harmonic constituents when the available data spans less than a synodic period. In contrast to tidal constituents, studies of the separation of tidal-current harmonics are rare, basically due to a dearth of the long-term observation data needed for such experiments. We conducted concurrent and monthly harmonic analyses for tidal current velocities and heights, using 2 years (2006 and 2007) of current and sea-level records obtained from the Tidal Current Signal Station located in the narrow waterway in front of Incheon Lock, Korea. Firstly, the l-year harmonic analyses showed that, with the exception of M2 and S2 semidiurnal constituents, the major constituents were different for the tidal currents and heights. K1, for instance, was found to be the 4th major tidal constituent but not an important tidal current constituent. Secondly, we examined monthly variation in the amplitudes and phase-lags of the S2 and K1 current-velocity and tide constituents over a 23-month period. The resultant patterns of variation in the amplitudes and phase-lags of the S2 tidal currents and tides were similar, exhibiting a sine curve form with a 6-month period. Similarly, variation in the K1 tidal constant and tidal current-velocity phase lags showed a sine curve pattern with a 6-month period. However, that of the K1 tidal current-velocity amplitude showed a somewhat irregular sine curve pattern. Lastly, we investigated and tested the inference methods available for separating the K2 and S2 current-velocity constituents via monthly harmonic analysis. We compared the effects of reduction in monthly variability in tidal harmonic constants of the S2 currentvelocity constituent using three different inference methods and that of Schureman (1976). Specifically, to separate out the two constituents (S2 and K2), we used three different inference parameter (i.e. amplitude ratio and phase-lag diggerence) values derived from the 1-year harmonic analyses of current-velocities and tidal heights at (near) the short-term observation station and from tidal potential (TP), together with Schureman's (1976) inference (SI). Results from these four different methods reveal that TP and SI are satisfactorily applicable where results of long-term harmonic analysis are not available. We also discussed how to further reduce the monthly variability in S2 tidal current-velocity constants.