https://doi.org/10.20575/00000055
Polar Data Journal, Vol. 8, 44–54, July 2024
Ⓒ 2024 National Institute of Polar Research. This work is distributed
under the Creative Commons Attribution 4.0 International license.

Hydrographic Data of the 62nd Japanese Antarctic Research
Expedition from January 2020 to February 2021
Natsuki SAITO1* and Mifuka ISHIKAWA1
1

Hydrographic and Oceanographic Department, Japan Coast Guard,
3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932.
*Corresponding author. Natsuki Saito (nankyoku@jodc.go.jp)(Received February 6, 2023; Accepted May 21, 2024)

Abstract: The Japan Coast Guard continues to conduct bathymetric surveys and tidal observations
for producing nautical charts around Syowa Station in Antarctica. The first author conducted theseobservations as a member of the 62nd Japanese Antarctic Research Expedition. This paper describes
the results of the bathymetric survey around Lützow-Holmbukta in January 2021 and the tidal effects
at Syowa Station, Antarctica, from January to December 2020.

1. Background & Summary
The Japan Coast Guard (JCG) has conducted multibeam bathymetric surveys around Syowa
Station in Antarctica since 2009 and tidal observations by the permanent tide station at Syowa Station
since 1971 to obtain bathymetric data for nautical charting purposes. The bathymetric data ensure thesafety of ship navigation around Syowa Station through the nautical charts in Antarctica published byeach member state within the framework of the Hydrographic Commission on Antarctica (HCA) of
the International Hydrographic Organization (IHO). In addition, the bathymetric data are also used as
basic data for studies on the evolutionary processes of the continental and oceanic crust, and on thereconstruction of paleoenvironments such as glacial erosion and depositional environments. Tidal
observation data contribute not only to the determination of the nautical chart datum and tidal
correction of bathymetric data but also to the monitoring of long-term changes in global sea level andtsunami.
The first author conducted observations as a member of the 62nd Japanese Antarctic Research
Expedition (JARE-62) following the JARE-611.
This paper reports the results of the bathymetric survey conducted around Lützow-Holmbukta inJanuary 2021 and the tidal observations at the Syowa Station, Antarctica. The tide gauge data wererecorded during the JARE-61 from January to December 2020.

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2. Location
The bathymetric survey was conducted off Lützow-Holmbukta between 67 °01'S and 67° 26'S,
and between 35°05'E and 36°34'E (Figure 1). The survey tracks by the JARE-62 are shown in red lines.
The JARE-62 surveyed the area adjacent to the south of the area surveyed by the JARE-61.
Tidal observations were conducted at Nishinoura, East Ongul Island (Figure 2). The tide gauges
and the tidal observation system are connected by cables. The tidal observation system is installed in
the Fundamental observation building, Syowa Station, approximately 600 m from the tide gauges atNishinoura.
3. Methods
The bathymetric surveys and tidal observations were conducted using essentially the same
methods as in the JARE-61, details written in Ikeuchi 20231.
Bathymetry data were acquired using a multibeam echosounder (SeaBeam 3020 Icebreaker,
ELAC SONAR GmbH)2 installed on the Shirase. The waterline correction for bathymetry data wasapplied using a draft value of Shirase measured at the time of departure from Syowa Station on January
21, 2021, before the bathymetric survey. The bathymetric surveys were conducted with full coverage
and an overlap ratio of at least 35% for each adjacent survey line. The high-density bathymetric grid
data without instrument outliers were calculated from the bathymetric soundings and theiruncertainties obtained with the multibeam echosounder by the statistical data processing method, theCombined Uncertainty and Bathymetric Estimator (CUBE) processing3, with the multibeam dataprocessing software (Caris HIPS and SIPS Ver.11, Teledyne Geospatial)4. The grid sizes of the CUBE
bathymetry were set to 100 m, depending on the beam footprint, a measure of the spatial resolution ofthe multibeam echosounder.
The tide gauge data was observed with two quartz-oscillator water level gauges (QWP-8-203DK, Meisei Electric Co., Ltd.)5 of the main (installed by JARE-59)6 and backup (installed by JARE56)7. As shown in Figure 3, a vertical offset of 5 m below the top of benchmark No. 1040 was applied
to the tidal data. The offset value has been used as the observation datum level for tidal observations
since February 1, 20018. Hourly tide gauge data were extracted from the 30-second tide gauge data,
and daily and monthly mean sea levels were calculated from the hourly data. Also, tidal harmonic
analysis using the least squares method was performed using 369 days of tidal data. The tidal harmonic
analysis is a calculation to determine the amplitude (H) and the phase lag (K) of each oscillation,
assuming that the tidal variation consists of a superposition of multiple cosine oscillations (MarineSurvey Technical Manual - Oceanographic and Meteorological Surveys - 4th Edition, 2005)9. The H
and K of each tidal constituent were calculated using the least squares method by minimizing thedifference between the estimated and measured values for 60 tidal constituents.

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4. Data Records
The bathymetric data were recorded from January 23 to 24, 2021. Figure 1 shows the track of thebathymetric surveys and the XCTD (eXpendable Conductivity, Temperature, and Depth) observationsites obtained for the sound speed correction of the bathymetric data. Figure 4 shows the seafloor
topographic map off Lützow-Holmbukta, mechanically color-coded using the GIS software (ArcGIS
10.5, ESRI Inc.)10. On the website of the Japan Oceanographic Data Center (JODC), the bathymetricdata are available in CSV format, and the XCTD data is available in tab-delimited ASCII text format.
The tide data were observed from January to December 2020. Daily and monthly mean sea levels
are shown in Table 1. The calculated tidal harmonic constants are shown in Table 2. The hourly data
used in the calculations is also available on the website of the JODC in CSV format.

5. Technical Validation
Total Propagated Uncertainty (TPU) of bathymetric data, an overall uncertainty of the various
error factors of each sensor associated with bathymetric data, is used as an index for evaluating theprecision of each bathymetry sounding. The TPU was calculated by considering the precisions ofvarious sensors, such as multibeam echosounder, surface sound speed, sound speed profile, tidal
observations, positioning, motion, and draft measurement. The typical uncertainties (95 % ConfidenceInterval (CI)) of the resulting CUBE bathymetric data off Lützow-Holmbukta are 10.7 ±4.5 m at
depths of approximately 3000–4300 m.
The precision (68 % CI) of tide gauge data is 0.05 % Full Scale (FS) over the observation range
of 0–20 m, i.e., less than 0.01 m. The calibration of the tide gauge is performed by visual observationof sea level change using a temporary measuring tide pole during the summer period. In the JARE-62,
measurements for calibrating the tide gauge were conducted from January 11 and 12, 2021, at
Nishinoura, East Ongul Island. The reduction ratio, the scale factor of the tide gauge, was 0.97, which
was the same as that of JARE-61 and nearly typical for seawater with a practical salinity unit of 34(Figure 3). The correlation coefficient between tide levels measured by the tide gauge and tide pole
was more than 0.99. From the calibration results, the validity of tidal observation data measured by
the tide gauge was confirmed.

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6. Figures

Figure 1. Ship track map of the JARE-62 (red lines) and JARE-61 (yellow lines) bathymetric surveys
in the Lützow-Holmbukta and approaches. Blue symbols are the XCTD observation sites.

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N. Saito and M. Ishikawa

Figure 2.

Location map of tide gauges at Nishinoura, tidal observation system installed in theFundamental observation building, and their connected cables at Syowa Station.

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Latitude：69-00-28Ｓ
Longitude：39-34-13E
Time Zone：Syowa Station Local Time （UTC+3h）
System：Hydraulic type（Subtracting the atmospheric pressures）
Tide gauge：QWP-8, Meisei Denki Co Ltd.
Visual tidal observation with a temporal tide pole gauge
Sensor channel：No.2
Reduction ratio：0.97
Intercept：-10.794m
The length of tide pole：3.00m
Observational day：2021/01/11-2021/01/12

Figure 3. Tide level diagram at Nishinoura, Syowa Station from the JARE-62 calibration.

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N. Saito and M. Ishikawa

Figure 4. Bathymetric chart off the Lützow-Holmbukta obtained by the JARE-62.

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7. Tables
Table 1. Hourly tidal observation during Jan.1–Dec.31, 2020 at Syowa Station.
The 24-hour total and mean tides, 25-hour total and mean tides, and monthly mean tides
listed in this table are calculated using hourly tide levels from Tide gauge data (URL:
https://jdoss1.jodc.go.jp/vpage/tide.html) posted at JODC. Time zones are based on localtimeat

SyowaStation.

Alldataareavailable

http://id.nii.ac.jp/1434/00000055 > Supplemental Tables

51in

SupplementalTables.

N. Saito and M. Ishikawa

Table 2. Harmonic constants at Syowa Station.

Syowa Station (Nishinoura)
Position : Lat. 69-00-28S , Lon, 39-34-13E
Epoch and Duration of Analysis :Epoch : 2020/01/01
Central Date : 2020/07/03
Duration in Days: 369 days
Missing Hour : 29 hours
Mean Sea Level : 257.4 cm
Harmonic Constants :H(cm) K(deg）H(cm) K(deg)SA

6.95 53.07

M2SSA

3.29 93.98

MKS2

0.09 136.85

MM1.83 220.42

LAM2

0.21 156.28

MSF

1.27 158.42

L2MF

1.85 201.20

T2

1.24 162.21

2Q10.83 333.70

S220.39 176.03

SIG10.96 325.71

R20.25 194.75

Q15.80 338.06

K25.92 175.07

RHO1O1

1.18 350.50

25.34 160.49

1.43 135.61

MSN20.06 68.85

24.30 350.11

KJ2

MP10.52 354.37

2SM20.25 107.46

M11.17 358.73

MO30.10 191.41

CHI10.267.89

M30.24 263.23

PI10.478.79

SO30.06 302.32

P17.45 355.62

MK30.05 235.37

S10.21 95.54

SK30.42 331.91

K122.25 357.50

MN40.23 43.43

PSI10.13 306.74

M40.44 101.44

PHI1

0.31 353.91

SN40.05 131.30

THE10.21 321.31

MS40.17 173.93

J10.96 353.29

SO10.17

OO1

0.35 39.30

MK41.910.07 186.52

S40.04 208.090.57 335.65

SK40.09 161.94

OQ20.06 219.90

2MN6

MNS20.11 359.15

M60.05 25.89
0.14 84.94

2N20.48 112.13

MSN60.09 152.46

MU20.60 105.13

2MS60.32 186.81

N24.64 148.84

2MK60.09 179.05

NU20.83 161.50

2SM60.11 248.59

OP20.10 80.37

MSK60.07 257.05

H(cm): Amplitude
K(deg): Phase lag:
The time from the time when the moon passes directly above to the storm surge.

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Author contributions
The first author conducted bathymetric surveys and tidal observations for calibration, maintained
the tide gauges in the summer period of JARE-62, and conducted data analysis and writing. The secondauthor conducted data analysis and writing.

Acknowledgments
The authors would like to express their gratitude to all the people of JARE-61, JARE-62, andShirase for their support and valuable and appropriate advice. The authors express their sincere
appreciation to Mr. Mitsuteru Kuno of the JARE-62 summer party who conducted the bathymetricsurvey with the first author. The authors express the sincere appreciation to Dr. Noriaki Obara of theJARE-61 wintering team, maintained the tide gauges at Syowa Station throughout the year.

References
1.

Ikeuchi, Y. Hydrographic Data of the 61st Japanese Antarctic Research Expedition from January 2019
to February 2020. Polar Data Journal. 2023, 7, p. 1–12. http://doi.org/10.20575/00000044.

2.

ELAC SONAR GmbH. “SB 3020 2G”. ELAC SONAR GmbH. https://www.elac-sonar.de/sphere-byelac/sb-3020/ (accessed 2024-7-8).

3.

Sumiyoshi, M., Kurita, H., Yasuhara, T., Hashimoto, T., Ogawa, H., Nagasawa, R., Nagano, K.,
Yoshizawa, M., Shinbo, T. and Akiyama, Y. Adoption of CUBE depths in multibeam hydrographic
survey results: introduction of optimization cases in foreign hydrographic organizations. Report ofHydrographic and Oceanographic Researches. 2020, 58, p. 66–79.

4.

Teledyne Geospatial. “HIPS and SIPS”. Teledyne Geospatial CARIS.
https://www.teledynecaris.com/en/products/hips-and-sips/ (accessed 2024-7-8).

5.

Meisei Electric Co., Ltd. “Quartz-oscillator Water Level Gauges (Type QWP)”. Meisei Electric Co.,
Ltd. https://www.meisei.co.jp/products/water/water_sub/p888 (accessed 2024-7-8).

6. Watanabe, T. Tidal observation. Japanese Antarctic Research Expedition 59th Report (2017–2019),
2019, p. 93–95 (in Japanese).
7.

Shimomura, H. Oceanographic Data of the 56th Japanese Antarctic Research Expedition fromDecember 2014 to March 2015. JARE Data Reports. 2016, 360 (Oceanography 39), p. 1–20.
https://doi.org/10.15094/00013552.

8.

Kinoshita, H. and Nosaka, T. Oceanographic Data of the 43rd Japanese Antarctic Research Expedition
from December 2001 to March 2002. JARE Data Reports. 2005, 282 (Oceanography 27), p. 1–63.
https://doi.org/10.15094/00003485.

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9.

Japan Marine Surveys Association. Marine Survey Technical Manual (Oceanographic andMeteorological Surveys). 4th Edition. Japan Marine Surveys Association, 2005, 330 p (in Japanese).

10. ESRI Japan Co. “ArcGIS”. ESRI Japan. https://www.esrij.com/products/arcgis/ (2024-7-8).

Data Citations
All observation data are located at website run by the JODC.
JODC website URL: https://www.jodc.go.jp/jodcweb/JDOSS/index.html.

Bathymetry data URL: https://www.jodc.go.jp/vpage/JAREdepth.html.
Download Methods: Check “JARE62” and click “get data”.

XCTD data URL: https://www.jodc.go.jp/vpage/scalar.html.
Download Methods:
1. Left-click on the map and move the mouse to 65°S 70°S 35°E 40°E.
2. Check "Select mesh" at the top of the map.
3. Click on the mesh at 65°S 70°S 35°E 40°E on the map.

Tide gauge data URL: https://jdoss1.jodc.go.jp/vpage/tide.html.
Download Methods:
1. Left-click on the map and move the mouse to the Syowa Station (69°0.467′S 039°34.217′E).
2. Click on the light blue inverted triangle (Tide station managed by the Japan Coast Guard) and click “getdata”.

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