A High Spatial Resolution FBG Sensor Array for Measuring Ocean Temperature and Depth

Abstract

Exploring and understanding the ocean is an important field of scientific study. Acquiring accurate and high-resolution temperature and depth profiles of the oceans over relatively short periods of time is an important basis for understanding ocean currents and other associated physical parameters. Traditional measuring instruments based on piezoelectric ceramics have a low spatial resolution and are not inherently waterproof. Meanwhile, sensing systems based on fiber Bragg grating (FBG) have the advantage of facilitating continuous measurements and allow multi-sensor distributed measurements. Therefore, in this paper, an all-fiber seawater temperature and depth-sensing array is used to obtain seawater temperature and depth profiles. In addition, by studying the encapsulation structure of the FBG sensors, this paper also solves the problem of the measurement error present in traditional FBG sensors when measuring seawater temperature. Through a theoretical analysis and seaborne test in the Yellow Sea of China, the sampling frequency of the all-fiber seawater temperature and depth profile measurement system is 1 Hz, the accuracy of the FBG sensors reaches 0.01 °C, and the accuracy of the FBG depth sensors reaches 0.1 % of the full scale. The resulting parameters for these sensors are therefore considered to be acceptable for most survey requirements in physical oceanography.

Keywords

Fiber Bragg grating / temperature-depth profile / cross-sensitivity / seaborne test verification

References

[1] Campagna C, Rivas A L, Marin M R. Temperature and depth profiles recorded during dives of elephant seals reflect distinct ocean environments. Journal of Marine Systems, 2000, 24(3): 299-312.

[2] Herschy R W. Hydrometry principles and practice, 2000, New York: John Wiley and Sons

[3] Holton J R. An introduction to dynamic meteorology. American Journal of Physics, 1973, 41(5): 752-754.

[4] Badan-Dangon A, Dorman C E, Merrifield M A, Winant C D. The lower atmosphere over the Gulf of California. Journal of Geophysical Research Oceans, 1991, 96(C9): 16877-16896.

[5] Cervone G. Combined remote-sensing, model, and in situ measurements of sea surface temperature as an aid to recreational navigation: crossing the Gulf Stream. International Journal for Remote Sensing, 2013, 34(2): 434-450.

[6] Myers D G, Hick P T. An application of satellite-derived sea surface temperature data to the Australian fishing industry in near real–time. International Journal of Remote Sensing, 1990, 11(11): 2103-2112.

[7] Zhang Z J, Cai Y, W F, Ruan J, Chai G Z. Study on robustness of underwater acoustic temperature field measurement method. Journal of Zhejiang University of Technology, 2012, 40(2): 172-177.

[8] Mei F H, Hou W. Application of non-acoustic submarine detection technology in aviation antisubmarine of trailing detection. Electronics Optics & Control, 2017, 27(7): 62-65.

[9] Pollard R. Frontal surveys with a towed profiling conductivity/temperature/depth measurement package (Sea Soar). Nature, 1986, 323(6087): 433-435.

[10] Sheppard C. Large temperature plunges recorded by data loggers at different depths on an Indian Ocean atoll: comparison with satellite data and relevance to coral refuges. Coral Reefs, 2009, 28(2): 399-403.

[11] Dinesh D, Gabriel L, Daniel T, Thomas N, Elfed L, Gerard D. Underwater depth and temperature sensing based on fiber optic technology for marine and fresh water applications. Sensors, 2017, 17(6): 1228.

[12] Tsuchiya M, Talley L D, McCartney M S. Water-mass distributions in the Western South Atlantic; A section from South Georgia Island (54S) northward across the equator. Journal of Marine Research, 1994, 52(1): 55-81.

[13] Bhansali S, Langebrake L C, Bhat S. MEMS based conductivity-temperature-depth sensor for harsh oceanic environment. OCEANS Proc. of IEEE, 2006, 2, 1785-1789.

[14] Albérola C, Millot C, Send U, Mertens C, Fuda J L. Comparison of XCTD/CTD data. Deep Sea Research Part I Oceanographic Research Papers, 1996, 43(6): 859-876.

[15] Sloyan B M, Talley L D, Chereskin T K, Fine R, Holte J. Antarctic intermediate water and subantarctic mode water formation in the Southeast Pacific: the role of turbulent mixing. Journal of Physical Oceanography, 2008, 40(7): 1558-1574.

[16] Flierl G R, Robinson A R. XBT Measurements of Thermal Gradients in the MODE Eddy. Journal of Physical Oceanography, 2010, 7(7): 300-301.

[17] Liu C J, Mao H B, Chen R Y, Wang D X. An analysis on moving vessel profiler observation in Northern South China sea in September 2004. Journal of Tropical Oceanography, 2005, 24(5): 77-82.

[18] Rudnick D L, Klinke J. The underway conductivity temperature depth instrument. Journal of Atmospheric & Oceanic Technology, 2007, 24(11): 1910-1923.

[19] Hisamune S, Amagai K, Kimura N, Kishida K. A study of factors relating to work accidents among seamen. Industrial Health, 2006, 44(1): 144-149.

[20] Chelton D B, Xie S P. Coupled ocean-atmosphere interaction at oceanic mesoscales. Oceanography, 2010, 23(4): 52-69.

[21] Prasad K V S R. Space borne SAR observations of oceanic internal waves in North Bay of Bengal. Natural Hazards, 2011, 57(3): 657-667.

[22] Song J X, Jiang Q, Huang Y Y, Li Y B, Jia Y X, Rong X W, . Research on pressure tactile sensing technology based on fiber Bragg grating array. Photonic Sensors, 2015, 5(3): 1-10.

[23] Dennison C R, Singlehurst D A, Wild P M. A distributed pressure measurement system comprising multiplexed in-fibre Bragg gratings within a flexible superstructure. Journal of Lightwave Technology, 2012, 30(1): 123-129.

[24] Arkwright J W, Underhill I D, Maunder S A, Jafari A, Cartwright N. Fiber optic pressure sensing arrays for monitoring horizontal and vertical pressures generated by traveling water waves. IEEE Sensors Journal, 2014, 14(8): 2739-2742.

[25] Zhang D P, Wang J, Wang Y J, Dai X. A fast response temperature sensor based on fiber Bragg grating. Measurement Science & Technology, 2014, 25(7): 75-105.

[26] Guo M J, Jiang D S, Yuan H C. Low temperature properties of fiber Bragg grating temperature sensors with two package methods. Optics & Precision Engineering, 2007, 15(3): 326-330.

[27] Bo Z, Yan G S, Deng Y J. Cross-sensitivity of fiber grating sensor measurement. Journal of Applied Optics, 2007, 28(5): 5-9.

[28] Le Z C. Design of strain diaphragm using in the microbend fiber-optic pressure sensor. Optics & Precision Engineering, 1994, 2895, 28-95.

[29] Liu Y Q, Guo Z Y, Zhang Y, Chiang K S, Dong X Y. Simultaneous pressure and temperature measurement with polymer-coated fiber Bragg grating. Electronics Letters, 2000, 36(6): 564-566.