Temperature profiling measurements by sea turtles improve ocean state estimation in the Kuroshio-Oyashio Confluence region
We demonstrate that assimilation of water temperature measurements by sea turtles into an operational ocean nowcast/forecast system improves representation of mesoscale eddies and front variations in the Kuroshio-Oyashio Confluence region. For a period from August to December in 2009, vertical ranges of the measurements by six turtles covered from surface to maximum 150 m depth, and the number of the measurements in the region was comparable to that of usual sampling by research vehicles and profiling floats. Comparison of the turtle measurements and products of an operational ocean nowcast/forecast system JCOPE2M elucidated low-temperature bias in JCOPE2M due to assimilation of high-resolution satellite sea surface temperature data. Additional assimilation of the turtle data into a modified JCOPE2M system with correction of the low-temperature bias led to reasonable modification of horizontal temperature/salinity gradient associated with northward moving warm core rings separating from the Kuroshio Extension and southward moving the Oyashio water intrusion branches. Effects of the turtle data assimilation propagated to far east of the Kuroshio-Oyashio confluence region along the subarctic boundary and front through advection. Another experiment assimilating the in situ profile data excluding the traditional temperature/salinity profiles data but including only the turtle data showed that the turtle measurements captured the warm core rings better than the Oyashio intrusion branches, suggesting possible optimum design of future ocean observing systems composed of different kinds of animals and/or autonomous underwater vehicles.
KeywordsOperational ocean nowcast/forecast system Sea turtles Biologging In situ temperature monitoring Multi-scale three-dimensional variational scheme
This work is supported by a research project entitled “Cyber ocean: next generation navigation system on the sea” funded by the CREST program (JPMJCR1685) of Japan Science and Technology Agency. It is also a part of the Japan Coastal Ocean Predictability Experiment (JCOPE) promoted by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). The Ssalto/Duacs altimeter products were produced and distributed by the Copernicus Marine and Environment Monitoring Service (CMEMS) (http://www.marine.copernicus.eu). Merged Satellite and In-situ Data Global Daily SST (MGDSST) was obtained from the NEAR-GOOS regional real-time data base. The Advance Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) SST data were downloaded from the Physical Oceanography Distributed Active Archive Center (PODAAC) ftp site: ftp://podaac.jpl.nasa.gov. In situ temperature and salinity profiles were obtained from the Global Temperature-Salinity Profile Program (GTSPP) website: http://www.nodc.noaa.gov/GTSPP/. Drifting buoys track data were obtained from the National Oceanographic Atmospheric Administration (NOAA)’s Global Drifter Program website: http://www.aoml.noaa.gov/phod/gdp/index.php. Comments from two anonymous reviewers and a handling editor were quite useful for improving earlier versions of the manuscript.
- Fischer AS, Hall J, Harrison DE, Stammer D, Benveniste J (2010) Conference summary—ocean information for society: sustaining the benefits, realizing the potential in proceedings of OceanObs’09: sustained ocean observations and information for society, vol. 1, Venice, Italy, 21–25 September 2009. In: Hall J, Harrison DE, Stammer D (eds) ESA Publication WPP-306. https://doi.org/10.5270/OceanObs09.Summary
- Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, White G, Woolen J, Zhu Y, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Leetemaa A, Reynolds R, Jenne R, Dennis J (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteorol Soc 77:437–471CrossRefGoogle Scholar
- Kida S, Mitsudera H, Aoki S, Guo X, Ito S, Kobashi F, Komori N, Kubokawa A, Miyama T, Morie R, Nakamura H, Nakamura T, Nakano H, Nishigaki H, Nonaka M, Sasaki H, Sasaki YN, Suga T, Sugimoto S, Taguchi B, Takaya K, Tozuka T, Tsujino H, Usui N (2015) Oceanic fronts and jets around Japan: a review. J Oceanogr 71:469–497CrossRefGoogle Scholar
- Kurihara Y, Sakurai T, Kuragano T (2006) Global daily sea surface temperature analysis using data from satellite microwave radiometer, satellite infrared radiometer and in-situ observations (in Japanese). Weather Bull 73:s1–s18Google Scholar
- Miyazawa Y, Varlamov SM, Miyama T, Guo X, Hihara T, Kiyomatsu K, Kachi M, Kurihara Y, Murakami H (2017) Assimilation of high-resolution sea surface temperature data into an operational nowcast/forecast system around Japan using a multi-scale three-dimensional variational scheme. Ocean Dyn 67:713–728CrossRefGoogle Scholar
- Palacz AP, Pearlman J, Simmons S, Hill K, Miloslavich P, Telszewski M, Sloyan B, Pearlman F, Bourassa M (2017) Report of the workshop on the Implementation of Multi-disciplinary Sustained Ocean Observations (IMSOO). Global Ocean Observing System (GOOS) Report No. 223, http://www.goosocean.org/imsoo-report
- Roquet F, Wunsch C, Forget G, Heimbach P, Guinet C, Reverdin G, Charrassin JB, Bailleul F, Costa DP, Huckstadt LA, Goetz KT, Kovacs KM, Lydersen C, Biuw M, Nost OA, Bomemann H, Ploetz J, Bester MN, McIntyre T, Muelber MC, Hindell MA, McMahon CR, Williams G, Harcourt R, Field IC, Chafik L, Nicholls KW, Boehme L, Fedak MA (2013) Estimates of the southern ocean general circulation improved by animal-borne instruments. Geophys Res Lett 40:6176–6180CrossRefGoogle Scholar