Sea surface temperature trend analysis by Mann-Kendall test and sen’s slope estimator: a study of the Hai Phong coastal area (Vietnam) for the period 1995-2020


  • Vu Duy Vinh Institute of Marine Environment and Resources, VAST, Haiphong City 04216, Vietnam
  • Sylvain Ouillon 1-UMR LEGOS, University of Toulouse, IRD, CNES, CNRS, UPS, 14 avenue Edouard Belin, 31400 Toulouse, France; 2-Department Water-Environment-Oceanography, University of Science and Technology of Hanoi (USTH), VAST, Hanoi 100000, Vietnam
  • Nguyen Minh Hai 1-Institute of Marine Environment and Resources, VAST, Haiphong City 04216, Vietnam; 2-Graduate University of Science and Technology, VAST, Hanoi, Vietnam



sea surface temperature, warming, trend, Mann-Kendall, Sen slope, ENSO, Hai Phong


Based on the Mann-Kendall test and Sen’s slope method, this study investigates the monthly, seasonal, and annual sea surface temperature (SST) trends in the coastal area of Hai Phong (West of Tonkin Gulf) based on the measurements at Hon Dau Station from 1995 to 2020. The results show a sea surface warming trend of 0.02°C/year for the period 1995-2020 (significant level α = 0.1) and of 0.093°C/year for the period 2008-2020 (significant level α = 0.05). The monthly SSTs in June and September increased by 0.027°C/year and 0.036°C/year, respectively, for the period 1995-2020, and by 0.080°C/year and 0.047°C/year, respectively, for the period 2008-2020. SST trends in winter, summer, and other months were either different for the two periods or not significant enough. This may be due to the impact of ENSO, which caused interannual SST variability in the Hai Phong coastal with two intrinsic mode functions (IMF) signals a period of ~2 (IMF3) and ~5.2 years cycle (IMF4). A combination of these signals had a maximum correlation of 0.22 with ONI (Oceanic Niño Index) delayed by 8 months. ENSO events took ~8 months to affect SST at Hai Phong coastal area for 1995-2020 and caused a variation of SST within 1.2°C.


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How to Cite

Vu Duy, V., Ouillon, S. ., & Nguyen Minh, H. (2022). Sea surface temperature trend analysis by Mann-Kendall test and sen’s slope estimator: a study of the Hai Phong coastal area (Vietnam) for the period 1995-2020. Vietnam Journal of Earth Sciences.