EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Open Access Open Access Nat. Hazards Earth Syst. Sci. Discuss.,Natural 1, 1943–1964, Hazards 2013 Natural Hazards www.nat-hazards-earth-syst-sci-discuss.net/1/1943/2013/ and Earth System doi:10.5194/nhessd-1-1943-2013and Earth System NHESSD Sciences Sciences © Author(s) 2013. CC Attribution 3.0 License. 1, 1943–1964, 2013 Discussions Open Access Open Access Atmospheric Atmospheric This discussion paper is/has been under review for the journal Natural Hazards and Earth Chemistry Chemistry King Tide floods in System Sciences (NHESS). Please refer to the corresponding final paper in NHESS if available. and Physics and Physics Tuvalu Discussions Open Access Open Access C.-C. Lin et al. Atmospheric Atmospheric Measurement Measurement Techniques Techniques Title Page Discussions Open Access King Tide floods in Tuvalu Open Access Abstract Introduction Biogeosciences C.-C. Lin, C.-R. Ho, andBiogeosciences Y.-H. Cheng Discussions Conclusions References Department of Marine Environmental Informatics, National Taiwan Ocean University, Open Access Open Access Tables Figures Keelung, Taiwan Climate Climate Received: 16 March 2013 – Accepted: 25 April 2013 – Published: 17 Mayof 2013 the Past of the Past J I Discussions Correspondence to: C.-R. Ho ([email protected]) J I Open Access Open Access Published by Copernicus Publications on behalf of the European GeosciencesEarth System Union. Earth System Back Close Dynamics Dynamics Discussions Full Screen / Esc Open Access Geoscientific Geoscientific Open Access Printer-friendly Version Instrumentation Instrumentation Methods and Methods and Interactive Discussion Data Systems Data Systems Discussions Open Access Open Access Geoscientific Geoscientific Model Development Model Development1943 Discussions Open Access Open Access Hydrology and Hydrology and Earth System Earth System Sciences Sciences Discussions Open Access Open Access Ocean Science Ocean Science Discussions Open Access Open Access Solid Earth Solid Earth Discussions Open Access Open Access The Cryosphere The Cryosphere Discussions Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract NHESSD The spatial and temporal distributions of sea level rise present regional floods in some certain areas. The low-lying island countries are obviously the spots affected severely. 1, 1943–1964, 2013 Tuvalu, an atoll island country located in the south-west Pacific Ocean, is suffering the 5 devastating effects of losing life, property, and intending migration caused by floods. King Tide floods in They blame the regional flooding to King Tide, a term used but not clearly identified by Tuvalu Pacific islanders. In this study, we clarify what King Tide is first. By the tide gauge and topography data, we estimated the reasonable value of 3.2 m as the threshold of King C.-C. Lin et al. Tide. This definition also fits to the statement by National Oceanic and Atmospheric 10 Administration (NOAA) of King Tide occurring once or twice a year. In addition, We cross validate the 19 yr data of tide gauge and satellite altimeter (1993–2012), the Title Page correlation coefficient indicates King Tide phenomenon is considerable connected to Abstract Introduction warm water mass. The 28 King Tide events revealed the fact that flooding can be referenced against spring tide levels, so can it be turned up by warm water mass. The Conclusions References 15 warm water mass pushes up sea level; once spring tide, storm surge, or other climate Tables Figures variability overlaps it, the rising sea level might overflow and so has been called “King Tide” for the floods in Tuvalu. This study provides more understanding of the signals of King Tide and an island country case study of regional sea level rise. J I J I 1 Introduction Back Close 20 As with the impacts of global warming and climate change, inundation and flooding Full Screen / Esc have become the common threats to island countries in the tropical oceans (Mimura et al., 2007). Tuvalu with the highest point less than 5 m up to sea level, is broadly Printer-friendly Version considered to be one of the island country most threatened by sea level rise (Church et al., 2006; Mimura et al., 2007; Webb and Kench, 2010; Wong, 2011). Because of Interactive Discussion 25 the low-lying setting and the vulnerable characteristic of coral islands, any oceanic in- fluential factors which were made worse by the effects of human and nature, can cause 1944 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | damages. The people in Tuvalu are already experiencing flooding in places. They call those floods pulling the Pacific Ocean farther ashore than normal “King Tide”, a term NHESSD connected to threaten their lives and properties. Not only wash over the coastline, it 1, 1943–1964, 2013 also seeps through small holes in the porous atoll ground which may wash away soils, 5 kill crops, contaminate freshwater, increase risk of disease, and decline agricultural productivity (Mortreux and Barnett, 2009). Originally, King Tide refers to any high tide King Tide floods in well above average height, or the highest spring tide in every year occurring in sum- Tuvalu mer or winter (http://www.msq.qld.gov.au/Tides/King-tides.aspx). The popular concept is that the King Tide is simply the very highest tide that usually occurs around the full C.-C. Lin et al. 10 moon or new moon. Back to the phenomenon of King Tide here, it is neither a high wa- ter phenomenon existing always, nor a series of continuous events, it happens mostly Title Page on the specific days of a year with regular tidal fluctuation. The duration can last for hours to days, but it leaves behind a trail of unforgettable disaster (EPA, 2011). There Abstract Introduction has been estimated the highest astronomical tide in Tuvalu should occur on 28 Febru- Conclusions References 15 ary 2006 over the period of 1990–2016 (AusAID, 2006). That day was as expected of occurring King Tide, bringing the severest floods with the record of sea level 3.44 m. Tables Figures Though adjusted of barometric and harmonic analysis, there still has been 20 cm un- known residuals left (AusAID, 2007). We regarded the combination of astronomical tide J I and regional climate activities can mainly be explained to the inundation of Tuvalu, but 20 what cause the unknown residuals need to be explained. J I Sea level rise is normally the first impression connected to global warming. Of many Back Close things about global warming misunderstood by the public when sea level rise is men- tioned, it typically refers to the global average, but this obscures the fact that not all Full Screen / Esc areas are rising. On the opposite, when we mentioned about flooding, it does not re- 25 fer to sea level rise globally. Limited by the length and accuracy of data, the historical Printer-friendly Version and projected sea level is always a subject of considerable and controversial in Tu- valu. Some previous studies (Becker et al., 2012; Cazenave and Llovel, 2010; Nerem Interactive Discussion et al., 2006) indicated that sea level in the western tropical Pacific is 3–4 times larger than the global average. A comment by Hunter (2002) noted a cautious estimate of 1945 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | present long-term sea level change at Tuvalu was a rate of rise between −1.1 and 2.7 mmyr−1 relative to the land, concerning the data affected by El Nino/Southern˜ Os- NHESSD cillation (ENSO) events. It’s of very similar magnitudes to the Intergovernmental Panel 1, 1943–1964, 2013 on Climate Change (IPCC) estimate of global average sea level rise during the 20th −1 5 century, 1–2 mmyr (Church et al., 2001). Eschenbach (2004a, b) estimated the rate of rise of 0.07 mmyr−1 based on an analysis of Mitchell et al. (2001) for the period King Tide floods in 1977–1998. Cabanes et al. (2001) used the sea level data from tide gauge for the Tuvalu period 1955–1996 but found out mean sea level has fallen in Tuvalu. Somehow, a con- sensus view unveils sea level rise is a trend and will be an unpreventable issue. The C.-C. Lin et al. 10 United States Environmental Protection Agency called the world that sea level rise will make today’s King Tides become the future’s everyday tides (EPA, 2011). The regional Title Page flooding or King Tide flooding will be more frequent and more severe. By the analysis of tide gauge and satellite altimeter data, Tuvalu’s present problem of inundation seems Abstract Introduction not simply being contributed by long trend of sea level rise by global warming. Some Conclusions References 15 oceanic factors need to be concerned. Except for estimating the basic foundation of regional sea level, examining the mech- Tables Figures anisms of ocean can help to understand sea level variability precisely. The sea level in tropical Pacific variability has been regarded with the association of ENSO (Tren- J I berth and Hurrell, 1994; Chambers et al., 2002; Church et al., 2006), the Asian– 20 Australian monsoon or the Pacific Decadal Oscillation (PDO) (Mantua et al., 1997). J I Cabanes et al. (2001) revealed that the dominant contribution to regional sea level Back Close variability results from non-uniform changes in ocean thermal expansion. Cazenave and Llovel (2010) indicated about 30 % of the observed rate of rise during 1993–2007 Full Screen / Esc was caused by ocean thermal expansion. Houghton et al. (1996) estimated that half 25 of rising was due to steric heating. Merrifield (2011) pointed out the sea level trend in Printer-friendly Version the western tropical Pacific has linked to remote wind forcing.