Monday, 8 January 2018

King tides due to “super moon” in early January

The photo at the end of this blogpost was taken on Thursday 4 January in Darling Harbour as I was walking out to get some lunch. The photo shows the water coming over the pedestrian platform at Convention Wharf, which is operated by the Sydney Harbour Foreshore Authority, a state government agency.

The king tide on that day was observed at points around Sydney, including at Farm Cove, also on Sydney Harbour. On 4 January the Seattle Post-Intelligencer reported a king tide in Puget Sound on the US west coast. The article noted that such tides associated with “super moons” occur over sets of three days. It set the words “king tide” in quotes.

On 4 January “high tides” were reported in The Northern Echo, a newspaper in Yorkshire.
The Environment Agency has issued flood warnings for seafront properties at Sandsend near Whitby and for homes alongside the River Ouse in York. 
The tide is expected to be at its highest along the North Yorkshire coast for tonight's evening high tide (Thursday, January 4), when peak spring tides were expected to coincide with unsettled weather at Sandsend and cause overtopping waves and spray.
A king tide was also chronicled at Gunnamatta Bay on 3 January by the Cronulla RSL Swimming Club, located in the south of Sydney. Also on 3 January there was flooding in the suburbs of Windsor and Newstead in Brisbane, which is on the tidal Brisbane river, a sluggish, brown stream that rises in the mountains west of the city and deposits its load of silt in the Pacific Ocean.

At Woy Woy on the Central Coast (population 11,000), it was reported on 3 January that the wharf had become completely submerged. There was flooding also in Newcastle on the same day as the water came up through drains into the streets. On 3 January it was also reported that flooding had occurred at Uralba and on the Bruxner Highway near Ballina (population 16,000) on the NSW North Coast. On 3 January the Sunshine Coast Daily in Queensland’s southeast north of Brisbane warned readers about high tides. The Sunshine Coast has a population of 280,000.
The spring tide, commonly known as a king tide, will reach 2.18m at Maroochydore and Caloundra and 2.29m on the Noosa River this morning.
On January 2, the Newcastle Herald reported that private jetties on Swansea Channel were inundated by rising water. Newcastle has a population of about 550,000 and is located about an hour’s drive north of the northernmost suburbs of Sydney.
In Newcastle, the water crept into the gutters around Wickham, Maryville and Carrington. 
The 2.08 metre tide was a millimetre lower than the last major king tide to hit the region in January 2009.
On 2 January it was reported by the Illawarra Mercury, published in Wollongong, a city of 280,000 people located south of Sydney, that an environmental group was asking people to take pictures on the king tide to raise awareness of global warming. The website is at

But it wasn’t just 2, 3, and 4 January that had king tides this month. The New Zealand Herald reported early in the afternoon on Friday 5 January that flooding had occurred in the city of Tauranga, which has a population of 138,000, on the Bay of Plenty in New Zealand. The Wairoa River broke its banks and flooded parts of the city. Flights were diverted from the city’s airport.

On the same day, the Otago Daily Times reported wild storms causing havoc in Rotorua (population 71,000) in the north of New Zealand.
Metservice warns that on top of today's coastal flooding in northern regions from king tides, western and southern areas are at risk, especially along Wellington's south coast tonight. 
King tides, gales and driving rain continue to cause widespread damage across the upper North Island. 
Thousands are still without power as trees and powerlines topple in the hurricane-strength winds blasting the island.
Wellington, the New Zealand capital, sits at the southern tip of the country’s North island on the Cook Strait that separates it from the South Island.

In Boston, record tides were reported on 5 January although the words “king tide” were set in quotes. TV channel WPRI reported:
The National Oceanic and Atmospheric Administration verified Friday that water levels at the federal agency’s Boston tide gauge reached a peak of 4.89 feet above the average of highest tide readings for the day. 
That broke the record of 4.82 feet above, set during the infamous Blizzard of ’78 in February of that year.
On 30 December there was a report about the expected super moon along with some explanation about why the tides would be so high on these days in early January. It turns out that on 2 January the earth was at perihelion – the point in its orbit which is closest to the sun for the whole of the year – but that wasn't the only thing causing king tides. The article explains:
The time between New Year’s Day [Monday 1 January] and Tuesday [2 January], the sun, moon and Earth will line up in what is known as syzygy. But the moon will also be at perigee [it’s closest point to the earth in its daily orbit. And] when this happens, astronomers [call] it perigee-syzygy! The gravitational forces exerted by the moon and sun create the timeless tides. These “tidal forces” are not the total gravitational forces exerted by the sun and moon on Earth, but the difference between these gravitational forces over the surface of the planet.
So the reason for the king tides earlier this month was the fact that the earth was at its closest point to the sun on those days, and at the same time the moon was at its closest point to the earth. Both the earth and moon move in ellipses, not circles, around the celestial bodies they orbit.

The king tide might also have served to remind residents of the cities named in this blogpost that in small island nations and in areas in low-lying regions around the world, communities where people live are being repeatedly inundated by salt water, which can have disastrous effects on agriculture as well as causing public nuisances as sewage systems are overrun.

Above: Captain Cook Cruises operates a ferry service between Circular Quay and Convention Wharf in Darling Harbour. The first service arrives daily at Convention Wharf at 9.30am and services continue every 30 minutes or so throughout the day until the last service arrives there at 6.42pm. The photo below shows the red-coloured ferry service stopping at Darling Harbour, though not quite at Convention Wharf, which is located a little way to its stern.

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