El Niño and La Niña phenomena

According to several meteorological services, we have entered into a new El Niño phase.

As part of our loss prevention efforts, Norwegian Hull Club monitors weather systems that can develop into hurricanes, typhoons or tropical storms. The official Atlantic hurricane season starts on 1st June and ends on 1st December. As for the entire Far East, their typhoon season is more or less year around, but most Typhoons occur from April to December, with peaks in May and November. There are however phenomena that may affect the severity of the seasons. According to several meteorological services, we have now entered into a new El Niño phase.

El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle. The ENSO cycle is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific (approximately between the International Date Line and 120 degrees West). La Niña is sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO.

El Niño

The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific.
Reported effects on shipping during the last cycle in 1997-1998 (widely regarded to be one of the strongest on record) included;

  • Lower than average water levels with resultant draft restrictions impacting certain Great Lakes trade; it did however also result in one of the lightest ice seasons on record.
  • Lower than average water levels with resultant draft restrictions impacting Lake Maracaibo, Venezuela trade.
  • Lower than average water levels with resultant draft restrictions impacting Panama Canal traffic.
  • Increased hurricane activity during the June-November Pacific season.
  • Increased monsoons in Southeast Asia
  • Reductions in US fruit crop production with a resultant impact on reefer rates.
  • Reductions in Australian grain crop production impacting the bulk trade.

The Australian Bureau of Meteorology has recently joined the U.S. Climate Prediction Center and the Japan Meteorological Agency in declaring that sea-surface temperatures in the equatorial Pacific are high enough - and the atmosphere above the ocean has reacted strongly enough - to mean a new El Niño phase has officially begun. These agencies do however utilize differing criteria for assessment of El Niño phenomena so consensus has yet to be formed as to the likely strength and period of this phase; preliminary models however are suggesting this El Niño could be ‘significant’ and ‘moderate-strong’.

La Niña

Conversely, La Niña episodes represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific (the cold phase) hence global climate impacts tend to be opposite to those of El Niño.
One specific impact on shipping during the last La Niña became readily apparent in Barranquilla, Columbia.
During September to December 2010 whilst the 2010-11 La Niña phase was peaking, numerous costly grounding and contact damage incidents occurred in Barranquilla.
Again, when the 2011-12 La Niña effects started more serious groundings occurred, some resulting in all commercial traffic in and out being blocked.

This was reportedly due to a combination of factors including;

  • Increased rainfall levels which in turn;
  • Increased silting at the river mouth / entrance to the channel, compounded by a then complacent attitude to dredging by the local authority; and
  • Increased cross currents at the entrance to the channel making it more difficult for the pilots to keep vessels dead center in the channel.

Norwegian Hull Club’s always urges all operators of shipping in all tropical storm/cyclone/hurricane/typhoon regions to apply the necessary precautions in protecting life and assets at sea.

For more info on safe quadrant theory please see:
http://www.norclub.no/assets/CasualtyInformation/Casualty-Information-No.-67-September-2008.pdf

On Norwegian Hull Club's web page, you can always keep track on current storm centres: http://www.norclub.no/services/weather-warning/

Sources:

The Australian Bureau of Meteorology: http://www.bom.gov.au/
U.S. Climate Prediction Center: http://www.cpc.ncep.noaa.gov/
Japan Meteorological Agency: http://www.jma.go.jp/jma/indexe.html

 HiRes2


2. Jul. 2015