SHOA

CHILEAN NAVY HYDROGRAPHIC AND OCEANOGRAPHIC SERVICE

Sea Surface Temperature (SST)

The Hydrographic and Oceanographic Service of the Navy (SHOA) has a network of sea level stations along the coast to monitor a series of oceanic and atmospheric variables. Mean Sea Level (MSL) and Sea Surface Temperature (SST) have been recorded for several years. These last two were obtained between 1950 and 1998 by someone who manually recorded the sea temperature using a mercury thermometer. Nowadays there are automatic record systems with thermistors that broadcast almost in real time, via satellite.

In this page the monthly maximum, minimum and average temperatures of 4 stations in the North and Center of Chile from 2002 to 2016. It is important to mention that the monthly average corresponds to the average of temperatures recorded at 10 AM (methodology settled by the countries of the CPPS). Additionally, a historic average is delivered for every place, which was calculated based on 20 years of measurements (1980 – 2000) and since 2014, the historic average corresponds to the average calculated based on 30 years of measurements (1981 – 2010).

Latitude: 18° 29' S Longitude: 70° 19' W

Next a table that sums up the values of the Sea Surface Temperature (SST), minimum, maximum and monthly for every month of the year selected. Additionally, the historic average of the SST is included, which can be used as a standard reference value for every month. .

MES TSM (ºC) mínima TSM (ºC) máxima TSM (ºC) Promedio mensual TSM (ºC) Promedio histórico

* This historic average was calculated based on a data base of the last 20 years (1980 – 2000).

valores mensuales de TSM para la estación

Graph of anomaly values of SST associated to the El Niño/ La Niña Event, since 1950 to date

To interpret the Sea Surface Temperature (SST) based on the global phenomena “El Niño” (warm event) or “La Niña” (cold event), a “monthly anomaly” is calculated and it is the result of the difference between the observed and historic values. This value is contrasted against the Oceanic Nino Index (ONI), which has become the standard used by the NOAA to identify episodes of El Niño and La Niña in the tropical Pacific. This index corresponds to a measurement of 3 months of the SST anomaly for the Region Niño 3.4, located between the 5°N - 5°S and 120 – 170°W. The events are defined as 5 periods of 3 consecutive months of anomaly values above 0.5°C for warm events (El Niño) and on or under the anomaly -0.5°C for cold events (La Niña). The threshold is divided in Weak (with an anomaly of 0.5 to 0.9°C), Moderate (1.0 to 1.4°C), Strong (1.5 to 1.9°C) and Very Strong (≥2.0°C).

anomalias mensuales de TSM para la estación

Image: Monthly discrepancies of SST for the Arica Station.