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 web page you can find the maximum, minimum and average monthly temperatures from four stations located in north and central Chile, from 2002 to date. It is important to mention that the monthly average corresponds to the average monthly temperatures recorded at 10 in the morning (methodology agreed on by the countries of the CPPS). Additionally, you can find the historic average of each place, which until 2013 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).



Arica

Latitude: 18° 29' SLongitude: 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 long term monthly mean of the SST is included, which can be used as a standard reference value for every month. .

Month SST Minimum degC SST Maximum degC SST Monthly Mean degC SST Long Term Monthly Mean degC
JAN16.123.719.318.8
FEB16.322.419.918.9
MAR16.721.618.918.7
APR16.220.818.017.7
MAY16.8
JUN16.2
JUL15.9
AUG15.9
SEP15.8
OCT16.2
NOV16.7
DEC17.7
* This long term monthly mean was calculated based on a data base of the last 30 years (1981-2010).

Graph of anomaly values of SST associated to the El Nino/ La Nina 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).

Image: Monthly anomalies of SST for the Arica Station.