Collecting observations in the Southern Ocean: NOAA Physical Sciences Laboratory

Collecting observations in the Southern Ocean aboard new Australian ship

PSD helps expand sparse database of measurements in this remote region

R/V Investigator (Credit: CSIRO)

NOAA's Chris Fairall and Sergio Pezoa, and CIRES' Bryon Blomquist—all of whom work at ESRL's Physical Sciences Division (PSD)—traveled to Hobart, Tasmania in March to install NOAA's seagoing Air-Sea Flux System on a new research vessel, the R/V Investigator, which is operated by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO). PSD is collaborating with CSIRO and scientists from the Australian Bureau of Meteorology to investigate the interaction of air-sea fluxes and boundary layer clouds, which will help expand the very sparse database of measurements in the Southern Ocean.

"The Southern Ocean is huge, poorly observed, and an important component of the Earth’s climate system, so every cruise there is extremely valuable," said Fairall, a physicist at PSD.

NOAA’s flux system is an instrument package that makes direct measurements of the exchange or flux of heat, water, and momentum between the atmosphere and the ocean. The system also measures meteorological variables such as sea surface temperature, wind speed, air temperature, humidity. Together, this information can be used to estimate how the ocean and atmosphere exchange heat in weather and climate models.

From March-April, Blomquist was aboard the R/V Investigator, which spent about 40 days at sea south of Tasmania. During that time, scientists studied a large ocean eddy that occupies that region, changed out a climate flux reference buoy, and measured clouds and air-sea fluxes. The cloud aspect of the cruise was referred to as CAPRICORN (Clouds, Aerosols, Precipitation, Radiation, and Atmospheric Composition over the Southern Ocean). Scientist also measured surface waves and CO2 fluxes during the cruise.

The NOAA flux system will provide direct measurements of the air-sea fluxes. Most applications of fluxes (say in climate models or satellite retrievals) use estimates of fluxes computed via a 'bulk algorithm' from more easily observed variables such as wind speed, air temperature, and sea surface temperature. The researchers expect that these direct observations will help to demonstrate the accuracy of the NOAA COARE bulk flux algorithm in the Southern Ocean and give them a way to verify other flux products, such as the Woods Hole Oceanographic Institution's OAFlux product. The observations collected will also allow researchers to evaluate the accuracy of the ship’s meteorological observing system as part of NOAA's Climate Observations program.

"The cruise just ended and, for NOAA, it was quite successful," said Fairall. "We got strong winds, very large waves (9 m), and typical Southern Ocean nasty weather."

Posted: April 25, 2016

PSD flux sensors on the bow tower of the R/V Investigator in Hobart, Tasmania. (Credit: Chris Fairall, NOAA)

DID YOU KNOW... The NOAA Air-Sea Flux System has been deployed about 35 times on various ships since 2000. In 2008, it was deployed in the Southern Ocean for the GasEx III project – but that was the only other deployment south of 40°S.

Related Links: PSD Ocean Climate Observations