Monday, December 17, 2012

Ocean observation system offers insight into marine ecosystem

Argo, a global observing system based on drifting sensors cycling from the surface to the ocean mid-depths, reached a major milestone with one million observations. The international research program has been building up an array which is now enabling new insights into the ocean's central influence on global climate and marine ecosystems after starting in late 1999 with 10 drifting robotic sensors deployed by Australia in the Indian Ocean.

The initial objective was to maintain a network of 3,000 sensors in ice-free open ocean areas, providing both real-time data and higher quality delayed mode data and analyses to underpin a new generation of ocean and climate services.

"We're still about 50 years behind the space community and its mission to reach the moon," says Dr. Susan Wijffels, a scientist with Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) and Argo co-chair.

"The world's deep ocean environment is as hostile as that in space, but because it holds so many clues to our climate future exploring it with the Argo observing network is a real turning point for science. In its short life the Argo data set has become an essential mainstay of climate and ocean researchers complementing information from earth observing satellites and uniquely providing subsurface information giving new insights into changes in the earth's hydrological warming rates and opening the possibility of longer term climate forecasting."

The Argo array today receives data from more than 3,500 sensors, and 28 countries contribute to cost of operating the program. The 1.5 meter tall robotic sensors cycle vertically every 10 days, sampling temperature and salinity. At the surface, the sensors transmit data collected via satellite to national centers across the globe. The sensor's ascent and descent is regulated by a hydraulic pump, powered with lithium batteries. Their life expectancy is between 4-9 years, averaging more than 200 profiles per sensor as they drift with the currents and eddies.

The sensors collect one profile approximately every four minutes, adding up to 360 profiles per day or 11,000 per month. Since the start of deep sea oceanography in the late 19th century, ships have collected just over half a million temperature and salinity profiles to a depth of 1 kilometer, and only 200,000 profiles to depths of 2 kilometers. At the present rate of data collection, Argo will take only eight years to collect its next million profiles.

Until now, almost 1,200 scientific papers are based on or incorporating data that has been generated since the start of the observing system, according to Wijffels. Argo data is now also being widely used in operational services for the community, including weather and climate prediction and ocean forecasting for environmental emergency response, shipping, defense, and safety at sea.

The ocean observation system Argo has collected one million data sets since late 1999.

Source: Global Adventures

Photo courtesy of Lel4ND via Flickr (CC BY 2.0)