Atlantic Meridional Transect
The Atlantic Meridional Transect is an ongoing research program that exploits the twice–annual passage of the RRS James Clark Ross between the United Kingdom and the Falkland Islands - before and after its use in the Antarctic research program in the Austral Summer - to obtain spatially–intensive time and space series data over the 13,500 kilometre transect.
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The transect starts at the U.K. and heads southwest to the first waypoint at a JGOFS time–series station at 47oN, 20oW. From there it follows the 20oW meridian to 13oN, after which it heads south and west to Montevideo (Uruguay) and Stanley (Falkland Islands).
The objectives of the AMT program include:
- Gauging the effects of anthropogenically induced environmental change on the physical and biological systems along the transcent;
- Improving knowledge of marine biogeochemical processes, ecosystem dynamics, food webs and fisheries, as well as characterize physical and biogeochemical provinces;
- Developing a research strategy to integrate shipboard measurements with remote sensing, modeling, etc. to maximally exploit the time and space series obtained on the transect;
- Providing calibration and validation of satellite sensors of ocean color, sea surface temperature, and solar radiation;
- Quantifying ecosystem responses to changes in the abundance of radiatively and chemically active trace gases; and
- Developing coupled physical–biological models of production and ecosystem dynamics.
The progress and limitations of AMT as of 2000 has been synthesized by Aiken et al.  as:
AMT cruises 1 to 7 (1995–1998) have seen the completion of phase 1 of the AMT programme, wherein many of the new, autonomous technologies and operational approaches have been pioneered and proven. There are obvious limitations in the programme, particularly one which has objectives related to issues of climate change. Notably, the physical oceanography is superficial, CTD casts have been limited to 200 m in most cases with no geostrophic reference and the spatial resolution of circa 400 km from typically 1 cast per day is too coarse. As a basin scale programme the AMT samples the temperate N. Atlantic poorly; there is no sampling north of 50oN. As a programme focused on climate change, a time series based on samples only twice a year has severe limitations, with no adequate resolution of the seasonal cycle in any province. Nevertheless, the fledgling four-year time series can already provide measurements of inter-annual variability, which is an essential pre-requisite for any study of decadal trends. With another 10 cruises planned over five years (1999–2003) during phase 2, the basis of a study of climate change will be well established.
During this period there must be a focus on those measurements that are sensitive to climate forcing or are known indices of anthropogenic influences on climate. Collaboration with other European national research activities is planned to improve the coverage of the seasonal cycle in the north Atlantic and create a European Atlantic Time and Space Series (EATSS) project. Core to this are the twice yearly transects of the other Antarctic research vessels, the Polarstern (Germany), the Hesperides (Spain) and the Pelagia (Netherlands) with opportunistic research cruises in the area 20–63oN, 20oW, by UK, German, French, Dutch, Belgian and Spanish vessels. If this develops, it will be true to say, that the AMT programme has laid down the foundation for a study of decadal trends in the marine ecosystems of the Atlantic Ocean with which to understand and model their responses to climate change.
- Physical Oceanography Index
- Atlantic Meridional Transect
- J. Aiken and A. J. Bale. An introduction to the Atlantic Meridional Transect (AMT) programme. Progress in Oceanography, 45:251–256, 2000.