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Feature Article

Supporting Satellite Research With Data Collected by Vessels

By Shawn R. Smith
Research Associate
Center for Ocean-Atmospheric Prediction Studies

Mark A. Bourassa
Associate Professor
Department of Earth, Ocean and Atmospheric Sciences
Florida State University
Tallahassee, Florida

and
Darren L. Jackson
Senior Associate Scientist
Cooperative Institute for Research in Environmental Sciences
Boulder, Colorado




Flow of SAMOS observations from a participating vessel through data quality processing to the national archive and user community.
Meteorological observations made over the oceans using Earth-orbiting satellites provide a wealth of environmental data to support the operational weather and ocean forecasting and research communities. Satellites routinely measure sea surface temperature and winds and recently have been used to estimate air temperature and humidity near the ocean surface. Each of these parameters is derived using complex retrieval algorithms that convert estimates of emitted or reflected radiance into the physical parameters desired by the meteorological and oceanographic stakeholders. Such retrieval algorithms are routinely tested and validated using ground-truth measurements. Typical sources include observations from vessels, drifting buoys and moorings.

Recently, the satellite community has sought marine meteorological observations collected at high-temporal sampling rates (at least once per minute) over a wide range of oceanic and atmospheric environments. This community needs in-situ observations that sample the full range of atmospheric conditions (e.g., high and low wind speeds, near-saturated moisture conditions) found in remote parts of the world’s oceans (e.g., Southern Ocean, South Pacific).

Also required are sampling rates and instrumental accuracies to capture the sharp moisture, temperature and wind gradients associated with oceanic and atmospheric fronts.

The Shipboard Automated Meteorological and Oceanography System (SAMOS) initiative collects the observations desired by the satellite community using a network of suitably equipped research vessels. Automated instruments on these vessels provide the desired sampling rates and instrument accuracies. In addition, research vessels operate in extreme environments and regions far outside shipping lanes used by merchant vessels.

The SAMOS initiative is complementary to the Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM) Voluntary Observing Ship (VOS) scheme, and some vessels contribute to both programs. Traditional VOS report observations at 1- to 6-hour intervals, much less frequently than the SAMOS, using instruments suitable for applications such as initialization of numerical weather prediction models and input to marine climate data sets.


Leveraging Existing Technology
The SAMOS is a computerized data-logging system that continuously records navigation (ship position, course, speed and heading), meteorology (winds, air temperature, pressure, moisture, rainfall and radiation) and near-ocean surface sea temperature and salinity parameters while a vessel is underway. Measurements are recorded at high-temporal sampling rates (typically 1 minute or less). The SAMOS usually includes a variety of research-quality sensors, such as mechanical and sonic anemometers, temperature and humidity probes, barometers, volumetric and optical rain gauges, radiometers, and water temperature and salinity sensors. Instruments in the SAMOS are purchased and deployed by the vessel operator, not by the SAMOS initiative.

Each research vessel captures data from these individual sensors using a shipboard data acquisition system (DAS), which combines the meteorological and oceanographic data with time and position data, typically from a GPS. Additional ship orientation (e.g., course over ground, heading) and motion parameters (speed over ground, speed over water, pitch, roll, heave) are also logged through the DAS. The SAMOS initiative provides a data pathway and management structure that leverages the vessel-deployed DAS and instrumentation to meet the scientific needs of the satellite community. To continue this article please click here.


Shawn R. Smith received his master’s in meteorology from the University of Wisconsin in 1992. He is the director of the research vessel data center at Florida State University and chairman of the SAMOS initiative.

Mark A. Bourassa studies air-sea interaction, remote sensing and related applications. He is the NASA Ocean Vector Winds Science Team leader and a codeveloper of a professional development course on climate and climate change.

Darren L. Jackson received his master’s in atmospheric science from Colorado State University in 1992. His research interests are application of infrared and microwave satellite remote sensing data toward research in meteorology, oceanography and air-sea interaction.




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