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Ocean observations

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Introduction

Observations of the physical properties of the ocean, mainly temperature and salinity, have been collected at a few locations since the late-1800s. Since the 1950s a succession of new instruments have been developed which have allowed a gradual increase in both the number of ocean observations and their geographic distribution. The introduction of satellite observations beginning in the 1970s, but reaching operational levels in the 1990s, has resulted in truly global coverage of surface variables, while deployment of the autonomous Argo observation system in the early 2000s has extended this global coverage throughout much of the upper 2000 meters.

Observations of ocean parameters are necessary for attaining knowledge of the ocean state and prediction of the future ocean states. As the ocean has a significant impact on the state of the atmosphere, the knowledge of the ocean state coupled with knowledge of the state of the Earth's atmosphere is necessary for the accurate prediction of global climate change. Other uses of this data include ocean modeling, data assimilation and reanalysis.

Essential Oceanic Climate Variables

The following are considered essential ocean climate variables by the OOPC (http://ioc3.unesco.org/oopc/obs/ecv.php) that are currently feasible with current observational systems.

Atmosphere Surface

Air Temperature
Precipitation (meteorology)
evaporation
Air Pressure, sea level pressure (SLP)
Surface radiative fluxes
Surface thermodynamic fluxes
Wind speed and direction
Surface wind stress
Water vapor

Ocean Surface

Sea surface temperature (SST)
Sea surface salinity (SSS)
Sea level
Sea state
Sea ice
Ocean current
Ocean color (for biological activity)
Carbon dioxide partial pressure (pCO2)

Ocean Subsurface

Temperature
Salinity
Ocean current
Nutrients
Carbon
Ocean tracers
Phytoplankton


Charts

Ocean Observation Sources

Satellite

There is a composite network of satellites that generate observations (http://ioc3.unesco.org/oopc/obs/surface_sat.php). These include:

Type Variables Observed Responsible Organizations
Infrared (IR) SST, sea ice CEOS, IGOS, CGMS
AMSR-class microwave SST, wind speed, sea ice CEOS, IGOS, CGMS
Surface vector wind (two wide-swath scatterometers desired) surface vector wind, sea ice CEOS, IGOS, CGMS
Ocean color chlorophyll concentration (biomass of phytoplankton) IOCCG
high-precision altimetry sea-level anomaly from steady state CEOS, IGOS, CGMS
low-precision altimetry sea level CEOS, IGOS, CGMS
Synthetic aperture radar sea ice, sea state CEOS, IGOS, CGMS

In Situ

There is a composite network of in situ observations (http://ioc3.unesco.org/oopc/obs/surface_insitu.php). These include:

Type Variables Observed Responsible Organizations
Global surface drifting buoy array with 5 degree resolution (1250 total) SST, SLP, Current (based on position change) JCOMM Data Buoy Cooperation Panel (DBCP)
Global tropical moored buoy network (about 120 moorings) typically SST and surface vector wind, but can also include SLP, current, air-sea flux variables JCOMM DBCP Tropical Moored Buoy Implementation Panel (TIP)
Volunteer Observing Ship (VOS) fleet all feasible surface ECVs JCOMM Ship Observations Team (SOT)
VOSClim all feasible surface ECVs plus extensive ship metadata JCOMM Ship Observations Team (SOT)
Global referencing mooring network (29 moorings) all feasible surface ECVs OceanSITES
GLOSS core sea-level network, plus regional/national networks sea level JCOMM GLOSS
Carbon VOS pCO2, SST, SSS IOCCP
Sea ice buoys sea ice JCOMM DBCP IABP and IPAB

Subsurface

There is a composite network of subsurface observations (http://ioc3.unesco.org/oopc/obs/subsurface.php). These include:

Type Variables Observed Responsible Organizations
Repeat XBT (Expendable bathythermograph) line network (41 lines) Temperature JCOMM Ship Observations Team (SOT)
Global tropical moored buoy network (~120 moorings) Temperature, Salinity, current, other feasible autonomously observable ECVs JCOMM DBCP Tropical Moored Buoy Implementation Panel (TIP)
Reference mooring network (29 moorings) all autonomously observable ECVs OceanSITES
Sustained and repeated ship-based hydrography network All feasible ECVs, including those that depend on obtaining water samples IOCCP, CLIVAR, other national efforts
Argo (oceanography) network temperature, salinity, current Argo
Critical current and transport monitoring temperature, heat, freshwater, carbon transports, mass CLIVAR, IOCCP , OceanSITES
Regional and global synthesis programmes inferred currents, transports gridded fileds of all ECVs GODAE, CLIVAR, other national efforts

Charts

Template:Space-based meteorological observation

Accuracy of Measurements

Historical Data Available

A variety of historical data sets is available here: http://www.whoi.edu/page.do?pid=7140

This site includes links to the ARGO Float Data, The Data Library and Archives (DLA), the Falmouth Monthly Climate Reports, Martha's Vineyard Coastal Observatory, the Multibeam Archive, the Seafloor Data and Observation Visualization Environment (SeaDOVE): A Web-served GIS Database of Multi-scalar Seafloor Data, Seafloor Sediments Data Collection, the Upper Ocean Mooring Data Archive, the U.S. GLOBEC Data System, U.S. JGOFS Data System, and the WHOI Ship Data-Grabber System.


There are a variety of data sets in a data library listed at Columbia University:

http://iridl.ldeo.columbia.edu/SOURCES/

This library includes some of the following:

LEVITUS94 is the World Ocean Atlas as of 1994, an atlas of objectively analyzed fields of major ocean parameters at the annual, seasonal, and monthly time scales. It is superceeded by WOA98.

NOAA NODC WOA98 is the World Ocean Atlas as of 1998, an atlas of objectively analyzed fields of major ocean parameters at monthly, seasonal, and annual time scales. Superceeded by WOA01.

NOAA NODC WOA01 is the World Ocean Atlas 2001, an atlas of objectively analyzed fields of major ocean parameters at monthly, seasonal, and annual time scales. Replaced by WOA05.

NOAA NODC WOA05 is the World Ocean Atlas 2005, an atlas of objectively analyzed fields of major ocean parameters at monthly, seasonal, and annual time scales.

Future Developments

Areas requiring research and development (http://ioc3.unesco.org/oopc/obs/challenges.php):

  • Satellite observations with higher resolution and accuracy and more spectral bands from geostationary satellites
  • improved capability for ocean color observations in coastal and turbid waters
  • improved interpretation of sea-ice data from satellites
  • satellite measurement of salinity
  • Observing system evaluation and design, including improvements in air-sea flux parameterizations.
  • Improvements in ocean platforms, including increased capabilities for Argo floats
  • improved glider technology and mooring technology.
  • New development in ocean sensors and systems, including improved bio-fouling protection, autonomous water sampling systems, optical and acoustic systems, airborne variable sensors, and two-way, low-cost, low-power telecommunications.
  • New and improved capability to measure biogeochemical variables, nutrients, and dissolved oxygen and carbon dioxide, as well as to identify organisms.
  • Improved instruments, including near-surface current meters, in-water radiometers, sensors for air-sea interface variables and turbulent fluxes, and VOS sensor systems.


The future of oceanic observation systems:
Guided unmanned underwater vehicles (http://rucool.marine.rutgers.edu/atlantic/)

Organizations

GOOS (The Global Ocean Observing System) http://www.ioc-goos.org
GCOS (Global CLimate Observing System) http://www.wmo.int
IOOS (Integrated Ocean Observing System) http://www.ocean.us/
Argo () http://www.argo.net/ , http://www.argo.ucsd.edu/
GODAE (Global Ocean Data Experiment) http://www.godae.org/Observing-the-ocean.html
OOPC (Ocean Observation Panel for Climate) http://ioc3.unesco.org/oopc/
OOI (Ocean Observatories Initiative) http://www.oceanleadership.org/ocean_observing

References

http://ioc3.unesco.org/oopc/
http://www.ioc-goos.org
http://www.wmo.int
http://www.ocean.us/
http://www.oceanleadership.org/ocean_observing
http://www.argo.ucsd.edu/
http://www.godae.org/Observing-the-ocean.html
http://rucool.marine.rutgers.edu/atlantic/
http://www.whoi.edu/page.do?pid=7140

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