Sunday, August 18, 2013

Global Ocean Observing System for Climate

Global Ocean Observing System for Climate The global ocean observing system for climate, which contributes to the global in situ component of the U.S. Integrated Ocean Observing System (IOOS), has now achieved about 61% of its initial design goal. While this observing system, implemented cooperatively by over seventy countries worldwide, serves multiple applications, it is designed primarily to address climate requirements defined by the international Global Climate Observing System (GCOS). The U.S. contribution to the system, described here, is implemented as an interdependent set of observational subsystems that constitute about half of the over 8,000 observing platforms deployed by the world community. While designed to provide information that is critical to NOAA’s climate and weather forecast missions, global ocean observations also support: coastal ocean applications marine hazard warning systems (e.g., tsunami warnings) transportation marine environment and ecosystem monitoring naval and other applications Global ocean observation assets Primary Observational Objectives of the Initial Global Ocean Observing System for Climate This system strives to deliver continuous instrumental records and global analyses of the following phenomena, which serve as scientific drivers of the observing system: Sea Surface Temperature and Surface Currents, to identify significant patterns of climate variability Ocean Heat Content and Transport, to better understand the extent to which the ocean sequesters heat, to identify where heat enters the ocean and where it emerges to interact with the atmosphere, and to identify changes in thermohaline circulation and monitor for indications of possible abrupt climate change. Air-Sea Exchanges of Heat, Momentum, and Freshwater, to identify changes in forcing functions driving ocean and atmospheric conditions, and to elucidate oceanic influences on the global water cycle. Sea Level, to identify changes resulting from trends and variability in climate. Ocean Carbon Uptake and Content, to better understand the extent to which the ocean sequesters CO2 and how cycling among ocean-land-atmosphere carbon reservoirs varies on seasonal-to-decadal time scales. Sea Ice Thickness and Extent, to elucidate climate variability and rapidly changing climate at high latitudes. (top) The Observational Subsystems on the in-situ Observing System Tide Gauges Tide Gauges Tide gauges are necessary for accurately measuring long-term trends in sea level change and for calibration and validation of the measurements from satellite altimeters, which are assimilated into global climate models for predicting climate variability and change. Surface Drifting Buoys Surface Drifting Buoys Global sea surface temperature analyses are derived from satellite retrievals, but the satellite measurements must be continuously calibrated using surface in situ measurements. The design for the global surface drifting buoy array (GCOS- 92) calls for 1,250 buoys to be maintained globally, spaced approximately 500 km apart in order to adequately tune satellite measurements. Tropical Moored Buoy Network Tropical Moored Buoy Network Most of the heat from the sun enters the ocean in the tropical/sub-tropical belt. Past understanding of the role of the tropics in forcing mid-latitude weather and climate has been garnered through the observations of the tropical moored buoy array in the Pacific Ocean, TAO/TRITON (Tropical Atmosphere Ocean/Triangle Trans-Ocean Buoy Network), which now comprises 67 moorings. A similar array of 17 surface moorings in the Atlantic basin, PIRATA (Prediction and Research Moored Array in the Tropical Atlantic) is further improving forecasting capabilities and is elucidating causes of longer-term changes in the ocean. The Indian Ocean array, RAMA (Research Moored Array for African- Asian-Australian Monsoon Analysis and Prediction), whose system design calls for 46 moorings, will complete global coverage of the Earth’s tropical oceans; 24 RAMA moorings have thus far been deployed. Ships of Opportunity Ships of Opportunity The global atmospheric and oceanic data from the Ships of Opportunity Program (SOOP) provide the foundation for understanding long-term changes in marine climate. The ships of opportunity are commercial carriers that transit scientifically important trans-oceanic routes; they volunteer to take ocean measurements using NOAA-supplied instruments, or host NOAA technicians during the transits to take the measurements. Argo Profiling Floats Argo Profiling Floats The heat content of the world’s oceans and the transfer of that heat to and from the atmosphere are variables central to the climate system and are directly responsible for influencing worldwide sea levels. The Argo array of profiling floats, which measures temperature and salinity down to 2000 meters below the ocean surface, provides broad-scale, basin-wide monitoring of the upper ocean heat content. The initial goal of three thousand homogeneously-distributed floats in active service throughout the world’s oceans, providing data without temporal bias, was achieved in October 2007. Ocean Reference Stations Ocean Reference Stations Sustained time-series of oceanic and atmospheric climate-relevant parameters and air-sea exchange of heat, freshwater and carbon dioxide are central to documenting and understanding trends and variability in the climate system. To this end, NOAA, together with international partners, is implementing a global network of ocean reference station moored buoys to provide the most accurate long-term climate data records of oceanic and near-surface atmospheric parameters in key ocean regimes. Ocean Carbon Networks Projections of global climate change are closely linked to assumptions about the interactions among the atmosphere, land, and ocean that control levels of atmospheric carbon dioxide. To this end, NOAA deploys carbon dioxide sampling on moored arrays and on Ships of Opportunity to analyze the seasonal variability of carbon exchange between the ocean and atmosphere. Additionally, in partnership with NSF, NOAA participates in systematic global ocean surveys that provide a comprehensive ocean carbon inventory once every ten years. Arctic Observing Network Arctic Observing Network Climate change is occurring rapidly in the Arctic, where the environment is particularly sensitive to climate variability and change. Therefore, a high priority program of sustained Arctic observations is being conducted utilizing ship-based cruises, permanent oceanographic moorings, gliders, ice beacons and buoys, supplemented by acquisition and analysis of historical and satellite-based data sets.

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