Sustaining Ocean Observations to Understand Future Changes in Earth's Climate (2017) / Chapter Skim
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1 Introduction
1 Introduction
Pages 15-26
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From page 15... ...
Sustained observations are also necessary to collect the critical data used to validate, calibrate, and refine climate models that provide insights about future events. Improved climate models will help to ensure the best possible answers to questions about future weather patterns (e.g., drought, heat waves, tropical storm strength and frequency, and agricultural growing seasons)
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From page 16... ...
Heat and CO2 are absorbed at the ocean's surface and, from there, transported throughout the ocean depths along complex pathways. Although exchange across the ocean's turbulent surface boundary layer can happen rapidly, in hours or days, and significant exchange of water between the boundary layer and the stratified main thermocline occurs over timescales of years to decades, deep water takes many decades to millennia to return to the surface, acting as long-term storage for heat and CO2 and thereby lessening the near-term impacts of climate change (Ciais et al., 2013)
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From page 17... ...
Through data assimilation, models can formally maximize the information that can be gained from available observations about present anomalies as a starting point for skillful projections out to decadal timescales. There are important emergent properties of the climate system that will require sustained and additional long-term observations to improve climate models, including the overall climate sensitivity (i.e., how much the global mean temperature changes for a given change in net absorption of solar radiation, known as radiative forcing)
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From page 18... ...
Salinity and temperature determine sea water density, which sets the vertical stratification of the ocean. Generally, temperature is the dominant driver of this stratification with warmest water at the surface and coldest in the deep ocean, but salinity can be an important determinant when fresh water inputs are large, such as in regions of high rainfall and river outflow, in polar regions where sea ice melts, and in cold waters where salinity dominates sea water density.
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From page 19... ...
Our current understanding of the sea-level budget has also benefited from some redundancy in the observing system components (sea surface height by satellite altimetry, thermosteric expansion from Argo floats, and ocean mass by satellite gravity) , which is fundamental for characterizing the drivers of sea-level change as well as their uncertainties.
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From page 20... ...
Satellites remotely collect complementary data on limited parameters such as sea surface height, sea surface temperature, surface wind stress, ocean mass, and, recently, sea surface salinity. Although satellites are only usable for some types of data collection, the integration of in situ and satellite observations through formal synthesis or data assimilation allows for detailed knowledge of specific aspects of the climate system, greater spatial coverage than is available for many in situ measurements alone, and intercalibration between observing platforms.
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From page 21... ...
component of the observing system as part of globally coordinated and multiplatform arrays of ocean observing elements. Engineering activities address platform design and improvement, including life extension and reliability, sensor selection and testing, power needs, and data telemetry and platform tracking.
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From page 22... ...
, and pressure, includes real-time preparation of temperature and salinity profiles as a function of pressure from the temperature and conductivity data with initial automated data quality screening, and also the delayed-mode preparation of fully quality-controlled temperature and salinity profiles drawing on additional sources, such as shipboard profiles, for float calibration. Data are provided through an Argo-specific data archive and forwarded to national ocean data archives.
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From page 23... ...
During the study, the committee will convene a workshop to gather expert opinions on the process for prioritizing long-term, ocean climate observations and discuss international approaches to selecting and sustaining ocean observations, as well as other top ics that are important for the design of sustainable, long-term ocean observing systems.
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From page 24... ...
The committee determined that sustained and improved measurements of heat, carbon, and fresh water system components will continue to provide and strengthen crucial information in understanding climate and significantly improve modeling capabilities, while also serving as the basis for findings that could be applied more broadly in the context of other important observations. The committee used global sea-level rise as an example of a climate-dependent property that requires global ocean observations and has great societal impact.
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From page 25... ...
For assessing shorter term climate variability and climate impacts, coastal regions play an important role, but with the exception of sea level these observations are less critical for understanding long-term climate trends. The budgets of heat, fresh water, and carbon that are foci of this report are dominated by the vast volume of the global open ocean.
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