A Scientific Strategy for U.S. Participation in the GOALS (Global Ocean-Atmosphere-Land System) Component of the CLIVAR (Climate Variability and Predictability) Programme (1998) / Chapter Skim
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6 Long-Term Observations and Analyses
6 Long-Term Observations and Analyses
Pages 20-30
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From page 20... ...
To be useful, measurements of seasonal-to-interannual climate variability must be consistent, continuous in duration, and of sufficient accuracy and resolution that the climate signals can be distinguished from instrumental noise and from high-frequency geophysical signals unrelated to climate variability. Because the phenomena being studied are generally of a large scale and influenced by processes in distant regions and because the intent is to improve climate predictions in locations remote from phenomena such as ENSO, long-term global coverage is essential for many aspects of GOALS.
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From page 21... ...
In conjunction with a comprehensive satellite observational program, the expansion of long-term oceanic observations under GOALS from the tropical Pacific to the tropical Indian and Atlantic Oceans and to higher latitudes is believed to be necessary to achieve additional improvements in seasonal-to-interannual predictability. This, of course, imposes significantly increased demands on observing systems as well as data management and data exchange systems.
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From page 22... ...
Delayed-mode exchange is managed directly by IOC's International Oceanographic Data Exchange system, which includes national, regional, and world centers. Enhancements to observing systems, and the collection and exchange of data for climate purposes are being planned by the Global Climate Observing System (GCOS)
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From page 23... ...
Space-based satellite observations will play an important role in providing global data coverage for many of the key variables required by GOALS with a spatial and temporal resolution, which cannot be matched by in situ measurements alone. In addition to providing much of the information necessary for coupled climate models, satellite observations of seasonal-to-interannual variability of ocean, atmosphere, and land variables will be used to assess and refine the models.
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From page 24... ...
Since the lead time to achieve operational status of a satellite sensor is a decade or longer, a coordinated long-range plan must be developed at the earliest possible opportunity in order to provide benefit to the latter stages of the GOALS program and any future research programs that evolve from GOALS. KEY VARIABLES The challenging combination of accuracy, spatial and temporal coverage and resolution, and duration requirements of the observational component of GOALS is compounded by the range of variables needed to address the scientific objectives of the program.
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From page 25... ...
In situ observations such as the TOGA-TAO array, temperature and salinity profiles from buoyancy-adjustable subsurface floats, drifter observations, island-based tide gauge measurements, and Volunteer Observing Ships (VOS) observations of upper-ocean thermal structure and the overlying atmosphere also must be maintained to validate and calibrate satellite observations and to provide measurements of vertical structure and surface properties that cannot be obtained from satellite observations alone.
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From page 26... ...
Ocean State Variables External Variables · upper ocean temperature · upper ocean currents · sea level · upper ocean salinity · optical absorption · sea ice extent, concentration, and thickness Atmosphere · wind stress · net surface solar radiation · downwelling longwave radiation · surface air temperature · surface humidity · precipitation State Variables External Variables · wind structure · thermal structure · surface air temperature · sea level pressure · water vapor structure · columnar water vapor and liquid water content · precipitation · cloud cover and height Lancl · sea surface temperature · net radiation at top of the atmosphere · land surface variables (listed below) State Variables External Variables · soil moisture · snow cover and depth · vegetation type, biomass, and vigor · water runoff · ground temperature · precipitation · net surface longwave and shortwave radiation · surface wind · surface air temperature · surface humidity · evaporation · evapotranspiration
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From page 27... ...
A close cooperation between the scientists involved in GOALS's model development effort and those involved in the development of observational data assimilation models is highly recommended by the GOALS Panel, because numerical models are an integral part of state-ofthe-art assimilation procedures. MEASUREMENTS AND OBSERVING SYSTEMS The priority state and external observations identified in Table 6-1 will be
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From page 28... ...
There may also be a need for new, long-term observational technologies to be developed and incorporated into operational systems following the findings of future process studies directed at improving models and their prediction skills. It is important that all measurements within observational programs are accompanied by sufficient "meta-data" in order to document changes in location, observing practices, satellite retrieval algorithms, instrumentation, and other characteristics such as exposure, space/time coverage, and accuracy.
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From page 29... ...
New objective analysis and assimilation techniques should also be developed, especially for ocean and land surface variables to determine land surface processes, ocean-atmosphere interactive processes, and the hydrological cycle. Historical data analysis warrants special mention.
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From page 30... ...
These data fields have changed and will continue to change in time as forecast models and their corresponding data assimilation schemes are improved. For this reason efforts to reanalyze historical data should continue and should be applied to operational atmospheric analyses, all oceanographic data and analyses, and satellite-based products.
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