GOALS (Global Ocean-Atmosphere-Land System) for Predicting Seasonal-to-Interannual Climate A Program of Observation, Modeling, and Analysis (1994) / Chapter Skim
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4 ELEMENTS AND GROWTH OF THE PROGRAM
4 ELEMENTS AND GROWTH OF THE PROGRAM
Pages 37-54
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From page 37... ...
Modeling, Observations, · Empirical studies, and Process studies. Modeling that involves development and application of improved coupled ocean-atmosphere models for data assimilation and prediction is the unifying theme of the proposed GOALS program.
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From page 38... ...
MODELING ~ _ The overall strategy for the GOALS modeling component is to work within the framework of the existing WCRP programs on climate modeling and to build on the success of the TOGA program.
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From page 39... ...
Evaluation of the modeled annual cycle thus requires a good annual climatology of important atmospheric, land, and oceanic quantities. This climatology must include global SST, land wetness, and surface wind stress as primary quantities; as well as global boundary-layer depths in the atmosphere and ocean; sea-level pressure; upper-level horizontal fluxes of heat, momentum, and moisture in the atmosphere; and fluxes of heat and fresh water in the ocean.
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From page 40... ...
Clouds influence the surface radiation budget and enhance sensible heat flux, evaporation, and the surface wind stress in the vicinity of deep convection (Iohnson and Nicholls, 1983~. Clearly the development and evaluation of atmosphere and ocean models for use in coupled models will require long, accurate records of global SST and wind stress.
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From page 41... ...
, at least away from coastal boundary current regions. Since cloud and humidity variations in the atmosphere affect the heat fluxes into the ocean, the problem of annual and longer-term SST variability in the ocean is fundamentally coupled to atmospheric variability.
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From page 42... ...
An accurate treatment of those atmosphere-land interactions provides potential for prediction of seasonal mean surface temperature and possibly rainfall over the continental United States. The development of realistic models of coupled ocean-landatmosphere systems for prediction of short-term climate variations will require comprehensive land-surface process models that predict soil moisture, land-surface albedo, snow pack, and surface roughness, rather than prescribe them.
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From page 43... ...
program will be crucial to making the long-term ocean observations needed by GOALS and will be essential for providing observations to operational government agencies. The TOGA TAO array, which measures surface winds and upper-ocean thermal structure in real time in the equatorial zone, will not be fully established until the very end of TOGA in 1994.
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From page 44... ...
Autonomous ocean profilers of temperature, salinity, and current offer potential for extended time series in remote regions at a considerably lower cost than present systems. The penetration of visible irradiance to depths below the upper layer of the ocean has a potentially large influence on the evolution of SST.
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From page 45... ...
radiosonde network across the global tropics is of particular concern, considering the emphasis in GOALS on predictions of regional atmospheric variations. Boundary-layer processes in particular must be understood and accurately modeled to achieve GOALS objectives pertaining to climate fluctuations of moisture convergence and precipitation.
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From page 46... ...
will provide unprecedented coverage of atmosphere, ocean, cryosphere, and land variability. For example, there will be radar scatterometer measurements to derive ocean-surface wind velocity; radar altimeter observations of sea-surface topography; radar measurements of tropical rainfall; passive microwave observations of sea-surface wind speed, sea ice, snow cover, and water vapor; and high-resolution spectrometer/radiometer estimates of SST, albedo, cloud fraction, surface irradiance, vegetation, and ocean color (see Table 4-1~.
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From page 47... ...
The ultimate suitability of the remote-sensing data would depend critically on rigorous analyses, reanalyses, and continuous verification with corresponding in situ data. Continuity and calibration of satellite measurements throughout the GOALS program would be very important and should be achieved by planning for brief intervals of overlap between aging and replacement spacecraft and by planning for a well-maintained, in situ observational network.
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From page 48... ...
At the same time, GOALS should also be ready to exploit new technological developments, which might conceivably offer more efficient operational services in the long term. EMPIRICAL STUDIES Empirical diagnostic studies of observational data would be carried out in conjunction with the other elements in the GOALS program.
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From page 49... ...
Reanalysis projects carried out at the National Center for Atmospheric Research, NMC, and other operational numerical weather prediction centers promise to provide greatly improved, global, "ridded data sets for empirical studies of short-term climate variability (Kaluay and lenne, 1991~. These reanalyzed data sets will extend further back into the past than currently available data sets of this type do, and they will be much more reliable, particularly in the tropics.
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From page 50... ...
Central to this effort would be the development of techniques for assimilating heterogeneous and sparse data into coupled models of the atmosphere, upper ocean, and land. In addition to examinations of the exchanges of energy, momentum, and water between the various components of the climate system, special emphasis would be placed on the determination of upper-ocean circulation and density structure; rates of change of the internal atmospheric structure due to water phase change and radiative heating; the spatial distribution of soil moisture, snow and ice; and measures of the distribution and properties of vegetation.
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From page 51... ...
. Process studies in the tropics could examine: oceanic heat balance in regions where the models have difficulty simulating SST; maintenance of the oceanic mixed layer in the presence of equatorial upwelling; the reflection of Rossby waves off the western boundary and related flow through the straits surrounding Indonesia; parameterization of the strong backing of the wind with height in the planetary boundary layer, which is not well-simulated in current numerical weather-prediction models; the role of the stratus cloud decks in the oceanic heat balance; the role of the western boundary currents in the oceanic heat balance and the transport of heat to higher latitudes; and atmosphere-ocean interaction in association with the 40-to-60day waves.
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From page 52... ...
Before process studies for GOALS got under way, it would be important to hold a series of implementation meetings during which the shape of process research and its interaction with the rest of the GOALS program could be better defined. CONSORTIA AND PRINCIPAL INVESTIGATOR GROUPS The four elements of GOALS modeling, observations, empirical studies, and process studies are highly interrelated, and the structure of the program must reflect those interrelationships (see Figure 4-1~.
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From page 53... ...
. Examples of hypothetical consortium themes are given in the text.
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From page 54... ...
Phenomena of interest might encompass boundary-layer processes in the equatorial-cold-tongue/ITCZ complexes, stratiform cloud decks, and the American monsoon. Still another possible consortium theme might be the local oceanic heat balances in contrasting regions of the tropical and extratropical oceans, with emphasis on understanding and modeling the SST variations.
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