Global Energy and Water Cycle Experiment (GEWEX) Continental-Scale International Project A Review of Progress and Opportunities (1998) / Chapter Skim
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3 DATA ASSIMILATION
3 DATA ASSIMILATION
Pages 43-52
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From page 43... ...
did not include the range of diabetic and hydrological processes that are now taken into account. It was thought that NWP models only had to carry dynamical atmospheric variables and that many physical processes, especially land surface processes, mattered merely for climate simulations.
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From page 44... ...
This analysis effort will further help to combine the disparate scales of atmospheric weather and climate with surface hydrologic scales. GCIP ACCOMPLISHMENTS Regional Model Analysis Archives A number of model analyses, including the NCEP and the ECMWF global data assimilation systems, have been available since the late 1970s.
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From page 45... ...
A continuously cycled data assimilation system has been developed for the Eta model and is undergoing final testing. Note: FCST= forecast; 0I = optimal interpolation.
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From page 46... ...
will provide hourly time records of various model outputs at some 300 "station" sites (Figure 3.2~. These products include time series of vertical latent heating and radiative heating profiles, soil moisture, soil temperature, precipitation, runoff, evaporation, snowmelt, and more.
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From page 47... ...
An LDAS is the land surface-hydrological component of the regional models that could be forced by observed or model fields and could cycle continuously on itself. Gridded precipitation fields provided by the precipitation analysis discussed below and hourly half-degree surface radiation fluxes inferred by the National Environmental Satellite Data and Information Service (NESDIS)
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From page 48... ...
An independent LDAS could thus provide estimates of soil moisture, surface evaporation, surface sensible heat flux, and runoff that should prove to be more reliable than those generated by the operational assimilation schemes for the same surface variables. The LDAS could also be used to explore land surface climate scenarios available from GCMs.
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From page 49... ...
Archive and Develop GCIP Analyses and Forecasts for Comparison with GCM Simulations, Global Analyses, and Field Observations Regional analysis systems being developed for limited-area NWP have great potential to assimilate data from high-resolution weather observing systems coming on-line in the near future over the United States. However, we need to know whether significant improvements result from current regional models or whether
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From page 50... ...
It would be useful to run regional models for longer periods, like GCMs, to determine the characteristic time scales of the processes, especially processes at the land surface. In fact, one of the primary goals of GCIP is to show that improved modeling of the land surfaceatmosphere interface in regional coupled models will improve predictions of weather and climate on a broad range of time scales from the diurnal to interannual.
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From page 51... ...
The impact of using such coarse global initializations, especially for the land surface, is unknown but potentially important because of the long time scales inherent in land surface processes. It is essential that regional analysis models have their own land surface initialization, independently from a global model analysis, to permit the assimilation of high-resolution GCIP observations, rather than reinitializing from global analyses.
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From page 52... ...
Operational analysis systems are constantly being modified and improvements being implemented. For example, the optimal interpolation schemes used in EDAS and MAPS will be replaced next year with a three-dimensional variational analysis method, which will allow, in particular, the direct incorporation of satellite water vapor radiance data (McNally and Vesperini, 1996)
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