These five objectives are modified slightly from GCIP's previous objectives (GCIP, 1993). The panel based this review on the modified objectives.


Substantial progress has been made toward GCIP's objective of characterizing the variability of water and energy cycling in the Mississippi basin. Further progress will require increased care in the estimation of such critical variables as precipitation and surface radiative fluxes. Improvements in the use of available measurements could markedly enhance the value of GCIP. Rigorous investigations of local and remote forcing of hydroclimatic anomalies are needed to satisfy the objective of explaining the observed variations of the water and energy cycles in the Mississippi River basin.

Some of the most advanced regional-scale models in the world are being developed by GCIP. Parameterizations in these models, including clouds, precipitation, and radiation require special attention, however. Large-scale hydrologic modules also have to be included in these models. Systematic comparisons, such as those being carried out by the Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS) over parts of the Mississippi basin are important for understanding model biases. High-resolution modeling studies—for example, of how the land surface affects the Great Plains low-level jet—are also important because many important features of low-level jets are not easily observed with the current sparse observational network.

GCIP is developing a comprehensive set of regional analysis archives from three regional data assimilation systems (Eta, Mesoscale Analysis and Prediction System, Regional Finite Element). These regional archives are likely to be highly model dependent, however, and must be compared with each other as well as with global analyses and field observations. Surface products will be one of the most innovative and potentially most problematic regional analysis outputs. These surface products have to be compared to outputs from hydrologic models, especially Land Data Assimilation Systems (LDASs), which are just beginning and require special attention. Finally, given all the scientific developments that will occur in the development of analysis methods for these surface variables as well as atmospheric variables, including longwave radiation and precipitation observations, it is important that GCIP begin to plan for an eventual reanalysis of GCIP projects.

GCIP's data collection and management effort has done a commendable job of beginning the initial data acquisition and archiving. It now has to add a scientific users group to identify data sets of highest priority to GCIP researchers. The scientific users group should recommend methods for the efficient archiving and reprocessing of high-volume Next-Generation Weather Radar (NEXRAD) data for climatological precipitation estimates. Methods to archive and access

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