Engineering topics

Kallberg, P.

Publications and source records attributed to Kallberg, P..

3 records

NASA NTRS1992

Saharan dust in the Amazon Basin

It is shown that Saharan dust enters the Central Amazon Basin in bursts that accompany major wet season rain systems. Low-level horizontal convergence feeding these rain systems draws dust from plumes that have crossed the tropical Atlantic under the large-scale circulation fields. Mass exchange of air between the surface and four kilometers over the eastern Amazon basin is calculated utilizing rawinsonde data collected during storm events. Mean concentrations of dust observed by aircraft over the western tropical Atlantic are employed to calculate the amount of dust injected into the basin.

Swap, R.↗

NASA NTRS1985

Results from two recent ovserving system experiments

Two Observing System Experiments were carried out at (ECMWF). The European Center for Medium Range Weather Forecasting impact of various observing systems were examined for two periods during the EGGE year: November 8 to 9, 1979 (OSE-1) and February 22 to March 7, 1979 (OSE-II). Attempts were made to understand the effect of the observing systems on both the analyses and the quality of the short and medium range forecasts. The results confirm that the impact of a particular observing system (e.g., SATEM) is dependent on the level of synoptic activity present in the areas where this particular observing system is the main soruce of meteorological information. SATOB data are also shown to be improtant for the analyses of tropical regions, whereas SATEM data are of paramount importance for the extratropical analyses over ocean areas. Aircraft data, where available, are an invaluable addition to the global observational data base. These results therefore demonstrate clearly the value of each of the observing systems. The fact that, in particular circumstances, there may be some redundancy between the systems is a strength rather than a weakness of the composite global observing system.

Uppala, S.↗

NASA NTRS1985

The response of numerical weather prediction analysis systems to FGGE 2b data

An intercomparison of analyses of the main PGGE Level IIb data set is presented with three advanced analysis systems. The aims of the work are to estimate the extent and magnitude of the differences between the analyses, to identify the reasons for the differences, and finally to estimate the significance of the differences. Extratropical analyses only are considered. Objective evaluations of analysis quality, such as fit to observations, statistics of analysis differences, and mean fields are discussed. In addition, substantial emphasis is placed on subjective evaluation of a series of case studies that were selected to illustrate the importance of different aspects of the analysis procedures, such as quality control, data selection, resolution, dynamical balance, and the role of the assimilating forecast model. In some cases, the forecast models are used as selective amplifiers of analysis differences to assist in deciding which analysis was more nearly correct in the treatment of particular data.

Hollingsworth, A.↗