Accession Number : ADA262204


Title :   A Normal-Mode Analysis of Rapid Teleconnections in a Numerical Weather Prediction Model. Part 1, Global Aspects


Descriptive Note : Journal article


Corporate Author : NAVAL RESEARCH LAB MONTEREY CA


Personal Author(s) : Gelaro, Ronald


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a262204.pdf


Report Date : Dec 1992


Pagination or Media Count : 18


Abstract : Global-scale interactions between the tropics and extratropics are investigated using a version of the U.S. Navy's global operational numerical weather prediction model. The primary goals of this study are (1) to demonstrate the importance of atmospheric teleconnections for medium-range numerical weather prediction and (2) to analyze the evolution and dynamic structure of the response in a sophisticated numerical forecast model. The model normal modes are used as the principal diagnostic tool for analyzing the response to sea surface temperature anomalies in the tropical Pacific. By monitoring the energy growth in the dominant horizontal and vertical modes and comparing these with conventional difference-field diagnostics, it is shown that the character of the long-term response is well established within one to two weeks after the heating anomaly is introduced. The growth rates and structures of these modes provide insights into the dynamic processes that control the model response. In the tropics, enhanced convection is clearly the dominant forcing mechanism for these modes. In the extratropics, a more complicated picture arises in which both meridionally propagating energy and in situ instabilities in the ambient flow appear to be important mechanisms for producing the observed wave patterns. The results clearly demonstrate that tropical forcing can have a significant global impact on time scales relevant to medium-range numerical weather prediction.


Descriptors :   *WEATHER FORECASTING , *AIR WATER INTERACTIONS , MATHEMATICAL MODELS , ANOMALIES , REPRINTS , GLOBAL , WEATHER , TROPICAL REGIONS , SURFACE TEMPERATURE , GEOPOTENTIAL , BOUNDARY LAYER FLOW , CONVECTION(ATMOSPHERIC) , MIXED LAYER(MARINE) , PACIFIC OCEAN , HEATING , OCEAN SURFACE , PREDICTIONS , MONITORING , BOUNDARY LAYER


Subject Categories : Meteorology
      Physical and Dynamic Oceanography


Distribution Statement : APPROVED FOR PUBLIC RELEASE