The Impact of High-Resolution SALLJEX Data on Global NCEP Analyses

A data assimilation study was performed to assess the impact of observations from the South American Low-Level Jet Experiment (SALLJEX) on analyses in the region east of the Andes Mountains from western Brazil to central Argentina. The Climate Data Assimilation Systems (CDAS)-1 and -2 and the Global...

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Bibliographic Details
Published in:Journal of climate 2007-12, Vol.20 (23), p.5765-5783
Main Authors: Herdies, Dirceu L., Kousky, Vernon E., Ebisuzaki, Wesley
Format: Article
Language:English
Subjects:
Acoustic data
Analytical forecasting
Atmospheric moisture
Balloon observations
Balloons
Climatic data
Climatic zones
Climatology
Data analysis
Data assimilation
Data collection
Datasets
Earth, ocean, space
Exact sciences and technology
External geophysics
General circulation models
General circulation. Atmospheric waves
Hot air balloons
Humidity
Low-level jets
Meridional wind
Meteorology
Modeling
Mountains
Rawinsondes
Research methodology
Resolution
Studies
Vertical profiles
Wind
Winter
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Summary:A data assimilation study was performed to assess the impact of observations from the South American Low-Level Jet Experiment (SALLJEX) on analyses in the region east of the Andes Mountains from western Brazil to central Argentina. The Climate Data Assimilation Systems (CDAS)-1 and -2 and the Global Data Assimilation System (GDAS) were run with and without the additional SALLJEX rawinsondes and pilot balloon observations. The experiments for each data assimilation system revealed similar features, with a stronger low-level flow east of the Andes when SALLJEX data were included. GDAS had the strongest low-level jet (LLJ) when compared with observations. In the experiments that used additional rawinsonde and pilot balloon data, the LLJ was displaced westward in comparison to the analyses run without the SALLJEX data. The vertical structure of the meridional wind in the analyses was much closer to observed rawinsonde profiles in the experiments that included SALLJEX data than in the control experiments, and the results show that, although there are more pilot balloon observations than rawinsonde observations in the SALLJEX dataset, most of the improvements in the analyses can be obtained by only including rawinsonde observations. This was especially true for GDAS. The results of this study can serve as a benchmark for similar data impact studies using higher-resolution data assimilation systems.
ISSN:0894-8755
1520-0442
DOI:10.1175/2007JCLI1375.1