Editorial Type:
Article
Article Type:
Research Article

Evidence of Tropical Forcing of the 6.5-Day Wave from Lightning Observations over Africa

Themis G. Chronis Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut

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Earle Williams Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts

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Emmanouil N. Anagnostou Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut

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Print Publication:
01 Oct 2007
DOI:
https://doi.org/10.1175/JAS4021.1
Page(s):
3717–3721
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Abstract

A study employing observations and climatic reanalysis data is concerned with links between convection and the well-documented 6.5-day stratospheric global wave. Observations from a long-range lightning detection network, known as ZEUS, reveal an in-phase behavior between the maximization of daily lightning activity over Africa and the intensification of the wave. To extend the observations on a climatological basis, the authors make use of the outgoing longwave radiation (OLR) as proxy for convection and the surface level pressure (SLP) as an indicator of atmospheric column forcing. Cross-spectral analysis shows significant peaks in coherency between OLR and SLP, apparent only over equatorial Africa and South America (Amazon basin), while strong coherency in this frequency band is absent over the Maritime Continent.

Corresponding author address: Prof. Emmanouil N. Anagnostou, Civil and Environmental Engineering, University of Connecticut, U-37, Storrs, CT 06269. Email: manos@engr.uconn.edu

Abstract

A study employing observations and climatic reanalysis data is concerned with links between convection and the well-documented 6.5-day stratospheric global wave. Observations from a long-range lightning detection network, known as ZEUS, reveal an in-phase behavior between the maximization of daily lightning activity over Africa and the intensification of the wave. To extend the observations on a climatological basis, the authors make use of the outgoing longwave radiation (OLR) as proxy for convection and the surface level pressure (SLP) as an indicator of atmospheric column forcing. Cross-spectral analysis shows significant peaks in coherency between OLR and SLP, apparent only over equatorial Africa and South America (Amazon basin), while strong coherency in this frequency band is absent over the Maritime Continent.

Corresponding author address: Prof. Emmanouil N. Anagnostou, Civil and Environmental Engineering, University of Connecticut, U-37, Storrs, CT 06269. Email: manos@engr.uconn.edu

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