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Modulation of precipitation over West Africa by equatorial waves

Schlüter, Andreas; Linden, Roderick van der; Vogel, Peter; Fink, Andreas H.; Knippertz, Peter

Abstract:
Equatorial waves can couple with deep convection and thus modulate rainfall on the synoptic timescale throughout the tropics. Until now, however, no comparative study of the influence of all the different wave types on precipitation has been performed specifically for West Africa. To fill this gap, the following wave types were analyzed for the pre-/post- and full monsoon season (April to October): (1) the Madden-Julian Oscillation (MJO), (2) Kelvin waves, (3) equatorial Rossby waves, (4) eastward-propagating inertia gravity waves, (5) mixed Rossby-gravity waves and (6) tropical disturbances/African Easterly Waves. The different wave types were filtered in the wavenumber-frequency spectrum of outgoing longwave radiation. Eight different wave phases were defined from a phase diagram that can be calculated from the time-derivative of the filtered wave signal. Subsequently, composites of dynamical and thermodynamical fields for each wave phase of the different wave types were plotted using the ERA Interim reanalysis from the European Centre for Medium-Range Weather Forecasts. This way the propagation of the wave can be depicted. All af ... mehr


Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung - Forschungsbereich Troposphäre (IMK-TRO)
Publikationstyp Poster
Jahr 2017
Sprache Englisch
Identifikator KITopen ID: 1000077202
Erschienen in European Geosciences Union General Assembly 2017, Vienna, Austria, 23rd - 28th April 2017
Bemerkung zur Veröffentlichung Geophysical Research Abstracts, 19(2017) EGU2017-15216
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