3/18/2023 0 Comments Preminder calendar app color bugThe development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. Tropical Cyclogenesis in a Tropical Wave Critical Layer: Easterly Wavesĭunkerton, T. National Oceanic and Atmospheric Administration, Department of Commerce — The AEWC dataset was created using a new algorithm developed by researchers at Georgia Tech and represents the first attempt to produce a standard easterly wave. A low pressure signal west of the Maritime Continent coupled with a warm zone across the South Indian Ocean coincides with AEW formation over the eastern Sahel.Īfrican Easterly Wave Climatology, Version 1 The air pressure and temperature regression features a N-S dipole indicating an anomalous northward ITCZ. The rainfall regression reflects a westward propagating AEW wave-train of higher values on 13N and lower values on 7N with a longitude spacing of 25°. The large scale environment is analyzed by regression of the AEW index onto daily fields of rainfall, surface air pressure and temperature in July-September season ( N = 1004). 2-8 day variance of satellite OLR reaches a maximum over the southern Arabian Peninsula, suggesting an upstream role for surface heating and the Somali Jet. Composite AEW temperature anomalies reveal a cool lower-warm upper layer heating profile. Composite convection is initiated over Ethiopia and subsequently intensifies following interaction with a zonal circulation located downstream. The anomalous 600 hPa wind circulation is comprized of a cyclonic-south anticyclonic-north rotor pair and accentuated easterly jet along 17N. Surface moisture is advected from central Africa towards the Red Sea during AEW formation. A daily African easterly wave (AEW) index is formulated from transient satellite rainfall and reanalysis vorticity, and the ten most intense cases are studied by composite analysis. This study explores the thermodynamic and kinematic features of easterly waves over northeast Africa in July-September season 2005-2015. Observed formation of easterly waves over northeast Africa
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