Identification

Title

Thermodynamic processes governing the evolution of developing and Strong Nondeveloping African Easterly Waves

Abstract

It is well known that African easterly waves (AEWs) can develop into tropical cyclones. However, the processes leading to development are not well understood. To this end, we examine a 38-yr climatology of AEW tracks sorted into developing AEWs (DAEWs) and strong nondeveloping AEWs (SNDAEWs). Wave-centered composites for tracks in the eastern Atlantic (40°–10°W, 5°S–30°N) and West African monsoon regions (10°W–20°E, 5°S–30°N) reveal that DAEWs occur over a more humid background state in both regions. The more humid environment causes DAEWs to exhibit heavier precipitation and wave amplification via vortex stretching. Examination of the column moist static energy (MSE) budget reveals that DAEWs exhibit stronger radiative heating and more moistening via horizontal MSE advection than SNDAEWs. The stronger horizontal MSE advection in DAEWs is due to a northeast shift in the maximum MSE relative to the wave axis, causing the northerlies in the wave to advect a higher MSE into the maximum precipitation. In contrast, MSE is maximum near the center of NDAEWs, making the moistening of the rainfall by horizontal MSE advection weaker. DAEWs exhibit stronger radiative heating per unit of rainfall relative to NDAEWs, suggesting that cloud-radiative feedbacks are stronger in these systems. The sum of horizontal MSE advection and radiative heating explains the buildup in MSE seen over the rainy region of the DAEWs that is not seen in SNDAEWs. These results underscore the importance of moisture, cloud–radiation interactions, and horizontal MSE advection in tropical cyclone (TC) development over these regions.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.net/ark:/85065/d74f1w57

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2025-06-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact