Identification

Title

African easterly wave evolution and tropical cyclogenesis in a pre‐Helene (2006) hindcast using the Model for Prediction Across Scales‐Atmosphere (MPAS‐A)

Abstract

Tropical cyclogenesis (TCG) remains an elusive phenomenon partly due to the limited understanding of complex water vapor-convection-wave interactions. The Model for Prediction Across Scales-Atmosphere (MPAS-A) was used to study the TCG of the African easterly wave (AEW) that became Hurricane Helene (2006). The two main objectives were: (a) evaluate the capability of MPAS-A to simulate TCG from an AEW by comparing MPAS-A—initialized with the Integrated Forecasting System (IFS) and the Global Forecast System (GFS)—with observations together with reanalysis and, (b) use the hindcast to investigate the role of moisture in the mechanisms that led to Helene's TCG. The more intense GFS-initialized pre-Helene was slower propagating and was associated with a wetter and stronger monsoon when compared to both the IFS-initialized simulation and observed. TCG occurred when net moisture flux within the boundary layer toward the center of the wave increased persistently. The reanalysis pre-genesis top-heavy vertical mass flux profile transitioned to a bottom-heavy profile during TCG, whereas the simulations had top-heavy and bottom-heavy profiles simultaneously, resulting from a more-intense and fast-occurring TCG than in the reanalysis. Moisture-vortex instability helped explain the vertical mass fluxes and the co-location of convection, moisture and wave vortex demonstrating to be an applicable theoretical model for TCG. Moisture mode was tested as a diagnostic tool for AEW evolution and TCG. The case exhibited some moisture mode properties, and it is proposed that AEWs become more moisture-mode like once reaching western Africa and during TCG. An AEW TCG pathway is proposed.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7x352c6

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

2023-02-01T00:00:00Z

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